Occupational Exposure Limits in Canada

Occupational Exposure Limits (OELs) in Canada: A Complete Guide for Employers

Occupational Exposure Limits (OELs) play a crucial role in protecting workers from harmful chemical and biological hazards in the workplace. Across Canada, provincial and territorial health and safety regulations require employers to identify, assess, and control all potential hazards—including airborne contaminants that may pose immediate or long-term health risks.

This guide explains how OELs are defined, how they differ across Canadian jurisdictions, and why many organizations rely on ACGIH TLVs as the scientific reference standard.

What Are Occupational Exposure Limits?

Occupational Exposure Limits (OELs) represent the maximum airborne concentration of a chemical substance that workers can be exposed to without likely experiencing adverse health effects.
These limits apply to substances known to be hazardous to human health. Where sufficient scientific evidence exists, an OEL reflects the level at which exposure may lead to harmful outcomes over an 8-hour workday or other designated time period.

Employers are legally required to ensure that a worker’s exposure does not exceed the applicable OEL in their jurisdiction.

How Are OELs Established in Canada?

OELs are set both federally and by each province and territory. Establishing or updating limits involves:

• Reviewing scientific toxicological research
• Consulting industry, government, and health experts
• Assessing emerging hazards and new evidence
• Considering practical implications for workplaces

Despite the extensive scientific basis for OELs, only about 1% of chemicals used in industry currently have exposure limits. As the number of chemicals in commerce grows, the list of regulated substances is expected to expand as well.

Occupational Exposure Limits in Each Province

Is there a gold standard for occupational exposure limits? What do you do if you operate businesses in more than one province? We have created a handy table to illustrate which provinces have their own occupational exposure limits.  

There is no single national standard for OELs in Canada, and limits vary significantly by province.
We have created a handy table to illustrate which provinces have their own occupational exposure limits.  For example:

Hydrogen sulfide (H₂S) 8-hour OEL::

• Alberta: 10 ppm
• British Columbia & other ACGIH-aligned jurisdictions: C10 ppm

Benzene OEL:

• ACGIH: 0.02 ppm
• BC: 0.5 ppm TWA 2.5 ppm STEL
• Alberta & Ontario: 0.5 ppm
• Quebec: 1 ppm
• Yukon: 10 ppm

If your organization operates in multiple provinces, the best practice is to apply the most protective (lowest) OEL across all your sites.

What Are OELs Based on in Each Province?

Below is an updated reference table showing what each Canadian jurisdiction bases its OELs on:

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Across Canada, most jurisdictions reference or consider ACGIH TLVs, but they adopt them at different times, which explains variations in the specific year or version used.

The Role of ACGIH in Occupational Exposure Limits

The American Conference of Governmental Industrial Hygienists (ACGIH) is recognized globally for its scientific leadership in industrial hygiene. Its TLV Committee:

• Reviews toxicological and epidemiological data
• Develops TLVs® (Threshold Limit Values) for over 700 chemical substances
• Develops BEIs® (Biological Exposure Indices) for over 80 biological markers
• Publishes annual updates informed by the latest scientific evidence

ACGIH TLVs are guidelines, not regulations, but they are widely considered the gold standard by industrial hygienists. They are based solely on health science and are not influenced by industry cost or technical feasibility.

Ensuring Compliance and Protecting Workers

Because OELs vary widely across Canadian provinces, employers must:

• Know the exposure limits that apply in each jurisdiction
• Monitor workplace air quality
• Implement engineering controls, administrative controls, and PPE
• Consider adopting the most protective OEL when operating across provinces

Using reliable hazard assessment tools can help streamline compliance and ensure workers remain safe.

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Want to learn more?

Discover how CHAMP from Chemscape can help your organization streamline chemical hazard assessments and maintain a hazard-free workplace.