Canada’s Toxic Wildfire Smoke Estimated to Have Caused More American Deaths Than 9/11
As smoke from Canada’s 2026 wildfires once again invades the United States, a new study reveals the estimated death toll from the country’s 2023 wildfire season.
With toxic smoke from Canada’s 2026 wildfires once again invading the United States, a major peer-reviewed study published in Nature provides an estimate of the potential death toll from wildfire smoke.
Researchers estimated that smoke from Canada’s record-breaking 2023 wildfire season caused an enourmous health burden across multiple continents.
They combined global atmospheric models, satellite and ground-based observations, wildfire-emissions inventories, population data, and established exposure–response relationships to estimate how much fine-particle pollution reached populated regions—and how many deaths were attributable to that exposure.
The study estimated that smoke from Canada’s 2023 wildfires alone resulted in:
4,100 acute deaths in the United States
41,900 premature deaths across North America
82,100 premature deaths worldwide
The 4,100 U.S. acute deaths were part of an estimated 5,400 short-term deaths across the United States and Canada during severe “Canada smoke days.”
The U.S. estimate alone exceeded the 2,977 people killed on 9/11.
Wildfire smoke contains particulate matter less than 2.5 micrometers in diameter, microscopic particles that can penetrate deep into the lungs and enter the bloodstream. Exposure can trigger inflammation and oxidative stress, worsen asthma and chronic lung disease, and increase the risk of heart attack, stroke, respiratory failure, and premature death.
Now, with another major Canadian wildfire season underway in 2026, millions of Americans are again being exposed to the same dangerous fine-particle pollution.
A few days ago, the Air Quality Index (AQI) in my area exceeded 600—far beyond the threshold classified as “hazardous.” I was furious that toxic smoke from another country had, yet again, made the air around my own home unsafe to breathe. Americans should not be forced indoors, exposed to dangerous pollution, or left to absorb the health consequences of repeated cross-border wildfire smoke.
Epidemiologist and Foundation Administrator, McCullough Foundation
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The Canadian Forrestry Department needs to evaluate their program! I have lived in the thumb of Michigan my entire life and didn’t experience these toxic wildfires until 2020.. maybe 2021! What are they doing different that is “firing up” the trees! Enough is enough!
You are assuming that any speculative numbers are even remotely correct. We learned during convid that the establishmnt ‘expert class’ modeling estimations were totally wrong! Nicholas and Dr McCullough, why do you trust the numbers now?