Wildfire Smoke and AQHI

Wildfires produce dense smoke that can be a major source of air pollution. This pollution contains gases and fine particles that penetrate deep into our lungs and bloodstream, sometimes leading to serious health effects.

Smoke may be carried hundreds or thousands of kilometres from the fire zone. Resulting air pollution (including smoke) may be present even if we can't see or smell smoke. There is no evidence of a safe exposure level for most of these pollutants. This means that smoke can impact our health even at very low levels. As smoke levels increase, our health risks increase.

Everyone is at risk from wildfire smoke, especially small children, pregnant people, seniors, people with lung or heart conditions and people involved in outdoor work or strenuous exercise.

Tips to reduce the risk of exposure to wildfire smoke:

  • Check the Air Quality Health Index for your area at the start of each day to help make decisions regarding your health. The higher the number, the greater the health risk and need to take precautions.
  • Stop outdoor activities and contact your health care provider if you or someone in your care experiences shortness of breath, wheezing (including asthma attacks), severe cough, dizziness, or chest pains. If you develop severe symptoms or need advice, contact your health care provider, or call Health 811.
  • Review your wildfire smoke plan and make sure you have enough medical supplies if the smoke continues to impact your community.
  • Keep your medications like rescue inhalers on you.
  • Check on family and friends who may be more susceptible to smoke.
  • Be aware of your mental health. If you experience any feelings of stress, anxiety, or depression, contact your mental health care provider for advice or visit https://www.wellnesstogether.ca/en-CA.
  • Avoid areas with heavy pollution like busy streets and industrial areas especially when the AQHI is higher.
  • Consider using a well-fitted respirator type mask (such as a NIOSH certified N95 or equivalent respirator) if you are required to work or spend long periods of time outdoors as it can help reduce your exposure to the fine particles in smoke. A 3-layer cloth or disposable mask provides moderate protection compared with a respirator. However, respirators or 3-layer cloth or disposable mask do not reduce exposure to the gases in wildfire smoke. Even when wearing a mask, it is important to listen to your body and reduce or stop activities if you are experiencing symptoms.

Note: Pregnant people and people with respiratory and cardiovascular conditions should talk to their health care providers before using masks for wildfire smoke.

  • You can prepare your home by finding ways to keep the wildfire smoke out and to keep indoor air clean, such as:
    • keep windows closed when the temperature is comfortable
    • do not smoke indoors
    • replace your furnace/central air HEPA filters and
    • if available, set your air conditioning system to recirculation mode when the outdoor air is poor, and bring in fresh air when the outdoor air has improved.
    • use an air purifier, if available, in rooms that you spend a lot of time in (avoid air purifiers that produce ozone).
    • if you have an HVAC system in your home, use the highest rated MERV filter for your system and set the fan to recirculate air constantly.
    • Go to a public facility with air conditioning, such as a library, shopping mall, or a recreation centre.
  • For more information, visit canada.ca.

Additional Information

Special Air Quality Statement (SAQS)

When a high risk (7 or greater) AQHI score is likely to last for 1 or 2 hours, a SAQS is issued for the area. The purpose is to allow the public to take the proper safety measures as it relates to their health.

Smog and Air Health Advisory (SAHA)

When a high risk (7 or greater) AQHI is likely to last a minimum of 3 hours, a SAHA is issued for the area. The purpose is to alert those with breathing problems to reduce or avoid unnecessary exposure to smog. It also informs industries that are major producers of pollution in the area that they should consider reducing their emissions for a short period of time if possible.

Air Quality Health Index (AQHI)

The AQHI is a scale made for the public to help identify how the quality of air around you affects your health. This tool was made by environmental and health professionals to communicate what the health risks are. It provides tips for both at risk and general populations. The higher the score, the more risks there are to your health.

The AQHI is measured on a 1-10+ scale, and divided into four risk groups, as seen below.

AQHI chart example

Government of Canada (2016).

How can you use the AQHI to protect your health?

Health Risk


Health Messages

At Risk Population*

General Population



ENJOY your usual outdoor activities.

IDEAL air quality for outdoor activities.



CONSIDER reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.

NO NEED TO MODIFY your usual outdoor activities unless your experience symptoms such as coughing and throat irritation.



RESCHEDULE or REDUCE strenuous activities outdoors. Children and the elderly should take it easy.

CONSIDER reducing or rescheduling strenuous activities outdoors if your experience symptoms such as coughing and throat irritation.

Very High

Above 10

AVOID strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion.

REDUCE or RESCHEDULE strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.

Government of Canada (2015).

*Those with heart or lung health problems are at a higher risk of complications. Follow your health care provider’s advice about exercise and how to manage your health problems during these times.

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