Study ties particle pollution from wildfire smoke to 24,100 US deaths
per year
[February 05, 2026]
By DORANY PINEDA
Chronic exposure to pollution from wildfires has been linked to tens of
thousands of deaths annually in the United States, according to a new
study.
The paper, published Wednesday in the journal Science Advances, found
that from 2006 to 2020, long-term exposure to tiny particulates from
wildfire smoke contributed to an average of 24,100 deaths a year in the
lower 48 states.
“Our message is: Wildfire smoke is very dangerous. It is an increasing
threat to human health,” said Yaguang Wei, a study author and assistant
professor in the department of environmental medicine at Icahn School of
Medicine at Mount Sinai.
Other scientists who have studied the death toll from wildfire smoke
were not surprised by the findings.
“The estimates they’re coming up with are reasonable,” said Michael
Jerrett, professor of environmental health science at the University of
California, Los Angeles who was not involved in the study. “We need more
of them. It’s only if we're doing multiple studies with many different
designs that we gain scientific confidence of our outcomes.”
‘These are real lives’ being lost due to wildfire smoke
The paper’s researchers focused on deaths linked to chronic exposure to
fine particulate matter, or PM2.5 — the main concern from wildfire
smoke.
These particles can lodge deep into lungs and enter the bloodstream.
Short-term exposure can trigger coughing and itchy eyes, but longer
term, they can make existing health problems worse and lead to a range
of chronic and deadly health issues, including respiratory illness,
cardiovascular and neurological diseases, and premature death.
“Wildfire smoke PM2.5 has emerged as significant environmental hazard in
the U.S., and it's driven by increasing frequency and intensity of
wildfires due to climate change,” said Min Zhang, a postdoctoral student
at the Icahn School and a study author.
Along with decades of forest mismanagement, growing development in
fire-prone areas has expanded the “urban wildland interface,” increasing
wildfire risk with real consequences for human health, said Jerrett.
“Nobody’s going to have ‘wildfire death’ on their death certificate
unless the fire actually burned them or a tree fell on them or something
like that,” said Jerrett. “But many of the people that are dying from
this exposure are ones that are already more vulnerable. These are real
lives that are being lost. This is not some arbitrary abstract
statistical concept.”
How researchers approached the study
The study's authors analyzed the link between annual average exposure to
PM2.5 from wildfire smoke and deaths by county in the lower 48. They
used federal mortality data across 3,068 counties of all causes of death
and several specific ones — circulatory, neurological and respiratory
diseases, as well as mental and behavioral disorders, tumors and
endocrine, nutritional and metabolic diseases.
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The Franklin Fire sends a plume of smoke into the sky, Dec. 10,
2024, in Malibu, Calif. (AP Photo/Eric Thayer, File)
 They also included deaths related to
falls and transport accidents — which are unlikely to be linked to
wildfire smoke — to ensure their other observations weren't biased.
“We found no association for car accidents and falls, while for
other diseases we found statistically significant effects,” said
Wei. Deaths from neurological diseases saw the biggest increase with
exposure to these particulates.
How pronounced the link was between particulate exposure and death
varied by season and demographics. A stronger association appeared
during cooler periods, and people in rural areas and younger
communities appeared to be more vulnerable.
Researchers also found that with every 0.1 microgram per cubic meter
increase of PM2.5 across all these places, about 5,594 more people
died each year.
Jerrett said the study had the benefit of a large study population
and that it includes most causes of deaths in the U.S. But he said
the county-level data could have led to over or underestimates
because wildfire smoke is very dynamic. “It doesn't just blanket a
large county all at once. There are going to be parts of the county
that gets it a lot worse.”
The study also did not account for other important factors, such as
whether a person smokes, he said.
Federal rollbacks on climate policy poses risks, authors say
Kai Chen, an associate professor of environmental sciences at the
Yale School of Public Health who has also studied the topic, said:
“I really like that they examined both the smoke and nonsmoke
PM2.5.” Various research has found that PM2.5 from wildfire smoke
has bigger health impacts than pollution from other sources, such as
car emissions, said Chen in an email, who was not involved in the
study.
The Trump administration's rollbacks in climate change policy, even
as the more destructive wildfires become more frequent in large part
due to global warming, poses critical risks, the study's authors
said. Quantifying the deadly threat that PM2.5 from wildfires poses
to human health shows the need for effective, urgent mitigation
strategies, backed by Environmental Protection Agency monitoring and
regulation, they said.
“This highlights the importance of controlling wildfire sourced
PM2.5, which is currently not regulated by the EPA as it is usually
regarded as natural disasters,” Chen agreed.
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