Following extinguishment of a fire, workers may enter the area for overhaul and fire cause and determination.


Products of combustion create a hazardous atmosphere, putting workers at risk of exposure to these contaminants.

Actions for employers

Employers must:

  • take all measures reasonably necessary in the circumstances to protect workers from exposure to a hazardous biological or chemical agent, 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

Note that generally, employers must protect workers from exposure to a hazardous biological or chemical agent without requiring them to 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 and should provide appropriate training on the safe and effective use of the respiratory protection equipment.

Reducing exposure to contaminants and other hazards

Consider the following actions, to reduce exposure to contaminants:

  • delay investigations until all phases of fire have been fully extinguished
  • put in place adequate and effective ventilation throughout the investigation
  • before respiratory protection is removed, conduct gross decontamination
  • understand the operation and limitations of air monitoring devices in use as some contaminants and carcinogens may not be detected

Ensure that either the immediate vicinity or the entire area is de-energized and that the natural gas, propane or other fuel sources are isolated, disconnected, or shut off.

Applicable regulations and acts


Applicable standards

For guidance on the administration of an effective respiratory protection program, fit testing protocols and training requirements, read CSA Standard Z94.4 Selection, use and care of respirators


Firefighter’s cancer prevention checklist

Read firefighter guidance notes: