When wildfire smoke from Canada turned New York City’s sky an eerie orange in June 2023, millions of Americans who’d never experienced such pollution got a glimpse of what has become routine for communities across the U.S. West. The smoke blanketed the Eastern Seaboard, closing schools and forcing residents indoors, a warning of what scientists now say will become far more deadly in the coming decades.
A study published this week in Nature projects that wildfire smoke will cause approximately 71,000 excess deaths each year by 2050 under current emissions trends—an increase of roughly 30,000 deaths over today’s levels.
When researchers calculated the economic toll using federal safety standards, these deaths represent $608 billion in annual damages, more than previous estimates of all other combined climate impacts in the United States, including heat-related deaths, crop losses and hurricane damage.
“Wildfire smoke was not really on people’s radar before 2018 or 2020, and it was not on Northeastern people’s radar before 2023 when Canadian wildfire smoke came,” said Minghao Qiu, lead author and assistant professor at Stony Brook University.
The research addresses a significant blind spot in how scientists and policymakers understand the damages caused by climate change. Despite smoke becoming a lived reality for millions, the tools used to assess climate damages and guide federal regulations have not incorporated how rising temperatures fuel more wildfires and the resulting health toll.
The research team faced a challenging puzzle: linking climate conditions to fire emissions, fire emissions to ground-level smoke concentrations and smoke exposure to human deaths. Each step involves uncertainty, but the scientists used extensive historical data to make their projections more reliable.
“Each of the steps is pretty complicated, so there’s a lot of uncertainty in it,” Qiu explained. “One of our contributions compared to previous research is we try to constrain each step using historical data as much as possible.”
The team analyzed county-level death records from 2006 to 2019 alongside satellite measurements of smoke pollution. By studying how natural variations in fire locations and wind patterns affected different communities, researchers isolated the health impacts of smoke from other factors that influence death rates.
Their findings reveal that even today’s baseline carries a substantial burden: Approximately 41,000 annual deaths from wildfire smoke occurred between 2011 and 2020, higher than previous estimates.
The researchers say these projections show what happens if we don’t do anything new to fight wildfires or protect people from smoke.
The research confirms that wildfire smoke poses unique dangers beyond typical air pollution. Particulate matter smaller than 2.5 micrometers (known as PM2.5) can penetrate deep into the lungs and enter the bloodstream. Wildfire smoke contains an especially toxic mixture when forests or buildings burn.
“There is just a whole mixture of toxic elements in the wildfire smoke,” Qiu said. Heavy metals and organic compounds in fire emissions may be particularly harmful. The study found increased deaths from heart attacks, strokes, cancer, diabetes complications and brain-related conditions.
The health impacts last far longer than scientists previously understood. The analysis detected increased death rates up to three years after smoke exposure, suggesting lasting damage to people already managing chronic health problems.
In a surprising finding, more than half of projected smoke deaths occur in Eastern states, far from major fire zones. Higher population density, smoke traveling thousands of miles on wind currents and significant health impacts even from relatively low smoke levels all contribute to this pattern.
“In Eastern US in general, you have not as high [smoke levels] as Western US, but they have this low smoke that could come from a few bad episodes over a year,” Qiu explained. “That still could accumulate enough pollution and lead to mortality.”
The five states facing the largest increases in smoke deaths by 2050 are California (5,060 additional deaths annually), New York (1,810), Washington (1,730), Texas (1,700) and Pennsylvania (1,600).
Even if nations dramatically cut greenhouse gas emissions, the study projects more than 60,000 annual smoke deaths by 2050. That’s because Earth’s climate system has built-in delays. Even stopping all emissions tomorrow wouldn’t prevent decades of continued warming.
“The return of mitigation will pay out in the longer run. We will not see its return by 2050,” Qiu said. “That shows the importance of adaptation.”
But adaptation options remain limited and complicated. Prescribed burns and forest thinning reduce the fuel that feeds wildfires, but these practices create their own smoke. Scientists generally believe prescribed fires still provide more benefits than costs. Still, major questions remain about how much burning is needed and where it should happen.
Indigenous communities have managed forests with fire for thousands of years, and some Western states, such as California, are now incorporating these traditional practices into public land management.
Indoor air filters show promise for protecting health during smoke events. However, even the cheapest filters can cost around $200, making them out of reach for many families. Qiu emphasized that making these technologies accessible to vulnerable populations, including pregnant people, children, people with asthma and cancer patients, hould be a policy priority.
“We know that wildfire smoke affects health and it is has been shown to increase mortality. This study tried to connect all of the dots and it gave us an inkling of what the future could look like under plausible climate scenarios. What we do about that between now and then is what I think we should focus on,” Colleen Reid, associate professor of geography and director of the Public Health Program at the University of Colorado Boulder, who was not involved in the study, told Mongabay in an email.
Reid said we need indoor “clean air spaces” for people to gather during smoke events. “We also need to be doing more to decrease emissions of carbon active pollutants so that we get ourselves onto a climate change trajectory that is less harmful.”
The researchers stress these numbers assume people don’t take any new actions to protect themselves or reduce smoke. “We certainly do hope that the estimates and projections can lead to positive policy changes that help reduce those numbers,” Qiu said. “This is preventable to some degree.”
Banner image Wildfires are increasing in number and intensity across the world, and their smoke is especially threatening children’s health. Image by Brendan O’Reilly, U.S. Forest Service- Pacific Northwest Region via Wikimedia Commons (Public domain).
Citation:
Qiu, M., Li, J., Gould, C. F., Jing, R., Kelp, M., Childs, M. L., … & Burke, M. (2025). Wildfire smoke exposure and mortality burden in the US under climate change. Nature, 1-3. doi:10.1038/s41586-025-09611-w
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