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Regulating Chemical Exposure (OELs)


The Occupational Health and Safety Regulation (OHSR) provides that Occupational Exposure Limits (OELs) for hazardous chemical substances are generally determined with reference to the Threshold Limit Values (TLVs) by the American Conference of Governmental Industrial Hygienists (ACGIH).

Each year, the ACGIH  publishes a list of substances for which they have set new or revised TLVs. 

When adopted, WorkSafeBC refers to these TLVs as OELs.

An OEL is the maximum allowed airborne concentration for a particular substance from which nearly all workers are believed to experience no adverse health effects over a working lifetime. OELs may be set out as an 8-hour time-weighted average concentration, short term exposure limit, or ceiling limit.

By utilizing the expertise, resources, and review process of the ACGIH, WorkSafeBC is able to ensure that OELs remain consistent with workplace practices, technological advances and other changes affecting occupational health and safety and occupational environment.

Exceptions to the ACGIH TLVs

To ensure that adopted exposure limits are appropriate for workers in British Columbia, section 5.48 of the OHSR provides WorkSafeBC with authority to develop OELs for specific chemical substances different from those established by the ACGIH.  OHS Policy R5.48-1 of the Prevention Manual, is the mechanism used to do so.

When ACGIH publishes its annual list, WorkSafeBC adds any changed or new OELs to the table of excluded substances in OHS Policy R5.48-1.  By doing so, the existing OELs for these substances continue to be in effect until WorkSafeBC’s Board of Directors makes a decision on adoption of the changes. This gives WorkSafeBC the opportunity to consult stakeholders prior to adopting new or revised ACGIH OELs.

Combined Table of Occupational Exposure Limits

To assist workplace parties in determining applicable exposure levels as required by the OHSR, an OHS Guideline has been developed, which has a table containing both the ACGIH TLVs and the OELs established through policy.

Ongoing Review of Occupational Exposure Limits

The Occupational Exposure Limit Review Committee is responsible for facilitating an ongoing review of exposure limits provided for in policy and proposed new TLVs developed by the ACGIH.

Registering exposure to a hazardous substance

Due to the latency and long period of exposure required for the onset of some occupational diseases, WorkSafeBC has developed an Exposure Registry Program as a way for workers, employers, and others to register a worker’s exposure to a harmful substance at work.

The information obtained through the registry will be kept as a permanent record of a worker’s exposure and will assist WorkSafeBC in the adjudication of any future claim for occupational disease caused by the workplace exposure.

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