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Guidelines Part 9
Guidelines Part 9 - Verification and testing
G9.24 Verifying all precautions
Issued August 1, 1999
Section 9.24 of the OHS Regulation states "Before a worker enters a confined space, pre-entry testing and inspection must be conducted to verify that the required precautions have been effective at controlling the identified hazards and that it is safe for a worker to enter".
Section 9.25 of the OHS Regulation requires the atmosphere in a confined space to be tested in a number of circumstances before a worker enters the confined space. The requirements of section 9.24 are not limited to atmospheric testing. Other hazards, such as entrapment, radiation, heat stress, noise and cold stress may also be present. These require assessment regarding the degree of risk to workers.
In addition, it is necessary to inspect before entry to ensure that all required controls are in place. These are similar to requirements for supervisor responsibility stated in section 9.7(2).
G9.25 Testing the atmosphere
Issued August 1, 1999; Revised November 17, 2003
Additional testing
Section 9.25(4) of the OHS Regulation states "While a worker is inside a confined space with a moderate or high hazard atmosphere, additional testing must be conducted as necessary to ensure the worker's continuing safety".
The intervals at which additional testing should occur depends on the outcome of the hazard assessment, the operations being performed in the space and the risk of the atmosphere changing substantially. In addition, the selection of appropriate instrumentation for testing of the space, together with the requirement of section 9.25(5) for continuous monitoring, may determine the frequency of testing that is practicable.
Continuous monitoring
Section 9.25(5) states "Whenever practicable, continuous monitoring of the atmosphere must be done".
"Practicable" is defined in section 1.1 of the OHS Regulation as meaning "that which is reasonably capable of being done". In determining what is "practicable", the relevant factors include:
- the availability in the marketplace of continuous monitoring devices,
- the reliability of continuous monitoring devices to detect contaminants within acceptable ranges to provide worker protection (this means in the range of the exposure limit or lower), and
- the potential for cross contamination or poisoning of the sensors for the instrumentation selected.
Low hazard atmospheres
Section 9.25(7) permits entry into low hazard atmospheres without pre-entry atmospheric testing if the conditions listed in paragraphs (a) to (d) are met. Condition (c) is that "prior representative sampling has demonstrated that the atmosphere within the space or group of similar spaces meets the low hazard atmosphere definition".
"Representative sampling" is acceptable if the sampling data is
- statistically significant,
- provides for the reliable determination of worker exposure, and
- obtained in accordance with the confidence limits stated in OHS Guideline G5.48-9.
G9.26 Procedures and equipment
Issued August 1, 1999
Section 9.26(4) of the OHS Regulation states "Test results, other than continuous monitoring results, must be posted without delay at all points of entry to the confined space".
Continuous monitoring provides continuous feedback to the personnel entering and working in the confined space. In effect, this provides better feedback than the posting of test results at all entrances to the confined space. However, the section does not exempt the employer from recording continuous monitoring test results at appropriate intervals as required by section 9.26(3). Many instruments used for this purpose are equipped with a data logging capability that makes it easy to record test results and to interpret the data. Otherwise, readings can be manually recorded at appropriate time intervals.
Keeping records of continuous monitoring will be particularly important for employers wanting to eliminate pre-entry atmospheric testing for a low hazard atmosphere confined space, as it may be a source for the data required by paragraph 9.25(7)(c).
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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.