Occupational Exposure Limits

  • Content last reviewed: December 2015

Occupational Exposure Limits (OELs) restrict the amount and length of time a worker is exposed to airborne concentrations of hazardous biological or chemical agents.

There are OELs for over 725 substances under R.R.O. 1990, Regulation 833 (Control of Exposure to Biological or Chemical Agents) and Ontario Regulation 490/09 (Designated Substances) under Ontario’s Occupational Health and Safety Act.

In 2004, the Ministry of Labour introduced a review process for OELs to ensure that these limits are regularly reviewed and updated. Under this process, the MOL releases for public consultation proposals for new or revised OELs based on the annual recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH). During consultations, stakeholders are invited to submit comments on any or all of the proposed changes.

Results of the Ministry’s 2013 and 2014 OEL consultations

The Ministry’s consultation on proposed changes to the OELs and/or listings for substances set out in its 2013 and 2014 consultation documents is complete. Effective July 1, 2015, changes based on these proposals will come into effect.

These changes include the adoption of all OEL proposals set out in the 2013 and 2014 “Review of Occupational Exposure Limits in Ontario” charts, with the following exceptions: the OELs for nitrogen dioxide (2013 OEL consultation), manganese and aliphatic hydrocarbon gases (2014 OEL consultation) remain unchanged while the Ministry further considers stakeholder feedback and determines next steps.

View the updated regulation.