How you can protect your health from wildfire smoke

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As intense wildfires send smoke drifting across parts of Western Canada, experts say it's important for residents to keep an eye on their health.

Here are some common questions about the risks of wildfire smoke and reminders on how you can help protect yourself when air quality plummets.

Why is wildfire smoke bad for your health?

Wildfire smoke contains a hazardous mixture of gases, pollutants and pieces of debris known as particles. The particles are produced when fire burns through trees, grass and buildings — including homes, which contain harmful household materials such as heavy metal, batteries and synthetic plastics.

Some bigger particles are easy to see, including dust, dirt or soot, but it's pieces that are invisible to the human eye that affect your health.

Microscopic particles known as PM2.5 — which can be narrower than a strand of human hair — can find their way into your lungs and even your bloodstream when you're exposed to smoke. Once that happens, the immune system responds and causes inflammation.

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Lasting inflammation exacerbates underlying heart and lung conditions like asthma or chronic obstructive pulmonary disease (COPD), which is a group of diseases interfering with airflow and breathing. 

Babies, children, seniors and pregnant people are also at risk. 

Even healthy people can experience stinging eyes, irritated sinuses, headaches or wheezing. It doesn't take long, either: Health Canada said there isn't any evidence to show smoke exposure is safe at any level.

Should I stay inside?

Reducing your exposure to smoke is the best way to protect your health. Health Canada recommends staying indoors and closing your windows on smoky days or moving to a cooling centre if it's too hot inside your home to do so.

People who want to exercise should find an indoor space or stop entirely until skies clear. 

"What we're trying to do is encourage people to be cautious and to stay inside with the windows closed, with your ventilation running if you can," said Dr. Courtney Howard, an emergency room physician in Yellowknife.

Experts recommend checking the air quality forecast before stepping out the door. 

"What you can do is watch the AQHI, the Air Quality Health Index, and think about modifying your activity," advised Samantha Green, a family physician at Unity Health Toronto and incoming president of the Canadian Association of Physicians for the Environment. 

The AQHI rates air pollution and health-risk levels in various Canadian cities on a scale between one and 10.

One to three represents a low health risk, four to six is a moderate risk and seven to 10 is considered high risk. Very high pollution levels are considered 10+.

Should I have an air purifier?

Health Canada does recommend air-cleaning devices that use high-efficiency air filters, though an air purifier doesn't need to be expensive to work. 

The Pacific Institute on Pathogens, Pandemics and Society and the B.C. Lung Foundation have instructions available online for how to make your own air purifier with a box fan, an air filter and some cardboard.

What about wearing a mask outside?

If you have to spend time outside, Health Canada recommends a well-fitted respirator type mask (such as a NIOSH-certified N95 or equivalent respirator) that doesn't let any air pass between the mask and face.

"One of the things you can do is get the N95 masks that are well fitted," Howard told CBC News. "You can tell that it fits well [because] when you breathe in, the mask kind of sucks into your face. If you can feel the air coming around the sides, then it's not a good fit or you maybe need to mould it more to your face."

Howard noted masks will help filter out the fine particles, but not the other gases from smoke. Anyone who develops symptoms, even while wearing a mask, should go back inside.

If you need to work outdoors, check with your provincial or territorial occupational health and safety organization or your local health authority for guidance on how to work safely.

Is there anything I can do to limit smoke in my home?

Aside from keeping windows shut, ensure seals around the windows are properly filled. You can use a wet towel to cover any cracks. Health Canada recommends you limit burning any incense, candles or wood stoves. 

After the smoke clears, be sure to open windows to circulate fresh air.

Find more tips on limiting smoke in your home here.

What about mental health?

Officials acknowledge smoky skies can chip away at mental health.

Howard was involved in a study that interviewed 30 residents in Yellowknife, which experiences wildfires every year. In the study, they were asked what it felt like to live through a long period of smoky air in 2014. 

"What people told us was that they felt anxious and irritable," she told CBC News. "They were cooped up, had that cabin fever … lots of comments about the decrease in physical activity. And so, of course, what that means is that people lose the treatment benefit that we know we get from being outside in nature, exercising." 

Health Canada said eating well, sleeping enough and keeping in touch with friends or family can help with stress and anxiety.