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Guidelines Part 5

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Guidelines Part 5 Contents

DEFINITIONS, DESIGNATION AS HAZARDOUS SUBSTANCES, AND GENERAL INFORMATION REQUIREMENT

G5.1.1 Biological agents

Guidelines Part 5 - Definitions, Designation as Hazardous Substances, and General Information Requirement

G5.1.1 Biological Agents

Issued February 1, 2008

Regulatory excerpt
Section 5.1.1 of the OHS Regulation ("Regulation") states:

For the purposes of section 5.2 and sections 6.33 to 6.40, the following biological agents are designated as hazardous substances:

(a) a liquid or solid material that is contaminated with a prion, virus, bacterium, fungus or other biological agent that has a classification given by the World Health Organization or Health Canada, as amended from time to time, as a Risk Group 2, 3 or 4 human pathogen that causes an adverse health effect;
(b) a biological toxin that causes an adverse health effect.

Purpose of guideline
This guideline provides information on Risk Groups 2, 3 and 4 human pathogens that cause adverse health effects.

Risk Groups
Risk Groups 2, 3, and 4 are a component of a universally agreed to classification system as adopted by the World Health Organization (WHO) and Health Canada, among other jurisdictions. This system is based on the biosafety containment classification system developed by the WHO, and the Public Health Agency of Canada (PHAC).

The following provides an overview of each Risk Group.

Risk Group 2: A pathogen that can cause human or animal disease but under normal circumstances is unlikely to be a serious hazard to healthy laboratory workers, the community, livestock, or the environment. Laboratory exposures rarely cause infection leading to serious disease; effective treatment and preventive measures are available and the risk of spread is limited. They are considered to represent a moderate risk to individuals and a limited risk to the community. Examples of Risk Group 2 pathogens include the Hepatitis B and Hepatitis C viruses, salmonella, and E. coli bacteria.
Risk Group 3: A pathogen that usually causes serious human or animal disease, or which can result in serious economic consequences but does not ordinarily spread by casual contact from one individual to another, or that can be treated by antimicrobial or antiparasitic agents. They are considered to represent a high risk to individuals but a low risk to the community. Examples of Risk Group 3 pathogens include the human immunodeficiency virus (HIV), the virus causing Creutzfeldt-Jacob disease, hantavirus, and tuberculosis.

Risk Group 4: A pathogen that usually produces very serious human or animal disease, often untreatable, and may be readily transmitted from one individual to another, or from animal to human or vice-versa directly or indirectly, or by casual contact. They are considered to represent a high risk to both the individual and the community. Examples of Risk Group 4 pathogens are the hemorrhagic fever viruses such as Ebola, Marlburg, and Lassa.

Guidelines Part 5 - Workplace Hazardous Materials Information System (WHMIS)

G5.3-1 WHMIS Application

Issued August 1, 1999; Editorial Revision January 2005

Section 5.3 of the OHS Regulation states:

(1) Sections 5.3 to 5.19 (the WHMIS Requirements) apply to employers and workers with respect to controlled products used, stored or handled at a workplace, except as provided in subsections (2) to (4).

(2) The provisions concerning a supplier label and MSDS do not apply if the controlled product is

(a) an explosive within the meaning of the Explosives Act (Canada),

(b) a cosmetic, device, drug or food within the meaning of the Food and Drugs Act (Canada),

(c) a control product within the meaning of the Pest Control Products Act (Canada),

(d) a prescribed substance within the meaning of the Atomic Energy Control Act (Canada) or any successor legislation, or

(e) a product, material or substance packaged as a consumer product and in quantities normally used by the consuming public.

(3) The provisions do not apply if the controlled product is

(a) wood or a product made of wood,

(b) tobacco or a product made of tobacco,

(c) a manufactured article, or

(d) being transported or handled pursuant to the requirements of the Transportation of Dangerous Goods Act, 1992 (Canada) or the Transport of Dangerous Goods Act.

(4) The provisions do not apply to a hazardous waste, except that the employer must ensure the safe storage and handling of a hazardous waste generated at the workplace through the combination of worker education and the information required by this Regulation.

Note: For products partially or completely exempted from WHMIS by subsections (2) to (4), the general information requirements of section 5.2 must be met. Also, information requirements are specified elsewhere for particular groups of substances, for example, hazardous wastes in sections 5.76 to 5.81; pesticides in Part 6 (Substance Specific Requirements), and explosives in Part 21 (Blasting Operations).

"Controlled product" is defined in section 2 of the federal Hazardous Products Act as "any product, material or substance specified by the regulations...to be included in any of the classes listed in Schedule II." Schedule II sets out the following classes:

The contents of these classes are set out in the Controlled Products Regulations made under the Hazardous Products Act.

G5.3-2 Fire extinguishers (adopted from WHMIS Bulletin #4)

Issued August 1, 1999

Any extinguisher pressurized to more than 2.71 atmospheres (40 psi) at 21.1°C (70°F) meets the criterion for inclusion in WHMIS Class A, Compressed Gases. Some retardants (or performance additives to prevent effects such as freezing or corrosion) may meet criteria for inclusion in WHMIS Class D, Poisonous and Infectious Materials. (In addition, older soda-acid extinguishers will fall into WHMIS Class E.) Refer to sections 34 and 43 of the Controlled Products Regulations.

Fire extinguishers do not qualify for exemption from WHMIS as manufactured articles, as per section 12(1) of the Hazardous Products Act, because under normal conditions of use they will expose workers to a compressed gas or other controlled products.

The following stipulations apply (except in the case described in the *NOTE below) to fire extinguishers intended for use in the workplace and that meet criteria for inclusion in WHMIS because of a compressed gas, toxic effect or other criteria.

Suppliers who sell extinguishers for use in the workplace must apply WHMIS supplier labels to the extinguishers and provide an MSDS (see definition for supplier label in section 5.1 of the OHS Regulation as well as section 5.8).
A firm which recharges a fire extinguisher for an employer must apply a WHMIS supplier label to the extinguisher and provide an MSDS, if these are not already applied and provided. (Note: where an employer recharges extinguishers "in house" a workplace label will suffice if a supplier label is not already on the extinguisher.)
A detachable pressurized cartridge used to pressurize a dry chemical extinguisher must be provided with a WHMIS label (in addition to the label on the extinguisher) unless the cartridge is immediately installed on the extinguisher after the cartridge is pressurized. Suppliers who pressurize such cartridges must provide a supplier label; employers who pressurize their own cartridges must provide, at minimum, a workplace label. Labels must be applied to individual cartridges unless an alternative acceptable arrangement is used. (An example of an acceptable alternative is to provide a WHMIS label on the container of individual cartridges as long as cartridges are immediately installed on the extinguisher after being removed from the container. Where a supplier and employer wish to adopt this alternative or any arrangement in which the employer undertakes to apply supplier labels to cartridges contained in an outer container, the employer must establish the arrangement in writing.)

A generic MSDS covering both the cartridge and the extinguisher will be considered acceptable for the purposes of providing an MSDS on the cartridge.

*NOTE:
Extinguishers which contain aliphatic halogenated hydrocarbons and are packaged in a size of container which is sold on a retail basis to the public may, in lieu of a WHMIS label and MSDS, bear a consumer label consistent with consumer labelling and packaging requirements under the Hazardous Products Act.

G5.3-3 Cylinders of breathing air (adopted from WHMIS Bulletin #5)

Issued August 1, 1999

What are the requirements to provide labels, MSDS and worker education and training on compressed gas cylinders of breathing air?

Compressed air cylinders used in self-contained breathing apparatus fall into WHMIS Class A, Compressed Gases.

Provincial requirements (for cylinders filled in-house)

Material Safety Data Sheets: MSDS's must be provided for synthetic mixtures of breathing gases. For cylinders of compressed respirable atmospheric air, an MSDS will not be required, as this air must meet the air quality required by the OHS Regulation.
Labels: Workplace labels specifying the product identity and reference to the MSDS are required on synthetic mixtures of breathing gases. Safe handling instructions must be provided through the worker education and training program. For cylinders of respirable atmospheric air which are identifiable to workers by size and shape, for which an MSDS is not required, and where worker instruction in the safe use of the SCBA is in place as required by part 8 of the OHS Regulation, further labelling or means of identification is not necessary.

Federal requirements (for pressurized cylinders sold or imported, or filled on contract)

Suppliers who provide cylinders with compressed synthetic mixtures for breathing purposes for use in a workplace must apply supplier labels and provide MSDS's.
Suppliers who provide cylinders with compressed atmospheric air for breathing purposes for use in the workplace will not be required to provide an MSDS and a reference to the MSDS on the supplier label on condition that the supplier label:
includes all other six elements (the product and supplier identifiers, Class A hazard symbol, specific risk phrases and precautionary statements, and first aid measures where appropriate),
is surrounded by the WHMIS border, and
includes a precautionary statement to the effect "Ensure cylinder is filled with air meeting the quality standards of the local regulatory agency."

NOTE:
If an outside contractor (who is not the original supplier of the cylinder) refills cylinders with atmospheric air, the contractor would be required only to provide his/her supplier identifier if the original supplier label was illegible. Otherwise, the contractor would be required to provide a supplier label as per the second bullet above.

G5.3-4 Exemptions (adopted from WHMIS Bulletin #9)

Issued August 1, 1999

Partially exempted products

Section 5.3(2) of the OHS Regulation exempts controlled products covered under subsections (a) to (e) only from the requirements for a supplier label and a material safety data sheet. All other aspects of the WHMIS program apply, including sections 5.6 and 5.7. In order that the employer can meet obligations for education and training of staff, he/she must search for hazard information and will normally approach the supplier first. While an MSDS is the obvious solution, the supplier may provide information in any format. If an MSDS is provided, it need not meet all the requirements that govern a WHMIS MSDS, but should contain sufficient information to allow safe use, handling and storage of the controlled product. Suppliers are encouraged to provide an MSDS meeting WHMIS standards.

Completely exempted products

Controlled products falling into the categories in section 5.3(3) of the OHS Regulation are exempt from all aspects of the federal and provincial WHMIS regulations. The requirement for information on these materials falls within the scope of section 5.2 of the OHS Regulation. Provision of MSDS by suppliers will assist employers in meeting their obligations under these sections.

Hazardous wastes

Under section 5.3(4) of the OHS Regulation an employer is responsible for providing sufficient information for safe handling and storage of a hazardous waste generated at that place of employment. Since the employer has first hand knowledge about the process generating the hazardous waste, it falls to the employer to identify the material and educate the employees. Information from MSDSs for waste components or precursors combined with the process knowledge will be the source of the information given to employees.

NOTE:

The information required for partially and completely exempted products and wastes will cover items such as hazards (toxicity, fire and explosion, reactivity), storage information, safe work procedures, protective equipment, spill, leakage and fire-fighting information, and first aid measures. No matter whether the controlled product is included fully in the WHMIS program or is partially or completely exempted, employees must know the hazard(s), how to protect themselves in normal work and in emergency situations, and where to find more information when it is needed.
For consumer products which are partially exempt from federal WHMIS requirements, WHMIS Core Material (1989) states "In such cases, the supplier is encouraged to make an MSDS available on request" (p. 2-59).
For pesticides, which are partially exempt, Agriculture Canada has stated in the Memorandum to Registrants #R-1-235 "It is possible that MSDS's may become mandatory for pesticides. Registrants are encouraged to supply, on a voluntary basis, MSDS's on their actives/products in a WHMIS format."

G5.3-5 Leaded surface coating materials

Revised April 9, 2009

Regulatory excerpt
Section 5.3(2)(e) of the Occupational Health and Safety Regulation ("OHS Regulation") states that:

(2) The provisions concerning a supplier label and MSDS do not apply if the controlled product is

...

(e) a product, material or substance packaged as a consumer product and in quantities normally used by the consuming public.

Purpose of guideline
The purpose of this guideline is to clarify the application of supplier label and Material Safety Data Sheet ("MSDS") requirements to leaded surface coating materials.

WHMIS requirements
Section 5.3(2)(e) of the OHS Regulation exempts "a product, material or substance packaged as a consumer product and in quantities normally used by the consuming public" from the supplier label and MSDS requirements set out in sections 5.3 to 5.19. This is based on section 12(f) of the federal Hazardous Products Act ("HPA"), which excludes a "product, material or substance included in Part II of Schedule I and packaged as a consumer product." from the provisions governing controlled products.

One type of product previously excluded under Part II of Schedule I of the HPA (Item 31) was liquid coatings containing more than 0.5% by weight of lead. Item 31 has been amended. Now, Schedule I excludes all "surface coating materials" regardless of lead content. A "surface coating material" is defined in the federal Surface Coating Materials Regulations ("SCMR") as "a paint or other similar material that dries to a solid film when a layer of it is applied to a surface. It does not include a material that becomes a part of the substrate."

The provisions of the OHS Regulation concerning supplier labels and MSDS do not apply to surface coating materials packaged as consumer products, regardless of whether they contain lead. On the other hand, surface coating materials that are used, stored or handled at a workplace and are not packaged as consumer products, continue to be subject to the supplier label and MSDS requirements in the OHS Regulation.

It should be noted that the SCMR prohibits the advertising, sale and importation of surface coating materials containing a lead concentration exceeding 600 mg/kg (0.06% w/w). Surface coating materials that are used for any of the applications listed in section 4(2) of the SCMR are exempt from this restriction, but specific labelling requirements apply if their lead content does exceed 0.06% w/w. These regulatory requirements are enforced by Health Canada.

G5.3-6 "For industrial use only" labels (adopted from WHMIS Bulletin #10)

Issued August 1, 1999

Do phrases such as "For Industrial Use Only" and "For Professional Use Only" where they appear on labels of containers of controlled products legally imply that the product is "intended for use in the workplace" and that the product is subject to WHMIS information requirements?

The phrases "For Industrial Use Only" and "For Professional Use Only" imply intent for product use in the workplace. Where the product is a controlled product WHMIS requirements apply.
The supplier has the alternative of removing such phrases from the label in order to qualify for any exemption permitted (for example as a consumer product).

G5.3-7 Warehousing of Controlled Products

Issued February 27, 2001

This guideline clarifies the application of the Occupational Health & Safety Regulation relative to federal requirements when a controlled product is "handled" in a warehouse. Section 5.3(3)(d) of the Occupational Health & Safety Regulation states, in part, that the provisions of the WHMIS requirements "do not apply if the controlled product is being transported or handled pursuant to the requirements of the Transportation of the Dangerous Goods Act, 1992 (Canada) or the Transport of Dangerous Goods Act."

The Transportation of Dangerous Goods Act defines handling as "loading, unloading, packing or unpacking dangerous goods in a means of containment or transport for the purpose of, in the course of, or following transportation and includes storing them in the course of transportation." Handling in this context does not include actual use of a controlled product. TDG requirements deal primarily with acute exposures and the use of symbol alerts and placards. Transportation workers are not expected to be exposed to hazards associated with the controlled product unless there is an emergency, short-term circumstance such as a transport vehicle accident and spill. Conversely, worker exposure to controlled products in a workplace can occur in a wider variety of circumstances and over a longer period of time. Hence, WHMIS requirements are more extensive than TDG and include the use of explicit labels and material safety data sheets.

Application of WHMIS or TDG depends on the flow of goods through commerce as outlined in the following flow chart (adapted from the WHMIS Core Material Manual). WHMIS requirements are meant to apply at points of sale or use rather than during shipment. Transportation generally means to and from workplaces.

Figure 5.3 Flow of goods through commerce - where WHMIS and TDG requirements apply

WHMIS, both federal (labels and MSDSs) and provincial (education and training, workplace labels), applies where controlled products are used, processed or repackaged in a warehouse. When warehoused, controlled products can be:

In "trans-shipment" (held in temporary storage between points of shipment)
Repackaged (assembled, packaged, labelled or relabelled)
Used

OHS Regulation sections 5.2(c) and 5.2(d) are non-WHMIS "general information requirements" that apply to a transshipment warehouse where in the case of an emergency or spill of a controlled product, an emergency response system must be established. This requires written emergency and spill cleanup procedures, and effective supervisor and worker training in these procedures.

A controlled product that is repackaged or used is subject to the WHMIS section of the OHS Regulation since workers may be exposed to the hazards of the controlled product.

The following table sets out the legislation and resources that apply to controlled products in a warehouse:

	Federal	Provincial -- Occupational Health and Safety Regulation	Other
Transshipment	TDG	Non-WHMIS sections [5.2(c) & 5.2(d)]	CANUTEC*
Repackaging	HPA/CPR**	WHMIS sections (5.3 - 5.19)
Used	HPA/CPR	WHMIS sections (5.3 - 5.19)

Notes to table:
* CANUTEC (Canadian Transport Emergency Centre), part of the TDG Directorate, Transport Canada, provides hazard information in case of transport-related emergencies situations. Phone: (613) 996-6666.
** HPA/CPR (Hazardous Products Act/Controlled Products Regulations)

G5.3-8 The application of WHMIS in agriculture

Issued January 1, 2005

This guideline provides information to farmers, ranchers and agriculture workers on the general framework of the Workplace Hazardous Materials Information System (WHMIS), the application of regulatory requirements to partially and completely exempted products, and the means of forwarding concerns to WorkSafeBC about products for which suppliers are not providing information meeting WHMIS requirements.

The Workplace Hazardous Materials Information System (WHMIS) was developed in 1988 as a major step in helping to ensure that employers and workers would be provided with information on the hazards and control measures for hazardous materials (termed "controlled products") in the workplace. The requirements were made applicable to agriculture in 1993.

Application to suppliers and workplaces

Broadly speaking, WHMIS applies on two levels.

Suppliers: The suppliers of controlled products are required, under federal legislation, to provide information to employers for controlled products used in the workplace. Typically, the information must be provided in two ways: container labels, and material safety data sheets (MSDS).
Workplace: Employers are required, under provincial legislation, to ensure controlled products received in the workplace have the necessary labels and MSDS, and to ensure that workers are educated and trained in the safe use of the products. Other obligations apply, for example, if a controlled product is transferred from the supplier container to another container in the workplace it is necessary to label or identify the workplace container. Sections 5.3 to 5.19 of the OHS Regulation cover the provincial WHMIS requirements.

Partially and completely exempt products

As shown in section 5.3 of the OHS Regulation, there are different degrees to which controlled products are covered by WHMIS.

Many industrial products are fully covered by WHMIS, meaning the supplier requirements for labels and MSDS apply, and the employer must ensure that workplace obligations under WHMIS are also met. Examples of such products in agriculture include compressed gas cylinders used in welding operations, fuel products on site, and some acids and caustics.

Some products are partially exempt. Examples include pesticides and drugs (including some sterilants and disinfectants). In these cases there isn't a federal requirement for WHMIS labels and MSDS, but typically the products must meet other federal labeling and information requirements specific to them. In the case of pesticides and some other partially exempt products, suppliers will often provide MSDS, and the buyer should obtain an MSDS wherever available. The employer must meet provincial WHMIS requirements for information, education and training of workers and other matters such as workplace labels, as covered in sections 5.3-5.19 of the OHS Regulation. See OHS Guideline G5.3-4 for more information on partially exempt products.

Also, note that section 6.75 of the OHS Regulation requires that employers make readily available to workers an MSDS or its written equivalent for pesticides used at the workplace. Obtaining an MSDS from the pesticide supplier will help ensure that the requirement is met. An MSDS compliant with WHMIS will include information on nine categories of:

Product information
Hazardous ingredients
Physical data
Fire and explosion hazard
Reactivity data
Toxicological properties
Preventive measures
First aid measures
Preparation information

If the MSDS does not fully meet WHMIS standards, but has sufficient information to ensure the health and safety of workers using, transporting or storing the product, the MSDS may be considered acceptable. See OHS Guideline G6.75 for a list of the information that would be considered equivalent.

Some products such as welding rods, which are manufactured articles, are completely exempt from both the federal and provincial WHMIS requirements. In such cases, where the article contains a hazardous material the employer is encouraged to obtain an MSDS if available. Section 5.2 of the OHS Regulation addresses general information requirements for any chemical or biological substance that could cause an adverse health effect, and would apply in this case. Section 5.2 covers general responsibilities to identify the hazards of the substance, educate the worker, and implement and follow safe work procedures. See OHS Guideline G5.3-4 for more information on completely exempt products.

What if a supplier is not providing adequate labels or MSDS where required by WHMIS?

The question has arisen of what can be done to ensure up-to-date MSDS and labels are received from suppliers where federal WHMIS requirements apply to controlled products sold to farmers and ranchers. A nationwide WHMIS administrative system involving all Canadian OHS jurisdictions is in place to help deal with this issue.

Where an agricultural workplace is unable to get the proper WHMIS information for a controlled product from the supplier or distributor, the farmer or rancher is encouraged to contact WorkSafeBC at the WorkSafe Call Centre (604) 276-3100 (long distance toll free at 1-888-621-7233), or the WorkSafeBC Regional Office nearest you. Many of WorkSafeBC occupational hygiene officers are designated to enforce federal WHMIS requirements on suppliers and distributors in this province. Where a distributor is providing product from elsewhere in Canada, WorkSafeBC will forward the concern to the responsible jurisdiction for their follow-up with the supplier.

For more information on the application of WHMIS, see the WorkSafeBC publication, WHMIS at Work, which is available on the WorkSafeBC web site at www.WorkSafebc.com

G5.5 WHMIS program (adopted from WHMIS Bulletin #1)

Issued August 1, 1999

Section 5.5 of the OHS Regulation states:

If controlled products are used in the workplace the employer, in consultation with the occupational health and safety committee, if any, or health and safety representative, if any, must establish and maintain an effective WHMIS program, as part of the overall workplace health and safety program, which

(a) addresses applicable WHMIS Requirements including education and training, and

(b) is reviewed at least annually, or more frequently if required by a change in work conditions or available hazard information.

What is the interpretation of the phrase, "in consultation with the joint occupational health and safety committee" where it applies to the development and implementation of the program of WHMIS instruction?

Consultation means meeting for the purpose of seeking information or advice. An employer has consulted with the joint occupational health and safety committee regarding the program of WHMIS instruction if two conditions are met:

Prior to the finalization of the program of instruction the Committee has the opportunity to review and provide information or advice on the entire program including its content, structure and means of implementation. Content means education in "how WHMIS works", education in the hazards of controlled products and training in work procedures as itemized in section 5(7)(a) to (d). Means of implementation include choice of instructors and the use of any in-course evaluation.
On completion of the implementation of the program of instruction, the employer asks for information and advice from the Committee on the effectiveness of the program.

Where a number of committees has been established in a large workplace, an acceptable arrangement is for the lead (master/central) committee to review the employer's general plan for WHMIS instruction covering the entire workplace, and for satellite (local) committees to review the program of instruction in the areas of their respective responsibilities.

G5.6 Worker education (adopted from WHMIS Bulletin #8)

Issued August 1, 1999

Section 5.6 of the OHS Regulation provides for worker education concerning the WHMIS system. Section 5.7 requires the employer to instruct the worker in the work procedures for implementing WHMIS.

Following are four questions to ask workers to check for adequacy of education and training on controlled products to which workers may be exposed.

What are the hazards of the controlled product?

The answer must reflect the possible adverse effects of the products in question. This demonstrates an understanding of generic hazard information (education).

How are you protected from those hazards?

The answer must demonstrate a worker understanding of proper procedures to follow for any involvement of the worker in the use, storage, handling or disposal of the product and the proper use of personal protective equipment. The answer must reflect adequate workplace control of the hazard by engineering or administrative means.

What do you do in case of an emergency?

The answer must show the worker's understanding of procedures to follow in the event of spill, release, fire or poisoning involving the controlled product, and include the use of personal protective equipment where applicable.

Where can you get further hazard information?

This question focuses on the worker's ability to access the significant information provided on labels and data sheets. Workers must know about the supplier label, workplace label and other means of identification applicable to the use of the product and must know the means of being able to obtain information significant to his/her health and safety from the MSDS.

G5.8-1 Supplier label (adopted from WHMIS Bulletin #2)

Issued August 1, 1999

Sections 13(b) and 14(b) of the Hazardous Products Act(HPA) require suppliers to fix labels to controlled products.

Section 5.8(1) of the OHS Regulation states:

An employer must ensure that the container of a controlled product or a controlled product received at a workplace is labelled with a supplier label." Subsection (3) provides that "If a label applied to a controlled product or a container of a controlled product becomes illegible or is accidentally removed from the controlled product or the container, the employer must replace the label with either a supplier label or a workplace label.

G5.8-2 Labelling on leased or rented chemical application units (adopted from WHMIS Bulletin #2)

Issued August 1, 1999

What are the suppliers' responsibilities to provide labelling on an application unit such as a solvent spray parts washer in the circumstance where the unit is leased or rented to an employer and the supplier, as a condition of the agreement, periodically empties the holding tank on the unit and recharges it with a controlled product?

The unit does not qualify for the manufactured article exemption because workers are likely to be exposed to controlled product during normal conditions of use. Under the Hazardous Products Act, the term "sale" is considered to include rental or leasing. The supplier is obligated to provide and apply a supplier label on the unit. If the label becomes illegible the employer must provide and apply a workplace label or a supplier label as required by section 5.8(3) of the OHS Regulation. He or she should contact the supplier to see if the supplier can provide a new supplier label at the earliest opportunity, for example, when the unit is recharged.

G5.8-3 Multi-container shipments of laboratory samples

Issued August 1, 1999

Sections 14 and 16 of the Controlled Products Regulations contain provisions governing the use of several containers and laboratory samples.

For multi-container shipments of laboratory samples to an outside laboratory the supplier and employer will be considered to meet the intent of legislation with the following procedures.

The supplier ensures the outer container bears a WHMIS supplier label. The label must provide, in addition to other required information items, the identity of all hazardous ingredients known or suspected to be contained in the enclosed samples.
The supplier ensures the container is provided with a lab analysis requisition form or equivalent which describes which inner containers contain (or are suspected to contain) controlled products. (Note: if a requisition form does not call for analysis of the controlled product in question, specific information on the ingredient must still be provided. Example: a blood sample submitted for a white cell count from a patient infected with hepatitis must be accompanied by information on the microorganism.)
The supplier and employer establish an agreement in writing which covers the above two points and provides the employer's assurance that:
- neither the samples nor any supplier information will be removed from the outer container prior to physical receipt by the lab department within the organization which receives shipment, and
- an information system is established in the lab, which ensures that each lab worker who could be exposed to a controlled product in any inner container knows the information, which would otherwise be required on a WHMIS label applied to the inner container. (This could be accomplished, for example, by instruction of the worker in the supplier identifier and emergency number combined with a means of identifying the specific hazardous ingredient in the lab sample.)

G5.14-1 Supplier material safety data sheet (MSDS)

Issued August 1, 1999

Section 13(a) and 14(a) of the Hazardous Products Act require a supplier to provide a MSDS with controlled products. Section 5.14(1) of the OHS Regulation states:

An employer who acquires a controlled product for use at a workplace must obtain a supplier MSDS for that controlled product if the supplier is required to prepare an MSDS.

Section 5.14(2) states:

When a supplier MSDS obtained under subsection (1) for a controlled product is 3 years old, the employer must, if possible, obtain from the supplier an up-to-date supplier MSDS for the controlled product if any of the product remains in the workplace.

G5.14-2 Fees (adopted from WHMIS Bulletin #3)

Issued August 1, 1999

Can suppliers charge a fee for a material safety data sheet either as a direct fee or in the form of shipping/handling expense?

If, under section 13(a) or 14(a) of the Hazardous Products Act, a supplier is required to provide a MSDS as a condition of sale or importation to a workplace, a supplier may not charge the purchaser a fee for the MSDS. This applies to the MSDS sent out with first shipment or where an employer requests an updated MSDS, in conformity with section 5.14(2) of the OHS Regulation.

However, where an employer is required to obtain an MSDS for a controlled product purchased prior to a supplier compliance point, legislation does not prohibit the supplier from charging a fee for an MSDS. In addition a fee may be legally charged where a supplier provides an MSDS to an employer for product partially or completely exempt from WHMIS pursuant to section 12 of the Hazardous Products Act (for example, pesticides or restricted products being sold as consumer products). However, the Board does not condone the practice of charging fees for MSDS in any circumstance. All instances of fees for MSDS are to be brought to the attention of the WHMIS Coordinator.

G5.15 Laboratory MSDS (adopted from WHMIS Bulletin #7)

Issued August 1, 1999

Section 5.15(2) of the OHS Regulation states:

For the purpose of subsection (1), "produces" does not include the escape of a controlled product from equipment or from another product nor does it include intermediate products undergoing reaction within a reaction or process vessel.

What are the circumstances in which a MSDS will be required for products produced and used by the employer in laboratories?

Products produced for immediate use in a reaction (or which are produced and consumed in a reaction) do not require production of an MSDS. Such products must be used immediately, be used in total and be consumed entirely during the reaction.
A MSDS must be available as required by legislation on all controlled products which are components of mixtures produced in laboratories.
For mixtures other than those intended for immediate use, a new MSDS for the mixture must be produced if either:

the hazard of the mixture is different from the hazard of the ingredients separately, or
the precautionary information reported on the MSDSs for ingredients is in conflict (for example, a different type of protective gloves or respiratory protection is recommended.)

As such, a new MSDS will not be required for dilutions with water and mixtures in which hazards and precautions are generally unchanged from those of the ingredients.

Guidelines Part 5 - Containers and storage

G5.22 Covers

Issued August 1, 1999; Editorial Revision August 2004

If an open container of a hazardous substance (as defined in section 106 of the Workers' Compensation Act) could pose a hazard, section 5.22 of the OHS Regulation provides that the container must be kept sealed or covered, when not in use. To determine if a hazard is present, an assessment should be conducted, which takes into consideration the substance's chemical properties, such as flammability, stability, reactivity, incompatibility, corrosivity, volatility, and physical properties, such as physical state (liquid vs. solid), boiling point and/or freezing point. The container's stability should be considered (see section 5.25 of the OHS Regulation and OHS Guideline 5.25), as well as the volume of the material relative to the room space. To evaluate compliance with this section, a hazard assessment is required.

In general, the following substances should always be covered when not in use: flammable solvents; oxidizing agents; reducing agents; strong acids and caustics; and volatile, toxic solvents. Combustible liquids should be covered when there is a possibility of an ignition source in the vicinity.

G5.25 Storage practices

Issued August 1, 1999

Section 5.25 of the OHS Regulation requires that a hazardous substance be stored "in a designated area, in a manner which ensures that it will not readily fall, become dislodged, suffer damage, or be exposed to conditions of extreme temperature." The term "suffer damage" includes damage to the substance resulting from chemical instability such as peroxidation, as well as exposure to light, shock or vibration. Under section 5.24, incompatible substances must not stored "in a manner that would allow them to mix in the event of container leakage, breakage or other such circumstance." For information on chemical stability and incompatibilities, the appropriate material safety data sheet should be referenced.

The general training and work procedure requirements of section 5.2(d) of the OHS Regulation also apply.

Guidelines Part 5 - Flammable and combustible substances

G5.27(2) Electrical Safety Act repealed

Issued August 13, 2008

Regulatory excerpt

Section 5.27(2) of the OHS Regulation ("Regulation") states:

(2) For the purposes of subsection (1) sources of ignition include open flame, spark-producing mechanical equipment, welding and cutting processes, smoking, static discharge and any electrical equipment or installation that is not approved for hazardous locations, as specified by the Electrical Safety Act.

Purpose of guideline
The purpose of this guideline is to clarify the requirements of section 5.27(2) of the Regulation as a consequence of the repeal of the Electrical Safety Act.

Electrical Safety Act repealed
The Electrical Safety Act has been repealed and is no longer in effect. The current applicable Act is the Safety Standards Act. The reference to the former Electrical Safety Act in section 5.27(2) of the Regulation is considered to be a reference to the Safety Standards Act and regulations made under that Act, as applicable, including the Electrical Safety Regulation. Requirements for electrical equipment in hazardous locations are addressed in Section 18 of the B.C. Electrical Code under the Electrical Safety Regulation.

G5.30 Dispensing

Issued August 1999

A flammable liquid storage room for dispensing or transferring a flammable liquid must be designed in accordance with section 5.30 of the OHS Regulation. Permitted quantities of combustible or flammable liquids that may be stored outside of an approved storage cabinet, room or area are specified in section 5.33. The definitions of "approved storage area", "approved storage cabinet" and "approved storage room" are provided in section 5.1.

This section applies to approved storage rooms, cabinets or areas, as defined under section 5.1. It does not apply to physically separated storage sheds, such as a small fuel shed.

Guidelines Part 5 - Substances under pressure

G5.38 Handling and securing containers

Issued August 1, 1999

Section 5.38(2) of the OHS Regulation requires that a compressed gas cylinder be secured to prevent falling or rolling during storage, transportation and use. Where practicable, the cylinder must be kept in the upright position.

Compliance with this section can be achieved either by

chaining the cylinders to a secure object (a method typically used by welding shops, machine shops, and other employers handling cylinders in relatively small numbers) or,
by using the "interlock" method of storing cylinders (a method used by gas manufacturers, distributors, transfill depots, subdivisions and company depots, or other member companies of the Compressed Gas Association.)

As shown in the Figure below (this is an overhead or "bird's eye" view), the interlock method consists of dovetailing the cylinders into a cohesive unit. This method is acceptable when cylinders are in an area shipping or receiving a large number of cylinders.

Guidelines Part 5 - Controlling exposure

G5.48-1 Table of exposure limits - background information

Issued October 29, 2003; Revised February 11, 2004; Revised February 4, 2005

Section 5.48 of the OHS Regulation ("Regulation") states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Section 5.1 of the OHS Regulation defines ACGIH:

"ACGIH" means the American Conference of Governmental Industrial Hygienists publication entitled "Threshold Limit Values and Biological Exposure Indices", dated 2002, as amended from time to time.

This guideline provides information on the significance of exposure limits for chemical and biological substances and the sources for those limits. It includes a link to the table of exposure limits established under section 5.48 of the OHS Regulation.

An exposure limit is a maximum allowed airborne concentration and is not intended to represent a fine line between safe and harmful conditions. In determining an exposure limit, it is not possible to take into account all factors that could influence the effect that exposure to the substance may have on an individual worker. Therefore, for all hazardous substances, regardless of any assigned exposure limit, the guiding principle is elimination of exposure or reduction to the lowest level that is reasonably achievable below the exposure limit.

Due to a wide variation in individual susceptibility, some workers may experience discomfort from some substances at concentrations at or below the exposure limit. Others may be affected more seriously by aggravation of a pre-existing condition, or by development of an occupational disease. Furthermore, other workplace contaminants may affect an individual's response. The effects of combined chemical exposures are often unknown or poorly defined.

The exposure limits adopted under section 5.48 are based on both ACGIH TLVs and Board policy. Substances covered by Board policy are of three broad types:

Those substances, previously listed in Table 5-4 of the OHS Regulation, that have lower exposure limits than the corresponding TLV in the ACGIH table called "Adopted Values" in Threshold Limit Values and Biological Exposure Indices.
Those substances for which a TLV is currently not considered feasible for B.C. workplaces. This exception is limited to formaldehyde, styrene, and wood dust (all forms).
Those substances, previously listed in Table 5-4 of the OHS Regulation, that are not currently listed in the ACGIH table of Adopted Values.

For the convenience of users, this guideline links to the Table of Exposure Limits for Chemical and Biological Substances, which lists all exposure limits for chemical and biological substances that are regulated by WorkSafeBC, whether the limits are based on ACGIH tables or Board policy.

Information is also available by contacting your local WorkSafeBC office or calling 604 276-3100 or toll-free 1 888 621-7233.

G5.48-2 Annual revisions to exposure limits

Issued October 29, 2003; Revised February 11, 2004; Revised February 4, 2005; Revised April 29, 2005; Revised November 28, 2008; Revised July 1, 2009

Regulatory excerpt

Section 5.48 of the OHS Regulation ("Regulation") states:

Except as otherwise determined by the Board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Section 5.1 of the Regulation defines ACGIH:

"ACGIH" means the American Conference of Governmental Industrial Hygienists publication entitled "Threshold Limit Values and Biological Exposure Indices", dated 2002, as amended from time to time.

Purpose of guideline
This guideline outlines the means WorkSafeBC has established for addressing responsibilities for exposure limits under the phrasing in section 5.48, "Except as otherwise determined by the Board."

Annual revisions
The ACGIH conducts an ongoing scientific review of chemical substances with the purpose of confirming existing Threshold Limit Values (TLVs) or proposing any revisions. Information on updates to TLVs are covered in the "Notice of Intended Changes" (NIC) table in the ACGIH TLV booklet. Annually, the ACGIH reviews the NIC and adopts changes to TLVs it considers appropriate.

The ACGIH issues TLVs only as recommendations for occupational hygiene practice, not as legal exposure limits. As a regulatory authority in BC, WorkSafeBC adopts legal exposure limits, as established in s. 5.48, based on ACGIH TLVs but subject to any modification it may deem necessary.

Each year, when the new ACGIH booklet becomes available, WorkSafeBC publishes the modifications in the Table of Exposure Limits. New and revised entries are shown in green shading. Deleted entries are shown as strike-through. These highlights are maintained until the next annual update to the Table. For further information about the Table, contact Regulatory Practices at 604-231-8644. For further information about modified entries in the Table and WorkSafeBC's annual adoption of ACGIH TLVs, contact the Policy and Research Division (phone 604-276-5160).

WorkSafeBC has established the Occupational Exposure Limit Review Committee (the Committee), which has responsibilities to the Board of Directors (the BOD) for making recommendations on exposure limits, under its terms of reference, which can be found on the WorkSafeBC web site at www.worksafebc.com.

Any proposed recommendations of the Committee are subject to a consultation process before being presented to the BOD, and the BOD is advised of the results of such consultation.

The Committee will review and consider the results of stakeholder consultation before finalized recommendations are forwarded to the BOD for decision.

If a decision is made by the BOD to make an exception for a substance of concern, a public hearing will be facilitated to determine whether the exception should be maintained.

Any decisions by the BOD to establish limits other than those based on ACGIH are recorded in Board policy, and are also entered into the Table of Exposure Limits for Chemical and Biological Substances. Both documents are found on the WorkSafeBC web site.

G5.48-3 Normal 8-hour work period

Issued originally as G5.48-2 August 1, 1999; Revised October 29, 2003

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Section 5.1 of the OHS Regulation defines "8-hour TWA limit":

"8-hour TWA limit" means the time weighted average (TWA) concentration of a substance in air which may not be exceeded over a normal 8 hour work period.

For an 8-hour TWA, a normal 8-hour work period will generally refer to a routine shift length of no more than 8 hours, over which exposure to an air contaminant occurs. In computing the TWA, breaks should be included if there is significant exposure during the breaks but not otherwise. For example, in the case of a routine shift length of 8 hours with an additional half-hour or three quarter-hour lunch break, the 8-hour work period is the TWA period, if there is no significant exposure over the lunch break. If significant exposure occurs during the lunch break, then the work period should be considered more than 8 hours and the exposure reduction factors stipulated in section 5.50 need to be applied. Note that 15-minute paid breaks (such as coffee breaks) should be included in the exposure period.

Refer to OHS Guideline G5.50 for assistance in applying the reduction factors.

G5.48-4 Conversions for ppm and mg/m³

Issued originally as G5.48-3 August 1, 1999; Revised February 11, 2004

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

The ACGIH's Threshold Limit Values and Biological Exposure Indices provides instructions for converting the exposure limit (8-hour TWA limit or STEL or ceiling) for gases and vapours from parts per million (ppm) to milligrams per cubic metre (mg/m³). This might be used in situations where a substance in measured or listed in milligrams per cubic metre and the Table of Exposure Limits for Chemical and Biological Substances lists that substance in parts per million.

Exposure limit in mg/m³	=	(limit value in ppm)(gram molecular weight of substance)

		24.45

Conversely, the formula for converting a known exposure limit in mg/m³ to the equivalent exposure limit in ppm is:

Exposure limit in ppm	=	(24.45)(limit value in mg/m³)

		gram molecular weight of substance

Gram molecular weight values are shown in the column labelled "MW" in the Table of Exposure Limits for Chemical and Biological Substances. The numeric value of 24.45 in both formulae is the molar volume of air in litres at normal temperature and pressure (NTP), which is considered to be 25ºC and 1 atmosphere (101.325 kPa or 760 mm Hg or 760 torr). Note that this is not the same as standard temperature and pressure (STP), which is 0ºC and 1 atmosphere.

If you are not dealing with measurements at NTP then you may need to calculate the molar volume of air for a temperature and pressure other than NTP and substitute this calculation for 24.45. Methods for calculating molar volumes can be found in standard occupational hygiene reference books such as those listed in OHS Guideline G5.53-4.

G5.48-5 Welding fume

Issued originally as G5.48-4 August 1, 1999; Revised February 11, 2004; Revised August 3, 2006

Regulatory excerpt
Section 5.48 of the OHS Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

(TWA refers to time-weighted average, and ACGIH refers to American Conference of Governmental Industrial Hygienists.)

Purpose of guideline
This guideline explains that welding fumes are of variable composition and provides information on substances that may be present. It also discusses the sources of information on welding fumes and how to determine applicable exposure limits. The term "welding" includes thermal cutting and allied processes such as brazing.

Welding fume composition
Establishing a worker's exposure to hazardous substances in welding fumes is not a simple matter since this depends on the material being welded as well as the process and electrodes used. Welding fumes may contain fluoride, and metals or oxides of metals such as aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, hexavalent chromium, cobalt, copper, iron, lead, manganese, nickel, silver, tin, titanium, vanadium and zinc.

Apart from welding fumes, hazardous levels of gases, including carbon monoxide, oxides of nitrogen, or ozone may also be present during welding. In addition, there may be a risk of asphyxiation when shielding gases such as argon are used, particularly in an enclosed or confined space. Decomposition products such as phosgene can form when coatings or residues on or near the object being welded are heated.

Sources of information on welding fumes
To determine the potential level of exposure to welding fumes, a systematic review of the base metal, electrode, and type of process is required. Information requirements for hazardous materials covered by WHMIS are found in sections 5.3-5.19 of the OHS Regulation, and for all substances, in section 5.2. The material safety data sheets (MSDS) or other applicable information sources should be used to identify hazardous ingredients and expected products of reaction and decomposition. Information on electrodes, the metal(s) being welded or cut, and the specific type of welding process should also be identified.

Exposure limits
Once the information on possible types of exposure has been determined, the Table of Exposure Limits for Chemical and Biological Substances should be consulted for the applicable exposure limit(s).

The employer must comply with the exposure limit for each of the individual constituents in the welding fume. An additive exposure limit as established in section 5.51 may apply if two or more of these hazardous substances demonstrate similar toxicological effects. See OHS Guideline G5.51 for further information.

(Note that sections 12.115 (Coatings on metals) and 12.117 (Silver solder) of the OHS Regulation address issues respectively of coatings on metals, and cadmium in silver solder.)

G5.48-6 Allergenic species of wood dust

Issued originally as G5.48-5 August 1, 1999; Revised February 11, 2004

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

The Table of Exceptions in Policy Item R5.48-1 of the Prevention Manual includes a listing for wood dust, all allergenic species. (As noted in OHS Guideline G5.48-1, substances with exposure limits that are not the current ACGIH TLVs are listed in the Table of Exceptions in this policy. They are included in the Table of Exposure Limits for Chemical and Biological Substances and indicated with an asterisk.) For the purposes of Policy Item R5.48-1, the following species should be considered allergenic for the purposes of "wood dust -- allergenic species". This list is derived from Chan-Yeung, M, Malo, J-L, "Aetological Agents in Occupational Asthma," European Respiratory Journal, Volume 7, 1994 (pp. 346-371).

Wood Species Considered to be Allergenic

Common name	Species name
Softwood
Western red cedar	Thuja plicata
California redwood	Sequoia sempervirens
Cedar of Lebanon	Cedra libani
Eastern white cedar	Thuja occidentalis

Hardwood
Oak, European	Quercus robur
Beech	Fagus spp.
Ash
	Fraxinus americanum
Tropical Wood
Abirucana	Pouteri
African maple	Triplochiton scleroxylon
African zebra	Microberlinia
Cabreuva	Myrocarpus fastigiatus
Central American walnut	Juglans olanchana
Cocabolla	Dalbergia retusa
Common name unavailable	Tanganyika aningre
Ebony, African	Diospyros crassiflora
Iroko or Kambala	Chlorophora excelsa
Fenambouk	Caesalpinea echinata
Kejaat	Pterocarpus angolensis
Kobite	Nesorgordonia papaverifera
Mahogany, African	Khaya spp.
Makore	Tieghemella hecklii
Quillaja bark	Species name unavailable
Pau Marfim	Balfourodendron riedelianum
Ramin	Gonystylus bancanus

G5.48-7 Nuisance dusts

Issued August 16, 2000; Revised February 11, 2004; Revised November 23, 2005

Regulatory excerpt
Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

(TWA refers to time-weighted average, and ACGIH refers to American Conference of Governmental Industrial Hygienists.)

Purpose of guideline
The term "nuisance dust" has been used for years to describe a group of dusts with similar effects on people. Nuisance dusts are insoluble or poorly soluble in water and do not cause toxic effects on humans other than by inflammation of the respiratory tract or by accumulation of material in the lung (lung overload).

Exposure limits for nuisance dusts involve additional terms such as "total dust," "respirable dust," and "Particles not otherwise classified PNOC)." This guideline explains the use of these terms. It also provides information on the exposure limits for PNOC and various nuisance dusts.

In addition, the guideline provides some technical information on a relatively new term that has begun to be used to describe dusts - "inhalable" particulate.

Total and respirable dusts
Historically, particulates in the air have been measured as "total dust." This term refers to dusts with a wide range of particle sizes capable of being deposited in the various regions of the human respiratory tract, from the nose and throat down into the gas exchange area of the lung.

Dusts have also been measured as "respirable dusts," which refers to the portion of total dust that is capable of passing through the upper respiratory tract and then being deposited in the gas exchange area of the lung.

Many nuisance dusts have an 8-hour TWA exposure limit of 10 mg/m³ for total dust, as shown in the Table of Exposure Limits for Chemical and Biological Substances (the Table). Examples include aluminum oxide, calcium sulfate, cellulose, emery, gypsum and Portland cement.

Such substances also have an 8-hour TWA of 3 mg/m³ for the respirable fraction of the dust. These substances are flagged in the Table with an End Note (N) which explains that an exposure limit based on the respirable fraction also applies.

PNOC (Particles not otherwise classified)
PNOC are nuisance dusts that have not been assigned individual occupational exposure limits. PNOC may arise in various circumstances, for example, some roadwork operations, grinding acrylics and buffing nails. PNOCs are assigned a TWA of 10 mg/m³ for the total dust, and a TWA of 3 mg/m³ for the respirable fraction.

Additional technical information - Inhalable particulate
Exposure limits adopted by WorkSafeBC are based in part on the threshold limit values of the ACGIH. The concept of "inhalable dust," which has been developed by the ACGIH, refers to dusts that can be deposited anywhere in the respiratory tract. Although it is similar to the concept of "total dust," it is considered to more accurately describe the range of particle sizes that are deposited.

Substances that have been reviewed by the ACGIH, and for which exposure limits based on "inhalable" dust have been adopted by WorkSafeBC, include magnesium oxide, molybdenum (metal and insolubles), and silicon carbide (non-fibrous). Over time, the ACGIH will continue to review the application of "inhalable" to other substances. As changes are adopted by WorkSafeBC they will be reported in the Table of Exposure Limits for Chemical and Biological Substances.

G5.48-8 Simple asphyxiants -- Inert gases or vapours

Issued October 29, 2003; Revised February 11, 2004

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

A number of gases and vapours, such as acetylene, argon, and nitrogen, when present in high concentrations in air, act primarily as simple asphyxiants without other significant physiological effects. (A simple asphyxiant is a substance that can displace oxygen in the air, resulting in suffocation from lack of oxygen.) The ACGIH does not assign a TLV, or exposure limit, because the limiting factor is the available oxygen in air, not the toxic nature of the substance itself. These substances are identified as "simple asphyxiants" in the STEL column of the Table of Exposure Limits for Chemical and Biological Substances.

An oxygen-deficient atmosphere is defined in section 1.1 of the OHS Regulation as air with less than 19.5% oxygen by volume, or where the partial pressure of oxygen is less than 16.3 kPA (122 mm Hg). Oxygen-deficient atmospheres do not provide adequate warning, and most asphyxiants are odourless. Note that several of the simple asphyxiants are highly flammable and can present explosion hazards, and under section 5.31 of the OHS Regulation employers must take account of this factor in limiting the concentration of the asphyxiant. Also note that the requirements of sections 5.27, 5.31 and 5.56 of the OHS Regulation apply.

G5.48-9 Measuring compliance with the exposure limits

Issued originally as G5.48-6, August 1, 1999; revised October 29, 2003

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

The following information outlines the protocol for officers in establishing compliance with this section, and is based largely on operating procedures practiced by Board prevention officers over the last 25-30 years. These follow recognized occupational hygiene principles. For further guidance on walkthrough surveys, exposure monitoring and evaluation of the exposure monitoring program, refer to OHS Guidelines G5.53-1 to G5.53-3.

Officers will not normally perform sampling if the employer has an acceptable workplace monitoring program in place, indicating that exposures are within the applicable exposure limits. In addition, officers will normally not sample for compliance purposes during temporary or emergency conditions, where exposures may be higher than normal. Officers may elect to conduct air sampling if they suspect that a problem exists and the employer has failed to conduct an exposure assessment or has an inadequate exposure-monitoring program. Additional circumstances under which an officer may be required to sample are outlined in OHS Guidelines G5.53-1 to G5.53-3.

Typically, the officer will select the worker or workers with the highest suspected exposures and conduct sampling during worst-case scenarios, such as during periods when activities or activity levels expected to result in the highest exposure are underway. In accordance with established occupational hygiene principles, compliance with exposure limits is determined by comparing the 95% upper and lower confidence limits of the mean exposure of a similarly exposed group to the exposure limit. The 95% upper and lower confidence limits represent a range of reasonable values that are intended to contain the average exposure level with 95% confidence. That is, one can be 95% confident that the upper and lower confidence limits will cover the mean exposure.

If only one sample is collected, sampling and analytical error must be accounted for. Use the coefficient of variation specified for the sampling method and follow the confidence limit guideline as described below. Contact the Occupational Disease Prevention Services section for information regarding the coefficient of variation for the analytical method of interest.

Formulae for calculating the upper and lower confidence limits can be found in standard occupational hygiene references. Three references that are acceptable to the Board are listed in OHS Guideline G5.53-4.

The guidelines for compliance with the exposure limits using the 95% confidence limits are outlined below.

If the average exposure does not exceed the exposure limit and the upper confidence limit (UCL) is less than the exposure limit, then there is more than 95% confidence that the employer is in compliance.
If the average exposure is greater than the exposure limit and the lower confidence limit (LCL) is also greater than the exposure limit, then there is more than 95% confidence that the employer is in non-compliance.
If the average exposure does not exceed the exposure limit, but the upper confidence limit exceeds the exposure limit, there is not 95% confidence that the employer is in compliance. Similarly, if the measured exposure exceeds the exposure limit, but the lower confidence limit is below the exposure limit, there is not 95% confidence that the employer is in non-compliance. For both of these situations, there is a "possible over-exposure." Note that the closer the lower confidence limit comes to exceeding the exposure limit, the more probable it becomes that the results are not in compliance. To more definitely determine whether the exposure levels are within compliance, further sampling is needed.

An officer may elect to sample on the employer's behalf or may require the employer to conduct the sampling under the provisions of section 5.53 of the OHS Regulation. Refer to OHS Guidelines G5.53-1 to G5.53-3 for further information.

Guidelines for compliance are shown schematically in the figure below.

Determining Compliance with Occupational Exposure LImits (OEL's)

G5.48-10 Use of indicator tubes to measure compliance

Issued originally August 1, 1999; Revised February 11, 2004

Section 5.48 of the Occupational Health and Safety Regulation states:

Except as otherwise determined by the board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Colourimetric indicator tubes are useful for assessing worker exposure. However, these devices are limited with regard to applicability, specificity, and accuracy. Their primary intention is for screening exposures and the user must be familiar with these critical limitations if proper judgements are to be made, particularly in the matter of assessing compliance. Indicator tubes should meet the criteria established by Title 42 CFR Part 84 of the U.S. Code of Federal Regulations. An independent testing agency, Safety Equipment Institute (SEI) took over the task of product testing from NIOSH in 1985. The SEI certifies a manufacturer's indicator tube if it meets the minimum requirement set out in the standard, as follows:
± 35% accuracy at one-half the exposure limit, and
± 25% at one to five times the exposure limit.

Adherence to a quality assurance plan is verified by testing samples obtained from the supplier. Contact the Occupational Disease Prevention Services section for further information.

In essence this means that one should read an indicator tube ±25% of the indicated reading if the exposure level is in the vicinity of the exposure limit unless several grab samples are taken to increase the statistical confidence, in accordance with acceptable occupational hygiene statistical practice. Indicator tubes can be used to measure non-compliance with either short-term exposure limits or ceiling limits. In the case of a single grab sample by detector tube, if the reading exceeds either the short-term exposure limit or the ceiling limit by 25%, there is sufficient evidence of non-compliance with the exposure limit. If the indicator tube reading is close to the short-term exposure limit or ceiling limit (within 25±% of the limit), and if it appears that an overexposure may exist, other more reliable sampling methods should be used before a decision is made. See also OHS Guideline G5.48-9 for guidelines on determining whether there is compliance with the exposure limits.

Readings from a short-term indicator tube should be compared to the appropriate short-term exposure limits in the Table of Exposure Limits for Chemical and Biological Substances (such as a short-term exposure limit or a ceiling limit). They should not be compared to 8-hour TWA limits. In addition, 8-hour time-weighted averages must not be calculated from results obtained using short-term indicator tubes.

Long-term indicator tubes connected to a sampling pump may be used to determine 8-hour time-weighted averages. These averages are then compared to the appropriate 8-hour TWA limit in the Table of Exposure Limits for Chemical and Biological Substances.

See OHS Guideline G5.48-1 for the Table of Exposure Limits for Chemical and Biological Substances.

G5.48-11 Sampling of thoracic fraction of sulfuric acid mist

Retired on July 6, 2007

G5.48-12 Establishing exposure limits for certain refined hydrocarbon mixtures

Issued July 1, 2009

Regulatory excerpt
Section 5.48 of the OHS Regulation ("Regulation") states:

Except as otherwise determined by the Board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

(TWA refers to time-weighted average, and ACGIH refers to American Conference of Governmental Industrial Hygienists.)

Purpose of guideline
This guideline provides an explanation of the means to determine occupational exposure limits for certain refined hydrocarbon solvent mixtures such as rubber solvent and VM & P Naphtha. Hydrocarbon solvents affect the central nervous system and can cause a variety of symptoms including dizziness, drowsiness, and eye and respiratory tract irritation.

Note: Due to the complexities inherent in the use and interpretation of the Reciprocal Calculation Procedure (RCP), it will usually be necessary for an occupational hygiene professional to be involved in the application of this method.

Background
The majority of WorkSafeBC exposure limits are for single substances (e.g. toluene) or for substances containing a common element (e.g. tungsten metal and insoluble compounds). These exposure limits are those prescribed by ACGIH or as otherwise determined by WorkSafeBC. They are shown in the WorkSafeBC Table of Exposure Limits for Chemical and Biological Substances.

Refined hydrocarbon solvents, such as Rubber Solvent and VM & P Naphtha, are complex mixtures produced by the distillation of petroleum over a particular boiling range. They consist of aliphatic (alkane), cycloaliphatic (cycloalkane), and aromatic hydrocarbons ranging from 5 to 15 carbon atoms in each molecule. The use of the mixture formula expressed in Regulation section 5.51, which takes additive effects into consideration, is difficult in these cases because these petroleum mixtures contain a large number of unique compounds and isomers, many of which do not have specific exposure limits. Because there are very many possible combinations of the various alkane, cycloalkane, and aromatic mixtures, it is necessary to calculate an exposure limit for each combination rather than list all possible calculated exposure limits in the Table of Exposure Limits for Chemical and Biological Substances.

The ACGIH has developed a means to calculate an exposure limit for specific refined hydrocarbon solvents, and has published the method (RCP) in Appendix H of the ACGIH publication Threshold Limit Values and Biological Exposure Indices, since 2009. The remainder of this guideline explains WorkSafeBC's adoption of this method and provides example calculations.

Reciprocal Calculation Procedure
The RCP is a method for deriving exposure limits (EL) for refined hydrocarbon solvents. This method is applicable if the toxic effects of the individual chemical components are additive (e.g., similar effects on the same organ or system).

The RCP calculation can only be applied to petroleum-based hydrocarbon solvents containing saturated aliphatics (alkanes and cycloalkanes) and aromatics with 5 to 15 carbon atoms and boiling points between 35°C and 329°C. The substances for which the RCP calculation applies are identified with an "(H)" in the Table of Exposure Limits (e.g. see Rubber Solvent, VM & P Naphtha). It would not apply to petroleum fuels, lubricating oils or solvents or solvent mixtures that already have an EL (e.g. benzene has its own EL and would have to be considered separately).

The RCP formula calculates an EL based on

The mass composition of the mixture
Hydrocarbon group "guidance values"
Substance-specific ELs, where applicable (see Note)

Note: The RCP does not apply to solvents containing benzene, n-hexane, or methylnaphthalene, which have individual ELs significantly less than the guidance values to which they would belong and have unique toxicological properties. Whenever present in the mixture, these components should be measured individually.

Guidance values have been developed by a number of researchers, groups, and regulatory authorities, based on the chemical and toxicological properties of various hydrocarbon groups (e.g., C5 - C6 alkanes and C7 - C8 aromatics). The guidance values adopted by WorkSafeBC (Table 1) were developed by the UK Health and Safety Executive, a recognized health and safety authority.

Table 1: Hydrocarbon Guidance Values

Hydrocarbon Group	Number of Carbon Atoms	Guidance Value (mg/m³)
Normal and branched chain alkanes (excluding n-hexane and n-heptane)	C5 - C6	1800
	C7 - C8	1200
	C9 - C15	1200
Cycloalkanes (excluding cyclohexane)	C5 - C6	1800
	C7 - C8	800
	C9 - C15	800
Aromatics (excluding benzene, toluene, xylene and its isomers, ethylbenzene, trimethylbenzene and its isomers, and cumene)	C7 - C8	500
	C9 - C15	500

The reciprocal calculation mixture formula is

$ELsolvmix equals 1 divided by: (Liquid mass fraction of group "a" (value between 0 and 1) divided by Guidance value for group "a" (from Table 1)) + (Liquid mass fraction of group "n" (value between 0 and 1) divided by Guidance value for group "n" (from Table 1))$

The resulting calculated EL_solvmix value should follow established recommendations regarding rounding. For calculated values <100 mg/m³, round to the nearest 25. For calculated values between 100 and 600 mg/m³, round to the nearest 50, and for calculated values >600 mg/m³, round to the nearest 200 mg/m³.

Example 1
The following is an example of how the RCP is applied to determine the EL for a solvent mixture (EL_solvmix). Rubber solvent typically contains the following percentage of hydrocarbons:

Component	Percent Hydrocarbon Composition	Guidance Value (mg/m³)
C7 - C8 alkanes & cycloalkanes	52%	800
C9 - C10 alkanes & cycloalkanes	40%	800
C7 - C8 aromatics	10%	500
Toluene	6%	75 (see Note)

Note: The exposure limit is expressed in mg/m³. The EL in the EL Table has been converted from ppm.

The RCP calculation for this mixture is

ELsolvmix equals 1 divided by: (0.52/800 + 0.40/800 + 0.10/500 + 0.06/75) Equals 1/0.00215 Equals 465 mg/m3, rounded to 450 mg/m3

Hence the EL for this particular type of refined hydrocarbon solvent mixture is 450 mg/m³.

Example 2
The material safety data sheet for a solvent showed the following percentages and chemical composition:

Component	Percent Hydrocarbon Composition	Guidance Value (mg/m³)
C7 - C8 alkanes & cycloalkanes	45%	800
C9 - C10 alkanes & cycloalkanes	40%	800
C7 - C8 aromatics	9%	500
Toluene	6%	75 (OEL)
Benzene	<1%	Not applicable

The RCP calculation for this mixture is:

ELsolvmix equals 1 divided by: (0.45/800 + 0.40/800 + 0.09/500 + 0.06/75) Equals 1/0.00204 Equals 490 mg/m3, rounded to 500 mg/m3

The EL for this particular solvent mixture is 500 mg/m³. However, benzene must be evaluated separately at the current EL for benzene.

Limitations of the reciprocal calculation method
Care in the use of the EL_solvmix should be observed where the mixture in question is known to have significant toxicokinetic interactions of components that are manifested at or below the guidance values.

The use of the RCP should be restricted to applications where the boiling points of the solvents in the mixture are relatively narrow, within a range of less than 45°C (i.e., vapour pressure within approximately one order of magnitude). The procedure should not be used in situations where the liquid composition is significantly different from the vapour composition.

The guidance values apply only to vapours and do not apply to mists or aerosols. The calculation does not apply to mixtures containing olefins or other unsaturated compounds or polycyclic aromatic hydrocarbons (PAHs).

Further reading
ACGIH Threshold Limit Values and Biological Exposure Indices, Appendix H (2009)
European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC). Occupational exposure limits for hydrocarbon solvents. Special Report No. 13. Brussels, Belgium (1997).
Farmer TH: Occupational hygiene limits for hydrocarbon solvents. Annals of Occupational Hygiene 40: 237-242 (1995).
McKee RH; Medeiros AM; Daughtrey, WC: A proposed methodology for setting occupational exposure limits for hydrocarbon solvents. J of Occ and Env Hygiene 2: 524-542 (2005).
UK Health and Safety Executive (UKHSE) EH40/2000. Occupational Exposure Limits (2000).

G5.48-13 Monitoring worker exposure to sulfur dioxide

Preliminary Issue September 28, 2009

Regulatory excerpt
Section 5.48 of the OHS Regulation ("Regulation")states:

Except as otherwise determined by the Board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA prescribed by ACGIH.

WorkSafeBC automatically adopts as occupational exposure limits the annual American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) upon their publication in March of each year, unless another determination has been made by WorkSafeBC.

Purpose of guideline
The purpose of this guideline is to communicate the existence of a vice-president directive suspending the application of section 5.48 with respect to sulfur dioxide.

Issues with the current requirement
In 2009, the Board of Directors adopted as the exposure limits (ELs) for British Columbia the TLVs published by ACGIH in the 2009 edition.

The ACGIH revisions to the TLVs in the 2009 edition included a change to the EL for sulfur dioxide (SO₂). The previous EL for SO₂ in B.C. was 2 ppm (8-hour TWA - time weighted average) and 5 ppm (STEL - short term exposure limit). With the adoption of the 2009 edition there is no longer a TWA; only a STEL which was reduced to 0.25 ppm.

Based on the new 2009 EL, WorkSafeBC has determined that the current sampling and analytical methods available for SO₂ have not been fully validated in the laboratory or field to levels reaching to 0.25 ppm. WorkSafeBC will be working to validate the sampling and analytical methodology for the new level. This work will proceed over a number of months, and accordingly, until this work is completed the 2009 EL for SO₂ cannot reliably be enforced.

SO₂ is a contaminant associated with several industries within B.C., e.g. metallurgical processes at several smelters, chemical processes in the pulp and paper industry, and as a contaminant of diesel exhaust.

Directive on issuing orders
WorkSafeBC prevention officers will not issue orders under section 5.48 or other sections of the Regulation where the determination of whether a violation has occurred references the 2009 EL prescribed for SO₂. Prevention officers will consider whether orders should be issued under the previous 2008 EL for SO₂ (8-hour TWA of 2 ppm and a STEL of 5 ppm), and any other applicable sections to deal with any risks to the health and safety of workers.

This vice-president directive is in effect until December 31, 2010 or until such earlier time as may be determined.

G5.49 Application of excursion limits

Issued January 1, 2007

Regulatory excerpt
Section 5.1 of the OHS Regulation ("Regulation") contains the following relevant definitions:

"ACGIH" means the American Conference of Governmental Industrial Hygienists publication entitled "Threshold Limit Values and Biological Exposure Indices", dated 2002, as amended from time to time;

"8-hour TWA limit" means the time weighted average (TWA) concentration of a substance in air which may not be exceeded over a normal 8 hour work period;

"short-term exposure limit" or "STEL" means the time weighted average (TWA) concentration of a substance in air which may not be exceeded over any 15 minute period, limited to no more than 4 such periods in an 8-hour work shift with at least one hour between any 2 successive 15 minute excursion periods;

"ceiling limit" means the concentration of a substance in air which may not be exceeded at any time during the work period;

Section 5.48 of the Regulation states:

Except as otherwise determined by the Board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Section 5.49 of the Regulation states:

If a substance referred to under section 5.48 is provided only with an 8-hour TWA limit, the employer must, in addition to the requirement of section 5.48, ensure that a worker's exposure to the substance does not exceed

(a) three times the 8-hour TWA limit for more than a total of 30 minutes during the work period, and

(b) five times the 8-hour TWA limit at any time.

Section 5.50(1) of the Regulation states:

If the work period is more than 8 hours in a 24 hour day, the 8-hour TWA limit must be reduced by multiplying the TWA limit by the following factors:
Factor Length of work period (in hours)
0.7 More than 8, but not more than 10
0.5 More than 10, but not more than 12
0.25 More than 12, but not more than 16
0.1 More than 16

Purpose of guideline
The purpose of this guideline is to explain, and provide examples of the application of excursion limits in section 5.49.

Background Information
Threshold Limit Values (TLVs) refer to airborne concentrations of chemical substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse health effects. There are three categories of TLVs: time-weighted average ("TWA") over an 8-hour period; short-term exposure limit ("STEL"), and a ceiling limit. Some chemical substances have been assigned values for a TWA and either a STEL or a ceiling limit, while other substances have been assigned TWA or ceiling limits only. (See also OHS Guidelines G5.48-1 to G5.48-4 for general information on exposure limits).

Section 5.49 of the Regulation establishes excursion limits for hazardous substances which have only been assigned a TWA by applying a formula to the assigned 8-hour TWA value. The purpose of excursion limits is to ensure workers are not exposed to excessively high short bursts of hazardous substances which could cause acute health effects.

Excursion limits are based on the premise that the maximum excursion should be related to the variability generally observed in actual industrial processes. Research has shown that if the variation of short-term exposure values is very high (greater than three times the average), it is an indication that the process is not under good control.

In order to be assured of satisfactory control of the industrial process and associated exposure values, a factor of three times the TWA is used. This ensures that only a small percentage of exposure values will exceed this value. If this excursion limit is exceeded, there is a high likelihood that further control measures are required.

Excursion limits apply only when neither a STEL nor ceiling value has otherwise been assigned to the substance. Section 5.49 is not meant to supersede any assigned STEL or ceiling limit.

Examples of Application of Excursion Limits
Elemental mercury has a TWA of 0.025 mg/m³ (No STEL or Ceiling limit)
The principle of excursion limits applies in this case since there is only a TWA for this substance. As per section 5.49(a), an employer must ensure that a worker's exposure to elemental mercury does not exceed 0.075 mg/m³ for more than a total of 30 minutes during the work period.

A worker exposed to a concentration of 0.080 mg/m³ for 15 minutes and to 0.060 mg/m³ for 15 minutes, is exposed, on average, to 0.070 mg/m³. This average value is less than 0.075 mg/m³ and is therefore in compliance with section 5.49(a).

As per section 5.49(b), the employer also must ensure that a worker's exposure to elemental mercury does not exceed 0.125 mg/m³ at any time during the work period. For example, a direct reading measurement of 0.15 mg/m³, taken with a calibrated mercury monitor, is a determination of non-compliance.

Acetic acid has a TWA of 10 ppm and a STEL of 15 ppm
The principle of excursion limits does not apply in this case because there is a STEL assigned for acetic acid. A worker is protected by the 8-hour TWA and is protected from high short burst exposures of acetic acid by the 15 minute STEL.

Chloroacetone has a ceiling limit of 1 ppm (No TWA or STEL)
The principle of excursion limits does not apply in this case because there is a ceiling limit assigned for chloroacetone. A worker is protected by setting a maximum permissible concentration in air, which must not be exceeded at any time during the work period.

Ethylene Oxide has a TWA of 0.1 ppm and a STEL of 1 ppm
The principle of excursion limits does not apply in this case because there is a STEL assigned for ethylene oxide. A worker is protected by the 8-hour TWA and is protected from high short burst exposures of ethylene oxide acid by the 15 minute STEL. Although there is no ceiling limit for ethylene oxide, the STEL also provides significant protection against very short, momentary high bursts - these bursts must not raise the 15 minute average concentration to higher than the STEL and must be limited to no more than 4 such periods in an 8 hour work shift with at least one hour between any 2 successive 15 minute excursion periods.

Application of Excursion Limits for Extended Work Periods
Section 5.50 of the Regulation and the associated OHS Guideline G5.50 explain how and when the TWA must be reduced for exposures during an extended work period. When the provisions for reduction of the TWA apply, this reduced value is the value to be used for excursion limit calculations in section 5.49.

For example, if a worker is exposed to airborne elemental mercury (8-hour TWA limit of 0.025 mg/m³, no STEL, no ceiling limit) routinely over a 12-hour work shift, then a reduction factor of 0.5 must be applied to the exposure limit, resulting in a reduced TWA limit of 0.0125 mg/m³. This worker must not be exposed to an average of more than (3 X 0.0125 =) 0.0375 mg/m³ for more than a total of 30 minutes during the 12-hour work period. The worker must not be exposed to more than (5 X 0.0125 =) 0.0625 mg/m³ at any time during the 12-hour work period.

G5.50 Extended work periods

Issued August 1, 1999; Revised February 11, 2004

Section 5.50(1) of the Occupational Health and Safety Regulation states:

If the work period is more than 8 hours in a 24 hour day, the 8-hour TWA limit must be reduced by multiplying the TWA limit by the following factors:

Factor	Length of work period (in hours)
0.7	More than 8, but not more than 10
0.5	More than 10, but not more than 12
0.25	More than 12, but not more than 16
0.1	More than 16

Where the work period exceeds 8 hours in a 24-hour day, the 8-hour TWA limit listed in the Table of Exposure Limits for Chemical and Biological Substances must be modified to ensure that workers on extended shifts are as equally protected as if they were working on conventional 8-hour shifts. Section 5.50(1) of the OHS Regulation provides the factors by which the 8-hour TWA limit must be reduced.

See OHS Guideline G5.48-1 for the Table of Exposure Limits for Chemical and Biological Substances.

Refer to OHS Guideline G5.48-3 for clarification of "normal" 8-hour shift.

This section envisages several consecutive workdays with shifts longer than the normal 8-hour shift, not an occasional overtime shift. If exposure occurs as a single event lasting less than 8 hours during a work shift and there is a recovery period of at least 16 hours (at work or otherwise) before any further exposure, the reduction factor would not normally apply.

G5.51 Additive effects

Issued August 1, 1999; Revised October 29, 2003

Section 5.51 of the Occupational Health and Safety Regulation states:

If there is exposure to a mixture of 2 or more substances with established exposure limits which exhibit similar toxicological effects, the effects of such exposure must be considered additive unless it is known otherwise, and the additive exposure must not exceed 100% when calculated as follows:
AE = %EL₁ + %EL₁ + ... %EL_n
where
(a) AE is the calculated additive exposure to the mixture,
(b) %EL₁ is the measured exposure to component 1 of the mixture expressed as a percentage of its exposure limit,
(c) %EL₂ is the measured exposure to component 2 of the mixture expressed as a percentage of its exposure limit, and
(d) %EL_n is the measured exposure to any additional components of the mixture expressed as a percentage of their respective exposure limits.

That is, if the sum derived from the equation exceeds 100%, the exposure limit of the mixture is considered as being exceeded.

This section applies to all exposure limits, with the exception of excursion limits (section 5.49), as they are not considered to be "established exposure limits." When considering additive effects, similar exposure limits must be compared (for example 8-hour TWA limits must be compared with 8-hour TWA limits; do not compare an 8-hour TWA limit and a STEL).

For effects to be considered additive, the substances must act upon the same target organ (such as the kidneys) or target organ system (such as the respiratory system) and have similar toxicological effects. Thus, substances with primarily acute effects would not be considered additive with substances which cause chronic effects, even if same organ or organ system was involved. For example, although both silica and ammonia affect the lungs, they would not be considered additive because exposure to silica causes a chronic condition (silicosis), while exposure to ammonia causes acute effects (respiratory tract irritation).

Some examples of processes where additive effects need to be considered are welding, painting, and plastics manufacturing. Additive effects should also be taken into account for exposure to diesel exhaust. If it is not clear whether additive effects apply, one should consult an occupational hygienist.

G5.52 Skin notation

Issued August 1999; Revised February 11, 2004

Section 5.52 of the Occupational Health and Safety Regulation states:

If skin absorption may contribute to the overall exposure, effective measures must be taken to limit exposure by this route.

This section applies to those substances listed with a "Skin" notation in the Table of Exposure Limits for Chemical and Biological Substances (see OHS Guideline G5.48-1).

The notation refers to the potential significant contribution to the overall exposure by skin absorption (called the cutaneous route) either by contact with vapours or, of probable greater significance, by direct skin contact with the substance. This includes contact with the mucous membranes of the eyes. Specific substances (vehicles) in solutions or mixtures can also significantly enhance potential skin absorption. Although some substances are capable of causing irritation, dermatitis, and sensitization in workers, these properties are not considered relevant by the ACGIH when assigning a "Skin" notation. However, a dermatological condition can significantly affect the potential for skin absorption.

The "Skin" notation is intended to alert the reader that air sampling alone is insufficient to quantify exposure accurately and that measures to prevent significant skin absorption should be considered. For guidance on measures to control exposure, refer to OHS Guideline G5.55 or consult with an occupational hygienist or occupational physician.

G5.53-1 Workplace monitoring

Issued August 1, 1999

Where a worker is or may be exposed to a hazardous substance, section 5.53 of the OHS Regulation requires an assessment of the potential for harmful exposure and monitoring, or sampling, of exposure levels to airborne contaminants. The program required under Section 5.53 has 3 major elements:

a walk-through survey
air sampling to assess the potential for overexposure, and
workplace monitoring to reliably characterize worker exposure, where workers may be exposed to an air contaminant at levels greater than 50% of the exposure limit. Section 5.53(4) provides that Workplace exposure monitoring and assessment must be conducted using occupational hygiene methods acceptable to the board.

As provided for under section 130(i) of the Workers Compensation Act and section 3.8 of the OHS Regulation, the joint committee should be involved in workplace monitoring, where feasible.

Officers may conduct sampling to determine compliance with both sections 5.48 and 5.53 of the OHS Regulation. Additional circumstances where an officer may be required to conduct workplace monitoring include the following:

claims investigations
accident investigations
investigations conducted under section 3.12(5)
dispute resolution
asbestos abatement projects and,
penalty assessments.

An officer may encounter situations were the employer has neither conducted a walk-through survey nor performed sampling of contaminants, as required. In these circumstances, the officer may elect to either assist the employer in conducting the survey or performing the sampling (as part of an inspection) or require the employer to conduct the survey or perform the sampling. In deciding whether to assist the employer, the officer may consider

the employers resources and abilities to
- conduct the survey or perform the sampling him- or herself, or
- engage professional services
the educational benefit to the employer of accompanying the officer on a walk-through survey, and
the employer's commitment to an occupational health and safety program under the provision of part 3.

Some questions to consider

does the firm have appropriate in-house expertise?
does the firm have access to technical support from either the parent corporation or a supplier of the harmful substance(s)?
are private occupational hygiene services for sampling and/or analytical work readily available in the community?

The manner in which compliance is assessed with each element of the program is described in detail below.

G5.53-2 Assessing compliance -- the walk-through survey

Issued August 1, 1999

Section 5.53(1) of the requires an employer to conduct a walk-through survey if a worker is or may be exposed to a harmful substance. An officer encountering an employer who has not conducted a walk-through survey at a workplace where, in the officer's opinion, workers may be exposed to a harmful substance, will require the employer to conduct the walk-through survey in accordance with this section.

If the employer conducts the walk-through survey and concludes that no worker may be at risk of overexposure to an airborne contaminant, and the officer accepts this conclusion as being reasonable, no further action will be necessary, unless there is a change in work conditions. If, on the other hand, the employer finds a worker potentially at risk of overexposure to an airborne contaminant, air sampling must be considered, as required by section 5.53(2). Depending on the outcome of the sampling, further action may be required under sections 5.53(3), 5.54 and 5.55 of the OHS Regulation.

The officer may determine that workers are at risk based on

observations at the worksite (this may be in the course of assisting an employer with a walk-through survey or during an inspection)
sampling results from the worksite or similar worksites or operations
first aid reports
worker complaints.

G5.53-3 Monitoring worker exposure

Issued August 1999; Revised February 11, 2004

Under section 5.53(2) of the OHS Regulation, the employer must conduct air sampling when the walk-through survey required under section 5.53(1) reveals that workers may be at risk of overexposure. The guidelines set out in OHS Guideline G5.48-9 are acceptable to the Board for complying with section 5.53(2). Normally, the employer would select one or more workers for sampling, which should be those workers who are likely to be the most heavily exposed on a given day (worst case conditions). Sampling results are then compared with exposure limits in section 5.48 (Table of Exposure Limits for Chemical and Biological Substances in OHS Guideline G5.48-1) using the guidelines in G5.48-9.

If the assessment conducted under section 5.53(2) reveals that a worker may be exposed to an air contaminant in excess of 50% of its exposure limit, -or measurement is not possible at 50% of the applicable exposure limit, additional workplace monitoring to reliably determine worker exposure is required under section 5.53(3)(a).

"Additional monitoring" differs from "worst case" sampling discussed in OHS Guideline G5.48-9 in that a larger number of samples are collected to account for day-to-day, as well as worker-to-worker, variability. The officer will not normally conduct the additional monitoring. The following is an acceptable process for carrying out the additional monitoring

collect samples over an appropriate period of time in order to obtain a reliable estimate of exposure,
group workers to be sampled on the basis of potential exposures (see the Note below),
take 6 - 10 samples from each group of workers,
calculate the mean exposure for each group
- If the mean exposure for some workers in the group is much higher than for other workers, the group is not similarly exposed and should be split into two or more groups.
calculate the geometric standard deviation for each mean exposure
- Formulae for calculating the standard deviation can be found in standard occupational hygiene references. Three references that are acceptable to the Board are listed in OHS Guideline G5.53-4.
calculate the 95% upper and lower confidence limits for each mean exposure
- Formulae for calculating the upper and lower confidence limits can be found in standard occupational hygiene references. Three references that are acceptable to the Board are listed in OHS GuidelineG5.53-4.
apply the guidelines of compliance outlined in OHS Guideline G5.48-9.

Note:
Officers should consider whether the employer has grouped workers with similar patterns of exposure together. Such grouping would normally be based on an examination of work processes, procedures, job descriptions, process schedules and weather conditions. Groups of workers with similar patterns of exposure are referred to as "similarly exposed groups" or "homogeneous exposed groups".

G5.53-4 Occupational hygiene methods acceptable to WorkSafeBC

Issued August 1, 1999; Revised November 17, 2003; Revised May 6, 2009

Regulatory excerpt
Section 5.53(4) of the OHS Regulation states:

Workplace exposure monitoring and assessment must be conducted using occupational hygiene methods acceptable to the Board.

Purpose of guideline
The purpose of this guideline is to provide information on the publications that detail occupational hygiene methods acceptable to WorkSafeBC. The guideline also explains how approval may be obtained to use methods that are not discussed in those publications.

Acceptable occupational hygiene methods
All elements of an assessment or monitoring program (e.g. hazardous materials survey, air sampling and bulk sampling) must be conducted using occupational hygiene methods acceptable to WorkSafeBC. WorkSafeBC accepts methods detailed in standard occupational hygiene references published by the National Institute for Occupational Safety and Health, the American Industrial Hygiene Association, the American Conference of Governmental Industrial Hygienists, and the U.S. Environmental Protection Agency, such as, for example:

A Strategy for Assessing and Managing Occupational Exposures. Published by the American Industrial Hygiene Association, Fairfax, Virginia, 2006, 3^rd edition (or later editions).

Occupational Exposure Sampling Strategy Manual. Published by the National Institute of Occupational Safety and Health. Cincinnati, Ohio, 1977 (or later editions).

The Occupational Environment: Its Evaluation, Control, and Management. Published by the American Industrial Hygiene Association, Akron, Ohio, 2003, 2^nd edition (or later editions).

Recognition, Evaluation, and Control of Indoor Mold. Published by the American Industrial Hygiene Association, Akron, Ohio, 2008 (or later editions).

Before using occupational hygiene methods that are not discussed in references published by the organizations listed above, the employer must obtain approval from the Regulatory Practices Department of WorkSafeBC.

G5.54-1 Exposure Control Plan

Issued August 1999; Revised October 29, 2003; Editorial Revision January 2006; Editorial Revision February 1, 2008

Regulatory excerpt
Section 5.54(1) of the OHS Regulation ("Regulation") states:

An exposure control plan must be implemented when

(a) exposure monitoring under section 5.53(3) indicates that a worker is or may be exposed to an air contaminant in excess of 50% of its exposure limit

(b) measurement is not possible at 50% of the applicable exposure limit, or
(c) otherwise required by this Regulation.

Purpose of guideline
The purpose of this guideline is to discuss when an exposure control plan is required. This includes providing specific sections under the Regulation where an exposure control plan is required.

When an exposure control plan is required
Section 5.54(1) of the Regulation requires the employer to implement an exposure control plan under certain specific circumstances. The elements that must be incorporated into the exposure control plan are listed in section 5.54(2).

An exposure control plan is required when any of the following conditions are present:

The results of exposure monitoring indicate that a worker is or may be exposed to an air contaminant at levels greater than 50% of its exposure limit.
Measurement is not possible at 50% of the applicable exposure limit.
An exposure control plan is required by another section of the Regulation.

If the employer has failed to conduct workplace monitoring under section 5.53(3), a WorkSafeBC prevention officer may order the employer to implement an exposure control plan if the prevention officer determines exposure exceeds 50% of the exposure limit.

The determination of whether an exposure control plan is required will typically be made on the basis of the additional monitoring under section 5.53(3). Worst-case sampling (see OHS Guideline G5.53-3) can also demonstrate exposure, although with less certainty. Where exposure greater than 50% of the exposure limit would occur only in an emergency, an emergency plan rather than an exposure control plan is required under sections 5.2 and 5.97 of the Regulation. For example, an accidental spill or leak of a substance may occur, which is otherwise contained or controlled below 50% of the exposure limit.

The word "may" in clause (a) in section 5.54(1) refers to situations where there is "possible exposure." The figure in OHS Guideline G5.48-9 shows that a guideline for determining possible exposure includes situations where the upper confidence limit is above the exposure limit and the lower confidence limit is below the exposure limit. For further clarification, refer to OHS Guidelines G5.48-9 and G5.53-3.

The levels of most common substances can be measured at the exposure limit. Even though exposure cannot be precisely measured or determined at 50% of the exposure limit, there may still be sufficient evidence for a knowledgeable person to reasonably conclude that there is no probability of exposure to levels greater than 50% of the exposure limit. In such cases no exposure control plan is required.

There are several other sections of the Regulation that require an exposure control plan. They are listed below.

Sections of the Regulation requiring an exposure control plan (ECP)

Section	Topic	Situations when an ECP is required


5.57	Controlling Exposure	Where it is not practicable to replace a material referred to in section 5.57(1) (designated substances) with a material that reduces the risk
6.3	Asbestos	If a worker is or may be exposed to potentially harmful levels of asbestos
6.34	Biological Agents	If a worker has or may have occupational exposure, as defined in section 6.33
6.43	Cytotoxic Drugs	If a worker is or may be occupationally exposed to a cytotoxic drug
6.60	Lead	If workers are or may be exposed to lead in excess of 50% of the exposure limits, or if exposure through any route of entry could result in elevated lead body-burdens, as defined by WorkSafeBC
6.119	Toxic Process Gases	If there is a risk of adverse health effects to workers from exposure to a toxic process gas
7.20	Ionizing and Non-Ionizing Radiation	If a worker exceeds, or may exceed, an applicable action level for ionizing or non-ionizing radiation
7.29	Heat Stress	If: A worker is or may be exposed to thermal conditions which could cause heat stress The thermal conditions could result in a worker's core body temperature exceeding 38°C (100°F) The thermal conditions are or may be in excess of the levels listed in the screening criteria for heat stress exposure in the heat stress and strain section of the ACGIH Standard for unacclimatized workers
7.34	Cold Stress	If a worker is or may be exposed to: Thermal conditions that could cause cold stress or injury Thermal conditions that could cause a worker's core body temperature to fall below 36°C (96.8°F) Thermal conditions that are below the levels classified as "little danger" to workers in the criteria for the cooling power of wind on exposed flesh in the cold stress section of the ACGIH Standard

G5.54-2 Elements of an exposure control plan

Issued August 1, 1999

The seven major elements that an exposure control plan must incorporate are listed in section 5.54(2) of the OHS Regulation. The exposure control plan will normally be in writing so that all its elements can be recorded properly. If an exposure control plan is functioning effectively in a workplace, and the elements of the plan are not complex and require only limited record keeping, writing the plan may not be necessary. Similar considerations will determine the need for written work procedures under section 5.54(2)(d). Section 5.2 may require written work procedures under certain conditions, even though a written exposure control plan is not necessary.

Additional details regarding some of the specific elements of an exposure control plan are described the following OHS Guidelines.

G5.54-3 Risk identification, assessment and control

Issued August 1, 1999

Under section 5.54(2)(b), the exposure control plan must incorporate risk identification, assessment and control. When identifying and assessing risk, the requirements of sections 5.53(1) and 5.53(3) for a walk-through survey and exposure monitoring apply. Continuous monitoring of the work area may also be required, when necessary, to ensure the continuing safety of workers. For example, section 6.128 (Toxic Process Gases) requires continuous monitoring in some workplaces. For controlling risk, section 5.55 applies.

To evaluate compliance with this section, an officer will

determine whether the hazards have been correctly identified,
establish whether the risk assessment is acceptable,
assess the practicability of any proposed control measures, and
evaluate whether those measures provide an acceptable level of protection to workers.

The degree of risk will depend on the probability, the extent, and the possible consequences of exposure (an injury or disease). Some of the factors that an employer should consider when performing a risk assessment are outlined in the table below.

Factors to be considered when performing a risk assessment

General	Specific


What is the nature of the hazard?	what are the body systems involved (e.g. lungs, skin)? what are the possible effects of exposure (e.g. breathing difficulties, scarring of tissues)? are there short-term or long-term effects (e.g. mild irritation, irreversible tissue damage, cancer)?
What is the nature of the exposure?	what are the specific substances to which workers may be exposed? what are the way(s) in which workers may be exposed (e.g. spills, during routine tasks or preventative maintenance)? what are the specific work methods or procedures which may result in exposure? who are the workers at risk for exposure (i.e. process workers, maintenance workers, outside contractors)? how many workers are potentially exposed?
Are there control measures in place to reduce the risk of exposure?	are there any engineering controls? (e.g. is the process enclosed or isolated?) are there administrative controls (e.g. is work scheduled to minimize time spent in the hazardous area)? is personal protective equipment available? (i.e. what type is available and how is it used?)

G5.54-4 Hygiene facilities and decontamination procedures

Issued August 1999; Editorial Revision February 1, 2008

Regulatory excerpt
Section 5.54(2)(e) of the OHS Regulation ("Regulation") states:

(2) The exposure control plan must incorporate the following elements:
(e) hygiene facilities and decontamination procedures, when required;

Purpose of guideline
The purpose of this guideline is to clarify that the walk-through survey required under section 5.53(1), the risk assessment performed under section 5.88, along with specific requirements in Parts 6 and 7, will help determine whether or not hygiene facilities and decontamination procedures are required.

Hygiene facilities and decontamination procedures
Section 5.54(2)(e) requires that the exposure control plan incorporate "hygiene facilities and decontamination procedures, when required." The walk-through survey required under section 5.53(1), as well as the risk assessment required under section 5.88, will determine the need for specific hygiene facilities and decontamination procedures. Certain sections of Parts 6 and 7 may also require hygiene facilities and decontamination procedures, such as for asbestos, lead, and biological agents designated as hazardous substances in section 5.1.1. Refer to the relevant OHS Guidelines for further assistance.

G5.54-5 Health monitoring

Issued August 1, 1999; Revised June 7, 2002; Editorial Revision October 2004

Under section 5.54(2)(f), the exposure control plan must incorporate "health monitoring, when required." Health monitoring may be required explicitly (such as under section 6.79, the Board may require health monitoring for workers exposed to pesticides in non-agricultural operations), or as an element of an exposure control plan. A list of the sections in which an exposure control plan is called for is tabulated in OHS Guideline G5.54-1.

The purpose of health monitoring is to protect workers from developing occupational disease by detecting biological indicators or adverse health effects at an early stage. Action can then be taken to prevent, reverse, reduce the severity, or arrest the progression of the adverse health effect or disease. Biological Action Values (BAV) for biological indicators are established by the Board, based on current information and are reviewed periodically. For further information, consult the occupational physicians of WorkSafeBC.

Health monitoring should be considered when

there is reasonable likelihood of a workplace exposure,
the exposure can potentially cause an occupational disease or adverse health effect, or
there is a means of detecting or measuring the disease, adverse health effect or its precursor or biological indicator.

The results of health monitoring are also useful in evaluating the effectiveness of the exposure control plan, particularly when it cannot be evaluated by exposure monitoring alone. This occurs when

the skin or the gut are significant routes of absorption,
the skin itself may be affected by contact exposure, or
exposure control is dependent on the use of personal protective equipment.

The skin and gut could be significant routes of exposure if the skin is in direct contact with a contaminant or if the contaminant is ingested and absorbed into the gut.

Biological monitoring of a substance, its metabolite or its biological effect can be a component of health monitoring. An appropriate biological indicator is one that can be detected before disease or an adverse health effect occurs. Preventive action can then be taken as required. Before undertaking biological monitoring, the following criteria regarding the biological test should be met. The test should

specifically assess the exposure or the effect,
be sufficiently sensitive to detect occupational exposure levels and effects,
vary quantitatively with the intensity of exposure and the risk of development of adverse effects,
provide more information on potential health risk than can be obtained from exposure monitoring alone,
be as non-invasive as possible,
be readily available and not be too time-consuming, complex or expensive,
be measured by analytical techniques which are accurate, specific and sensitive, and
have minimal storage and transport limitations.

Substances for which the Board considers health monitoring may be appropriate include, but are not limited to

lead,
cadmium,
mercury,
respiratory sensitizers (such as cedar dust or isocyanates),
4,4'-methylene bis[2-chloroaniline] or MOCA, and
organophosphate compounds.

Health monitoring does not necessarily entail sophisticated testing, requiring medical or nursing personnel. Although setting up a health monitoring system is best done by an occupational health physician or nurse, its day-to-day functioning can often be managed by a qualified person, such as an occupational hygienist or health and safety manager. For some substances, health monitoring may only require an early reporting system linked with periodic inquiries about signs and symptoms, self-checks (such as examination of the skin for signs of sensitivity) by a lay person such as a first aid attendant or supervisor). When biological or biological effect monitoring is necessary, the services of appropriate medical, nursing or technical personnel may be required for ordering tests and taking samples. A physician or nurse must interpret the results.

Health, biological and biological effect monitoring should only be carried out with the informed consent of the worker. The individual should be advised of the purpose of the tests and biological samples should be analyzed only for the substances or effects for which consent has been obtained. Informed consent should ensure that the worker is made aware of any consequences that might occur if the results of the monitoring indicate that exposure should be reduced.

Personal results of health monitoring, as well as their interpretation, should be given to individual workers. Unless the worker's written informed consent for release is obtained, only categorical results (such as a range of values rather than specific measurement values) should be released to any person other than the individual or the worker's family physician). Both the worker and the employer should be advised about the worker's fitness to work, along with any work restrictions or recommended health and safety precautions.

Records concerning health, biological and biological effect monitoring should be kept and maintained in a form, which is easily linked to job and exposure records, while still observing the rules of confidentiality.

Although this section does not stipulate the period of time that records must be retained, they should be kept as long as practicable. This is especially important for identifying and assessing work-related health changes associated with changes over time in work processes, practices or control measures, as well as for detecting occupational diseases with delayed onset. In terms of confidentiality, standard guidelines and current accepted practice of regulatory bodies and recognized occupational health organizations should be followed. These include, for example, the Royal College of Physicians and Surgeons, the Canadian Medical Association, the British Columbia Medical Association, the Occupational and Environmental Medicine Association of Canada, and the American College of Occupational and Environmental Medicine. Employers, in conjunction with worker health and safety representatives and occupational health personnel, should develop written policy regarding confidentiality. This policy, as well as any monitoring records, should be reviewed periodically.

Health monitoring programs should be reviewed and re-evaluated on a regular basis, and when

there is a change in work processes or substance usage,
there is a significant change in the results of air monitoring, where a significant change may indicate either that the exposure limit is being exceeded or that control measures are keeping exposure levels below 50% of the exposure limit,
signs or symptoms of occupational ill health are reported and investigated, as required by section 5.59 of the OHS Regulation, or
results of biological or biological effect monitoring exceed recommended limits.

G5.54-6 Documentation

Issued August 1999; Editorial Revision February 1, 2008

Regulatory excerpt
Section 5.54(2)(g) of the OHS Regulation ("Regulation") states:

(2) The exposure control plan must incorporate the following elements:
(g) documentation, when required.

Purpose of guideline
The purpose of this guideline is to specify when documentation is specifically required under certain sections.

Documentation
Section 5.54(2)(g) provides that the exposure control plan must incorporate "documentation, when required." Documentation is specifically required under certain sections. Some examples include

Section 6.4 of the Regulation - inventory of asbestos-containing materials
Section 6.32 - records of asbestos-containing materials inventories and risk assessments, inspections, and air monitoring results
Section 6.34(1) - records of all workers who have occupational exposure, as defined in section 6.33

Documentation is also required under section 5.2 and whenever workplace monitoring is conducted under section 5.53.

G5.54-7 Drywall sanding requirements

Issued June 14, 2002; Revised February 11, 2004; Editorial Revision June 6, 2007

Regulatory excerpt
Section 5.54(1) of the OHS Regulation ("Regulation") states:

An exposure control plan must be implemented when
(a) exposure monitoring under section 5.53(3) indicates that a worker is or may be exposed to an air contaminant in excess of 50% of its exposure limit,

(b) measurement is not possible at 50% of the applicable exposure limit, or

(c) otherwise required by this Regulation.

Purpose of guideline
The purpose of this guideline is to clarify how Part 5 of the Regulation should be applied to control workers' exposure to the hazard of dust from drywall sanding operations. It includes a sample exposure control plan to assist the drywall installation industry in meeting the requirements of section 5.54(2) of the Regulation.

Background
Workers sanding drywall filler compounds are exposed to large amounts of fine dust. Depending on the supplier, drywall filler compounds contain calcite, gypsum, mica, kaolin, perlite, talc, and silica and may contain trace amounts of crystalline silica, a designated substance (see section 5.57 of the Regulation). WorkSafeBC has evaluated the dust exposures typically experienced by drywall sanders in a variety of workplaces, from wood frame residential construction to concrete high-rise construction, during both pole-sanding and hand-sanding activities. This evaluation found that drywall sanders are exposed to high dust levels, typically up to 8 times the exposure limit for "Particles (Insoluble or Poorly Soluble) not otherwise Classified (PNOC)" in the Table of Exposure Limits for Chemical and Biological Substances (see OHS Guideline G5.48-1). These results are consistent with research reports from other agencies.

Workers' exposure to crystalline silica from drywall sanding was found to be typically at or below the detection limit for crystalline silica (less than 0.02 mg/m³). Bulk samples of the various drywall filler compounds analyzed by WorkSafeBC all contained less than 1% crystalline silica. PNOC applies to dusts that contain no asbestos, contain less than 1% crystalline silica, and are known not to produce significant organic disease or toxic effect when exposures are maintained under reasonable control.

Application of the Regulation
Section 5.54(1)(a) of the Regulation requires an exposure control plan for drywall sanding operations as WorkSafeBC has established that workers involved in such operations are routinely overexposed to PNOC. The 8-hour TWA limit for PNOC as total dust is 10 mg/m³. The substance also has an 8-hour TWA limit of 3 mg/m³ for the respirable fraction of the dust.

Section 5.55 of the Regulation requires control measures to minimize or eliminate workers' exposure to airborne contaminants. The following "hierarchy of controls" is listed with substitution as the most preferable option and personal protective equipment as the least preferable (see OHS Guideline G5.55 for additional information):

Substitution
Engineering controls
Administrative controls
Personal protective equipment (PPE)

Substitution means replacing the substance of concern with a less harmful substance. For drywall filler compounds, crystalline silica would be the one substance of concern for elimination by substitution. Substitution would mean finding a filler compound with no crystalline silica content. The presence of crystalline silica in filler compounds is the result of small amounts present in the raw materials used in the manufacture of the drywall filler. Although manufacturers can specify raw material with the lowest amount of contamination with crystalline silica, achieving a product that is totally free of crystalline silica content is not feasible. Substitution with a product that requires no sanding or produces less dust would be ideal from a business and health perspective; however, no such product has yet been developed.

WorkSafeBC has reviewed control options and recognizes the following:

Local exhaust ventilation, such as the use of a high velocity/low volume extraction system attached to a sander, is not considered a viable option at this time. This is based on the findings of a joint WorkSafeBC/industry committee that the desired quality of finish required for prepping walls to be painted cannot be achieved by the present technology.
Wet sanding is not considered a viable option at this time. It wets the drywall paper and the desired quality of finish for large, new wall assemblies cannot be achieved. However, wet sanding may be viable for small touch-up jobs in dust-sensitive areas such as finished offices, computer labs, and clean rooms.
Respiratory protection is a viable option to control worker exposure to drywall sanding dust at this time.

The minimum respiratory protective device acceptable to WorkSafeBC for PNOC is a half-facepiece respirator fitted with N95 particulate filters or an N95 filtering facepiece respirator, having a minimum assigned protection factor of 10 (NIOSH TC-84A-xxx approvals only, where xxx is the assigned approval number). See also OHS Guideline G8.33(2)-1 for a list of other acceptable filtering facepiece respirators Only those respirators capable of being seal checked and/or fit tested, as applicable, are to be selected.

WorkSafeBC recognizes respiratory protection as the only current viable option for controlling exposure with the following conditions:

The industry is expected to actively investigate and evaluate the suitability of new technologies and methods for drywall installation and finishing as they become available. If suitable equipment or methods are found to lower worker exposure to drywall sanding dust, it is expected the industry will adopt the new technology or method(s). This is as required by section 5.55 of the Regulation.
The use of respiratory protection is to be accompanied by the use of other available control measures as follows:
- Restricting access to the drywall sanding area to the personnel required for the sanding operation.
- Posting signs at the access routes to the drywall sanding area stating:
  - Entry to the area is restricted to authorized personnel
  - A warning to unprotected workers of the hazards
  - Precautions for entering the area
  - For example, a sign stating "Authorized Personnel Only, Drywall sanding operation in process, Respiratory protection required" would be acceptable.
- Scheduling the entry of workers who do not have respiratory protection (such as workers delivering materials or inspecting the area) to times when the airborne dust levels will be at their lowest, for example at the start of a shift or after a break. Workers without respiratory protection will be limited to a brief exposure to the hazardous area, such as a few minutes a few times each shift.
- Training workers in the hazards and control measures associated with drywall sanding.
- Coordinating with other sub-trades and the prime contractor on-site to minimize the need for workers not directly involved in the drywall sanding operation to be near the dust hazard area.
- Providing wash-up facilities for workers to wash dust off their hands and face before meal breaks and at the end of the shift.
- Arranging for workers to change to clean clothing upon completion of their sanding task so they do not wear dust-contaminated clothing in other work areas.

Sample Exposure Control Plan for Drywall Sanding

Purpose and Responsibilities

This plan provides direction to the supervisors and workers of ______________________________________________________________
on the company's policies and procedures for drywall sanding operations. It covers all standard work practices including the use of pole sanders, sanding sponges, and hand-held sanding blocks for sanding of joints, corners, and seams where drywall filler compounds have been applied.

The employer is responsible for the following:

Providing a job-specific exposure control plan (ECP) for each project to deal with the hazards and risks associated with sanding operations
Reviewing periodically the effectiveness of the ECP, which may require sampling of worker exposure levels to drywall filler dust when there are significant changes in exposure conditions during non-standard work practices
Ensuring that personal protective equipment is readily available and used and mechanical ventilation equipment is provided and used where deemed necessary
Ensuring supervisors and workers are educated and trained to an acceptable level of competency
Maintaining records of training, fit-test results, crew talks, and inspections
Coordinating the work with the prime contractor and other employers to ensure a safe work environment

The supervisor is responsible for the following:

Providing adequate instruction to workers on the hazards associated with drywall sanding and on the precautions specified in the job-specific plan covering hazards at the location
Selecting and implementing the appropriate control measures
Ensuring that workers using respirators have been properly fit-tested and that the results are recorded
Directing the work in a manner that ensures the risk to workers is minimized and adequately controlled
Liaising with the prime contractor and other sub-contractors to ensure a safe work environment

The worker is responsible for the following:

Using the assigned protective equipment in an effective and safe manner
Setting up the operation in accordance with the site-specific plan
Following established work procedures as directed by the supervisor
Reporting any unsafe conditions or acts to the supervisor

Risk Identification and Assessment

Drywall taping compounds may contain calcite, gypsum mica, kaolin, perlite, talc, and silica. Most of these substances do not have individual component or specific exposure limits. Evaluations conducted by WorkSafeBC and the National Institute for Occupational Safety and Health (NIOSH) have found that the exposure of drywall sanders to crystalline silica is less than posted exposure limits and mostly at or below the detection limit. Dusts without established exposure criteria are called "Particles (Insoluble or Poorly Soluble) Not otherwise Specified (PNOC)". The general criteria for these dusts is that they contain no asbestos, have less than 1% crystalline silica, and are known not to produce significant organic disease or toxic effect when exposures are maintained under reasonable control.

The exposure control requirements for drywall sanding are to address the hazard of PNOC concentration. An 8-hour TWA limit of 10 mg/m³ for total dust and 3 mg/m³ for respirable dust applies to drywall dust. WorkSafeBC evaluation of worker exposure to dust from drywall filler sanding operations has determined 80% of the exposures are above the 8-hour TWA limit of 10 mg/m³ for PNOC. The PNOC exposure levels can be as much as 8 times the 8-hour TWA limit.

Control Options

Company policy is to use the following control options to eliminate or reduce the risk to workers from the hazard of drywall sanding dust exposure. Every effort will be made to ensure the need to sand is reduced or minimized in the taping and filling stages of drywall installation. Care in and use of proper and appropriate filling procedures, methods, and practices will reduce the need to sand out joint compounds. If sanding is required, the following hierarchy of control measures needs to be considered:

Engineering control options: A combination of local and general ventilation systems
Administrative control options: Pole sanding or wet sanding when practicable

NOTE: Wet sanding of large, new wall assemblies is not considered a viable option; however, it may be practicable for small touch-ups in dust-sensitive areas such as finished offices, computer labs, and clean rooms.

Personal protective equipment (PPE):
- The minimum respiratory protective device for use in drywall sanding is a half-facepiece respirator fitted with N95 particulate filters or a particulate facepiece N95 respirator (NIOSH TC-84A-xxx approvals only, where xxx is the assigned approval number). Only those respirators capable of being seal checked or fit tested will be selected.
Coveralls

A combination of the above control options should be considered to ensure maximum protection for workers.

In addition, consideration must be given to the following:

Restricting access to the sanding area.
Posting all access routes to the designated sanding area with signs warning unprotected workers of the hazards, listing precautions for entering the area, and restricting the area to authorized personnel only. (Signs stating "Authorized Personnel Only, Drywall sanding operation in process, Respiratory protection required" are acceptable.)
Coordinating with the prime contractor and other sub-trades to ensure other workers on-site are not placed to do work in the dust hazard area.
Scheduling the entry of workers who do not have respiratory protection (such as workers delivering materials or inspecting the area) to times when the airborne dust levels will be at their lowest, for example at the start of a shift or after a break. Workers without respiratory protection will be limited to a brief exposure to the hazardous area, such as a few minutes a few times each shift.

Education and Training

Workers and supervisors involved in drywall filler sanding will be educated and instructed in the health hazards associated with the sanding operations and will be trained in the operation and use of the sanding equipment and control measures, including the safe use, limitations, and maintenance of the respiratory protection used.

Written Work Safety Procedures

The following written procedures will be made available on-site for the direction of workers:

A site-specific exposure control plan (such as this document, modified accordingly with site-specific requirements)
Specific instructions when any engineering control options are used to supplement the required personal protective equipment (such as use and maintenance of local exhaust ventilation systems; proper set-up of general ventilation such as pedestal fans)
Respirator instructions provided by the supplier (manufacturer's booklet)
Respiratory protection program (see Regulation Part 8 and WorkSafeBC's Breathe Safer manual)

Hygiene Practices and Cleanup Procedures

All workers sanding drywall filler compounds are to change into coveralls or work clothes in a "clean area."

Workers will have and use facilities for washing of their hands and face before meal breaks and at the end of each shift.

Health Monitoring

Workers will promptly report any symptoms of exposure to the job site first aid attendant and their supervisor for further investigation.

Documentation

The company will keep records of the instruction and training provided to workers, respirator fit-test records, any related crew talks, and any reported unsafe conditions or deficiencies noted in workplace inspections or reported to the supervisor on the site.

Annual Review

The employer will undertake, on an annual basis, the following:

Evaluation of the control options and work procedures used
Evaluation of any new technologies and methods that have come onto the market
Review of first aid reports and any reported health-related symptoms
Review of documentation for training and education
Review of the respirator program

The annual review will be done in consultation with the joint health and safety committee, and/or worker health and safety representative, if applicable.

G5.55 Type of controls

Issued August 1, 1999; Revised February 11, 2004

Section 5.55 of the Occupational Health and Safety Regulation states:

Section 5.55 of the OHS Regulation requires that control measures be implemented to eliminate the exposure or control it below harmful levels and below the applicable exposure limit established under section 5.48. Those limits are available in the Table of Exposure Limits for Chemical and Biological Substances (see OHS Guideline G5.48-1).

Other useful sources of information in making the determination of a potentially harmful level include the MSDS, supplier's recommendations, and reference literature, such as the Documentation of Threshold Limit Values and Biological Exposure Indices published by the ACGIH.

Acceptable control options include substitution, engineering control, administrative control, and personal protective equipment. Good occupational hygiene practice considers this to be the "hierarchy of controls." That is, substitution is the most preferable option and personal protective equipment is the least preferable.

Section 5.55(2) requires that, when selecting a substitute, the employer ensure that the hazards of a substitute are known and that the risk to workers is reduced by its use. Factors that should be considered in selecting a suitable substitute include:

The exposure limit
Route(s) of exposure
Acute and chronic effects
Warning properties
Flammability or other hazards
Work procedures
Training and supervision required

The only circumstances under which WorkSafeBC would consider personal protective equipment to be a primary means of control are when the conditions of section 5.55(3) are met. Section 5.55(3)(b) permits the use of respirators when engineering or administrative controls are insufficient to reduce exposure below the exposure limit (for example, while sandblasting in a booth). In section 5.55(c), the term "emergency conditions" includes leaks, rescue situations, or repair efforts when controls break down. The definition of "temporary" is provided in section 5.1 of the OHS Regulation.

G5.56 Oxygen deficiency

Issued August 1, 1999

Section 5.56 of the OHS Regulation requires that the airborne concentration of any gas or vapour be controlled to ensure that a worker is not exposed to an oxygen deficient atmosphere. An oxygen deficient atmosphere is one in which the concentration of oxygen is below that required to sustain normal respiration. The process of respiration includes breathing, as well as the exchange of oxygen and carbon dioxide (between the lungs and the blood and also between the blood and tissues).

At standard pressure and temperature, atmospheric air at sea level contains 20.95% oxygen. This atmosphere is oxygen deficient at concentrations of oxygen of 19.5% or less. The IDLH (immediately dangerous to life or health) concentration of oxygen in atmospheric air at sea level is 14%. At 3660 metres (10,000 feet) above sea level, the IDLH concentration of oxygen is 20.9% Further information on oxygen deficient atmospheres is found in WorkSafeBC publications "Breathe Safer" and "Confined Space Entry Program: A Reference Manual." See also the definitions for "oxygen deficient" and "IDLH" in section 1.1 of the OHS Regulation.

Section 5.56 also lists some examples of gases that can cause an oxygen deficient atmosphere. Because some of these gases are flammable, the requirements of sections 5.27 and 5.31 also apply.

G5.57 Designated substances

Issued August 1, 1999; Revised February 11, 2004; Revised February 4, 2005; Revised January 1, 2009

Regulatory excerpt
Section 5.57 of the OHS Regulation ("Regulation") states:

(1) If a substance identified as any of the following is present in the workplace, the employer must replace it, if practicable, with a material which reduces the risk to workers:

(a) ACGIH A1 or A2, or IARC 1, 2A or 2B carcinogen;

(b) ACGIH reproductive toxin;

(c) ACGIH sensitizer;

(d) ACGIH L endnote.

(2) If it is not practicable to substitute a material which reduces the risk to workers, in accordance with subsection (1), the employer must implement an exposure control plan to maintain workers' exposure as low as reasonably achievable below the exposure limit established under section 5.48.

(3) The exposure control plan must meet the requirements of section 5.54.

Purpose of guideline
Section 5.57(1) requires that designated substances be replaced or substituted, whenever practicable, with a less hazardous material, and if that is not practicable, measures must be taken to keep a worker's exposure to a level as low as is reasonably achievable.

The purpose of this guideline is to provide background information on the designations for carcinogenicity, reproductive effects, sensitization, and L endnotes as referenced in section 5.57(1), and to describe factors to consider when determining the practicability of using substitute materials.

Section 5.57(1)(a): Carcinogenic substances - ACGIH and IARC notations

The ACGIH (American Conference of Governmental Industrial Hygienists) and IARC (International Agency for Research on Cancer) notations for carcinogens are defined as follows:

ACGIH "A1" applies to those substances confirmed as human carcinogens based on the weight of evidence from epidemiological studies.
ACGIH "A2" applies to those substances that are considered suspected human carcinogens.
IARC "1" applies to substances categorized as carcinogenic to humans, and used when there is sufficient evidence of carcinogenicity in humans.
IARC "2A" applies to substances deemed probably carcinogenic to humans on the basis of limited evidence of carcinogenicity in humans.
IARC "2B" applies to substances deemed possibly carcinogenic to humans.

For additional information on the background and rationale for the different categories of carcinogens, refer to the current edition of the ACGIH's Threshold Limit Values and Biological Exposure Indices ("TLV Booklet"), the current edition of the ACGIH's Documentation of TLVs and BEIs, and the current publications of IARC's Overall Evaluations of Carcinogenicity to Humans. Both agencies provide information on their web sites

ACGIH can be found at http://www.acgih.org
IARC can be found at http://www.iarc.fr/

Section 5.57(1)(b): ACGIH reproductive toxins
ACGIH reproductive toxins are noted by the letter "R" in the notations column of the Table of Exposure Limits for Chemical and Biological Substances.

Substances designated by the ACGIH as reproductive toxins have the potential for causing adverse reproductive effects on female and male reproductive organs, tissues, or cells; on fertility; on the embryo or fetus; and may result in developmental abnormalities; tumours; and adverse effects on the newborn. If the toxin's reproductive hazards form the basis of the TLV, then this will be noted in the "TLV® Basis" column in ACGIH's annually updated TLV Booklet, commonly known as the "TLV booklet." Epichlorohydrin is an example of such a substance. For ACGIH reproductive toxins that do not form the basis of the TLV, refer to the ACGIH publication Documentation of TLVs and BEIs for additional information regarding the potential for adverse reproductive effects.

Section 5.57(1)(c): ACGIH sensitizers
ACGIH sensitizers are identified by the letter "S" in the notations column of the Table of Exposure Limits for Chemical and Biological Substances.

This provision refers to substances that have been designated by ACGIH as having a sensitization effect. The ACGIH identifies sensitizers in several ways. The designation "SEN" in the "Notations" column of ACGIH's annually updated TLV booklet, refers to the potential for a substance to produce sensitization as confirmed by human or animal data. Methyl methacrylate is an example of such a substance. For some substances, such as isophorone diisocyanate and natural latex rubber, the ACGIH determined that the sensitization effect of these substances is a primary determining factor on which the TLV is based. These substances are identified as entries in the "TLV® Basis" column of the TLV booklet. For other substances identified as sensitizers that do not meet ACGIH's SEN or TLV® Basis criteria, refer to the ACGIH publication Documentation of TLVs and BEIs for additional information regarding the potential for sensitization. Diethylene triamine is an example of such a substance.

The "S" notation in the Table of Exposure Limits for Chemical and Biological Substances covers all ACGIH-identified sensitizers.

For a substance with a TLV based on sensitization, the TLV is meant to protect workers from becoming sensitized to the substance. However, it is not intended to and likely will not protect those workers who have already become sensitized.

Depending on the substance, workers can become sensitized to the substance through the respiratory system, the skin, or the eyes. Sensitization often involves a response by the body's immune system. Initially, there may be little or no response to a sensitizing substance. However, after a person is sensitized, subsequent exposure may cause severe reactions even at low exposure concentrations, including at levels below the exposure limit.

Section 5.57(1)(d): L endnote
The "L" endnote appears for some substances in the "TWA" column of the Table of Exposure Limits for Chemical and Biological Substances. "L" is defined as "exposure by all routes should be carefully controlled to levels as low as possible." WorkSafeBC uses this notation primarily for substances considered highly toxic, and which have not been assigned a TLV. Examples of substances in this category include benzo(a)pyrene, chrysene, and rosin core solder thermal decomposition products (colophony).

Substitution
Section 5.57(2) prescribes that if substitution is not practicable for those substances listed in subsection (1), the employer must implement an exposure control plan to ensure a worker's exposure is kept as low as reasonably achievable to levels below the exposure limit. As indicated by section 5.57(3), the exposure control plan must meet the requirements of section 5.54.

In selecting a suitable substitute, the employer is not expected to pursue substitutes for materials that are essential or integral to the product or process. Nevertheless, the employer is required to meet the requirements of sections 5.48 and 5.57(2) and (3).

To evaluate compliance with section 5.57, the following questions should be considered:

Is the substance essential or integral to the process?
Are alternative materials available?
Are the alternatives practicable?
Are the hazards of the alternative known?
Is the risk to the worker reduced by the alternative?

Refer to OHS Guidelines G5.54-1 to G5.54-3 for further information on expectations for exposure control plans.

Also note that section 5.57 establishes requirements only for substances with the specified designations in the notations column of the Table of Exposure Limits for Chemical and Biological Substances. As discussed above, for carcinogens, those designations are based on two authorities, ACGIH and IARC. For substances with sensitization and adverse reproductive effects, the designations are based on ACGIH.

Given the limits to the currency and completeness of information on these effects when based on such lists, the designations in the Table may not reflect currently available information on such effects that may be found, for example, on updated MSDS used in the workplace. To address such matters the Regulation also requires, under the provisions of Part 5, the use of such updated information in assessing adverse health effects and establishing safe work procedures.

G5.58 Protective policy

Issued August 1, 1999; Revised October 29, 2003; Editorial Revision October 2004; Editorial Revision January 1, 2009

Regulatory excerpt
Section 5.58 of the OHS Regulation ("Regulation") states:

(1) At any worksite where a worker is exposed to a substance which is identified in section 5.57(1) as an ACGIH reproductive toxin or an ACGIH sensitizer, the employer must develop policy and procedures appropriate to the risk, which may include protective reassignment.

(2) The policy and procedures required by subsection (1) must

(a) inform workers about the reproductive toxin and identify ways to minimize exposure to the toxin for a worker who has advised the employer of pregnancy or intent to conceive a child, and

(b) identify ways to eliminate or minimize exposure to a sensitizer for a worker who is or may be sensitized to that substance.

Purpose of guideline
The purpose of this guideline is to provide additional information about protective reassignment and exposure control plans.

Protective policy
The policy and procedures may include protective reassignment, meaning that a worker may be relocated from a high-risk to a low-risk work area, based on the risk assessment carried out for the exposure potential.

"Exposure" or routes of exposure in this section include inhalation, ingestion, and skin absorption. The policy and procedures must be appropriate to the level of risk. Since exposure levels to substances exhibiting reproductive and sensitization toxic effects must be kept as low as reasonably achievable, section 5.57(2) of the Regulation requires that an exposure control plan be implemented. For example, at a given level of exposure in the workplace, the risk may be minimal. In this case, a policy that informs workers about the material and its reproductive toxicity or sensitizing capability may be all that is required. For further guidance, contact WorkSafeBC.

G5.59 Investigating symptoms

Issued August 1, 1999

Under section 5.59(1) of the OHS Regulation, the potential for exposure must be investigated and assessed when a worker exhibit signs or report symptoms of overexposure to a harmful substance present in the workplace. Where signs or symptoms are shown to be associated with workplace exposure, section 5.59(2) requires further investigation to address and resolve the worker's concern. The employer must consult with the occupational health and safety committee, if any, or worker health and safety representative, if any. These requirements are consistent with sections 3.9 and 3.10 of the OHS Regulation, which provide that hazardous conditions must be investigated and remedied without delay.

The investigation of symptoms should include an initial review of hazardous substances present in the workplace with an emphasis on those materials that the worker(s) exhibiting signs or symptoms of overexposure are exposed to. For controlled products controlled under the Hazardous Products and the Controlled Products Regulation, this would mean a review of the material safety data sheets to identify the hazardous ingredients and toxicological properties. For complaints associated with indoor air quality (see OHS Regulation G4.79), fugitive emissions, intermediate reaction products or environmental contaminants, exploratory air sampling may have to be conducted to identify the contaminant. Once the hazardous substance(s) are identified, the employer should consider the symptoms workers are experiencing to determine if there is a relationship between the symptoms and the exposure. One should consider not only consider the substance, but also the circumstances that give rise to the exposure. If a relationship is found, then a further investigation should be conducted to identify a means of controlling the hazard. When identifying a means of controlling the hazards, the requirements of section 5.55 of the OHS Regulation apply.

Section 5.59(3) requires that the investigation be documented, that records are made available to workers and that records are maintained for a minimum of 10 years. The records should include the following information:

the signs or symptoms of reported overexposure,
the harmful substance(s) considered in the investigation,
the relationship (if any) between the reported symptoms and exposure to the harmful substance(s) investigated,
workplace conditions considered (i.e., locations, tasks, process conditions), and
any action(s) taken to control the hazard(s).

Table of Exposure Limits for Chemical and Biological Substances

Explanation of table headings
Table of Exposure Limits
* Download PDF version (77 KB) of the table.

Explanation of table headings

Substance [CAS No.]

Lists chemicals and other substances in alphabetical order. Numerals and prefixes, for example, 1,3-, tert-, o-, sec-, cis-, are disregarded in determining alphabetical order.
In square brackets is the Chemical Abstracts Services (CAS) registry number. This is a unique identification number assigned specifically to that substance, and can be a convenient way to identify substances.
WorkSafeBC reviews and updates this Table annually. If the exposure limit for a substance has been revised or newly adopted since January 1, 2003 this Table reports the change with the words "Revised (year)." Each year, newly included substances and amended substances are highlighted. Recent deletions of substances from the Table are shown as strike through (e.g. ~~Emery~~).
Additional explanation about this table is available at G5.48-2 Annual revisions to exposure limits.

TWA
This is the 8-hour time weighted average (TWA) limit, as defined in section 5.1 of the OHS Regulation.

Units: Exposure limits are reported in ppm, mg/m³, or f/cc. In general, substances present in air as a vapour or gas are reported in parts per million (ppm). Substances present in air as an aerosol (dust, fume, mist) and mixtures such as diesel fuel are typically reported in milligrams per cubic metre (mg/m³). See OHS Guideline G5.48-4 for a procedure to convert from one type of unit to the other. Fibrous substances, such as synthetic vitreous fibres (e.g., glass wool fibres) are reported in fibres per cubic centimetre (f/cc). This is equivalent to fibres per millilitre, or f/ml, which is another common term.
Endnotes: Letters in parentheses indicate endnotes, which are explained at the end of the table. Substances which have an "L " endnote are subject to section 5.57 (Designated substances) of the OHS Regulation. For more information see OHS Guideline G5.57.

STEL
This is the short-term exposure limit or STEL, which is defined in section 5.1 of the OHS Regulation. Note that:

"C" indicates a ceiling limit, which is defined in section 5.1 of the OHS Regulation.
The units ppm and mg/m³ are used as in the TWA column.
In some cases, the term "simple asphyxiant " is used. This is a gas or vapour that can displace oxygen in the air, resulting in possible suffocation from lack of oxygen. Because simple asphyxiants do not have other significant toxic effects, an exposure limit is not applicable. The limiting factor is the available oxygen. See section 5.56 of the OHS Regulation (Oxygen deficiency).

Notations
The notations identify substances considered to be carcinogens, sensitizers and those with adverse reproductive effect under section 5.57 of the OHS Regulation. Section 5.57 deals with requirements for substitution and keeping exposure as low as reasonably achievable below the exposure limit. The notations column also indicates substances that contribute significantly to overall exposure by the skin route, in which case section 5.52 of the OHS Regulation applies. Note that:

ACGIH notations A1 and A2 and IARC notations 1, 2A and 2B indicate substances designated as carcinogens under section 5.57(1) of the OHS Regulation. The different categories used by the two organizations indicate different levels of certainty of carcinogenic effect, eg. from confirmed carcinogen to probable or possible. For more information see OHS Guideline G5.57.
The letter "S" indicates that the substance is a sensitizer under section 5.57(1) of the OHS Regulation. For more information see OHS Guideline G5.57.
The letter "R" means that the substance has an adverse reproductive effect under section 5.57(1) of the OHS Regulation. For more information see OHS Guideline G5.57.
The term "Skin" identifies substances that contribute significantly to the overall exposure by the skin route. For more information see OHS Guideline G5.52.

Table of Exposure Limits for Chemical and Biological Substances

October 23, 2009

Substance [CAS No.]	TWA	STEL	Notations
Substance [CAS No.]	TWA	STEL/Ceiling	Notations
Abate (See Temephos)
Acetaldehyde [75-07-0]		C 25 ppm	2B
Acetamide [60-35-5]			2B
Acetic acid [64-19-7]	10 ppm	15 ppm
Acetic anhydride [108-24-7]	5 ppm
Acetone [67-64-1]	250 ppm	500 ppm
Acetone cyanohydrin [75-86-5]		C 1ppm	Skin
Acetonitrile [75-05-8]	20 ppm		Skin
Acetophenone [98-86-2]	10 ppm
Acetylene [74-86-2]		Simple asphyxiant
Acetylene tetrabromide (See 1,1,2,2 Tetrabromoethane)
Acetylsalicylic acid (Aspirin) [50-78-2]	5 mg/m³
Acrolein [107-02-8]		C 0.1 ppm	Skin
Acrylamide, Inhalable [79-06-1] Revised 2005	0.03 mg/m³ (V)		Skin; 2A
Acrylic acid [79-10-7]	2 ppm		Skin; R
Acrylonitrile [107-13-1]	2 ppm		Skin; 2B
Adipic acid [124-04-9]	5 mg/m³
Adiponitrile [111-69-3]	2 ppm		Skin
Alachlor, Inhalable [15972-60-8] Revised 2007	1.0 mg/m³ (V)		S
Aldrin, Inhalable [309-00-2] Revised 2007	0.05mg/m³ (V)		Skin
Aliphatic hydrocarbon gases [C1-C4] Revised 2004	1000 ppm
Allyl alcohol [107-18-6]	0.5 ppm		Skin
Allyl amine [107-11-9]	2 ppm
Allyl chloride [107-05-1]	1 ppm	2 ppm
Allyl glycidyl ether [106-92-3]	1 ppm		S
Allyl propyl disulfide [2179-59-1] Revised 2006	0.5 ppm		S
Aluminum metal and insoluble compounds [7429-90-5] , Respirable, Revised 2008	1.0 mg/m³
4-Aminodiphenyl [92-67-1]	(L)		Skin; A1, 1
2-Aminopyridine [504-29-0]	0.5 ppm
Amitrole [61-82-5] Revised 2006	0.2 mg/m³		R
Ammonia [7664-41-7]	25 ppm	35 ppm
Ammonium chloride - Fume [12125-02-9]	10 mg/m³	20 mg/m³
Ammonium perfluorooctanoate [3825-26-1]	0.01 mg/m³		Skin
Ammonium sulfamate [7773-06-0]	10 mg/m³ (N)
tert-Amyl methyl ether (TAME) [994-05-8]	20 ppm		R
Aniline [62-53-3]	2 ppm		Skin
o-Anisidine [90-04-0]	0.5 mg/m³		Skin; 2B
p-Anisidine [104-94-9]	0.5 mg/m³		Skin
Antimony and compounds, as Sb [7440-36-0]	0.5 mg/m³
Antimony hydride (Stibine) [7803-52-3]	0.1 ppm
Antimony trioxide - Production [1309-64-4]	(L)		A2; 2B
ANTU [86-88-4]	0.3 mg/m³
Argon [7440-37-1]		Simple asphyxiant
Arsenic and inorganic compounds, as As [7440-38-2]	0.01 mg/m³		A1, 1
Arsine [7784-42-1] Revised 2007	0.005 ppm
Asbestos - All forms [1332-21-4]	0.1 f/cc (F)		A1, 1
Asphalt (Bitumen) fume, as benzene-soluble aerosol, Inhalable [8052-42-4]	0.5 mg/m³		2B
Atrazine [1912-24-9]	5 mg/m³
Azinphos-methyl, Inhalable [86-50-0]	0.2 mg/m³ (V)		Skin; S
Barium and soluble compounds, as Ba [7440-39-3]	0.5 mg/m³
Barium sulfate [7727-43-7]	10 mg/m³ (N)
Benomyl, Inhalable [17804-35-2] Revised 2008	1 mg/m³		R, S
Benz[a]anthracene [56-55-3] Revised 2006	(L)		A2, 2B
Benzene [71-43-2]	0.5 ppm	2.5 ppm	Skin; A1, 1
Benzidine [92-87-5]	(L)		Skin; A1, 1
Benzidine based dyes			2A
Benzo[b]fluoranthene [205-99-2]	(L)		A2, 2B
Benzo[a]pyrene [50-32-8] Revised 2006	(L)		A2, 1
Benzotrichloride [98-07-7]		C 0.1 ppm	Skin; A2, 2A
Benzoyl chloride [98-88-4]		C 0.5 ppm	2A
Benzoyl peroxide [94-36-0]	5 mg/m³
Benzyl acetate [140-11-4]	10 ppm
Benzyl chloride [100-44-7]		C 1 ppm	2A
Beryllium and compounds, as Be, Inhalable [7440-41-7] Revised 2009	0.00005 mg/m³		Skin; S, A1, 1
Biphenyl [92-52-4]	0.2 ppm
Bis(2-dimethylaminoethyl) ether (DMAEE) [3033-62-3]	0.05 ppm	0.15 ppm	Skin
Bismuth telluride - Se-doped [1304-82-1]	5 mg/m³
Bismuth telluride - Undoped [1304-82-1]	10 mg/m³ (N)
Borate compounds, Inorganic, Inhalable [1303-96-4; 1330-43-4; 10043-35-3; 12179-04-3] Revised 2005	2 mg/m³	6 mg/m³
Boron oxide [1303-86-2]	10 mg/m³
Boron tribromide [10294-33-4]		C 1 ppm
Boron trifluoride [7637-07-02]		C 1 ppm
Bromacil [314-40-9]	10 mg/m³
Bromine [7726-95-6]	0.1 ppm	0.2 ppm
Bromine pentafluoride [7789-30-2]	0.1 ppm
Bromochloromethane [74-97-5]	200 ppm	250 ppm
Bromoform [75-25-2] Revised 2009	0.5 ppm
1-Bromopropane [106-94-5] Revised 2005	10 ppm		R
1,3-Butadiene [106-99-0]	2 ppm		A2, 1
n-Butane [106-97-8]	600 ppm	750 ppm
n-Butanol [71-36-3]	15 ppm	C 30 ppm
sec-Butanol [78-92-2]	100 ppm
tert-Butanol [75-65-0]	100 ppm
Butenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3]; including isobutene [115-11-7] Revised 2008	250 ppm
2-Butoxyethanol (EGBE) [111-76-2] Revised 2003	20 ppm
2-Butoxyethyl acetate [112-07-2] Revised 2003	20 ppm
n-Butyl acetate [123-86-4]	20 ppm
sec-Butyl acetate [105-46-4]	200 ppm
tert-Butyl acetate [540-88-5]	200 ppm
n-Butyl acrylate [141-32-2]	2 ppm		S
n-Butylamine [109-73-9]		C 5 ppm	Skin
Butylated hydroxytoluene (BHT), Inhalable, (2,6-Di-tert-butyl-p-cresol) [128-37-0]	2 mg/m³ (V)
tert-Butyl chromate, as CrO3 [1189-85-1]		C 0.1 mg/m³	Skin
n-Butyl glycidyl ether (BGE) [2426-08-6] Revised 2005	3 ppm		Skin; S; R
n-Butyl lactate [138-22-7]	5 ppm
n-Butyl mercaptan [109-79-5]	0.5 ppm		R
n-Butyl methacrylate [97-88-1]	50 ppm
o-sec-Butylphenol [89-72-5]	5 ppm		Skin
p-tert-Butyltoluene [98-51-1]	1 ppm
Cadmium and compounds, as Cd [7440-43-9]	0.01 mg/m³		A2, 1
Cadmium and compounds, Respirable, as Cd [7440-43-9]	0.002 mg/m³		A2, 1
Calcium arsenate, as As [7778-44-1]	0.01 mg/m³		A1, 1
Calcium carbonate (incl. Limestone, Marble) [1317-65-3]	10 mg/m³ (N)	20 mg/m³
Calcium chromate, as Cr [13765-19-0]	0.001 mg/m³		A2, 1
Calcium cyanamide [156-62-7]	0.5 mg/m³
Calcium hydroxide [1305-62-0]	5 mg/m³
Calcium oxide [1305-78-8]	2 mg/m³
Calcium silicate - Synthetic nonfibrous [1344-95-2]	10 mg/m³ (E,N)
Calcium sulfate, Inhalable [7778-18-9]	10 mg/m³
Camphor - Synthetic [76-22-2]	2 ppm	3 ppm
Caprolactam, Dust [105-60-2]	1 mg/m³	3 mg/m³
Captafol [2425-06-1]	0.1 mg/m³		Skin; 2A; S
Captan, Inhalable [133-06-2]	5 mg/m³		S
Carbaryl, Inhalable [63-25-2] Revised 2008	0.5 mg/m³ (V)		Skin; R
Carbofuran, Inhalable [1563-66-2] Revised 2004	0.1 mg/m³ (V)
Carbon black [1333-86-4]	3.5 mg/m³		2B
Carbon dioxide [124-38-9]	5000 ppm	15,000 ppm
Carbon disulfide [75-15-0]	4 ppm	12 ppm	Skin
Carbon monoxide [630-08-0]	25 ppm	100 ppm	R
Carbon tetrabromide [558-13-4]	0.1 ppm	0.3 ppm
Carbon tetrachloride [56-23-5]	2 ppm		Skin; A2, 2B
Carbonyl fluoride [353-50-4]	2 ppm	5 ppm
Catechol [120-80-9]	5 ppm		Skin; 2B
Cellulose [9004-34-6]	10 mg/m³ (N)
Cesium hydroxide [21351-79-1]	2 mg/m³
Chlordane [57-74-9]	0.5 mg/m³		Skin; 2B
Chlorinated camphene [8001-35-2]	0.5 mg/m³	1 mg/m³	Skin; 2B
o-Chlorinated diphenyl oxide [31242-93-0]	0.5 mg/m³
Chlorine [7782-50-5]	0.5 ppm	1 ppm
Chlorine dioxide [10049-04-4]	0.1ppm	0.3 ppm
Chlorine trifluoride [7790-91-2]		C 0.1 ppm
Chloroacetaldehyde [107-20-0]		C 1 ppm
Chloroacetic acid [79-11-8]	0.3 ppm
Chloroacetone [78-95-5]		C 1 ppm	Skin
2-Chloroacetophenone [532-27-4]	0.05 ppm		S
Chloroacetyl chloride [79-04-9]	0.05 ppm	0.15 ppm	Skin
p-Chloroaniline [106-47-8]			2B
Chlorobenzene [108-90-7]	10 ppm
o-Chlorobenzylidene malononitrile [2698-41-1]		C 0.05 ppm	Skin
Chlorobromomethane (see Bromochloromethane)
1-Chloro-1,1-difluoroethane [75-68-3]	1000 ppm
Chlorodifluoromethane [75-45-6]	500 ppm	1250 ppm
Chlorodiphenyl (42% chloride) [53469-21-9]	1 mg/m³		Skin; 2A
Chlorodiphenyl (54% chloride) [11097-69-1]	0.5 mg/m³		Skin; 2A
Chloroform [67-66-3]	2 ppm		2B; R
bis(Chloromethyl) ether [542-88-1]	0.001 ppm		A1, 1
Chloromethyl methyl ether [107-30-2]	(L)		A2, 1
1-Chloro-1-nitropropane [600-25-9]	2 ppm
Chloropentafluoroethane [76-15-3]	1000 ppm
Chloropicrin [76-06-2]	0.1 ppm
1-Chloro-2-propanol [127-00-4] Revised 2008	1 ppm		Skin; R
2-Chloro-1-propanol [78-89-7] Revised 2008	1 ppm		Skin; R
beta-Chloroprene [126-99-8]	10 ppm		Skin; 2B; R
2-Chloropropionic acid [598-78-7]	0.1 ppm		Skin; R
o-Chlorostyrene [2039-87-4]	50 ppm	75 ppm
o-Chlorotoluene [95-49-8]	50 ppm
4-Chloro-o-Toluidine [95-69-2]			2A
Chlorotrifluoromethane [75-72-9]	1000 ppm
Chlorpyrifos, Inhalable [2921-88-2] Revised 2003	0.1 mg/m³ (V)		Skin
Chromite ore processing (Chromate), as Cr	0.05 mg/m³		A1
Chromium - Metal [7440-47-3]	0.5 mg/m³
Chromium (III) inorganic compounds, as Cr [7440-47-3]	0.5 mg/m³
Chromium (VI) inorganic compounds - Insoluble, as Cr [7440-47-3]	0.01 mg/m³		A1, 1
Chromium (VI) inorganic compounds - Water soluble, as Cr [7440-47-3]	0.025 mg/m³	C 0.1 mg/m³	A1, 1
Chromyl chloride [14977-61-8]	0.025 ppm
Chrysene [218-01-9] Revised 2006	(L)		2B
Clopidol [2971-90-6]	10 mg/m³ (N)
Coal dust - Anthracite, Respirable	0.4 mg/m³
Coal dust - Bituminous, Respirable	0.9 mg/m³
Coal tar pitch volatiles, as benzene-soluble aerosol [65996-93-2]	0.2 mg/m³		A1, 1
Cobalt and inorganic compounds, as Co [7440-48-4]	0.02 mg/m³		2B
Cobalt carbonyl, as Co [10210-68-1]	0.1 mg/m³
Cobalt hydrocarbonyl, as Co [16842-03-8]	0.1 mg/m³
Copper - Dusts and mists, as Cu [7440-50-8]	1 mg/m³
Copper - Fume, as Cu [7440-50-8]	0.2 mg/m³
Cotton dust - Raw	0.2 mg/m³ (G)
Coumaphos, Inhalable [56-72-4] Revised 2006	0.05 mg/m³ (V)		Skin
Cresol, all isomers [1319-77-3; 95-48-7; 108-39-4; 106-44-5]	10 mg/m³		Skin
Crotonaldehyde [4170-30-3]		C 0.3 ppm	Skin
Crufomate [299-86-5]	5 mg/m³
Cumene [98-82-8]	25 ppm	75 ppm
Cyanamide [420-04-2]	2 mg/m³
Cyanogen [460-19-5]	10 ppm
Cyanogen chloride [506-77-4]		C 0.3 ppm
Cyclohexane [110-82-7]	100 ppm
Cyclohexanol [108-93-0]	50 ppm		Skin
Cyclohexanone [108-94-1] Revised 2003	20 ppm	50 ppm	Skin
Cyclohexene [110-83-8]	300 ppm
Cyclohexylamine [108-91-8]	10 ppm
Cyclonite [121-82-4]	0.5 mg/m³		Skin
Cyclopentadiene [542-92-7]	75 ppm
Cyclopentane [287-92-3]	600 ppm
Cyhexatin [13121-70-5]	5 mg/m³
2,4-D (2,4-Dichlorophenoxy-acetic acid) [94-75-7] (see 2,4-Dichlorophenoxyacetic acid and its esters)
DDT (Dichloro-diphenyltrichloroethane) [50-29-3]	1 mg/m³		2B
Decaborane [17702-41-9]	0.05 ppm	0.15 ppm	Skin
Demeton, Inhalable [8065-48-3]	0.05 mg/m³ (V)		Skin
Demeton-S-methyl, Inhalable [919-86-8]	0.05 mg/m³ (V)		Skin; S
Diacetone alcohol [123-42-2]	50 ppm
2,4-Diaminoanisole [615-05-4]			2B
2,4-Diaminotoluene [95-80-7]			2B
Diazinon, Inhalable [333-41-5] Revised 2003	0.01 mg/m³ (V)		Skin
Diazomethane [334-88-3]	0.2 ppm		A2
Diborane [19287-45-7]	0.1 ppm
1,2-Dibromo-3-chloropropane [96-12-8]			2B
2-N-Dibutylaminoethanol [102-81-8]	0.5 ppm		Skin
Dibutyl phenyl phosphate [2528-36-1]	0.3 ppm		Skin
Dibutyl phosphate, Inhalable [107-66-4] Revised 2009	5 mg/m³ (V)		Skin
Dibutyl phthalate [84-74-2]	5 mg/m³		R
Dichloroacetic acid [79-43-6] Revised 2005	0.5 ppm		Skin; 2B; R
Dichloroacetylene [7572-29-4]		C 0.1 ppm
o-Dichlorobenzene [95-50-1]	25 ppm	50 ppm
p-Dichlorobenzene [106-46-7]	10 ppm		2B
3,3'-Dichlorobenzidine [91-94-1]	(L)		Skin; 2B
1,4-Dichloro-2-butene [764-41-0]	0.005 ppm		Skin; A2
2,2-Dichlorodiethyl sulfide (Mustard Gas) [505-60-2]			1
Dichlorodifluoromethane [75-71-8]	1000 ppm
1,3-Dichloro-5,5-dimethyl hydantoin [118-52-5]	0.2 mg/m³	0.4 mg/m³
1,1-Dichloroethane [75-34-3]	100 ppm
1,2-Dichloroethane (see ethylene dichloride)
1,2-Dichloroethylene, all isomers [540-59-0; 156-59-2; 156-60-5]	200 ppm
Dichloroethyl ether [111-44-4]	5 ppm	10 ppm	Skin
Dichlorofluoromethane [75-43-4]	10 ppm
Dichloromethane [75-09-2]	25 ppm		2B
2,2'-Dichloro-n-methyldiethylamine (Nitrogen mustard) [51-75-2]			2A
1,1-Dichloro-1-nitroethane [594-72-9]	2 ppm
1,3-Dichloropropene [542-75-6]	1 ppm		Skin; 2B
2,4-Dichlorophenoxyacetic acid and its esters [94-75-7] Revised 2006	10 mg/m³	20 mg/m³	2B
2,2-Dichloropropionic acid, Inhalable [75-99-0]	5 mg/m³
Dichlorotetrafluoroethane (Cryofluorane) [76-14-2]	1000 ppm
Dichlorvos (DDVP), Inhalable [62-73-7]	0.1 mg/m³ (V)		Skin; 2B; S
Dicrotophos, Inhalable [141-66-2]	0.05 mg/m³ (V)		Skin
Dicyclohexylmethane-4,4'-diisocyanate [5124-30-1] (see Methylene bis (4-cyclohexyl-isocyanate))
Dicyclopentadiene [77-73-6]	5 ppm
Dicyclopentadienyl iron [102-54-5]	10 mg/m³ (N)
Dieldrin [60-57-1]	0.25 mg/m³		Skin
Diesel fuel, as total hydrocarbons, Inhalable [68334-30-5; 68476-30-2; 68476-31-3; 68476-34-6; 77650-28-3]	100 mg/m³ (V)		Skin
Diethanolamine, Inhalable [111-42-2] Revised 2009	1mg/m³ (V)		Skin
Diethylamine [109-89-7]	5 ppm	15 ppm	Skin
2-Diethylaminoethanol [100-37-8]	2 ppm		Skin
Diethylene triamine [111-40-0]	1 ppm		Skin; S
Di(2-ethylhexyl)phthalate (DEHP) [117-81-7]	5 mg/m³
Diethyl ketone [96-22-0]	200 ppm	300 ppm
Diethyl phthalate [84-66-2]	5 mg/m³
Diethyl sulfate [64-67-5]			2A
Difluorodibromomethane [75-61-6]	100 ppm
Diglycidyl ether (DGE) [2238-07-5] Revised 2007	0.01 ppm		R
Diisobutyl ketone [108-83-8]	25 ppm
Diisocyanates, not elsewhere specified, NOS	0.005 ppm	C 0.01ppm
Diisopropylamine [108-18-9]	5 ppm		Skin
3,3'-Dimethoxybenzidine [119-90-4]			2B
Dimethoxymethane [109-87-5]	1000 ppm	1250 ppm
N,N-Dimethylacetamide [127-19-5]	10 ppm		Skin; R
Dimethylamine [124-40-3]	5 ppm	15 ppm
Dimethylaniline [121-69-7]	5 ppm	10 ppm	Skin
3,3'-Dimethylbenzidine [119-93-7]			2B
Dimethyl carbamoyl chloride [79-44-7] Revised 2007	0.005 ppm		Skin; A2, 2A
Dimethyl disulfide [624-92-0] Revised 2007	0.5 ppm		Skin
Dimethyl ether [115-10-6]	1000 ppm
Dimethylethoxysilane [14857-34-2]	0.5 ppm	1.5 ppm
Dimethylformamide [68-12-2]	10 ppm		Skin
1,1-Dimethylhydrazine [57-14-7]	0.01 ppm		Skin; 2B
1,2-Dimethylhydrazine [540-73-8]			2A
Dimethyl phthalate [131-11-3]	5 mg/m³
Dimethyl sulfate [77-78-1]		C 0.1 ppm	Skin; 2A
Dimethyl sulfide [75-18-3] Revised 2004	10 ppm
Dinitolmide [148-01-6] (See 3,5-Dinitro-o-toluamide)
Dinitrobenzene, all isomers [528-29-0; 99-65-0; 100-25-4; 25154-54-5]	0.15 ppm		Skin
Dinitrol-o-cresol [534-52-1]	0.2 mg/m³		Skin
3,5-Dinitro-o-toluamide [148-01-6] Revised 2007	1 mg/m³
Dinitrotoluene [25321-14-6]	0.2 mg/m³		Skin; 2B; R
n-Dioctyl phthalate [117-84-0]	5 mg/m³
1,4-Dioxane [123-91-1]	20 ppm		Skin; 2B
Dioxathion, Inhalable [78-34-2]	0.1 mg/m³ (V)		Skin
1,3-Dioxolane [646-06-0]	20 ppm		R
Diphenylamine [122-39-4]	10 mg/m³
Dipropyl ketone [123-19-3]	50 ppm
Diproplyene glycol methyl ether [34590-94-8]	100 ppm	150 ppm	Skin
Diquat, Inhalable [2764-72-9]	0.5 mg/m³		Skin
Diquat, Respirable [2764-72-9]	0.1 mg/m³		Skin
Disulfiram [97-77-8]	2 mg/m³
Disulfoton, Inhalable [298-04-4]	0.05 mg/m³ (V)		Skin
Diuron [330-54-1]	10 mg/m³
Divinyl benzene [1321-74-0]	10 ppm
Dodecyl mercaptan [112-55-0] Revised 2004	0.1 ppm		S
Dyfonate, Inhalable [944-22-9] Revised 2006	0.1 mg/m³ (V)		Skin
Endosulfan, Inhalable [115-29-7] Revised 2009	0.1 mg/m³ (V)		Skin
Endrin [72-20-8]	0.1 mg/m³		Skin
Enflurane [13838-16-9]	2 ppm
Epichlorohydrin [106-89-8]	0.1 ppm		Skin; 2A; R
EPN, Inhalable [2104-64-5] Revised 2003	0.1 mg/m³		Skin
Ethane [74-84-0] Revised 2004 See Aliphatic Hydrocarbon gases [C1-C4] Revised 2008
Ethanol [64-17-5] Revised 2009		1000 ppm
Ethanolamine [141-43-5]	3 ppm	6 ppm
Ethion, Inhalable [563-12-2] Revised 2003	0.05 mg/m³		Skin
2-Ethoxyethanol (EGEE) [110-80-5]	5 ppm		Skin; R
2-Ethoxyethyl acetate (EGEEA) [111-15-9]	5 ppm		Skin; R
Ethyl acetate [141-78-6]	150 ppm
Ethyl acrylate [140-88-5]	5 ppm	15 ppm	2B; S
Ethylamine [75-04-7]	5 ppm	15 ppm	Skin
Ethyl amyl ketone [541-85-5] Revised 2007	10 ppm
Ethyl benzene [100-41-4]	100 ppm	125 ppm	2B
Ethyl bromide [74-96-4]	5 ppm		Skin
Ethyl tert-butyl ether (ETBE) [637-92-3]	5 ppm		R
Ethyl butyl ketone [106-35-4]	50 ppm	75 ppm
Ethyl chloride [75-00-3]	100 ppm		Skin
Ethyl cyanoacrylate [7085-85-0]	0.2 ppm
Ethyl methacrylate [97-63-2]	50 ppm
Ethylene [74-85-1] Revised 2005	200 ppm
Ethylene chlorohydrin [107-07-3]		C 1 ppm	Skin
Ethylenediamine [107-15-3]	10 ppm		Skin; S
Ethylene dibromide [106-93-4]	0.5 ppm		Skin; 2A
Ethylene dichloride (1,2-dichloroethane) [107-06-2]	1 ppm	2 ppm	2B
Ethylene glycol - Aerosol [107-21-1]		C 100 mg/m³
Ethylene glycol - Particulate [107-21-1]	10 mg/m³	20 mg/m³
Ethylene glycol - Vapour [107-21-1]		C 50 ppm
Ethylene glycol dinitrate (EGDN) [628-96-6]	0.05 ppm		Skin
Ethylene oxide [75-21-8]	0.1 ppm	1 ppm	A2, 1; R
Ethyleneimine [151-56-4] Revised 2009	0.05 ppm	0.1 ppm	Skin; 2B
Ethyl ether [60-29-7]	400 ppm	500 ppm
Ethyl formate [109-94-4]	100 ppm
2-Ethylhexanoic acid, Inhalable [149-57-5]	5 mg/m³ (V)		R
Ethylidene norbornene [16219-75-3]		C 5 ppm
Ethyl mercaptan [75-08-1]	0.5 ppm
N-Ethylmorpholine [100-74-3]	5 ppm		Skin
Ethyl silicate [78-10-4]	10 ppm
Fenamiphos, Inhalable [22224-92-6] Revised 2006	0.05 mg/m³ (V)		Skin
Fensulfothion, Inhalable [115-90-2] Revised 2005	0.01 mg/m³ (V)		Skin
Fenthion, Inhalable [55-38-9] Revised 2006	0.05 mg/m³ (V)		Skin
Ferbam, Inhalable [14484-64-1] Revised 2009	5 mg/m³
Ferrovanadium dust [12604-58-9]	1 mg/m³	3 mg/m³
Flour dust, Inhalable	0.5 mg/m³		S
Fluorides (as F)	2.5 mg/m³
Fluorine [7782-41-4]	0.1 ppm
Fluroxene [406-90-6]	2 ppm
Fonofos (see Dyfonate) [944-22-9]
Formaldehyde [50-00-0]	0.3 ppm	C 1 ppm	A2, 1; S
Formamide [75-12-7]	10 ppm		Skin
Formic acid [64-18-6]	5 ppm	10 ppm
Furfural [98-01-1]	2 ppm		Skin
Furfuryl alcohol [98-00-0]	5 ppm	10 ppm	Skin
Gallium arsenide, Respirable [1303-00-0] Revised 2005	0.0003 mg/m³		1
Gasoline [86290-81-5]	300 ppm	500 ppm	2B
Germanium tetrahydride [7782-65-2]	0.2 ppm
Glutaraldehyde, Activated & inactivated [111-30-8]		C 0.05 ppm	S
Glycerin - mist [56-81-5]	10 mg/m³
Glycerin - mist, Respirable [56-81-5]	3 mg/m³
Glycidol [556-52-5]	2 ppm		2A
Glyoxal, Inhalable [107-22-2]	0.1 mg/m³ (V)		S
Grain dust (oat, wheat, barley)	4 mg/m³ (E)
Graphite - All forms except graphite fibres, Respirable [7782-42-5]	2 mg/m³
Gypsum [13397-24-5]	10 mg/m³ (N)	20 mg/m³
Hafnium and compounds, as Hf [7440-58-6]	0.5 mg/m³
Halothane [151-67-7]	2 ppm		R
Helium [7440-59-7]		Simple asphyxiant
Heptachlor [76-44-8]	0.05 mg/m³		Skin; 2B
Heptachlor epoxide [1024-57-3]	0.05 mg/m³		Skin
Heptane (n-Heptane) [142-82-5]	400 ppm	500 ppm
Hexachlorobenzene (HCB) [118-74-1]	0.002 mg/m³		Skin; 2B
Hexachlorobutadiene [87-68-3]	0.02 ppm		Skin
Hexachlorocyclopentadiene [77-47-4]	0.01 ppm
Hexachloroethane [67-72-1]	1 ppm		Skin; 2B
Hexachloronaphthalene [1335-87-1]	0.2 mg/m³		Skin
Hexafluoroacetone [684-16-2]	0.1 ppm		Skin; R
Hexafluoropropylene [116-15-4] Revised 2007	0.1 ppm
Hexahydrophthalic anhydride, all isomers, Inhalable [85-42-7; 13149-00-3; 14166-21-3] Revised 2004		C 0.005 mg/m³ (V)	S
Hexamethyl phosphoramide [680-31-9]			Skin; 2B
Hexamethylene diisocyanate (HDI) [822-06-0]	0.005 ppm	C 0.01 ppm	S
n-Hexane [110-54-3]	20 ppm		Skin
Hexane, other isomers	200 ppm
1,6-Hexanediamine [124-09-4]	0.5 ppm
1-Hexene [592-41-6]	50 ppm		R
sec-Hexyl acetate [108-84-9]	50 ppm
Hexylene glycol [107-41-5]		C 25 ppm
Hydrazine [302-01-2]	0.01 ppm		Skin; 2B
Hydrogen [1333-74-0]		Simple asphyxiant
Hydrogenated terphenyls - Nonirradiated [61788-32-7]	0.5 ppm
Hydrogen bromide [10035-10-6] Revised 2004		C 2 ppm
Hydrogen chloride [7647-01-0] Revised 2003		C 2 ppm
Hydrogen cyanide, as CN [74-90-8]		C 4.7 ppm	Skin
Cyanide salts, as CN [592-01-8; 151-50-8; 143-33-9]		C 5 mg/m³	Skin
Hydrogen fluoride, as F [7664-39-3]		C 2 ppm
Hydrogen peroxide [7722-84-1]	1 ppm
Hydrogen selenide [7783-07-5]	0.05 ppm
Hydrogen sulfide [7783-06-4]		C10 ppm
Hydroquinone [123-31-9] Revised 2008	1 mg/m³		S
2-Hydroxypropyl acrylate [999-61-1]	0.5 ppm		Skin; S
Indene [95-13-6] Revised 2008	5 ppm
Indium and compounds, as In [7440-74-6]	0.1 mg/m³
Iodides, Inhalable Revised 2008	0.01 ppm (V)
Iodine, Inhalable [7553-56-2] Revised 2008	0.01 ppm (V)	0.1 ppm
Iodoform [75-47-8]	0.6 ppm
Iron oxide dust, as Fe [1309-37-1]	5 mg/m³
Iron oxide fume , as Fe [1309-37-1]	5 mg/m³	10 mg/m³
Iron pentacarbonyl [13463-40-6]	0.01 ppm
Iron salts - soluble, as Fe	1 mg/m³	2 mg/m³
Isoamyl alcohol [123-51-3]	100 ppm	125 ppm
Isobutanol [78-83-1]	50 ppm
Isobutyl acetate [110-19-0]	150 ppm
Isobutyl nitrite, Inhalable [542-56-3]		C 1 ppm (V)
Isooctyl alcohol [26952-21-6]	50 ppm		Skin
Isophorone [78-59-1]		C 5 ppm
Isophorone diisocyanate [4098-71-9]	0.005 ppm	C 0.01 ppm	S
Isopropanol (Isopropyl alcohol) [67-63-0] Revised 2003	200 ppm	400 ppm
2-Isopropoxyethanol [109-59-1]	25 ppm		Skin
Isopropyl acetate [108-21-4] Revised 2003	100 ppm	200 ppm
Isopropylamine [75-31-0]	5 ppm	10 ppm
N-Isopropylaniline [768-52-5]	2 ppm		Skin
Isopropyl ether [108-20-3]	250 ppm	310 ppm
Isopropyl glycidyl ether (IGE) [4016-14-2]		C 50 ppm
Kaolin, Respirable [1332-58-7]	2 mg/m³ (E)
Kerosene [8008-20-6]/Jet fuels [64742-47-8], as total hydrocarbon vapour, Revised 2003	200 mg/m³ (P)		Skin
Ketene [463-51-4]	0.5 ppm	1.5 ppm
Lead - elemental and inorganic compounds, as Pb [7439-92-1]	0.05 mg/m³		Elemental 2B; R/Other inorganic 2A, R
~~Lead arsenate, as Pb3(AsO4)2 [3687-31-8]~~	~~0.15 mg/m³~~		~~2A ; R~~
Lead chromate, as Cr [7758-97-6]	0.012 mg/m³		A2; 2A; R
Lead chromate, as Pb [7758-97-6]	0.05 mg/m³		A2; 2A; R
Lindane [58-89-9]	0.5 mg/m³		Skin
Liquified petroleum gas (L.P.G.) [68476-85-7]	1000 ppm	1250 ppm
Lithium hydroxide [1310-65-2]		C 1 mg/m³
Lithium hydride [7580-67-8]	0.025 mg/m³
Magnesite [546-93-0] Revised 2006 (See Particles Not Otherwise Classified (PNOC))
Magnesium oxide (fume), Inhalable [1309-48-4] Revised 2003	10 mg/m³
Magnesium oxide, Respirable dust and fume, as Mg [1309-48-4]	3 mg/m³	10 mg/m³
Malathion, Inhalable [121-75-5] Revised 2003	1 mg/m³ (V)		Skin
Maleic anhydride [108-31-6]	0.1 ppm		S
Manganese - Elemental & inorganic compounds, as Mn [7439-96-5]	0.2 mg/m³		R
Manganese cyclopentadienyl tricarbonyl, as Mn [12079-65-1]	0.1 mg/m³		Skin
Mercury - Alkyl compounds, as Hg [7439-97-6]	0.01 mg/m³	0.03 mg/m³	Skin
Mercury - Aryl compounds, as Hg [7439-97-6]	0.05 mg/m³	C 0.1 mg/m³	Skin
Mercury - Elemental, as Hg [7439-97-6]	0.025 mg/m³		Skin; R
Mercury - Inorganic compounds, as Hg [7439-97-6]	0.025 mg/m³		Skin; R
Mercury -- Methyl, as Hg [7439-97-6]	0.01 mg/m³	0.03 mg/m³	Skin
Mesityl oxide [141-79-7]	10 ppm	25 ppm
Methacrylic acid [79-41-4]	20 ppm
Methane [74-82-8] Revised 2004 See Aliphatic Hydrocarbon gases [C1-C4] Revised 2008
Methanol [67-56-1]	200 ppm	250 ppm	Skin
Methomyl [16752-77-5]	2.5 mg/m³
Methoxychlor [72-43-5]	10 mg/m³
2-Methoxyethanol (EGME) [109-86-4] Revised 2006	0.1 ppm		Skin; R
2-Methoxyethyl acetate (EGMEA) [110-49-6] Revised 2006	0.1 ppm		Skin; R
Methoxyflurane [76-38-0]	2 ppm
4-Methoxyphenol [150-76-5]	5 mg/m³
1-Methoxy-2-propanol (PGME) [107-98-2]	50 ppm	75 ppm
2-Methoxy-1-propanol [1589-47-5]	20 ppm	40 ppm
1-Methoxypropyl-2-acetate [108-65-6]	50 ppm	75 ppm
2-Methoxypropyl-1-acetate [70657-70-4]	20 ppm	40 ppm
bis-(2-Methoxypropyl) ether (DPGME) (see Dipropylene glycol methyl ether) [34590-94-8]
Methyl acetate [79-20-9]	200 ppm	250 ppm
Methyl acetylene [74-99-7]	1000 ppm
Methyl acetylene-propadiene mixture (MAPP) [59355-75-8]	1000 ppm	1250 ppm
Methyl acrylate [96-33-3]	2 ppm		Skin; S
Methylacrylonitrile [126-98-7]	1 ppm		Skin
Methylal (see Dimethoxymethane) [109-87-5]
Methylamine [74-89-5]	5 ppm	15 ppm
Methyl n-amyl ketone [110-43-0]	50 ppm
N-Methyl aniline [100-61-8]	0.5 ppm		Skin
Methyl bromide [74-83-9]	1 ppm		Skin
Methyl tert-butyl ether (MTBE) [1634-04-4]	50 ppm		R
Methyl n-butyl ketone [591-78-6] Revised 2008	5 ppm	10 ppm	Skin; R
Methyl chloride [74-87-3]	50 ppm	100 ppm	Skin; R
Methyl chloroform [71-55-6]	350 ppm	450 ppm
Methyl 2-cyanoacrylate [137-05-3]	0.2 ppm
Methylcyclohexane [108-87-2]	400 ppm
Methylcyclohexanol [25639-42-3]	50 ppm
o-Methylcyclohexanone [583-60-8]	50 ppm	75 ppm	Skin
2-Methylcyclopentadienyl manganese tricarbonyl, as Mn [12108-13-3]	0.2 mg/m³		Skin
Methyl demeton, Inhalable [8022-00-2] Revised 2007	0.05 mg/m³ (V)		Skin
Methylene bisphenyl isocyanate (MDI) [101-68-8]	0.005 ppm	C 0.01 ppm	Skin; S
4,4'-Methylene bis(2-chloroaniline) (MBOCA; MOCA) [101-14-4] Revised 2009	0.01 ppm		Skin; A2, 1
Methylene bis (4-cyclo-hexyl-isocyanate), [5124-30-1]	0.005 ppm	C 0.01 ppm
Methylene chloride (See Dichloromethane)
4,4'-Methylene dianiline [101-77-9]	0.01 ppm		Skin; 2B
Methyl ethyl ketone (MEK) [78-93-3]	50 ppm	100 ppm
Methyl ethyl ketone peroxide (MEKP) [1338-23-4]		C 0.2 ppm
Methyl formate [107-31-3]	100 ppm	150 ppm
Methyl hydrazine [60-34-4]	0.01 ppm		Skin
Methyl iodide [74-88-4]	2 ppm		Skin
Methyl isoamyl ketone [110-12-3]	50 ppm
Methyl isobutyl carbinol [108-11-2]	25 ppm	40 ppm	Skin
Methyl isobutyl ketone [108-10-1]	50 ppm	75 ppm
Methyl isocyanate [624-83-9]	0.02 ppm		Skin; S
Methyl isopropyl ketone [563-80-4]	200 ppm
Methyl mercaptan [74-93-1]	0.5 ppm
Methyl methacrylate [80-62-6]	50 ppm	100 ppm	S
1-Methyl naphthalene [90-12-0] Revised 2007	0.5 ppm		Skin
2-Methyl naphthalene [91-57-6] Revised 2007	0.5 ppm		Skin
Methyl parathion, Inhalable [298-00-0] Revised 2009	0.02 mg/m³ (V)		Skin
Methyl propyl ketone (2-pentanone) [107-87-9]	150 ppm	250 ppm
Methyl silicate [681-84-5]	1 ppm
alpha-Methyl styrene [98-83-9]	50 ppm	75 ppm
		C 100 ppm
Methyl vinyl ketone [78-94-4]		C 0.2 ppm	Skin; S
Metribuzin [21087-64-9]	5 mg/m³
Mevinphos, Inhalable [7786-34-7] Revised 2003	0.01 mg/m³ (V)		Skin
Mica, Respirable [12001-26-2]	3 mg/m³
Molybdenum - Metal and insoluble compounds, Respirable [7439-98-7]	3 mg/m³
Molybdenum - Metal and insoluble compounds, Inhalable [7439-98-7]	10 mg/m³
Molybdenum - Soluble compounds, as Mo, Respirable [7439-98-7]	0.5 mg/m³
Monochloroacetic acid [79-11-8] See Chloroacetic acid
Monocrotophos, Inhalable [6923-22-4]	0.05 mg/m³ (V)		Skin
Morpholine [110-91-8]	20 ppm		Skin
Naled, Inhalable [300-76-5]	0.1 mg/m³ (V)		Skin; S
Naphthalene [91-20-3]	10 ppm	15 ppm	Skin; 2B
1,5-Naphthalene diisocyanate [3173-72-6]	0.005 ppm	C 0.01 ppm
beta-Naphthylamine [91-59-8]	(L)		A1, 1
Natural gas [8006-14-2] Revised 2004 See Aliphatic Hydrocarbon gases [C1-C4] Revised 2008
Natural rubber latex, as Total proteins, Inhalable [9006-04-6] Revised 2004, 2008	0.0001 mg/m³		Skin; S
Neon [7440-01-9]		Simple asphyxiant
Nickel - Insoluble inorganic compounds, as Ni [7440-02-0]	0.05 mg/m³		A1, 1
Nickel - Elemental, Soluble inorganic compounds, as Ni [7440-02-0]	0.05 mg/m³		A1, 1
Nickel carbonyl, as Ni [13463-39-3]	0.001 ppm
Nickel subsulfide, as Ni, Inhalable [12035-72-2]	0.1 mg/m³		A1, 1
Nicotine [54-11-5]	0.5 mg/m³		Skin
Nitrapyrin [1929-82-4]	10 mg/m³ (N)	20 mg/m³
Nitric acid [7697-37-2]	2 ppm	4 ppm
Nitric oxide [10102-43-9]	25 ppm
p-Nitroaniline [100-01-6]	3 mg/m³		Skin
Nitrobenzene [98-95-3]	1 ppm		Skin; 2B
p-Nitrochlorobenzene [100-00-5]	0.1 ppm		Skin
4-Nitrodiphenyl [92-93-3]	(L)		Skin; A2
Nitroethane [79-24-3]	100 ppm
Nitrogen [7727-37-9]		Simple asphyxiant
Nitrogen dioxide [10102-44-0]		C 1 ppm
Nitrogen trifluoride [7783-54-2]	10 ppm
Nitroglycerin (NG) [55-63-0]	0.05 ppm		Skin
Nitromethane [75-52-5]	20 ppm		2B
1-Nitropropane [108-03-2]	25 ppm		2B
2-Nitropropane [79-46-9]	5 ppm		2B
Nitropyrene, mono, di, tri, tetra, isomers [5522-43-0; 57835-92-4]			2B
n-Nitrosodiethanolamine [1116-54-7]			2B
n-Nitrosodiethylamine [55-18-5]			2A
n-Nitrosodimethylamine [62-75-9]	(L)		Skin; 2A
n-Nitrosomethylethylamine [10595-95-6]			2B
n-Nitrosomorpholine [59-89-2]			2B
n-Nitrosopiperidine [100-75-4]			2B
n-Nitrosopyrrolidine [930-55-2]			2B
Nitrotoluene, all isomers [88-72-2; 99-08-1; 99-99-0]	2 ppm		Skin
5-Nitro-o-toluidine, Inhalable [99-55-8] Revised 2007	1 mg/m³
Nitrous oxide [10024-97-2]	25 ppm		R
Nonane - All isomers [111-84-2]	200 ppm
Octachloronaphthalene [2234-13-1]	0.1 mg/m³	0.3 mg/m³	Skin
Octane, all isomers [111-65-9]	300 ppm
Oil mist - mineral, mildly refined	0.2 mg/m³		1
Oil mist - mineral, severely refined	1 mg/m³
Osmium tetroxide [20816-12-0]	0.0002 ppm	0.0006 ppm
Oxalic acid [144-62-7]	1 mg/m³	2 mg/m³
p,p'-Oxybis(benzenesulfonyl hydrazide), Inhalable [80-51-3] Revised 2008	0.1 mg/m³		R
Oxygen difluoride [7783-41-7]		C 0.05 ppm
Ozone - Heavy work [10028-15-6]	0.05 ppm
Ozone - Moderate work [10028-15-6]	0.08 ppm
Ozone - Light work [10028-15-6]	0.1 ppm
Ozone - Light, mod., or heavy workload =/< 2 hrs [10028-15-6]	0.2 ppm
Paraffin wax fume [8002-74-2]	2 mg/m³
Paraquat, Respirable [4685-14-7]	0.1 mg/m³
Paraquat [4685-14-7]	0.5 mg/m³
Parathion, Inhalable [56-38-2] Revised 2003	0.05 mg/m³ (V)		Skin
Particles (Insoluble or Poorly Soluble) Not Otherwise Classified (PNOC)	10 mg/m³ (N)
Pentaborane [19624-22-7]	0.005 ppm	0.015 ppm
Pentachloronaphthalene [1321-64-8]	0.5 mg/m³		Skin
Pentachloronitrobenzene [82-68-8]	0.5 mg/m³
Pentachlorophenol [87-86-5]	0.5 mg/m³		Skin
Pentaerythritol [115-77-5]	10 mg/m³ (N)
Pentane, all isomers [78-78-4; 109-66-0; 463-82-1]	600 ppm
Pentyl acetate, all isomers [628-63-7; 626-38-0; 123-92-2; 625-16-1; 624-41-9; 620-11-1]	50 ppm	100 ppm
Perchloroethylene (See Tetrachloroethylene)
Perchloromethyl mercaptan [594-42-3]	0.1 ppm
Perchloryl fluoride [7616-94-6]	3 ppm	6 ppm
Perfluorobutyl ethylene [19430-93-4] Revised 2004	100 ppm
Perfluoroisobutylene [382-21-8]		C 0.01 ppm
Perlite [93763-70-3] Revised 2006 (See Particles Not Otherwise Classified (PNOC))
Persulfates, as persulfate	0.1 mg/m³
Phenol [108-95-2]	5 ppm		Skin
Phenothiazine [92-84-2]	5 mg/m³		Skin
N-Penyl-beta-naphthylamine [135-88-6]
o-Phenylenediamine [95-54-5]	0.1 mg/m³
m-Phenylenediamine [108-45-2]	0.1 mg/m³
p-Phenylenediamine [106-50-3]	0.1 mg/m³		S
Phenyl ether - Vapour (Diphenyl ether) [101-84-8]	1 ppm	2 ppm
Phenyl glycidyl ether (PGE) [122-60-1] Revised 2008	0.1 ppm		Skin; 2B; S; R
Phenyl isocyanate [103-71-9]	0.005 ppm	C 0.01 ppm
Phenylhydrazine [100-63-0]	0.1 ppm		Skin
Phenyl mercaptan [108-98-5]		C 0.1 ppm
Phenylphosphine [638-21-1]		C 0.05 ppm	R
Phorate, Inhalable [298-02-2] Revised 2005	0.05 mg/m³ (V)		Skin
Phosgene [75-44-5]	0.1 ppm
Phosphine [7803-51-2]	0.3 ppm	1 ppm
Phosphoric acid [7664-38-2]	1 mg/m³	3 mg/m³
Phosphorus (yellow) [12185-10-3]	0.1 mg/m³
Phosphorus oxychloride [10025-87-3]	0.1 ppm
Phosphorus pentachloride [10026-13-8]	0.1 ppm
Phosphorus pentasulfide [1314-80-3]	1 mg/m³	3 mg/m³
Phosphorus trichloride [7719-12-2]	0.2 ppm	0.5 ppm
Phthalic anhydride [85-44-9]	1 ppm		S
m-Phthalodinitrile [626-17-5]	5 mg/m³
Picloram [1918-02-1]	10 mg/m³ (N)
Picric acid [88-89-1]	0.1 mg/m³		S
Pindone [83-26-1]	0.1 mg/m³
Piperazine and its Salts, as Piperazine [110-85-0]	0.3 mg/m³	1 mg/m³	S
Piperidine [110-89-4]	1 ppm
Plaster of Paris [26499-65-0]	10 mg/m³ (N)	20 mg/m³
Platinum - Metal [7440-06-4]	1 mg/m³
Platinum - Soluble salts (as Pt) [7440-06-4]	0.002 mg/m³		S
Polyvinyl chloride (PVC), Respirable [9002-86-2] Revised 2008	1 mg/m³
Portland cement [65997-15-1]	10 mg/m³ (E,N)
Potassium hydroxide [1310-58-3]		C 2 mg/m³
Propane [74-98-6] Revised 2004 See Aliphatic Hydrocarbon gases [C1-C4] Revised 2008
Propane sultone [1120-71-4]	(L)		2B
n-Propanol (n-Propyl alcohol) [71-23-8] Revised 2007	100 ppm
Propargyl alcohol [107-19-7]	1 ppm		Skin
beta-Propiolactone [57-57-8]	0.5 ppm		2B
Propionaldehyde [123-38-6]	20 ppm
Propionic acid [79-09-4]	10 ppm
Propoxur [114-26-1]	0.5 mg/m³
n-Propyl acetate [109-60-4]	200 ppm	250 ppm
Propylene [115-07-1] Revised 2006	500 ppm
Propylene dichloride [78-87-5] Revised 2006	75 ppm	110 ppm	S
Propylene glycol dinitrate [6423-43-4]	0.05 ppm		Skin
Propylene oxide [75-56-9]	2 ppm		2B; S
Propyleneimine [75-55-8] Revised 2009	0.2 ppm	0.4 ppm	Skin
n-Propyl nitrate [627-13-4]	25 ppm	40 ppm
Pyrethrum [8003-34-7]	5 mg/m³		S
Pyridine [110-86-1] Revised 2004	1 ppm
Quinone [106-51-4]	0.1 ppm
Resorcinol [108-46-3]	10 ppm	20 ppm
Rhodium, Metal and insoluble compounds as Rh [7440-16-6]	0.1 mg/m³	0.3 mg/m³
Rhodium - Soluble compounds, as Rh [7440-16-6]	0.001 mg/m³	0.003 mg/m³
Ronnel, Inhalable [299-84-3] Revised 2006	5 mg/m³ (V)
Rosin core solder thermal decomposition products (colophony) [8050-09-7]	(L)		S
Rotenone (commercial) [83-79-4]	5 mg/m³
Rouge [1309-37-1]	10 mg/m³ (E,N)
Rubber solvent (Naphtha) [8030-30-6] Revised 2009	(H)
Selenium and compounds, as Se [7782-49-2]	0.1 mg/m³
Selenium hexafluoride [7783-79-1]	0.05 ppm
Sesone [136-78-7]	10 mg/m³ (N)
Silica, Amorphous - Diatomaceous earth (uncalcined) Total [61790-53-2]	4 mg/m³
Silica, Amorphous - Diatomaceous earth (uncalcined), Respirable [61790-53-2]	1.5 mg/m³
Silica, Amorphous - Fume Total [69012-64-2]	4 mg/m³
Silica, Amorphous - Fume, Respirable [69012-64-2]	1.5 mg/m³
Silica, Amorphous - Precipitated and gel, Total [112926-00-8]	4 mg/m³
Silica, Amorphous - Precipitated and gel, Respirable [112926-00-8]	1.5 mg/m³
Silica, Crystalline - alpha quartz [14808-60-7; 1317-95-9] and Cristobalite, Respirable [14464-46-1] Revised 2006	0.025 mg/m³		A2, 1
Silicon [7440-21-3] Revised 2006 (See Particles Not Otherwise Classified (PNOC))
Silicon carbide Nonfibrous, Inhalable, [409-21-2] Revised 2003	10 mg/m³ (E)
Silicon carbide, Nonfibrous, Respirable, [409-21-2] Revised 2003	3 mg/m³ (E)
Silicon carbide, Fibrous (including whiskers) [409-21-2] Revised 2003	0.1 f/cc (F)		A2
Silicon tetrahydride (Silane) [7803-62-5]	0.5 ppm	1 ppm
Silver and Compounds (as Ag) [7440-22-4]	0.01 mg/m³	0.03 mg/m³
Soapstone	6 mg/m³ (E)
Soapstone, Respirable	3 mg/m³ (E)
Sodium azide (as Sodium azide) [26628-22-8]		C 0.29 mg/m³
Sodium azide (as Hydrazoic acid vapour) [26628-22-8]		C 0.11 ppm
Sodium bisulfite [7631-90-5]	5 mg/m³
Sodium fluoroacetate [62-74-8]	0.05 mg/m³		Skin
Sodium hydroxide [1310-73-2]		C 2 mg/m³
Sodium metabisulfite [7681-57-4]	5 mg/m³
Starch [9005-25-8]	10 mg/m³ (N)
Stearates	10 mg/m³ (J)
Stoddard solvent (mineral spirits) [8052-41-3]	290 mg/m³	580 mg/m³
Strontium chromate, as Cr [7789-06-2]	0.0005 mg/m³		A2
Strychnine [57-24-9]	0.15 mg/m³
Styrene - monomer [100-42-5]	50 ppm	75 ppm	2B
Subtilisins, as crystalline active enzyme [1395-21-7; 9014-01-1]		C 0.00006 mg/m³	S
Sucrose [57-50-1]	10 mg/m³ (N)
Sulfometuron methyl [74222-97-2]	5 mg/m³
Sulfotepp (TEDP), Inhalable [3689-24-5] Revised 2005	0.1 mg/m³ (V)		Skin
Sulfur dioxide [7446-09-5] Under review. See G5.48-13	2 ppm	5 ppm
Sulfur hexafluoride [2551-62-4]	1000 ppm
Sulfuric acid, Thoracic [7664-93-9] Revised 2004	0.2 mg/m³ (M)		A2, 1
Sulfur monochloride [10025-67-9]		C 1ppm
Sulfur pentafluoride [5714-22-7]		C 0.01 ppm
Sulfur tetrafluoride [7783-60-0]		C 0.1 ppm
Sulfuryl fluoride [2699-79-8]	5 ppm	10 ppm
Sulprofos, Inhalable [35400-43-2] Revised 2009	0.1 mg/m³ (V)		Skin
Synthetic Vitreous Fibres - Continuous filament glass fibres	1 f/cc (F)
Synthetic Vitreous Fibres - Continuous filament glass fibres, Inhalable	5 mg/m³
Synthetic Vitreous Fibres - Glass wool fibres	1 f/cc (F)
Synthetic Vitreous Fibres - Rock wool fibres	1 f/cc (F)
Synthetic Vitreous Fibres -Slag wool fibres	1 f/cc (F)
Synthetic Vitreous Fibres - Special purpose glass fibres	1 f/cc (F)		2B
Synthetic Vitreous Fibres - Refractory ceramic fibres	0.2 f/cc (F)		A2, 2B
2,4,5-T (2,4,5-Trichlorophenoxyacetic acid) [93-76-5]	10 mg/m³
Talc - Containing no asbestos fibres, Respirable [14807-96-6]	2 mg/m³ (E)
Talc - Containing asbestos fibres [14807-96-6]	0.1 f/cc (K)		A1, 1
Tantalum - Metal [7440-25-7]	5 mg/m³
Tantalum oxide dusts, as Ta [1314-61-0]	5 mg/m³
Tellurium and compounds (NOS), as Te, excluding hydrogen telluride [13494-80-9]	0.1 mg/m³
Tellurium hexafluoride [7783-80-4]	0.02 ppm
Temephos, Inhalable [3383-96-8] Revised 2005	1 mg/m³ (V)		Skin
Terbufos, Inhalable [13071-79-9]	0.01 mg/m³ (V)		Skin
Terepthalic acid [100-21-0]	10 mg/m³ (N)
Terphenyls [26140-60-3]		C 5 mg/m³
1,1,2,2-Tetrabromoethane, Inhalable [79-27-6] Revised 2006	0.1 ppm (V)
1,1,1,2-Tetrachloro-2,2-difluoroethane [76-11-9] Revised 2008	100 ppm
1,1,2,2-Tetrachloro-1,2-difluoroethane [76-12-0] Revised 2008	50 ppm
1,1,2,2-Tetrachloroethane [79-34-5]	1 ppm		Skin
Tetrachloroethylene (Perchloroethylene) [127-18-4]	25 ppm	100 ppm	2A
Tetrachloronaphthalene [1335-88-2]	2 mg/m³
Tetraethyl lead, as Pb [78-00-2]	0.075 mg/m³		Skin
Tetraethyl pyrophosphate (TEPP), Inhalable [107-49-3] Revised 2007	0.01 mg/m (V)		Skin
Tetrafluoroethylene [116-14-3]	2 ppm		2B
Tetrahydrofuran [109-99-9] Revised 2005	50 ppm	100 ppm	Skin
Tetramethyl lead, as Pb [75-74-1]	0.075 mg/m³		Skin
Tetramethyl succinonitrile [3333-52-6]	0.5 ppm		Skin
Tetranitromethane [509-14-8]	0.005 ppm		2B
Tetrakis (hydroxymethyl) phosphonium chloride [124-64-1] Revised 2005	2 mg/m³
Tetrakis (hydroxymethyl) phosphonium sulfate [55566-30-8] Revised 2005	2 mg/m³		S
Tetryl [479-45-8]	1.5 mg/m³		S
Thallium and soluble compounds, as Tl [7440-28-0]	0.1 mg/m³		Skin
4,4' Thiobis (6-tert-butyl-m-cresol) [96-69-5] (see Cresol, all isomers)
Thioglycolic acid [68-11-1]	1 ppm		Skin
Thionyl chloride [7719-09-7]		C 1ppm
Thiram, Inhalable [137-26-8] Revised 2008	0.05 mg/m³ (V)		S
Tin - Metal [7440-31-5]	2 mg/m³
Tin - Oxide and inorganic compounds, except tin hydride, as Sn [7440-31-6]	2 mg/m³
Tin - Organic compounds, as Sn [7440-31-6]	0.1 mg/m³	0.2 mg/m³	Skin
Titanium dioxide [13463-67-7] Revised 2006	10 mg/m³ (N)		2B
o-Tolidine [119-93-7]			Skin; 2B
Toluene [108-88-3] Revised 2007, 2008	20 ppm		R
Toluene-2,4-diisocyanate (2,4-TDI) [584-84-9]	0.005 ppm	C 0.01 ppm	2B; S
Toluene-2,6-diisocyanate (2,6-TDI) [91-08-7]	0.005 ppm	C 0.01 ppm	2B; S
o-Toluidine [95-53-4] Revised 2009	2 ppm		Skin; 1
m-Toluidine [108-44-1]	2 ppm		Skin
p-Toluidine [106-49-0]	2 ppm		Skin
Tributyl phosphate [126-73-8]	0.2 ppm
Trichloroacetic acid [76-03-9]	1 ppm
1,2,4-Trichlorobenzene [120-82-1]		C 5 ppm
1,1,2-Trichloroethane [79-00-5]	10 ppm		Skin
Trichloroethylene [79-01-6] Revised 2007	10 ppm	25 ppm	A2, 2A
Trichlorofluoromethane [75-69-4]		C 1000 ppm
Trichloronaphthalene [1321-65-9]	5 mg/m³		Skin
1,2,3-Trichloropropane [96-18-4]	10 ppm		Skin; 2A
1,1,2-Trichloro-1,2,2-trifluoroethane [76-13-1]	500 ppm	1250 ppm
Trichlorphon, Inhalable [52-68-6] Revised 2003	1 mg/m³
Triethanolamine [102-71-6]	5 mg/m³
Triethylamine [121-44-8]	1 ppm	3 ppm	Skin
Trifluorobromomethane [75-63-8]	1000 ppm
1,3,5-Triglycidyl-s-triazinetrione [2451-62-9]	0.05 mg/m³		R; S
Trimellitic anhydride, Inhalable [552-30-7] Revised 2008	0.0005mg/m³ (V)	0.002 mg/m³	Skin; S
Trimethylamine [75-50-3]	5 ppm	15 ppm
Trimethyl benzene (mixed isomers) [25551-13-7]	25 ppm
Trimethyl hexamethylene diisocyanate [28679-16-5]	0.005 ppm	C 0.01 pm
Trimethyl phosphite [121-45-9]	2 ppm
Tri-n-Butyltin compounds [688-73-3]	0.05 mg/m³
2,4,6-Trinitrotoluene (TNT) [118-96-7]	0.1 mg/m³		Skin
Triorthocresyl phosphate [78-30-8]	0.1 mg/m³		Skin
Triphenyl phosphate [115-86-6]	3 mg/m³
Tungsten - Metal and insoluble compounds [7440-33-7]	5 mg/m³	10 mg/m³
Tungsten - Soluble compounds, as W [7440-33-7]	1 mg/m³	3 mg/m³
Turpentine [8006-64-2] and selected monoterpenes [80-56-8; 127-91-3; 13466-78-9] Revised 2003	20 ppm		S
Uranium (Natural) - Insoluble compounds, as U [7440-61-1]	0.2 mg/m³	0.6 mg/m³	A1, 1
Uranium (Natural) - Soluble compounds, as U [7440-61-1]	0.05 mg/m³		A1
n-Valeraldehyde [110-62-3]	50 ppm
Vanadium pentoxide, Respirable dust and fume, as V₂O₅ [1314-62-1]		C 0.05 mg/m³	2B
Vanadium pentoxide, Total dust, as V₂O₅ [1314-62-1]	0.2 mg/m³		2B
Vegetable oil - Mist, except castor, cashew nut, or similar irritant oils [8008-89-7]	10 mg/m³
Vegetable oil, Mist, Respirable, except castor, cashew nut, or similar irritating oil [8008-89-7]	3 mg/m³
Vinyl acetate [108-05-4]	10 ppm	15 ppm	2B
Vinyl bromide [593-60-2]	0.5 ppm		A2, 2A
Vinyl chloride [75-01-4]	1 ppm		A1, 1
4-Vinyl cyclohexene [100-40-3]	0.1 ppm		2B; R
Vinyl cyclohexene dioxide [106-87-6]	0.1 ppm		Skin; 2B; R
Vinyl fluoride [75-02-5]	1 ppm		A2, 2A
N-Vinyl-2-pyrrolidone [88-12-0] Revised 2003	0.05 ppm
Vinylidene chloride [75-35-4]	1 ppm
Vinylidene fluoride [75-38-7]	500 ppm
Vinyl toluene, all isomers [25013-15-4]	25 ppm	75 ppm
VM & P Naphtha [8032-32-4] Revised 2009	(H)
Warfarin [81-81-2]	0.1 mg/m³
Wood dust - Allergenic species	1 mg/m³		1
Wood dust - Non-Allergenic Hardwood	1 mg/m³		A1, 1
Wood dust - Non-Allergenic Softwood	2.5 mg/m³		1
Xylene [1330-20-7] (o, m & p isomers) [95-47-6; 108-38-3; 106-42-3]	100 ppm	150 ppm
m-Xylene alpha,alpha'-diamine [1477-55-0]		C 0.1 mg/m³	Skin
Xylidine - Mixed isomers, Inhalable [1330-73-8]	0.5 ppm (V)		Skin
Yttrium - Metal [7440-65-5]	1 mg/m³
Yttrium and compounds, as Y [7440-65-5]	1 mg/m³
Zinc chloride - Fume [7646-85-7]	1 mg/m³	2 mg/m³
Zinc chromates, as Cr [13530-65-9; 11103-86-9; 37300-23-5]	0.01 mg/m³		A1
Zinc oxide, Respirable [1314-13-2] Revised 2003	2 mg/m³	10 mg/m³
Zinc stearate [557-05-1]	10 mg/m³ (N)	20 mg/m³
Zirconium [7440-67-7] and compounds, as Zr [7440-67-7]	5 mg/m³	10 mg/m³

Endnotes

(E) - the value is for particulate matter containing no asbestos and less than 1% crystalline silica.
(F) - the value for fibres longer than 5 microns, with an aspect ratio of equal than/greater than 3:1, as determined by the membrane filter method at 400 - 450 times magnification (4 mm objective), using phase-contrast illumination.<
(G) - as measured by the vertical elutriator, cotton-dust sampler, see TLV Documentation.
(H) - reciprocal calculation method, see OHS Guideline G5.48-11.
(J) - does not include stearates of toxic metals.
(K) - should not exceed 2 mg/m³ respirable particulate.
(L) - exposure by all routes should be carefully controlled to levels as low as possible.
(M) - refers to sulfuric acid contained in strong inorganic acid mists.
(N) - the 8-hour TWA listed in the Table is for the total dust. The substance also has an 8-hour TWA of 3 mg/m³ for the respirable fraction.
(O) - sampled by method that does not collect vapour.
(P) - application restricted to conditions in which there are negligible aerosol exposures.
(V) - vapour and aerosol.

* Download PDF version (77 KB) of the table.

Guidelines Part 5 - Ventilation

G5.62 Ventilation - Submitting plans

Issued August 1, 1999; Revised October 29, 2003

Section 5.62 of the Occupational Health and Safety Regulation states:

The employer or the employer's agent must submit to the board drawings and specifications for an existing or proposed ventilation system if requested by the board.

Section 5.62 applies to industrial ventilation systems. It does not apply to heating, ventilation, and air conditioning (HVAC) systems, which are covered under section 4.71.

Officers may request plans to evaluate compliance with a previously written order or with the general requirements for industrial ventilation. It may be appropriate to request plans in any of the following situations:

The installation of a new process requires addition(s) to the existing industrial ventilation system.
The process being built or modified is uncommon and a generic industrial ventilation plan or guideline is not available in the ACGIH Industrial Ventilation Manual.
The process being built or modified involves the control of a highly toxic material.
The employer or employer's agent is unable to answer basic questions about the proposed system change, including basic areas of knowledge, as it applies to the workplace or process in question, for:

air flow requirements
fan static pressure
method of filtration
capture velocity
air flow patterns

Examples of highly toxic materials include methylene bisphenyl isocyanate (MDI), hexamethylene diisocyanate (HDI), and other substances identified in section 5.57(1).

If the Board requests a plan, the Board's role is to review the plan with respect to the regulatory requirements as noted above.

G5.63 Building modification

Issued August 1999

Sections 4.73 and 5.63 of the OHS Regulation require the owner of a building to permit an employer to install a ventilation system if required by the Regulation.

The requirement under section 4.73 applies to ventilation systems for maintaining indoor air quality, not to industrial ventilation systems. For example, installation of a ventilation system may be required in situations where the building has no existing HVAC system or the HVAC system is inadequate for the occupancy. All such work, however, is subject to the approval of the owner, acting reasonably. In the context of this section, "the owner, acting reasonably" is taken to mean that the owner cannot be unreasonable when rejecting the project.

Generally, the operation and maintenance of the heating, ventilation and air conditioning (HVAC) system is the responsibility of the building owner or owner's agent, although this responsibility may be varied by commercial agreement. A statute or regulation overrides a private contract, therefore the requirements of this section take precedence over any term of a lease agreement that might be contrary to the responsibility cast by the OHS Regulation. However, the responsibility for the cost of the installation or upgrade will likely be determined by the lease agreement.

Section 5.63 applies to industrial ventilation systems, not to systems for maintaining indoor air quality or thermal comfort. The latter is covered under section 4.73 of the OHS Regulation.

G5.70 Discharged air

Issued August 1, 1999; Revised October 29, 2003

Section 5.70 of the OHS Regulation states:

(1) The use of a ventilation system designed to recirculate contaminants into the work area is restricted by the provisions of Table 5-1.

(2) A ventilation system that discharges air from the work area must be designed to minimize the likelihood of exposing any worker at a workplace, including an adjacent workplace,

(a) to an air contaminant in a concentration which exceeds either 10% of its applicable exposure limit in this Part or an acceptable ambient air quality standard established by an authority having jurisdiction over environment and air standards, whichever is greater, and

(b) if practicable, to an objectionable odour.

Section 5.70 applies to industrial ventilation systems. It does not apply to heating, ventilation, and air conditioning (HVAC) systems, which are covered under section 4.77, which contains similar wording to section 5.70(2).

Table 5-1 sets out situations when recirculation is not permitted, when it is permitted with written approval from the Board, and when it is permitted without such approval. The table states that the Board may grant approval for recirculation for "any contaminant not otherwise listed in the table."

Recirculation of substances identified by section 5.57(1) are not permitted, unless otherwise permitted in Table 5-1.

Authorities having jurisdiction over environmental air standards are the B.C. Ministry of Water, Land and Air Protection and Environment Canada for all regional districts in B.C. except the Greater Vancouver Regional District (GVRD). The GVRD sets and enforces its own standards for air quality within the GVRD.

Section 5.70 applies to minimizing exposure of all workers, including those at adjacent workplaces, even if those workers are employed by other employers. The term " likelihood" in subsection (2) refers to the probability that a worker may be exposed to discharge air from a ventilation system. If conditions, such as the direction of the prevailing wind, the discharge velocity of the exhaust air, or thermal effects in the air stream, routinely direct contaminants towards areas where workers are located, then this section applies.

Contaminated air that is allowed to escape through a wall or ceiling opening could re-enter the work area or an adjacent location. If this situation is thought to exist, the problem needs to be investigated to identify the nature of the contaminants, as well as the employer responsible for generating them. Typically, in determining if a worker overexposure to the limits set by section 5.70 exists, it is necessary to sample the air in the worker's breathing zone and not the air discharged from a ventilation system. The quantity of air contaminant discharged from a ventilation system falls under the jurisdiction of Environment Canada or the B.C. Ministry of Water, Land and Air Protection. The Board's jurisdiction is the exposure of the worker, who may be located some distance away from the discharge point, and due to mixing and dilution, the concentration at that location may be significantly lower than at the discharge point. However, it may be helpful for determining the nature and/or the source of a particular contaminant by area sampling adjacent to the discharge.

In determining the practicability of taking action to control an objectionable odour arising from discharged air, first determine if the contaminants can be identified:

If identification is possible, initially evaluate whether the concentration exceeds 10% of its applicable exposure limit or an acceptable air quality standard.
If identification of the constituents is not possible or if the odour continues to be a concern at levels less than 10% of the exposure limit, the practicability of controlling the emission should then be discussed with the employer responsible for generating the odour.

A decision to issue orders to control the odour will be determined on the basis of the duration of exposure, the availability of control technology and the offensiveness of the emission. If workers are experiencing other health effects, such as sensitivity or acute reactions, the Board's occupational health physicians should be consulted.

Some options for controlling an objectionable odour include:

Decreasing the concentration of the contaminant in the exhaust
Repositioning the stack
Increasing the stack height

However, before recommending that the position or the height of the stack be altered, the officer should consider whether this change will constitute a further hazard that is not practicable to control (for example, whether the required stack height will be unstable or whether the new position affect the structural integrity of the building). If there is a further hazard, alternative control technologies for objectionable odours should be considered.

Guidelines Part 5 Internal combustion engines

G5.73 Engine servicing and work area assessment for mobile equipment operated indoors

Issued June 6, 2006

Regulatory excerpt
Section 5.73 (indoor operation) of the OHS Regulation states:

If mobile equipment powered by an internal combustion engine is operated indoors or in an enclosed work area:

(a) the engine must be adequately serviced and maintained to minimize the concentration of air contaminants in the exhaust, and

(b) the work area must be assessed to determine the potential for exposure of workers to harmful levels of exhaust components.

Section 5.74 (Emission controls) of the OHS Regulation states:

If a worker is or may be exposed to an exhaust gas component in concentrations exceeding the applicable exposure limits, exhaust gas scrubbers, catalytic converters, or other engineering controls must be installed.

Purpose of guideline
This guideline provides information on

The scope of application of section 5.73 to equipment with internal combustion engines
Harmful emissions associated with the operation of internal combustion engines of the major fuel types - gasoline, natural gas, diesel, and propane (also termed liquefied petroleum gas or LPG)
The importance of adequate servicing and maintenance of internal combustion engines and specific requirements for servicing and maintaining these engines
The importance of adequately assessing the work area to determine the potential for exposure of workers to harmful levels of exhaust components, along with information on how to do that assessment

Scope of section 5.73

Mobile equipment
"Mobile equipment" is defined in Part 16 (Mobile equipment) of the OHS Regulation, as "a wheeled or tracked vehicle which is engine or motor powered, together with attached or towed equipment, but not a vehicle operated on fixed rails or tracks." Based on this definition, section 5.73 applies to vehicles such as ice resurfacers, forklift trucks, excavators and skidsteer loaders, if powered by an internal combustion engine.

Indoor and enclosed work areas
Section 5.73 applies to mobile equipment used indoors or in an enclosed work area. Refer to OHS Guideline G5.75 for a discussion of the meaning "indoors." For the purposes of this guideline, the term "enclosed" refers to any other work area where the operation of an internal combustion engine may result in the build up of harmful exhaust gases. Such areas may include but are not limited to vehicle parking garages, tractor trailers, ferries with enclosed or partly enclosed car decks, or a building under construction, at a stage when natural air flows may become restricted.

It should be noted that section 5.73 is one of a series of requirements on the use of internal combustion engines, found in sections 5.72 to 5.75 of the OHS Regulation. Other requirements such as section 5.55 on types of controls also apply.

Air contaminants in exhaust emissions
Section 5.73 refers both to "air contaminants" and "exhaust components." For the purposes of this guideline these terms will be considered to be interchangeable.

Although section 5.73 technically applies to a wide range of air contaminants that may be emitted during internal combustion engine operation, for practical purposes the number of exhaust components that need to be considered is usually limited to relatively few components, as discussed below.

Propane/gasoline/natural gas
For engines powered by gasoline, propane, and natural gas, the major harmful emissions are carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NO_x).

Studies have shown that the HC components of the exhaust are generally not significant until the level of CO produced results in worker exposures well in excess of the applicable exposure limits. As a result, generally only CO or oxides of nitrogen (principally nitrogen dioxide or NO₂), need to be considered when these fuel types are being used.

Diesel
Determining primary air contaminants of concern from diesel powered equipment is more problematic, as the number of contaminants of significance can be considerable. The major components of diesel exhaust include carbon monoxide, hydrocarbons, aldehydes, nitrogen oxides, sulfur dioxide (SO₂), diesel particulate matter and polynuclear aromatic hydrocarbons (PAH). Diesel particulate matter is a complex aggregate of solid and liquid material. Diesel particulate is very fine and as such is totally respirable.

Engine servicing and maintenance - section 5.73(a)

Section 5.73(a) requires that the engine of the mobile equipment be adequately serviced and maintained to minimize the concentrations of air contaminants in the exhaust. Some general considerations related to this requirement are provided below along with recommendations for specific fuel types.

General considerations
This requirement of section 5.73(a) can only be met by implementing an effective program of regular servicing and maintenance of the engine. The levels of exhaust contaminants from engines of all fuel types can be reduced by an effective program of regular servicing and maintenance. The program should consider both the specifics of how the servicing and maintenance is to be performed, as well as the frequency.

Maintenance and servicing should be performed in accordance with the instructions of the manufacturer or those of a qualified mechanic for the type of equipment being used. The frequency of servicing should be determined by the information from the manufacturer or mechanic, together with the results of workplace assessment and ongoing monitoring.

Minimizing the concentration of one contaminant in an engine's exhaust may result in the increase of another, in addition to potentially adversely compromising engine performance. Hence, "minimizing the concentrations," in the context of this guideline, refers to striking the optimum balance between contaminant emission levels and engine performance.

Experience has shown that specific obligations need to be met, depending on the fuel type, in order to ensure that contaminant levels are minimized in the exhaust.

Propane/gasoline/natural gas
Maintenance involves typical adjustments and parts replacement required to maintain engine performance. However, to ensure that the concentrations of air contaminants in the exhaust are effectively minimized for these fuel types, exhaust emission levels should be directly measured. Exhaust gas measurement completes the preventive maintenance program and gives the employer a good quality control tool for determining an adequate schedule for adjustments and parts replacement.

As a general rule, exhaust emissions should be analyzed before performing any servicing or maintenance, as well as afterwards. The exhaust gas analyzer used for measuring should be at least a four gas model (CO, CO₂, HC, and oxygen) and preferably include NO₂ as well. At a minimum, it should meet BAR-90 specifications of the California Bureau of Automotive Repair. The need to analyze for NO₂ can usually be determined from workplace air monitoring results. Emission levels should be measured both at idle and also under load.

The optimum balance between good power efficiency and emissions will vary depending on the engine and fuel type. This balance will usually be achieved when the ratio of air to fuel is the exact amount required for complete combustion (e.g. about 14 to 1 for propane).

In general, for engines not equipped with specific emission controls such as catalytic converters, the level of carbon monoxide in the exhaust should not exceed about 1% for propane (with the optimum between about 0.5% - 0.8%) and about 2% for gasoline. It should be noted that if CO levels are much below 0.5%, then NO₂ will need to be evaluated as well.

For engines equipped with catalytic converters, a thermocouple installed either downstream of the catalyst or both upstream and downstream, can be used as an indicator of whether the catalyst has reached operating temperature (emissions will be considerably higher until this temperature is reached). Indoor emissions can be reduced by keeping equipment outside until the catalyst has reached operating temperature. Thermocouples can also help determine if the catalytic converter needs replacement, that is, when the operating temperature cannot be reached.

A gasoline powered engine may produce a visible smoke in the exhaust and a significant odour if it is running significantly out of tune or is otherwise in need of servicing or repair. Engines powered by propane or natural gas may not, so the absence of significant odour or smoke haze in the workplace is not a reliable indicator of acceptable air quality.

Diesel
It is essential that diesel engines be serviced and maintained in accordance with the schedule recommended by the manufacturer. Particular attention should be paid to the regular replacement of the fuel filter and to fuel injector servicing. In addition, diesel fuel designed for on-road use (i.e. diesel fuel with the lowest available sulfur level) should be used in order to minimize sulfur related emissions.

Visible smoke from the exhaust of a diesel engine may be an indicator of the need for tuning or servicing as follows:

Blue smoke (mainly oil and unburnt fuel) - may indicate a badly worn engine in need of servicing
Black smoke (soot, oil and unburnt fuel) - indicates mechanical fault with the engine, such as defect in the fuel delivery system or the engine is working near its maximum speed
White smoke (water droplets and unburnt fuel) - produced when the engine is started from cold. Where appropriate the engine should be warmed up outside

NOTE: Where visible smoke is excessive, opacity testing, using the protocol in Society of Automotive Engineers (SAE) smoke test procedure J1667, or other applicable particulate emission test may be needed in order to demonstrate that emissions have been minimized.

Work area assessment - section 5.73(b)
The extent of the work area assessment required will depend on the circumstances of each workplace. In most cases actual measurement of air contaminants or an indicator of them will be necessary on a regular basis, in order to meet the requirements of section 5.73(b).

Measurement of the air contaminant levels may not be needed in circumstances where contaminant levels measured are minimal and exhaust emission controls have been provided, an effective service maintenance program is in place, and workplace ventilation rates are adequate. If at any time the workplace assessment suggests that workers may be exposed to levels above the applicable exposure limit, then equipment operation should be suspended until additional controls are provided.

Measuring exposure to air contaminants must be conducted using occupational hygiene methods acceptable to WorkSafeBC (refer to guideline G5.53). Both the short term exposure limit as well as the 8-hour limit must be considered for contaminants such as CO. Since NO₂ is assigned a ceiling limit, maximum exposure must be anticipated and evaluated. Re-evaluation is required if circumstances of use are altered which could increase exposure.

Preliminary assessment
In most cases, a preliminary assessment to determine the general suitability of equipment should be conducted before the equipment is put into operation. An additional air contaminant assessment may also be required, depending on the results of the preliminary assessment.

The preliminary assessment should consider factors such as

Is an alternative type of safer equipment available, which is practical to use under the circumstances, such as non-internal combustion engine options, or other equipment and engine fuel type options?
Can engine exhaust be practicably vented to the outdoors? This may be feasible where the mobile equipment remains essentially in one area for extended periods of time or moves slowly. For example, where mobile equipment such as excavators, concrete saws, or elevating work platforms are being used in construction.
Frequency and pattern of operation.
Type of fuel. Gasoline powered engines generally emit higher levels of CO than other fuel types, while propane and diesel emit higher levels of NO₂. In general, unless the equipment is provided with emission controls, a gasoline powered engine is not recommended for use under circumstances where the equipment is regularly operated indoors or in enclosed work areas. Quality of fuel should also be considered.
Engine size. Small engines generally emit proportionately higher levels of CO.
Exhaust contaminant levels.
Types of emission controls. With emission controls, contaminant levels can be expected to be significantly reduced.
Natural ventilation rate. The larger the work area volume the greater the natural ventilation rate.
Mechanical ventilation rate. The ACGIH Industrial Ventilation Manual, for example, stipulates a ventilation flow rate of 5000 cubic feet per minute (cfm) per forklift; studies have shown that this same ventilation rate is necessary to control the emissions from some small engines not designed for indoor operation.

Air contaminant assessment
Some guidance is provided below on the circumstances in which an additional air contaminant assessment is needed, and on acceptable levels of air contaminants for specific engine fuel types. In all cases, the employer must ensure that worker exposure does not exceed the exposure limits set out in section 5.48 of the OHS Regulation.

The level of air contaminants emitted in the engine's exhaust will generally be significantly higher when the engine is first started from cold. Thus, whenever possible, the equipment should be brought to operating temperature outdoors or with the exhaust vented directly outside, before running the equipment inside.

The initial air testing should be conducted under the conditions in the workplace that are expected to result in the highest exposure levels. If air contaminant levels under these "worst case" conditions are well within the applicable exposure limits (e.g. meets with the Low exposure level criteria described below), then additional air testing would not likely be required.

Air testing considerations are provided below for engines operating on different types of fuels. In some cases where more than one fuel type is involved (for example in vehicle parking garages or ferries) a broader range of air contaminants may need to be considered to adequately assess exposure.

Exposure levels are defined as follows:

Low exposure refers to exposure levels of less than one-tenth of the corresponding occupational exposure limit
Moderate exposure refers to exposure levels of from one-tenth to less than one-half of the exposure limit
High exposure refers to exposure levels of one-half or more of the exposure limit

Gasoline/propane/natural gas
For engines not equipped with emission controls, carbon monoxide (CO) can generally be used as a good indicator of overall exposure levels. However, even if CO levels are low, nitrogen dioxide (NO₂) exposure levels will also need to be evaluated. (Very low CO levels usually indicate that engine is running lean, which will result in higher NO₂ emissions). If the engine is equipped with a catalytic converter (which reduces CO and HC) or 3-way catalytic converter with air/fuel ratio feedback control system (which reduces CO, HC, and NO₂) then it is essential that NO₂ be evaluated as well.

Depending on the level of exposure, the suggested frequency for air contaminant assessment is as follows:

Low exposure - no additional air testing is required provided the service and maintenance program (which includes exhaust gas analysis as outlined previously) is established and maintained. Re-evaluation should be done if conditions of operation change
Moderate exposure - frequency of air testing will depend on exposure levels, types of controls, and workplace experience. In any case re-evaluation should be done at least every six months
High exposure - continuous monitoring for contaminant(s) of concern should be conducted. In any case, at least weekly monitoring is required

Special cases:

Ice arenas - Experience has shown that significant problems with indoor air quality can arise from the indoor operation of the ice resurfacing machine as well as the ice edger. Such workplaces should be equipped with continuous monitoring equipment for both CO and NO₂ and monitoring should be conducted at 1.8 metres (6 feet) or so above ice level. Periodic evaluations for CO and NO₂ levels should also be conducted in other areas of the arena complex not serviced by continuous monitors.
Construction sites - Since ventilation options may be limited on construction sites when working in relatively confined areas, consideration should always be given to use of mobile equipment which does not result in the accumulation of exhaust contaminants in the work area. Where this is not practical, ongoing monitoring for CO needs to be conducted to ensure that both the short-term exposure limit and 8-hour limit are not exceeded.
Small engines - Some small portable equipment such as power washers, concrete saws, floor burnishers, and generators may be powered by internal combustion engines. Such equipment is not considered to be mobile equipment under the OHS Regulation, and hence is not subject to section 5.73. However, before using any such equipment indoors the employer should ensure the equipment is designed by the manufacturer for indoor use. Fatalities have occurred as a result of indoor use of equipment designed solely for operation outdoors. If no other options are practical, then the ventilation rate should be measured and shown to be at least 5000 cfm per engine or the engine exhaust must be effectively ventilated directly to the outside. In any case, ongoing monitoring for CO will be required to ensure exposure limits are not exceeded.

Diesel
Although evaluating worker exposure to air contaminants generated by diesel engines tends to be more challenging than with other common fuel types, due to the number of potential air contaminants, diesel exhaust emissions are usually more visible. For example, they contain over ten times more particulate matter or smoke than gasoline engine emissions. In addition they are more directly irritating. As such, a more subjective evaluation can also prove useful as a workplace exposure assessment tool.

Since diesel exhaust generally contains relatively low levels of carbon monoxide, CO alone cannot be used as a reliable indicator of exposure. Nitrogen dioxide NO₂) is a principal concern, but contaminants such as aldehydes and diesel particulate matter may also be significant.

As a minimum, exposure evaluation will need to include CO and NO₂. Where exposure to both of these contaminants is within the applicable exposure limits, and where particulate (smoke) levels are not significant and workers are not experiencing any irritant or other ill effects that may be attributable to exposure to diesel exhaust, direct evaluation of other air contaminants may not be required. Where diesel powered equipment is being regularly operated indoors or in an enclosed work area, air monitoring for air contaminants other than CO and NO₂ should be conducted, unless contaminant levels are well within their respective exposure limits.

Once the relationship between CO and NO₂ and other diesel exhaust contaminant levels has been established for a given set of workplace circumstances, a single gas such as CO may be used for continuous or ongoing monitoring purposes. In this instance, the CO level to be used as an indicator of acceptable air quality will be significantly less than the 8-hour occupational exposure limit of 25 ppm. Ambient CO levels of less than 10 ppm are to be achieved before other contaminants can be assumed to be within acceptable levels.

For certain applications, such as where heavy duty or larger diesel engines are being operated, carbon dioxide (CO₂) may also be used as an indicator of contaminant levels. For example, where CO₂ levels are less than about 1000 ppm and the subjective criteria referred to above have also been met, then all contaminant levels associated with diesel exhaust are likely within acceptable limits. If representative indicators such as CO₂ are used as the only indicator of harmful exposure to exhaust components, the employer is expected to support this approach using additional assessment criteria.

The following table summarizes how CO₂ levels and/or a combination of CO and NO₂ readings could be used to assess the potential for worker exposure to harmful levels of diesel exhaust components. (The table is adapted from "Control of Diesel Exhaust Emissions in the Workplace" Health & Safety Executive, U.K.)

Table: Exposure levels and emission controls

Low	Medium	High
No visible haze in the workplace	Occasional white, blue, or black smoke visible in the workplace	Permanent white, blue, or black smoke
No visible soot deposits	Soot deposits visible	Heavy soot deposits especially near emission points
No complaints/reports of irritancy or other ill effects	A few complaints of irritancy or other ill effects	Worker complaints widespread
CO₂ levels less than 800 ppm and/or CO <8 ppm and NO₂ levels less than 50% of the exposure limit of 1ppm (ceiling)	CO₂ levels near 800 ppm and/or CO levels approaching 10 ppm or NO₂ levels approaching the exposure limit	CO₂ levels in excess of 1000 ppm and/or CO levels in excess of 10 ppm or NO₂ levels above the exposure limit
Controls likely to be adequate - periodic reevaluation	Controls may not be adequate. Additional assessment for other contaminants will likely be required or additional controls	Controls not likely adequate. Immediately cease operations and decide on new control strategy before resuming. Reevaluation required

G5.75 Mobile equipment emission controls

Issued: July 27, 2005

Regulatory excerpt
Section 5.75 (Mobile equipment emission controls) states:

Mobile equipment manufactured after January 1, 1999 that is regularly operated indoors must be
(a) equipped with an emission control system that includes a feedback control for air/fuel ratio, and a three-way catalytic converter if the mobile equipment is powered by gasoline, propane or natural gas, or other measures acceptable to the Board, or

(b) equipped with a scrubber or other emission control system that reduces particulate emissions by at least 70% when tested according to the procedures of the Mine Safety and Health Administration, US Department of Labour, or must meet another standard acceptable to the Board, if the mobile equipment is powered by diesel fuel.

Purpose of this guideline
This guideline provides information on the circumstances in which emission controls are expected on mobile equipment powered by internal combustion engines, when used indoors. The guideline deals largely with section 5.75, but also discusses several related requirements. It explains what is meant by the terms "regularly operated" and "indoors" in section 5.75 and also points out a specific requirement in agriculture.

The context of section 5.75
This provision is one of a series of requirements on the use of internal combustion engines indoors, found in sections 5.72 to 5.75 of the OHS Regulation.

Section 5.72 addresses the obligation to vent engine exhaust to the outdoors where possible. Typically this requirement applies to engines that are fixed in place and to those locations where vehicles undergo engine repair or maintenance.

For mobile equipment operated indoors or in enclosed areas, section 5.73 requires a risk assessment be done to assess the potential for exposure of workers to harmful levels of air contaminants. It also requires that engines be adequately maintained and serviced.

Section 5.74, which applies to both fixed and mobile equipment used indoors, requires that engineering controls be installed on the equipment, but only if workers are or may be exposed to harmful levels of air contaminants as a result of engine operation.

Section 5.75 is a technology-based requirement that establishes an obligation to install certain emission control equipment on newer mobile equipment manufactured after January 1, 1999, when the equipment is "regularly operated indoors" to help prevent any likelihood of the over-exposure of workers to air contaminants.

Typically employers who own equipment will be expected to ensure any necessary modifications are made to ensure compliance with section 5.75. In cases where suppliers provide equipment in a lease or rental arrangement, and it is known that the equipment would be regularly operated indoors, then under the Workers Compensation Act, the supplier also carries responsibilities for compliance.

The remainder of this guideline discusses what is meant by the phrasing "regularly operated indoors" and provides information on its application to agriculture.

What is meant by "regularly operated"?
The term "regularly operated," as it applies to indoor use, means that the equipment is either typically used indoors (that is, for a majority of its use time), or is used indoors on a recurring and substantial basis.

Examples of equipment that is typically used indoors include ice-surfacing equipment at indoor skating rinks, and forklifts used inside warehouses to move product around the warehouse or to handle deliveries in the warehouse to and from loading bays. Such equipment, if manufactured after January 1, 1999, is required to have emission control equipment installed as per section 5.75.

Section 5.75 is also applicable to equipment that is used indoors on a recurring and substantial basis, even though it is typically used outdoors. There are two points of clarification in this case.

The recurring use should be ongoing to require the installation of emission controls. For example, if a piece of equipment such as a bobcat is used indoors for a week or two to excavate some subsoil during the renovation of a foundation, but is otherwise always used outdoors, then emission control equipment would not be required.
Where a piece of mobile equipment is used indoors on an ongoing recurring basis that use must also be reasonably substantial in extent. For example, if a forklift is used indoors on a recurring basis, but for no more than 15-20% of its total use time on a typical day, then normally section 5.75 will not apply. Under this scenario, section 5.75 is not expected to apply to a piece of mobile equipment that is operated indoors only for purposes such as parking the equipment, maintenance or repairs.

However, in both the above cases the areas in which the equipment is used must be assessed to determine the potential for workers to be exposed to harmful levels of exhaust components, as required by section 5.73(b). If usage of a piece of mobile equipment, regardless of its extent, (or date of manufacture) exposes or may expose a worker to concentrations of an exhaust gas component exceeding the applicable exposure limit, then section 5.74 applies and an exhaust gas scrubber, catalytic converter or other engineering controls must be installed.

What is meant by "indoors"?
This term is intended to apply to those buildings or other structures that will tend to prevent natural air flow, and trap exhaust contaminants within the structure. Typically, a four-sided roofed structure that is structurally open on at least two sides where the equipment is being operated will not be considered to be "indoors". If the area in which the equipment is being operated is enclosed on three of the four sides it would likely be considered to be an indoor environment, even if it has a number of doors that could be left open. If the area where the equipment is being operated is substantially open above, it may not be considered to be indoors if at least one side is also open.

Application to agriculture
Note that the requirements of the OHS Regulation did not apply to agriculture until January 1, 2005. As a result, section 28.33 makes the requirements of section 5.75 applicable in agriculture only to equipment purchased for first use after January 1, 2006. This guideline also applies to that agriculture equipment.

Guidelines Part 5 - Hazardous wastes and emissions

G5.80 Hazardous wastes and emissions - Sharp-edged waste

Issued August 1999; Editorial Revision February 1, 2008

Regulatory excerpt
Section 5.80 of the OHS Regulation ("Regulation") states:

Broken glass, metal or similar rigid, sharp-edged waste must be disposed of in separate, puncture proof waste containers and the contents of the containers must be clearly identified.

Purpose of guideline
The purpose of this guideline is to discuss disposal procedures for sharp-edged waste. It also discusses features of an acceptable puncture-proof waste container.

Sharp-edged waste
Under section 5.80 of the Regulation, sharp-edged waste must be disposed of in separate, puncture-proof waste containers and the contents of the containers must be clearly identified. This section applies to broken glass, metal, or other similar rigid sharp-edged waste. The requirements for needle sharps contaminated with either biological agents or cytotoxic drugs are addressed under sections 6.36 and 6.57.

An acceptable "puncture-proof waste container" should be rigid enough to contain whatever waste it was intended to hold. Thus, plastic or paper bags should not be used for broken glass, but metal or fibreboard (thick cardboard) chemical drums would be acceptable. In this section, "clearly identified" normally means affixing an identifier label on the container, for example "broken glassware."

Guidelines Part 5 - Personal hygiene

G5.82 Employer's responsibility

Issued August 1, 1999

Section 5.82 of the OHS Regulation outlines employer's responsibility to provide effective means of removing hazardous substances defined in section 5.1 from a worker's skin or clothing. This section applies to work processes where a worker's skin or clothing may become contaminated with substances that, if not removed prior to the completion of the work shift, would present a hazard from inhalation or ingestion. Examples include finely divided lead or lead compounds, mercury, silica dust, pesticides and asbestos fibres.

Section 5.82(1)(b) requires the employer to "launder or dispose of the protective clothing on a regular basis, according to the hazard." Note that the provisions of section 12.157 of the OHS Regulation also apply. That is, the employer must advise the operator of the laundry or dry cleaning facility in writing of any potential hazards.

If the work process is "high hazard", then the provisions of section 5.82(2) also apply. To determine whether the process is high hazard, the toxicity of the material should be considered, as well as the potential for exposure. If the material is highly toxic and there is a high potential for worker exposure, then the process should be considered high hazard. When evaluating the potential for exposure, the officer should take into account that exposure can result not only from direct use of the substance, but also from cross-contamination (of food, clothing, cigarettes) and/or from ongoing contact with contaminated clothing or other personal materials. The requirements of sections 5.55 and 5.57 of the OHS Regulation must also be considered. Under these sections, substitution of less hazardous materials must be considered where possible to reduce the level of hazard. Refer to OHS Guidelines G5.55 and G5.59 for further information.

Examples of high hazard substances include, but are not limited to, asbestos, lead, mercury, cadmium, cobalt, nickel, and pesticides. Examples of operations in which high hazard substances are likely to be handled are as follows:

- lead or asbestos abatement	- foundries
- saw filing	- cathode manufacturing
- battery re-manufacturing	- manufacturing operations using radioactive materials
- smelting operations	- coal tar/pitch operations
- electrical repair	- exploratory rock drilling
- PCB handling	- abrasive blasting
- environmental remediation	- broadcast spraying of pesticides
- steel manufacturing

In remote locations where provision of change rooms and shower facilities may not be practicable, the employer is permitted, under section 5.82(3), to provide separate clothing storage and adequate washing facilities. In these circumstances, the employer may need to use PPE that can be easily decontaminated and implement other contaminant control measures to minimize the likelihood of accidental contact with the high hazard materials. Refer to OHS Guideline G 5.91 for additional information on the requirements for emergency washing facilities in remote work sites.

G5.83 Worker's responsibility

Issued August 1, 1999

Section 5.83 of the OHS Regulation requires that workers engaged in a work process covered by section 5.82 wear the PPE supplied by the employer, wash effectively before each work break and at the end of the work shift, and shower at the end of the work shift, if required by the hazard.

To evaluate compliance with this requirement, the officer should first consider whether the employer

has fulfilled his or her responsibility to adequately train, instruct and supervise workers in the required procedures, as per section 115 of the Workers Compensation Act, and
used disciplinary action to further discourage the use of unacceptable work procedures, where necessary.

One can determine if the employer has met his or her responsibilities for training by asking the worker the following questions:

do you work with hazardous materials? If so, what are they?
what precautions are required to prevent or minimize exposure?
what do you do to remove the material(s) from your skin or clothing?
where are the wash and/or shower facilities?
what are the consequences of not following the instructions regarding personal hygiene?

It is possible to issue orders on both the worker and the employer if both are at fault. Section 116 of the Workers Compensation Act, "General duties of workers," also applies. Depending on whether the employer has fulfilled his or her responsibilities to train and supervise and the worker followed that training and supervision, orders may be issued on the employer and/or the worker for violations of sections 115, 116 and 83 of the Workers' Compensation Act.

Guidelines Part 5 - Emergency washing facilities

G5.85 Where required

Issued August 1, 1999

Section 5.85 of the OHS Regulation requires that the employer provide appropriate emergency washing facilities within a work area. This section applies to workplaces where there is a risk of exposure to harmful or corrosive materials or other materials that may burn or irritate. Work activities for which emergency washing facilities will likely be required include, but are not limited to, maintenance of ammonia refrigeration equipment, chlorine unloading operations, and caustic degreasing processes.

The selection of appropriate facilities will depend on the degree of risk associated with the workplace or work activity. Refer to Table 5-2 for guidance in identifying workplaces where emergency washing facilities are required. Before selecting emergency washing facilities, one must identify the potential hazard for workers followed by an assessment of the level of risk, as required by section 5.88. Refer to OHS Guideline G 5.88 for further assistance. Table 5-3 outlines the type of equipment required, as well as where such equipment should be located.

G5.86 Water supply

Issued August 1, 1999

Section 5.86 of the OHS Regulation specifies the water supply requirements for emergency eyewash facilities. Emergency eyewash facilities may be plumbed or portable (non-plumbed). Under this section, only a potable water supply is to be used for plumbed facilities. For non-plumbed units, either a potable water supply or an isotonic saline flushing solution (such as 0.85% to 1.0% sodium chloride buffered to a pH of 7.3 ‹ 7.4) may be used. Potable water, according to the Regulations for Agricultural Operations (WCB April 30, 1993), means water fit for human consumption.

Although portable, self-contained emergency eyewash units should deliver a buffered anti-bacterial saline solution over a 15-minute flush. Any effective antibacterial agent, suitable for ophthalmic use, added to tap water will help preserve the water and reduce the possibility of pathogens developing in the flushing solution. Buffered solutions may be less irritating to the eye than tap water and can improve the effectiveness of portable eyewash units because small amounts of these solutions can be very efficient at partially neutralizing the contaminant.

G5.88 Risk assessment

Issued August 1, 1999

Section 5.88 of the OHS Regulation requires that the employer conduct a risk assessment before selecting emergency washing facilities. Emergency eyewash and/or shower facilities should be selected to address the potential hazard(s) associated with the substances used, the tasks performed and the work area. Refer to Tables 5-2 and 5-3 respectively for guidance in evaluating risk and selecting appropriate facilities.

The general approach to be taken in conducting a risk assessment is discussed in OHS Guideline G 5.54-3 ("Risk identification, assessment and control"). Some of the specific factors that should be considered when evaluating the need for emergency washing facilities include the nature and the quantities of the hazardous material involved, as well as the potential for contacting the material during work activities. The table below provides some guidelines that may be helpful for assessing whether a work activity poses a risk to the eyes or skin.

Affected Organ	Nature of the Exposure	Risk Level
Eyes	any volume of "very hazardous material" splashed into the eyes	High
Skin	more than 100 mL of "very hazardous material" splashed above the waist, or more than 1 litre of "moderately hazardous material" splashed onto the body, with possible splashing above the waist	High
Eyes	any volume of "moderately hazardous material" splashed into the eyes	Moderate
Skin	less than 100 mL of "very hazardous material" splashed onto unprotected skin above the waist, or less than 1 litre of "moderately hazardous material" splashed onto unprotected skin, with possible splashing above the waist	Moderate
Eyes	any volume of "low hazard material" splashed into the eyes	Low
Skin	less than 100 mL of "very hazardous material" splashed below the waist, or less than 1 litre of "moderately hazardous material" splashed below the waist	Low

Notes:

Very Hazardous Materials: materials classified as WHMIS Class E (Corrosive Materials) or WHMIS Class D1A (Very Toxic Material), which meet the criteria for acute dermal toxicity.

Moderately Hazardous Materials: materials classified as WHMIS Class D2B (Toxic Material), which cause reversible irritation to skin and eyes.

Low Hazard Material: materials that may irritate skin or eyes due to physical, as opposed to their chemical, nature (e.g., particulates generated from grinding). For these materials, the availability of emergency flushing equipment is less critical than the availability of first aid.

G5.89 Table 5-3 Provision and location of emergency washing equipment

Issued August 1, 1999; Editorial Amendment November 18, 2009

Regulatory excerpt
Section 5.89 of the OHS Regulation ("Regulation") states:

(1) The employer must ensure, except where it is not practicable to provide a permanent water supply, such as at a remote or transient worksite, that emergency eyewash and shower facilities are provided and located as specified in Table 5-3.

(2) Requirements for tempered water in Table 5-3 do not apply if the advice of a medical professional indicates that tempered washing would increase the risk of injury in a particular application.

Purpose of this guideline
This guideline describes how to determine whether the water supply for emergency washing equipment must be tempered.

Background
Examples of workplaces where it may be impracticable to provide permanent facilities include remote or transient work sites. Refer to Regulation sections 5.90 and 5.91, and the associated OHS Guidelines, for emergency washing requirements at transient and remote worksites, respectively.

Table 5-3 in the Regulation lists the emergency eyewash and shower equipment required for high, moderate, and low risk workplaces. In addition, it prescribes where the required equipment must be located in relation to the hazard area. Equipment should be located in readily accessible, well marked locations, and there must be unobstructed access.

Depending on the outcome of the risk assessment conducted under section 5.88, the employer may be required to install one or more of the following:

Continuous flow emergency shower facility
Continuous flow eyewash facility
Drench hose
Personal eyewash unit
Supplementary eyewash facility

Tempered or non-tempered
The results of the risk assessment will also determine whether the water supply must be tempered or non-tempered. Each of these terms has been defined in section 5.1 of the Regulation. For more detailed information on emergency washing facilities and design criteria, including acceptable temperature ranges, inlet water pressures, and water flow rates, refer to ANSI Standard Z358.1-1998 (American National Standard for Emergency Eyewash and Shower Equipment).

For both high and moderate risk workplaces, Table 5-3 requires the provision of tempered water in primary emergency washing facilities. However, under section 5.89(2), tempered water is not required if the advice of a medical professional indicates that tempered washing would increase the risk of injury in a particular application. A medical professional is a physician registered under the Medical Practitioners Act. Examples of situations in which the use of tempered water may not be appropriate include

Cryogenic chemicals: irrigation water should not exceed body temperature
Thermal burns: application of cold water to the burn immediately after contact may be preferable to reduce the potential for tissue damage
Caustic soda and potassium: because both are very reactive with water, an immediate flush with a neutralizing or buffered solution may be appropriate, followed by a tempered water flush

For high and moderate risk work locations, non-tempered drench hoses are not an approved substitute for a tempered continuous flow shower or eyewash facilities, although they can be used as supplementary washing facilities to commence the flush. In moderate risk work areas where the risk assessment conducted under section 5.88 indicates that a hazard exists only for small areas of the body or face, WorkSafeBC would consider non-tempered drench hoses to be acceptable supplemental emergency shower and eyewash facilities. See Table 5-3 for specific information.

G5.90 Mobile shower units

Issued April 1, 2006

Regulatory excerpt
Section 5.90 of the OHS Regulation states:

(1) The employer must ensure that portable self-contained units are provided, where it is not practicable to provide a permanent water supply at transient worksites such as construction sites.

(2) The employer must ensure that portable self-contained units at these transient worksites are capable of delivering a minimum flush duration of 15 minutes (or more if required by the nature of the material) if there is a high or a moderate risk of injury to the eyes or skin.

Purpose of guideline
This guideline provides recommendations to the oil and gas sector for the use of mobile shower units. This guideline applies only to oil and gas worksites where it is not practicable to provide a permanent water supply but where a portable self-contained unit (e.g. mobile shower unit) is available.

Recommended use of mobile shower units
Enform's Pumping of Flammable Fluids Industry Recommended Practice (IRP) Volume 8 - 2009 (IRP 8) (http://www.enform.ca/pdf/irp8_final_mar2009.pdf) in section 8.10 (attached as Appendix A) has specifications for mobile shower units related to

The capabilities and capacities of the mobile shower/eyewash units and drench hoses
Training requirements for, and responsibilities of, the operators of these units
Equipment requirements for operators of the mobile shower units
Personal protective equipment requirements for mobile shower unit operators
Factors determining the use of mobile shower units

Employers should follow the specifications for mobile shower units outlined in IRP 8, where applicable.

Where combination fire-shower truck units are used as portable self-contained units under section 5.90, in addition to the specifications in IRP 8, the following should be met:

Procedures should reflect that the combination fire-shower truck is present at the site primarily for personnel emergencies and that the truck must be positioned in a safe place that provides ready access by workers.
The combination fire-shower truck unit should be configured so that the onboard water supply is used for emergency washing equipment only. If the fire system can draw from the onboard water storage tank, the fire system should be isolated from the onboard storage tank by physically disconnecting them, installing a blind, or locking a valve.

Note: Where there is any conflict between the requirements of the OHS Regulation and IRP 8 the OHS Regulation applies.

Appendix A
Excerpt from "Pumping of Flammable Fluids", Industry Recommended Practice (IRP), Volume 8 - 2009

8.10 Mobile Safety Shower Requirements

8.10.1 Scope

Shower units are intended to provide standby safety services for workers whenever hazardous fluids (see WHMIS guidelines) are being pumped or handled. There are several different designs of shower units available on the market.

The intent of this section is to recommend MINIMUM standards for:
The capabilities and capacities of the shower/eyewash units, and drench hoses

Training requirements for, and responsibilities of, the operators of these units

Equipment requirements for operators of the shower units

Factors determining the use of shower units

8.10.2 Capabilities and Capacities of Mobile Shower Units

In order to meet the requirements set out in the O H & S GSR 448/83 Section 16 (1) and the First Aid Regulation 48/2000 Section 13, suitable on-site facilities shall be provided as defined in Provincial/Territorial Regulations and ANSI - Z358.1 - 1998). On-board water supplies are typically 1.9m³ - 2.3m³(500 - 600 US gallons). Each person that could be exposed to hazardous fluids requires 1.15m³ (300 US gallons) of potable water available for safety shower use. Seasonal weight restrictions (road bans) may limit the amount of water allowed on-board the mobile shower units. This factor will have to be taken into account when determining the need for a supplemental potable water supply.

ANSI Standard Z358.1 - 1998, Sections 4, 5 and 8, set out the following minimum standards for shower units, eyewash units, and drench hoses:
Each shower head shall be capable of delivering a minimum of 76 liters per minute (20 US gpm) of "flushing solution" for a minimum of 15 minutes. This requires a minimum of 1.14m³ (300 US gallons) for each person exposed to hazardous fluids.
Each eyewash unit shall be capable of delivering flushing fluid to the eyes at a rate of not less that 1.5 liters per minute (0.4 US gpm) for 15 minutes
Each drench hose shall be capable of delivering a minimum of 11.4 liters per minute (3 US gpm) of flushing fluid for a minimum of 15 minutes
The delivered flushing fluid temperature shall be "tepid". Tepid is defined in the ANSI Standard as "moderately warm; lukewarm"
If the number of persons required to be in the HOT ZONE exceeds the on-board water supply of a mobile shower unit, supplemental (tepid) potable water shall be required.

Refer to ANSI Standard Z358.1 - (latest edition) for more information on the performance requirements and inspection and maintenance of safety shower equipment.

The following minimum standards should also be observed:
The showering area must be fully enclosed and heated and large enough to comfortably accommodate one adult per shower head
The showering area shall be provided with forced air ventilation

The "recovery area" shall not be used for transportation of the victim, and may only be used for first aid purposes until medical aid arrives at the scene. The shower stalls must not be used as a "recovery area"

A First Aid Kit in accordance with Provincial/Territorial First Aid Regulations

Two self-contained breathing apparatus (SCBA)

The shower unit must be fully mobile in order to change position on location to effectively compensate for changes in wind direction or movement of other equipment on location

The shower unit must be separated from any potential hazard, shall not be located within the HOT ZONE and be within 10 second walking distance from the HOT ZONE.

Shower units located on tank trucks delivering acid or other fluids to the location are to be used by the tank truck operator only and shall not be factored in when determining the number of shower heads required to provide adequate protection for personnel working in the HOT ZONE.

Ordinary showers installed in travel trailers etc. do not meet the ANSI standard and shall not be not be factored in when determining the number of shower heads required to provide adequate protection for personnel working in the HOT ZONE.

8.10.3 Training and Responsibilities of Safety Shower Operators

Operators of shower units shall be competent in the operation of the unit they will be required to operate.

Operators of shower units shall have current and valid training certificates in the following:
Standard First Aid/CPR

H₂S Alive

Transportation of Dangerous Goods (TDG)

WHMIS

The shower unit operator's duties and responsibilities shall be limited to the following:
The administering of first aid to on-site personnel exposed to chemical/corrosive substances

Provide assistance for on-site first aid

The safe operation of the shower unit; eyewash unit, and drench hose

Review of hazard awareness with all personnel

Instruction of personnel who may be exposed to hazardous materials in the location and proper use of the emergency shower units

8.10.4 Personal Protective Equipment (PPE) Requirements for Safety Shower Operators

Operators of shower units shall be equipped with a complete acid/chemical resistant wet suit including gloves, rubber boots, eye protection, Fire Retardant Clothing (FRC) and a hard hat. FRC must meet CSA or CGSB Standards.

8.10.5 Determining Factors for the Number of Safety Shower Units Required

The following should be taken into account when determining the number of shower units, eyewash units, drench hoses and supplemental supply of potable water required:
The number of personnel working in the HOT ZONE. The HOT ZONE area will differ from job site to job site, and will have to be determined at the job site

Some acid job HOT ZONEs are on the rig floor when the treating iron is suspended

The number of pumping units and volume of acid on-site

The shower unit(s), eyewash unit(s), and drench hose(s) should be on location when the acid is being transferred, mixed, or under pressure on the surface. This shall include the time when back pressure is being used to circulate the acid to the bottom

The shower unit(s), eyewash unit(s), and drench hose(s) shall remain on location until all pumping equipment has been rigged out

G5.91 Remote workplaces

Issued August 1, 1999

Under section 5.91 of the OHS Regulation, the employer is permitted to provide an effective means of flushing the eyes or skin at remote work sites if it is not practicable to provide a portable self-contained unit. Examples of remote work sites include remote logging operations, tree-planting activities, other forestry operations, remote field pumping stations. The selection of "effective means" must be based on the results of a risk assessment conducted in accordance with section 5.88. Factors that would affect the practicability of providing portable units include, but are not limited to, the availability of a plumbed water supply or a source of heat.

In high risk, remote work sites, the employer should consider

substituting a material that reduces the risk to workers, as required under section 5.55(1)(a)
isolating or enclosing the material to minimize the likelihood of accidental contact with the eyes or skin, and
providing personal protective equipment that is impenetrable, provides good coverage, can be easily decontaminated or disposed of.

Workers should be trained in both the location and use of the emergency facilities.

Regardless of the level of risk, a clean source of water should be provided to wash exposed body parts. Some options that employers in remote and/or transient work locations might consider using include

portable, electrically-tempered shower systems (these are available for both indoor and outdoor use and can provide pressurized water meeting ANSI requirements),
portable shower trailers,
collapsible solar bags,
IV saline drip (to permit continuous flush during transport to a plumbed facility),
nearby lakes or streams (in the summer months), or
water baths.

G5.93 Testing

Issued August 1, 1999; Editorial Revision August 2004

Section 5.93 of the OHS Regulation requires that the employer test emergency washing facilities. Section 4.3 of the OHS Regulation requires that equipment must be used and maintained in accordance with the manufacturers' requirements. This means that the facility must be tested upon initial installation in accordance with manufacturers' instructions. Where manufacturers' instructions address other issues, such as flushing or otherwise protecting solutions from micro-organisms, those instructions must be complied with as well. Plumbed facilities must be tested after initial installation and on a monthly basis thereafter. Portable (i.e., non-plumbed) eyewash units must be protected from contamination and refilled regularly with fresh solution to prevent the growth of microorganisms.

It is good practice to maintain records of testing, inspection and maintenance of plumbed and non-plumbed eyewash facilities. These records could be in the form of a log book, preventative maintenance cards, tagging or other similar method and should include the date and time of the test, any defects noted and corrective action taken.

G5.94 Training

Issued August 1, 1999

Under section 5.94 of the OHS Regulation , the employer is required to provide adequate training to workers on the location and proper use of emergency washing facilities. To evaluate compliance with this section, officers ask the worker the following questions:

do you work with hazardous materials? If so, what are they?
what precautions are required to prevent or minimize exposure?
what do you do to remove the material(s) from your skin or clothing?
where are the emergency wash and/or shower facilities?
how do you activate the unit?
how long should you remain in the shower (or how long should you run the eyewash unit)?

G5.95 Protection from freezing

Issued August 1, 1999

Section 5.95 of the OHS Regulation requires the employer to ensure that emergency washing facilities, as well as the piping from the water supply, are protected from freezing. Measures to protect water supply lines from freezing, include

heat or steam tracing lines,
locating water supply lines and actuation valves underground beneath frost line,
installing special valves that allow water to drain down automatically to a point below the frost line after the equipment is used,
providing thermostatically controlled induction-heated shower and piping systems,
circulating warm water in the pipes, or
using dry pipes from a warm building.

If emergency washing facilities are attached to an existing building, a pull cable can be installed on the inside valve to bring warm water from the neighbouring building into the facilities on demand. If the washing facilities are not attached, heated, self-contained units are recommended.

Guidelines Part 5 - Emergency procedures

G5.97 Emergency plan

Issued August 1, 1999

Section 5.97 of the OHS Regulation requires the employer to develop a written emergency plan appropriate to the hazards of the workplace. In accordance with sections 5.98 to 5.102, the plan must include

- inventory of hazardous substances, - risk assessment, - procedures for evacuation, - procedures for spill cleanup and reentry, and - training and drills.

Depending on the type of emergency, the plan should also identify the relevant local or provincial agencies to be consulted or notified. For example, the relevant agencies include, but may not be limited to, the local fire and police departments, WorkSafeBC, the Ministry of Environment. The officer or the employer should consult with the Prevention Information Line for an up-to-date list.

G5.99 Risk assessment

Issued August 1, 1999

Under section 5.99 of the OHS Regulation , the employer must assess the risks posed by hazardous substances from accidental release, fire or other such emergency. Section 5.98 requires that an inventory of all hazardous substances at the workplace be conducted. The general approach to be taken when conducting a risk assessment is discussed in OHS Guideline G 5.54-3. Some of the specific factors that should be considered when developing an emergency plan are outlined in the table below.

Factors to be considered when evaluating the risks posed by hazardous substances
General	Specific
What is the nature of the hazard?	what are the body systems involved (i.e., eyes, skin, lungs)? what are the possible effects of exposure (i.e., irritation, burns, breathing difficulties, death)? are the effects short-term (i.e., nausea) or long-term (i.e., brain damage)?
What is the nature of the exposure?	what specific substances are present in the workplace? what events or circumstances, failures or errors could cause conditions leading to an emergency (i.e., accidental release, fire)? if there was an accidental release, how would workers be exposed (e.g., ruptured flange or pipes)? in the event of a fire, how would workers be exposed (i.e., to substances themselves, to the products of combustion, etc.)? how many workers would be at risk? who else might be at risk (i.e., adjacent workplaces, nearby community)?
What control measures are in place to minimize risk?	are engineering controls in place (e.g., pressure release valves, fail-safe valves, sprinklers)? has appropriate personal protective equipment been identified?

G5.101 Procedures for spill cleanup and re-entry

Issued August 1, 1999

The note statement following section 5.101 of the OHS Regulation indicates that it may be necessary to notify other jurisdictions and agencies in the event of a spill. In British Columbia, anyone who learns of a hazardous chemical release must immediately contact the Provincial Emergency Program at 1-800-663-3456.

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Disclaimer: The Worker and Employer Services Division issues Guidelines to help with the application and interpretation of sections of the Occupational Health and Safety Regulation and with divisions of the Workers Compensation Act that relate to health and safety. Guidelines are not intended to provide exclusive interpretations but to assist with compliance. WorkSafeBC ("Workers' Compensation Board of B.C.") does not warrant the accuracy or the completeness of the online version of the Guidelines and neither WorkSafeBC nor its board of directors, employees or agents shall be liable to any persons for any loss or damage of any nature, whether arising out of negligence or otherwise, which may be occasioned as a result of the use of the online version of the Guidelines.

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Guidelines Part 5

Guidelines Part 5 Contents

DEFINITIONS, DESIGNATION AS HAZARDOUS SUBSTANCES, AND GENERAL INFORMATION REQUIREMENT

WORKPLACE HAZARDOUS MATERIALS INFORMATION SYSTEM (WHMIS)

CONTAINERS AND STORAGE

FLAMMABLE AND COMBUSTIBLE SUBSTANCES

SUBSTANCES UNDER PRESSURE

CONTROLLING EXPOSURE

VENTILATION

INTERNAL COMBUSTION ENGINES

HAZARDOUS WASTES AND EMISSIONS

PERSONAL HYGIENE

EMERGENCY WASHING FACILITIES

EMERGENCY PROCEDURES

Guidelines Part 5 - Definitions, Designation as Hazardous Substances, and General Information Requirement

G5.1.1 Biological Agents

Guidelines Part 5 - Workplace Hazardous Materials Information System (WHMIS)

G5.3-1 WHMIS Application

G5.3-2 Fire extinguishers (adopted from WHMIS Bulletin #4)

G5.3-3 Cylinders of breathing air (adopted from WHMIS Bulletin #5)

G5.3-4 Exemptions (adopted from WHMIS Bulletin #9)

G5.3-5 Leaded surface coating materials

G5.3-6 "For industrial use only" labels (adopted from WHMIS Bulletin #10)

G5.3-7 Warehousing of Controlled Products

G5.3-8 The application of WHMIS in agriculture

G5.5 WHMIS program (adopted from WHMIS Bulletin #1)

G5.6 Worker education (adopted from WHMIS Bulletin #8)

G5.8-1 Supplier label (adopted from WHMIS Bulletin #2)

G5.8-2 Labelling on leased or rented chemical application units (adopted from WHMIS Bulletin #2)

G5.8-3 Multi-container shipments of laboratory samples

G5.14-1 Supplier material safety data sheet (MSDS)

G5.14-2 Fees (adopted from WHMIS Bulletin #3)

G5.15 Laboratory MSDS (adopted from WHMIS Bulletin #7)

Guidelines Part 5 - Containers and storage

G5.22 Covers

G5.25 Storage practices

Guidelines Part 5 - Flammable and combustible substances

G5.27(2) Electrical Safety Act repealed

G5.30 Dispensing

Guidelines Part 5 - Substances under pressure

G5.38 Handling and securing containers

Guidelines Part 5 - Controlling exposure

G5.48-1 Table of exposure limits - background information

G5.48-2 Annual revisions to exposure limits

G5.48-3 Normal 8-hour work period

G5.48-4 Conversions for ppm and mg/m3

G5.48-5 Welding fume

G5.48-6 Allergenic species of wood dust

G5.48-7 Nuisance dusts

G5.48-8 Simple asphyxiants -- Inert gases or vapours

G5.48-9 Measuring compliance with the exposure limits

G5.48-10 Use of indicator tubes to measure compliance

G5.48-11 Sampling of thoracic fraction of sulfuric acid mist

G5.48-12 Establishing exposure limits for certain refined hydrocarbon mixtures

G5.48-13 Monitoring worker exposure to sulfur dioxide

G5.49 Application of excursion limits

G5.50 Extended work periods

G5.51 Additive effects

G5.52 Skin notation

G5.53-1 Workplace monitoring

G5.53-2 Assessing compliance -- the walk-through survey

G5.53-3 Monitoring worker exposure

G5.53-4 Occupational hygiene methods acceptable to WorkSafeBC

G5.54-1 Exposure Control Plan

G5.54-2 Elements of an exposure control plan

G5.54-3 Risk identification, assessment and control

G5.54-4 Hygiene facilities and decontamination procedures

G5.54-5 Health monitoring

G5.54-6 Documentation

G5.54-7 Drywall sanding requirements

G5.55 Type of controls

G5.56 Oxygen deficiency

G5.57 Designated substances

G5.58 Protective policy

G5.59 Investigating symptoms

Table of Exposure Limits for Chemical and Biological Substances

Explanation of table headings

G5.48-4 Conversions for ppm and mg/m³