Exhaust produced by diesel engines is a complex mixture of gases, vapours and particulates. The gas portion of diesel exhaust is mostly carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide and sulfur oxides.

Vapours include hydrocarbons, such as Polycyclic Aromatic Hydrocarbons (PAHs). The particulate portion of diesel exhaust is made up of particles such as carbon, organic materials (including PAHs), and traces of metallic compounds.


The International Agency for Research on Cancer, part of the World Health Organization, has classified diesel engine exhaust as carcinogenic to humans. It found that diesel exhaust is a cause of lung cancer and noted a positive association with an increased risk of bladder cancer.

Actions for employers

Employers must:

  • make sure the fire station is adequately ventilated by either natural or mechanical means so that the atmosphere does not endanger the health and safety of workers
  • take all measures reasonably necessary in the circumstances to protect workers from exposure to diesel exhaust components, including:
    • substitution of the hazardous biological or chemical agent
    • engineering controls
    • administrative controls, including work practices
    • hygiene facilities and practices
    • where applicable, personal protective equipment

Hierarchy of controls

Consider the hierarchy of controls to reduce exposure to diesel exhaust gases, vapours and particulate.


  • Remove diesel powered engines from service and replace with electric engines.

Engineering controls


  • Install direct capture (tailpipe) exhaust system extractors, which are considered to be the most effective engineering control.
  • Other ventilation controls that may supplement direct capture include:
    • install and maintain demand-control gas sensor systems (CO, NO2) that are interlocked to activate ventilation
    • provide general (dilution) mechanical ventilation to supplement local exhaust ventilation systems
    • provide sufficient makeup fresh air to replace air exhausted
    • ensure that the discharge of air from any exhaust system prevents the return of contaminants to the workplace
    • adjust ventilation systems to maintain a negative pressure on the apparatus floor relative to adjacent areas


  • Isolate living quarters, laundry rooms and office areas from the apparatus floor by ensuring doors are self-closing and have adequate door seals.
  • Protect pole holes with covers or enclose them in vestibules with appropriate doors.


  • Modify existing engines to reduce emissions.
  • Use low emission engines.
  • Use pressurized, filtered air truck cabs.

Administrative controls

Written procedures

  • Prepare written standard operating procedures for the station, including ventilation system operation/maintenance and truck operation/maintenance.

Truck and equipment operation

  • Implement a no-idle policy inside the truck bay.
  • Move apparatus outdoors as soon as possible after start-up, after the low-pressure warning devices deactivate on apparatus equipped with air brakes.
  • Keep doors closed when engines are idling outdoors in the immediate vicinity of the fire station.
  • Store PPE off apparatus floor.

Choice of fuel

  • Use low sulphur diesel fuel.
  • Use diesel fuel additive to improve combustion.

Air monitoring

  • Monitor workplace for diesel exhaust emissions, such as CO and NO2, to ensure exposure is as low as possible.
  • Install CO monitors in station living quarters and training rooms.

Maintenance and testing

  • Regularly maintain all mechanical ventilation systems to ensure they are operating as designed.
  • Perform regular preventive maintenance of diesel-powered engines and equipment to minimize hazardous emissions.
  • Conduct engine emission testing at idle and load settings.
  • Use on-board emission control system diagnostics check.


  • Open windows and doors to provide natural ventilation if it will not interfere with other controls in place.
  • Regularly wash clothing, blankets, bedding, drapes and other surfaces which may become contaminated with particulates and other products of combustion.

Educating workers

  • Educate workers on the hazards of exposure to diesel exhaust and control measures in place.
  • Educate workers on the symptoms of engine combustion problems, such as exhaust smoke colour or engine performance.
  • Perform all tasks in a manner to minimize exposure to exhaust gases.

Personal protective equipment

As a last line of defense, consider the use of respiratory protection, coveralls or other PPE as appropriate to reduce exposure to diesel exhaust gases, vapours and particulates.

Note that generally, employers must protect workers from exposure to a hazardous biological or chemical agent without requiring them to wear and use a respirator. Where exposure to these hazards cannot be avoided or effectively controlled, employers must provide a respirator appropriate in the circumstances to protect the workers from exposure.

Applicable regulations and acts



For more tips on reducing exposure to carcinogens, read the Firefighter’s Cancer Prevention Checklist

For further information about research on diesel engine exhaust, read International Agency for Research on Cancer: Diesel engine exhaust carcinogenic

NFPA 1500 Standard on Fire Department Occupational Safety, Health and Wellness Program