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Forest Fire Smoke and Your Health

What's in forest fire smoke?

Forest fire smoke is made up of a mixture of gases and very small particles that are produced when wood and other organic matter burn. The small particles in forest fire smoke also occur with many other types of air pollution and have been linked to serious effects on people’s health.  Smoke also contains toxic gases like carbon monoxide that can also be harmful to your health.

Smoke particles are small and so can get deep into our lungs. Some particles are even small enough to get into the alveoli, or air sacs, of our lungs and may be absorbed into the bloodstream.

What are the short-term health risks?

Your body will try to protect itself against the smoke particles by making more tears and mucous. This can cause runny noses, scratchy throat, irritated sinuses and headaches.  If the smoke is heavy and lasts for days or weeks, you may also develop a cough.

People who already have heart or lung problems may feel the effects of smoke earlier and worse than others in the community.

Who are most at risk from forest fire smoke?

  • Children
  • Seniors
  • Pregnant women
  • People who already have chronic heart or lung conditions
  • People who are very active doing work or sports outside

How can I protect myself and minimize the health effects of fire smoke?

  • Stay out of the smoke as much as possible.
  • If it looks smoky outside, it is best not to go outdoors to do physical activity and a good time to stay indoors with the windows closed.  Be careful - homes can get really hot with the windows closed. Use air conditioning, if it is available, or indoor fans to keep cool, and be sure to drink plenty of water to stay hydrated. 
  • If you have an air cleaner that will reduce levels of small particles in indoor air, use it and stay in the room where it is located. 
  • Use air conditioning in cars and keep windows closed. Remember, vehicles should never be run in an enclosed space like a garage. 
  • Avoid using smoke-producing appliances such as wood stoves and even candles.
  • Do not smoke tobacco – smoking puts added stress on your lungs and on those around you.
  • If you have asthma or other respiratory conditions, be vigilant about avoiding smoke and taking your prescribed medicine.  Speak with your health care provider to get the specific advice that is right for you.

If you have uncontrolled coughing, wheezing or choking, or your breathing does not improve when you go indoors, consult your health care provider or call Telehealth Ontario (1-866-797-0000 or TTY at 1-877-797-0007). 

When are smoke levels dangerous?

When visibility is worse, smoke is worse.  

Tune in to local news media for updates on local conditions. 

Where can I learn more about local conditions?

Local conditions can change quickly. Please refer to the Ontario Ministry of Natural Resources:


Thank you to the Thunder Bay District Health Unit and the Northwestern Health Unit for contributing to this document.

Source: Ontario Ministry of Health and Longterm Care