Here's how wildfire smoke exposure can impact your health
Shaki Sutharsan
| CBC News | Posted: June 4, 2025 1:57 AM | Last Updated: June
6
People with chronic health conditions, seniors, children among
most vulnerable
Image | Prairies-Wildfires 20250603
Caption: A view of La Ronge, Sask. is seen in this handout
photo on Tuesday, June 3, 2025. (Derek Cornet/HO-Facebook/The
Canadian Press)
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As communities battle out-of-control fires in Alberta,
Saskatchewan and Manitoba, thousands of residents — including
those in surrounding regions — are being exposed to wildfire
smoke, increasing their risk for short- and long-term health
effects.
To date, more than 25,000 people have been forced to evacuate
from the three provinces. Over two million hectares have burned
so far this wildfire season, which typically runs from May to
September.
The smoke plumes are heaviest above northwestern Ontario and
central Manitoba, but have also spread into the Upper Midwest
in the United States, according to Environment and Climate
Change Canada.
Satellite data also shows that smoke has crossed the Atlantic
Ocean into parts of Europe, with more to come this week.
Exposure to wildfire smoke — especially if it's heavy and over
a long period of time — can cause adverse health effects in
anybody, regardless of health status or age. But even mild
wildfire exposure can significantly impact at-risk groups, such
as people with chronic health conditions, seniors, young
children and pregnant women.
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Wildfire smoke causes irritation for most people
Wildfire smoke is a mixture of gases, water vapour and
particles. Of them, fine particles are the biggest health risk.
They cannot be seen by the human eye, but are linked to many
health issues.
Dr. Angela Yao, a senior scientist at the B.C. Centre for
Disease Control's environmental health services, says the most
common symptom is irritation. That can mean a runny nose, itchy
eyes, a mild cough and headaches. Most symptoms are mild, and
last until the air quality improves.
However, "the small particles or gas in the smoke can get
really deep into your lungs and cause inflammation," Yao said.
That can increase the risk of respiratory infections, like
pneumonia.
WATCH | Concerns around wildfire smoke exposure:
Media Video | Wildfire smoke raising air quality, health
concerns for Canadians
Caption: Heavy smoke has become a major health concern as
wildfires continue to sweep across Western Canada — and even
parts of the United States. Locations most affected have been
issued air quality alerts, and those with underlying health
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In more severe cases, exposure can cause shortness of breath,
dizziness and heart palpitations, according to the B.C. CDC,
which recommends medical attention.
"For people with chronic conditions such as asthma, [chronic
pulmonary heart disease], heart disease or diabetes, smoke can
exacerbate their conditions," said Yao.
* Sask. fire evacuee describes driving through thick smoke to
safety
* Environment Canada issues wildfire air quality alerts for
Edmonton area, most of northern Alberta
A recent study published by the American Chemical Society's
Environment Science & Technology journal examined B.C. wildfire
seasons between 2016 to 2019. It found that infants whose
mothers were exposed to wildfire smoke during pregnancy were
more likely to experience ear infections and lower respiratory
infections after they were born.
Yao said there is "substantial evidence" on adverse birth
outcomes, such as lower birth weight, as a result of wildfire
smoke exposure.
Photogallery | IN PHOTOS | Canadian wildfire smoke hits U.S.
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How can you protect yourself?
Seeking cleaner indoor air is the most important and effective
way to protect yourself during a wildfire smoke event, Yao
said.
It's also important to keep your doors and windows closed,
especially when you're operating air purifiers in your home.
"If your home or the building you're in is equipped with a HVAC
system that has air cleaning functions, make sure the filters
are adequate in filtering out smoke, and have [them] upgraded,"
Yao said.
She said if your space doesn't have built-in air filters, you
can use a portable one or make your own, with a box fan and
furnace filters.
* A B.C. program is helping vulnerable residents breathe
easier with homemade air cleaners
"If it gets too hot or too smoky in your home, consider
visiting public spaces, such as community centres, libraries or
shopping malls, which tend to have cleaner and cooler indoor
air," Yao said.
She encouraged people to be aware of local wildfire smoke
forecasts and use the air quality health index to evaluate
whether they should be limiting time spent outdoors during a
wildfire smoke event.
"When there's prolonged wildfire smoke, it is really hard to
just stay indoors all the time," Yao said. "Knowing the
forecast and the air quality locally is going to be very
crucial when we're dealing with these kinds of events."
Embed | Air Quality Health Index (AQHI)
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