A study led by Minghao Qiu of Stony Brook University, published on May 8 in Science Advances, reports that wildfire smoke has significantly raised ground-level ozone and contributed to excess deaths from wildfire smoke across the United States each year.
The findings highlight a health risk that is not always visible. While earlier research has focused on particulate matter from wildfires, this study draws attention to ozone—an invisible gas linked to respiratory and cardiovascular problems, reduced cognitive performance, and increased mortality.
“As we move further into spring and then summer, wildfires will most likely increase in the United States and all of North America, and scientists should be thinking about the effects of increased ozone from fires in addition particulates emitted into the air,” said Qiu, who is an assistant professor at Stony Brook University’s School of Marine and Atmospheric Sciences. The study was led by Yangmingkai Li during his time as a visiting undergraduate researcher with Qiu’s group.
The research combined nearly two decades of surface ozone measurements (2006-2023), meteorological data, satellite data, and machine learning models to quantify changes in surface ozone during fire episodes across the continental U.S. Using satellite-based National Oceanic and Atmospheric Administration Hazard Mapping System smoke plume data helped determine smoke days for comparison with non-smoke days while controlling for temperature and ultraviolet radiation. The researchers found that wildfire smoke can raise daily ground-level ozone by up to 16 percent in some regions—including parts of the eastern U.S. and Midwest—enough to increase illnesses and deaths caused partly by fire-related pollution. They estimate that these increases contribute to more than 2,000 excess deaths annually among people ages 65 or older.
Qiu said two key points emerged: “The true health effects and death toll from wildfire smoke are likely higher than previously thought, given that prior research has not factored in ozone exposure,” he said. “Even days with relatively good visibility post wildfires – may still contain the unseen ozone from the fires that harm health because particulate matter pollution and ozone pollution do not often overlap.”
Researchers also note their findings suggest increases in wildfire-related ozone could undermine progress made toward reducing overall national levels of this pollutant over time.
Stony Brook University News contributed media coverage supporting academic excellence at Stony Brook University through its communications team based out of Long Island while offering journalists access to university experts on topics such as science or health according to the official website.