By Jane Doe | WASHINGTON – 2025/06/12 19:15:49
Smoke drifting from Canadian wildfires has triggered air quality alerts stretching across the U.S. Midwest and Northeast, mirroring conditions seen during the historic 2023 fire season. The ongoing blazes in Canada’s boreal forests are raising concerns about potential health impacts and the overall severity of this year’s fire season.
Cities including Minneapolis, Green Bay, Indianapolis, Cincinnati, Columbus, Pittsburgh, D.C., Philadelphia, and New York are experiencing elevated air pollution levels due to the combination of wildfire smoke and ground-level ozone exacerbated by heat.
The Canadian fire season has started intensely, with approximately 8.6 million acres already burned, according to the Canadian Interagency Forest Fire Center. This figure surpasses Canada’s seasonal average of 6.5 million acres since 1983,with three months still remaining in the fire season.
The current rate of burning in Canada is tracking similarly to 2023, a year marked by unprecedented smoke exposure in the U.S. Fire experts in Canada are worried that this year could bring a similar crisis.
“Everyone is on pins and needles expecting a year as bad as 2023,” said Robert Gray, a Canadian wildfire ecologist based in Chilliwack, British Columbia. “The forecast for most of Canada is definitely above normal for temperatures and below normal for precipitation.”
In 2023, approximately 43 million acres were consumed by wildfires across Canada.
According to GRAY, the majority of this year’s smoke originates from the dense boreal forests in northern British Columbia, Alberta, and Saskatchewan. These regions typically experience wildfires in May and June due to long days and rising temperatures. The future trajectory of the fire season hinges on weather conditions.
“It can be a swift two-week blip. The boreal starts to burn, the aspen starts to leaf out and then the weather changes,” GRAY said, referring to aspen trees common to these forests. “If we don’t get the rains and leaf-out with the aspen, it could just keep going.”
Some areas of northern British Columbia have been experiencing drought conditions as 2022, according to the BC Wildfire Service, which predicted “an increased likelihood of large,challenging fires” in parts of the province.
GRAY noted that drought, low winter snowfall, and an increase in “overwintering” fires are contributing to the heightened risk of a severe fire season.
Overwintering fires persist through the winter by smoldering underground in forest duff and peat, reigniting in the spring.
“We have fires that started in 2023, and they held over through the winter into 2024,” GRAY said. “Some of the same fires have popped up this year.”
Smoke from fires in northern British Columbia is frequently enough carried to the U.S. by the jet stream, a high-altitude air current that influences weather patterns.
“That’s a pretty structured pattern. That doesn’t change a lot. Provided that central and northern B.C. are burning in the boreal, that pattern is going to deliver smoke to the central and northeast U.S.,” GRAY said.
While some smoke remains aloft, causing hazy skies without considerably impacting ground-level air quality, other times it poses a direct risk to public health.
Wildfire smoke is a growing hazard across the U.S., eroding decades of progress made under the clean air Act.
Exposure to wildfire smoke can cause inflammation and weaken the immune system, especially when particles enter the lungs and bloodstream. This can elevate the risk of respiratory illnesses, including asthma and lung cancer, especially among vulnerable populations such as older adults, pregnant individuals, infants, and children. Wildfire smoke has also been linked to respiratory disease,preterm birth,and miscarriage.
“Everyone is on pins and needles expecting a year as bad as 2023,” said Robert Gray, a canadian wildfire ecologist.
Understanding Wildfires and Air Quality
Table of Contents
Wildfires are uncontrolled burns that occur in wildland areas, often triggered by lightning or human activity. The smoke produced by these fires contains particulate matter,gases,and other pollutants that can significantly degrade air quality.Exposure to wildfire smoke can have serious health consequences, especially for vulnerable populations.
Frequently Asked Questions About Wildfire smoke
- What are the primary health risks associated with wildfire smoke exposure?
- Wildfire smoke exposure can cause respiratory irritation, reduced lung function, bronchitis, exacerbation of asthma and heart failure, and premature death.
- Who is most vulnerable to the effects of wildfire smoke?
- Children, pregnant women, older adults, and people with pre-existing heart and lung conditions are most vulnerable.
- How can I protect myself from wildfire smoke?
- Stay indoors, use air purifiers, wear a mask (N95 or P100), and avoid strenuous activity outdoors.
- What are “overwintering” fires?
- “Overwintering” fires are fires that continue to burn underground through the winter, often in peat or other organic soils, and then resurface in the spring.
Sources
- Canadian Interagency Forest Fire Centre: https://www.nifc.gov/fire-information/statistics
- BC Wildfire Service: https://blog.gov.bc.ca/bcwildfire/summer-2025-seasonal-outlook/#:~:text=Regional%20drought%20and%20Fire%20Danger,pose%20challenges%20to%20wildfire%20response.
- Environmental Protection Agency (EPA): https://www.epa.gov/pm-pollution/particulate-matter-pm-basics
- Centers for Disease Control and Prevention (CDC): https://www.cdc.gov/air/wildfire-smoke/default.htm
- National Interagency Fire Centre (NIFC): https://www.nifc.gov/fire-information/statistics
- USDA forest Service: https://www.fs.usda.gov/treesearch/pubs/52974
By jane Doe
jane Doe is a reporter covering environmental issues.
