wildfire-driven ozone – Researchers using a deep-learning model say rising wildfire-driven smog has increased ground-level ozone across much of the U.S., contributing to more than 300 additional premature deaths every year since 2013, with particularly high exposure during the 2023 C
For many people, wildfire smoke is something you can see—an orange haze clinging to summer air. But the danger doesn’t end with the visible soot. New research links wildfire-driven smog to worsening ground-level ozone pollution, and the health toll it can bring.
Ground-level ozone is made when gases released by wildfires react in sunlight. The main ingredients are carbon monoxide from wildfire emissions and nitrogen oxides. which combine chemically under sunny conditions to form ozone at the surface. Ozone is complicated: in the upper atmosphere. in the stratosphere. it helps protect Earth by shielding people from harmful ultraviolet rays. On the ground. the same molecule becomes harmful when inhaled. worsening respiratory problems—especially for people with asthma or other breathing conditions.
The study’s central finding is stark. Since 2013, wildfire-driven ozone has been associated with more than 300 additional premature deaths every year across the U.S., researchers say. The team reached that estimate by feeding surface ozone levels and premature death data into a deep-learning model.
The model also traced how ozone trends shifted over time. Between 2003 and 2015. ground-level ozone decreased. which the scientists say likely followed tightened controls on ozone-forming chemicals released by human activity. including car tailpipe emissions. That improvement reversed between 2015 and 2024. when the model showed ozone levels increasing—especially in the Midwest and parts of the western U.S.
When researchers ran different scenarios in the model, they found a clear counterfactual: without wildfire additions, surface ozone in the Midwest would have continued its decline after 2015.
That matters for how people think about distance in a wildfire age. Wildfires have been on the rise because of climate change, according to NASA. The study pointed to how smoke and pollutants travel far beyond the flames. The 2023 fire season offered a vivid example: wildfires blazing in Canada pushed smoke into the northeastern and midwestern U.S. turning the skies an orange hue in both regions.
In that season, the analysis found that fires exposed 148 million Americans to surface ozone levels above the standards considered safe by the U.S. Environmental Protection Agency. Midwesterners experienced those unsafe levels for more than a week.
“People in the Midwest may think fires burning far away will not affect them,” said study co-author Jun Wang, an atmospheric scientist at the University of Iowa, in a NASA statement. “But once wildfire pollution is in the air, it can move across regions.”
The consequences show up in the numbers too. The resulting smog was linked to 7,974 premature deaths in the U.S. in 2023 alone, the researchers calculated.
The study was funded by NASA and published online on June 4 in the journal Science. In their paper, the researchers wrote that the results “underscore the escalating public health burden of wildfire-driven [ozone] pollution.”
wildfires ozone pollution ground-level ozone premature deaths deep-learning model NASA funded research Science journal U.S. Environmental Protection Agency standards Jun Wang University of Iowa climate change respiratory health carbon monoxide nitrogen oxides