Exposure to smoke from wildfires is associated with a significantly higher risk of stroke, according to a study published in the European Heart Journal. The research was conducted by scientists at Emory University’s Rollins School of Public Health and led by Yang Liu, who examined the relationship between wildfire smoke exposure and stroke risk.
The researchers estimate that in the United States alone, wildfire smoke may be linked to approximately 17,000 stroke cases each year. “Wildfires are becoming one of the leading sources of air pollution,” Liu says. “At the same time, stroke remains a major cause of death and disability worldwide, and its incidence is rising. Traditional risk factors such as hypertension and diabetes do not fully explain this upward trend.”
The study analyzed health data from nearly 25 million Americans aged 65 and older. Between 2007 and 2018, about 2.9 million strokes occurred within this population. Using artificial intelligence models, the team estimated individual exposure to wildfire smoke based on levels of PM2.5, fine particulate matter measuring 2.5 micrometers or less in diameter. The analysis also accounted for other air pollutants and established stroke risk factors, including smoking and socioeconomic status.
The findings show that for every one microgram per cubic meter increase in average wildfire-related smoke concentration, the risk of stroke rose by 1.3 percent. By comparison, a similar increase in PM2.5 from other sources such as traffic or power plants was associated with a 0.7 percent increase in stroke risk.
“These results suggest that wildfire smoke may be particularly harmful to the brain and blood vessels,” Liu explains. Because many fires occur in remote areas, rural and suburban populations are often exposed to higher levels of smoke. The particles produced by wildfires can trigger inflammation and oxidative stress, damaging blood vessels and promoting the formation of blood clots.
According to the authors, wildfire smoke exposure is not only an immediate respiratory hazard but may also raise long-term stroke risk. Preventive measures, including the use of indoor air filtration systems and limiting outdoor physical activity on heavily smoked days, could help reduce exposure. In an accompanying editorial, Kai Chen of the Yale School of Public Health notes that the study adds to growing evidence of the long-term health effects of wildfire smoke and supports recognizing PM2.5 as a major long-term health risk, not merely an environmental threat.
