As deadly wildfires raged in the Canadian province of Manitoba this summer, Republican lawmakers in nearby US states penned letters asking that Canada be held accountable for the smoke drifting south.
“Our skies are being choked by wildfire smoke we didn’t start and can’t control,” wrote Calvin Callahan, a Republican state representative from Wisconsin, in a letter dated early August.
Callahan, along with lawmakers from Iowa, Minnesota and North Dakota, filed a formal complaint with the US Environmental Protection Agency (EPA) urging an investigation into Canada’s wildfire management.
Manitoba premier Wab Kinew quickly condemned the move, accusing the lawmakers of throwing a “timber tantrum” and playing “political games”.
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By August, the wildfires had scorched more than two million acres in Manitoba, forced thousands to evacuate, and killed two people – a married couple who authorities said were trapped by fast-moving flames around their family home.
As September draws to a close, data shows that 2025 is on track to be Canada’s second-worst wildfire season on record.
A study published in the Nature journal in September has revealed that smoke from Canada’s wildfires has also had far-reaching, fatal consequences. It estimates that the 2023 wildfires – the country’s worst on record by area burned – caused more than 87,500 acute and premature deaths worldwide, including 4,100 acute, smoke-related deaths in the US and over 22,000 premature deaths in Europe.
Wildfire smoke contains PM2.5 – a type of air pollution – that is known to trigger inflammation in the body. It can exacerbate conditions like asthma and heart disease, and, in some causes, can damage neural connections in the brain.
“These are big numbers,” said Michael Brauer, a professor at the University of British Columbia who co-authored the study. He added the findings show wildfire smoke should be treated as a serious health issue, akin to breast cancer or prostate cancer.
For some American lawmakers, the blame falls squarely on Canada.
“Canada’s failure to contain massive wildfires,” Callahan wrote in August, “has harmed the health and quality of life of more than 20 million Americans in the Midwest.”
Their complaints raise the question: Could Canada be doing more to curb its wildfires – and by extension, their smoke?
Climate and fire experts in both countries told the BBC that the answer is largely no.
“Until we as a global society deal with human-cased climate change, we’re going to have this problem,” said Mike Flannigan, an emergency management and fire science expert at Thompson Rivers University in British Columbia.
