Occupational Exposure Limits in Canada

September 9, 2020

 Occupational Exposure Limits in Canada

All Provincial and Territorial Health and Safety Codes across Canada set out rules for employers to assess all current and potential hazards at the workplace. Harmful substances are part of this category of potential hazards which includes anything that may create or currently creates a danger including a chemical or a biological hazard if a worker can be exposed.  

What are Occupational Exposure Limits?

Employers need to ensure the worker’s level of exposure does not exceed its occupational exposure limit. Occupational Exposure Limits (OELs) are set for certain substances that are classified as highly hazardous to human health; for some of these substances, there is sufficient scientific evidence, which determines how much exposure may lead to an adverse health outcome.  

How are OELs Set?

OELs in the workplace are set by the federal government and by every province individually.  There is a significant amount of research and consultation that goes into adopting each exposure limit. Consider the additional cost of updating every limit as new research becomes available. There is also the common truth that only 1% of the chemicals used in industry even have exposure limits. The list is guaranteed to grow with time.  

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 and which provinces are streamlining their processes.  OELs do vary by province, for example the hydrogen sulfide 8-hour exposure limit is 10 ppm in Alberta and 1 ppm in BC and other jurisdictions that adopt ACGIH TLVs. The benzene exposure limit is 0.5 ppm in Alberta, Ontario and ACGIH but 1ppm in Quebec and 10 ppm in Yukon. If an OEL for a hazardous substance at your workplace differs between provinces you are operating in, it is best to adopt the higher standard and the province with the lower OEL.  

What are OELs Based on in Each Province? 


OEL Based On



British Columbia 



2019 ACGIH TLVs 

New Brunswick 

1997 ACGIH TLVs 

Newfoundland & Labrador 


Nova Scotia 





Schedule 1 Chemical Substances 


Table 1 Occupational Exposure Limits for Ontario Workplaces 


Table 21 Contamination Limits 


Schedule 1 Permissible Exposure Values  


Schedule O Contamination Limits 


Schedule O Contamination Limits 


Table 8 Permissible Concentrations for 

Airborne Contaminant Substances 

Generally, all OELS stem from the ACGIH TLVs. But there can be some differences between provinces and employers still need to check their own provincial regulations. As you see from the above chart the year of ACGIH TLVs regulated to be used can vary by province.  

Occupational Exposure Limits and the ACGIH

The American Conference of Governmental Industrial Hygienists (ACGIH) TLV Committee is tasked with investigating, recommending, and annually reviewing occupational exposure limits for chemical substances. Separate from any government body, ACGIH is a scientific organization that advances occupational and environmental health. They publish an annual guide containing TLVs® (Threshold Limit Values) or exposure guidelines for over 700 chemical substances, and BEIs® (Biological Exposure Indices) or limits on over 80 more biological substances. The TLV and BEI Booklet are developed as guidelines to assist in the control of health hazards and is not a regulation. These resources are recommendations for use in the practice of industrial hygiene and to inform regulators of the latest research and expert analysis.  

ACGIH is considered the gold standard for setting OELs by many professionals. The reality is their recommendations are not always adopted due to insufficient technology to control or measure, and lack of funding and political will for regulatory updating and reviews.  

Want to learn more? Let our experts help you keep a hazard-free workplace with our chemical hazard assessment management program.