Preventing the health effects of exposure to wildfire smoke

During forest fires, smoke can be carried great distances. It is mainly composed of fine particles (PM_2.5) whose concentration in the ambient air can be measured. Exposure to wildfire smoke can have health effects, which vary depending on:

• the particle concentration;
• the duration of exposure;
• the intensity of physical activities;
• the presence of health problems.

Get the latest information on air quality in your community:

• Wildfire smoke forecast maps
• Active weather warnings and air quality advisories
• Map showing the latest fine particulate matter concentrations (PM_2.5)

Air quality may have deteriorated even if you cannot see any smoke. It is difficult to predict the intensity of the smoke plumes that will affect inhabited areas and which direction the smoke will go. Smoke from wildfires can be carried hundreds or thousands of kilometres from the fire zone. The dispersion of particles observed at a given location is influenced by weather conditions, especially rain and the direction and strength of the wind.

Detailed information on real-time air quality is available on the maps mentioned above. Choose the sensor closest to your location and note the PM_2.5 concentration of fine particles displayed. If possible, it is recommended that you check the latest PM_2.5 measurement closest to your location.

Adapt your activities, paying particular attention to the symptoms you might be experiencing. Everyone is different. People who are more sensitive may experience symptoms and have to adapt their activities at lower concentrations than those suggested.

If air quality is poor, here are the recommendations for outdoor activities, depending on air quality.

The recommendations for indoors based on outdoor air quality (if the concentrations of PM_2.5 are 30 micrograms and above) are as follows:

Close windows and exterior doors as long as the temperature does not cause severe discomfort. Heat is generally more damaging to health than poor air quality. 

If you have a:

• portable, window or heat pump air conditioner: keep using it, as it does not let outside air in;
• air exchanger: switch it off or put it in recirculation mode;
• air filtration d’air: turn it on in the room(s) where people spend the most time;
• central (mechanical) ventilation system: reduce the intake of outdoor air to a minimum (unless equipped with a MERV 13 or higher filter), without stopping the ventilation.

People who do sports breathe deeper and faster, which means more air pollutants enter their lungs. People who are physically active outdoors are more exposed to fine particles when air quality is poor. They should pay extra attention to any symptoms they might experience.

Just as an outdoor sports event may be cancelled or rescheduled due to thunderstorms, extreme heat or other weather conditions, it is important to consider air quality when making a decision about a sports event.

Mild symptoms may occur with exposure to fine particles from wildfire smoke. These symptoms are short‑lived and resolve on their own:

• smarting eyes;
• sinus irritation;
• runny nose;
• mild cough;
• sore throat;
• headache.

More severe symptoms that usually occur in people with asthma or heart diseases include:

• severe cough;
• shortness of breath;
• wheezing;
• dizziness;
• heart palpitations;
• chest pain.

If you have symptoms:

• Go inside and stay there.
• Keep asthma medications handy.
• Call Info‑Santé 811 or 911 depending on the severity of the symptoms (for example, chest pain).
• Tell loved ones as needed (e.g., parents, chlidren, neighbors).

Take care of your mental health

If you feel anxious, stressed or sad, psychosocial help is available. Staff specialized in psychosocial intervention are available to support you, advise you and direct you to resources that will meet your needs or those of your loved ones. Contact Info‑Social 811 and choose option 2 to talk to one of these people. This service is free and confidential. It is offered 24 hours a day, 7 days a week.

When air quality is very poor, it is recommended to limit outdoor activities.

If you are going outside and the air quality is poor or very poor, you can wear an N95 mask to reduce your exposure to fine particles in the smoke. If you have asthma or another respiratory disease, wearing an N95 mask could help relieve symptoms when air quality is poor. If you decide to wear one, make sure it is certified by NIOSH or an equivalent body and fits well over your clean‑shaven face, with the straps pulled tight. You should not feel any air coming between the mask and your face.

Note that N95 masks are not available for children. In addition, medical masks, fabric face coverings and wet cloths are less effective in protecting against smoke.

Portable filtration devices can help improve indoor air quality if equipped with HEPA filters and properly selected, operated and maintained.

They are not necessary if your home has a ventilation system with adequate filtration (MERV 13 or higher). The people who could benefit the most are those who live in the areas most exposed to wildfire smoke and who have asthma, lung disease or heart disease. Portable filtration devices are not a means of protection that is considered necessary for the entire Quebec population.

If you would like to use one, see Health Canada’s recommendations.