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Backgrounder
Document d'information

GOVERNMENT COMMITS TO REGULARLY UPDATE OCCUPATIONAL EXPOSURE LIMITS

The Ontario government's new revision system for occupational exposure limits (OELs) ensures that standards for more than 700 substances in the workplace are regularly updated. More protective limits for four hazardous workplace substances have also been introduced. The Ministry of Labour worked with industry and labour groups to develop the new, more protective limits.

This move is part of the government's commitment to the health and safety of Ontario workers. Exposure to hazardous substances is a major cause of occupational illness among workers and adds significant costs to businesses through lost time and higher workplace insurance premiums.

What are OELs?

OELs, regulated under the Occupational Health and Safety Act (OHSA), restrict the amount and duration of workers' exposure to hazardous workplace substances--such as asbestos, benzene, lead and silica.

Ontario workplaces are required to monitor exposure levels of a wide range of dangerous substances, and develop control programs to ensure compliance with OELs. Ministry of Labour inspectors and hygienists enforce OEL compliance by conducting inspections of workplaces. Medical, scientific and technical staff support inspectors and hygienists.

If the ministry believes a workplace is exceeding an OEL, written orders are issued to the employer to take the necessary steps to come into compliance, or to prevent possible future non-compliance.

How have OELs been determined?

Historically, Ontario has based OELs on the list of recommended Threshold Limit Values published by the American Conference of Governmental Industrial Hygienists (ACGIH). ACGIH is an internationally recognized body that provides updated recommendations that are adopted by many North American jurisdictions.

The ACGIH annually publishes entries and revisions for its list of recommended limits. Up until now, there has been a delay in reviewing the updated ACGIH recommended list and revising Ontario's OELs. As of today, Ontario workers will be better protected because of the new system to ensure limits for exposure to chemicals in the workplace are updated regularly.

In 1986, the Regulation respecting Control of Exposure to Biological or Chemical Agents (Regulation 833) was passed. Based on the exposure limits recommended by the ACGIH in 1985, the regulation required employers to protect workers from exposure to 587 hazardous biological or chemical agents.

In 1994, more protective exposure limits were set for 19 substances. In 2000, new or more protective OELs for 204 substances were included in the regulation to reflect current knowledge respecting their toxicity.

The new system for updating OELs:

Under the government's new system, OELs will be reviewed and updated on a regular basis, ensuring that the protection of Ontario workers is always based on the most current scientific and medical knowledge.

In October 2001, the Ministry of Labour began to meet with stakeholders on developing a revision system for updating OELs. Based on the input received from industry and labour groups, the Ministry of Labour will regularly update OELs based on new ACGIH recommendations and their relevance to Ontario. Additional updates can be made beyond the ACGIH recommendations based on the best available scientific and medical research.

More Protective Limits:

In addition, more protective limits for four substances have been introduced: Benzene, Carbon Monoxide, Manganese (dust and compounds), and 1,3-Butadiene.

Time Weighted Average Exposure Value (TWAEV): the maximum allowable average concentration of the substance in the air, calculated for an eight-hour day or 40-hour workweek.

Short Term Exposure Value (STEV): the maximum average concentration of the substance in the air, for any 15-minute period.

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See also:

News Release [ April 26, 2004 ]