The Ontario Government is strengthening protection for workers by implementing updated occupational exposure limits (OELs) for hazardous workplace substances and proposing changes for 2008. The Ontario Ministry of Labour (MOL) is seeking input on the proposed adoption of new or revised OELs or listings of 21 chemical substances. Ontario currently has OELs for over 725 hazardous chemical substances.

Regulated under the Occupational Health and Safety Act (OHSA), OELs restrict the amount and duration of a workers’ exposure to a hazardous substance, such as asbestos, silica and lead. OELs are established concentrations which, if not exceeded, will generally not cause adverse health effects to those workers exposed.

On July 18, 2008, the MOL began a 60-day consultation period for changes to 2008 limits allowing stakeholders to comment on the proposed new and revised OELs for the listed hazardous substances. The proposed limits are based on recommendations by the American Conference of Governmental Industrial Hygienists (ACGIH) whose recommendations regarding exposure limits are the basis of OELs in Canada, the United States and Europe. The MOL has posted a table on their website that contains new or revised OELs or listings, proposed for 21 substances based on changes recently recommended by the ACGIH. Included in the proposal are the proposed OELs for two substances not previously listed in Ontario regulations. It includes the consolidation of four separate listings for aluminum and its compounds into one listing for aluminum metal and insoluble compounds and the withdrawal of three listings due to ACGIH’s determination of insufficient data to support the OEL. In addition, the proposal includes the withdrawal of specific exposure limits for welding fume, not otherwise specified, in accordance with ACGIH practice. Worker exposure to welding fume would be regulated by the OELs for the individual components of the fume along with the OEL for particles, insoluble or poorly soluble.

The MOL fully acknowledges that stakeholder input is an essential part of the OEL updating process. Since a reduction in the exposure limits or changes in the particle size fraction may impact sampling and analytical methods, the MOL is seeking comments regarding these changes as revised limits. The MOL invites stakeholders to submit their comments on any or all of the proposed OEL changes. The MOL advises stakeholders that specific concerns should contain a clear description of the rationale and appropriate documentation to support the concern. In addition, where an exposure limit for a hazardous substance has not been recommended and is not under consideration by the ACGIH, the MOL invites stakeholders during this consultation period, to nominate the substance for the development of an OEL. The submission should include a proposed limit and supporting documentation used by a jurisdiction that has adopted the proposed limit. The 60-day consultation period ends September 18, 2008. Submissions to the MOL may be mailed, faxed, or sent electronically. Visit for additional information.

Controlling the amount of time that workers are exposed to potentially harmful chemicals, and setting acceptable limits for these chemicals, can help prevent long-term health problems from developing and can reduce health care and compensation costs for employers.