New diesel exposure limit for underground mines in Ontario

Hazard alert poster on health effects of diesel exhaust

Law reduces exposures to harmful chemicals and allows robots to detect hazards

New rules to improve ventilation requirements in underground mines and lower exposure to harmful diesel exhaust to the most protective levels in North America came into effect in July. Long-term exposure to diesel exhaust can be a significant cause of lung cancer in miners.

Regulations will also allow for the use of track-mounted robots in mines to increase safety. These specialized machines with a high-definition camera will be controlled by an operator to identify loose rocks, misfired explosives and other safety hazards, while keeping workers out of danger.

These amendments respond to calls from unions for a reduction of how much diesel particulate miners can be exposed to underground and follow recommendations from the Mining Health, Safety and Prevention Review and recent coroner’s inquests.

Quick Facts

  • Regulatory amendments came into force on July 1, 2023, and others in effect on September 1, 2023, gave employers time to comply.
  • Effective September 1, 2023, the new exposure limit is a time-weighted average exposure to elemental carbon of not more than 0.12 milligrams per cubic metre of air, instead of 0.4 milligrams per cubic metre of air based on total carbon
  • Ontario has 37 underground mines. About 12,000 miners work below ground and Ontario mines employ approximately 29,000 workers in total

Additional Resources

Mining diesel regulation - Ontario

Occupational Health and Safety Act - Ontario

Health effects of diesel exhaust in mines - WSN

Free training resources on diesel emission hazards for all industries - WSN

Reducing diesel particulate matter in underground mines: Two successful examples - WSN

Infographic: Proper use of respirators in mines and mining plants

Controlling diesel particulate matter in underground mines - Occupational Cancer Research Centre

Ventilation assessment: A snapshot of mine ventilation practices in underground mines

Ministry-approved health and safety training: Supervisor Common Core: Mine Ventilation – Underground Mining