TOPSHOT - A firefighter monitors the spread of the Auto Fire in Oxnard, North West of Los Angeles, California, on January 13, 2025. US officials warned "dangerous and strong" winds were set to push deadly wildfires further through Los Angeles residential areas January 12 as firefighters struggled to make progress against the flames. At least 24 people have been confirmed dead from blazes that have ripped through the city, reducing whole neighborhoods to ashes and leaving thousands without homes. (Photo by ETIENNE LAURENT / AFP) (Photo by ETIENNE LAURENT/AFP via Getty Images)
Los Angeles, California – A new study has found that wildfires fueled by climate change have contributed to thousands of premature deaths and billions of dollars in economic damages across the United States, particularly in western states like California and Oregon.
Published Friday in Nature Communications Earth & Environment, the study estimates that between 2006 and 2020, climate change played a role in roughly 15,000 deaths caused by exposure to fine particulate matter (PM2.5) from wildfire smoke. The economic toll is staggering: approximately $160 billion in related costs.
“We’re seeing a lot more of these wildfire smoke events,” said Dr. Nicholas Nassikas, a Harvard Medical School physician and co-author of the study. “What does it really mean in a changing environment for things like mortality, which is kind of the worst possible health outcome?”
By comparing real-world fire conditions to models of a hypothetical world without human-driven warming, researchers are examining how wildfire activity contributes to climate change. They then linked that activity to levels of PM2.5—tiny particles that can infiltrate the lungs and bloodstream—and used existing research to estimate the number of related deaths.
Out of 164,000 total deaths tied to wildfire smoke during the 15-year span, about 10% were attributable to climate change, with some western counties experiencing 30% to 50% higher mortality rates.
PM2.5 is considered one of the deadliest forms of air pollution. It is known to cause respiratory and cardiovascular problems, particularly in vulnerable groups such as children, the elderly, pregnant people, and outdoor workers. Studies suggest wildfire-sourced PM2.5 may be even more toxic than industrial pollution, especially when fires burn synthetic materials in urban areas.
Climate change—primarily driven by fossil fuel combustion—is intensifying droughts, drying out vegetation, and increasing the likelihood and severity of fires across the western U.S. “These numbers are really significant,” said Jacob Bendix, a professor emeritus at Syracuse University. “This study drives home how far-reaching the impacts are.”
Still, some experts urge caution. Patrick Brown of Johns Hopkins University noted that while climate change is a major driver, other non-climate factors like forest management and public health interventions are also critical. “The more immediate life-saving action may be fuel breaks, prescribed burns, or ignition-source regulation,” Brown said.
Ultimately, the authors emphasize that while land management can help reduce immediate risks, addressing the root cause—greenhouse gas emissions—is essential to preventing further harm.
“Part of the study is raising awareness,” Nassikas said. “But once we understand that, the next question is: What interventions can we deploy, from the personal to the global scale?”
