What is 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 contain other types of air pollution and have been linked to serious health effects. Smoke also contains toxic gases like carbon monoxide that can be harmful to your health.

Smoke particles are small and can get deep into your lungs and may be absorbed into the bloodstream.

What are the health risks?

Your body will try to protect itself against the smoke particles by making more tears and mucous. This may cause runny nose, scratchy throat, irritated sinuses and headaches. If the smoke is heavy and lasts for days or weeks, you may also develop a cough. Certain sensitive populations (children, older adults, pregnant women) may feel the effects of smoke earlier and have more severe symptoms than others in the community. Smoke exposure can worsen existing lung conditions such as COPD and asthma, and worsen cardiovascular outcomes.  Most people will recover quickly from smoke exposure.

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).

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 smokey outside, it is best to stay indoors, with the windows closed, whenever possible. If the indoor temperature rises to an uncomfortable level, 
    opening the window may be necessary to avoid heat exhaustion. Ideally, use air conditioning, if it is available, or indoor fans to keep cool, and be sure to
    drink plenty of water to stay hydrated.
  • Reduce or avoid outdoor physical activity when possible.
  • 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, where possible.
  • Use air conditioning (on the recirculate setting) 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.
  • Limit smoking tobacco as much as possible – 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 take your prescribed medicine. Speak with your health care 
    provider to get the specific advice that is right for you.

Smoke exposure and outdoor activities

Smoke from forest fires is unpredictable. If you do not smell smoke in the specific area you plan to use, outdoor activity can still occur.  

Where can I learn more about local conditions? 



Staying indoors can provide some protection from pollution sources. This depends on how tightly sealed a home is and if the air conditioning unit can re-circulate indoor air. Generally, newer homes or buildings are more likely to be “tightly sealed’ and can keep outdoor air pollution out more than older homes or buildings. In ‘leaky’ homes or buildings, outdoor air pollution can easily come inside and provide little protection. In any home, if doors and windows are open, indoor and outdoor air pollution will be similar.



Air cleaners - Ideally the choice to purchase an air cleaner is made prior to a smoke emergency, as it may be difficult to access one during the event. High efficiency particulate air (HEPA) filter air cleaners that do not produce excess ozone can help reduce indoor particle levels. Their effectiveness will depend on if the unit is properly matched to the size of the indoor space. Types of units vary from single room to large central room air cleaners. Only portable room units that do not produce excess ozone should be used. See the following link from California Air Resources Board (CARB) that certify air cleaners that produce little to no ozone: California Certified Air Cleaning Devises



Air conditioners - Make sure to set your air conditioners (at home and in your car) to re-circulate indoor air rather than drawing outdoor air.  If the air temperatures become too hot, open your windows and doors.