A short-term spike in air pollution in New Jersey due to the 2023 Canadian wildfires is associated with higher stroke rates and more severe strokes, according to a preliminary study published March 3, 2026, which will be presented at the American Academy of Neurology’s 78th Annual Meeting, April 18-22, 2026, in Chicago and online.
Wildfire smoke contains pollutants such as ozone and particulate matter, making it not only a nuisance but also a potential public health hazard. The 2023 Canadian wildfires caused unprecedented air quality declines across the northeastern United States. Our findings show that short-term exposure to increased air pollution from these wildfires is associated with higher incidence and severity of stroke. ”
Elizabeth Celseo, MD, study author, Rowan University Cooper School of Medicine, Camden, NJ
For this study, researchers used the stroke registry to identify all stroke cases that occurred in June and July 2023, as well as the same months of the previous year. Ischemic stroke is the most common type of stroke. Hemorrhagic strokes are more serious and often more fatal.
The researchers examined U.S. Environmental Protection Agency data for both time periods from air quality monitors in Camden, New Jersey. They calculated the average daily exposure to ozone, which when inhaled can cause shortness of breath, cough and worsening symptoms such as asthma. They also calculated the average daily exposure to fine particulate matter, air pollution made up of particles smaller than 2.5 micrometers in diameter, also known as PM2.5.
While the median ozone concentration was 36 ppb, the 2023 wildfires caused ozone levels to peak at 136 ppb. Particulate matter reached 211 micrograms per cubic meter (μg/m3), with a median concentration of 48.5 μg/m3.
Daily air quality data matched the timing of each stroke. Because the effects of pollution can take several days to affect the body, the researchers also considered levels from one to two days before the participants had their strokes.
Regarding ozone levels, 72% of days were below 50 ppb and 28% of days were above recommended levels. The World Health Organization’s guideline for ozone is 50 ppb. Researchers compared 42 strokes that occurred on days when ozone was above average to 80 strokes that occurred on days when ozone was below average. For strokes that occurred on above-average ozone days, the stroke incidence, or rate of new stroke cases, was 1.25 per day, compared to 0.93 strokes that occurred on below-average days.
After adjusting for factors such as age, gender, race, and cause of stroke, the researchers found that more average ozone days were associated with a 0.32 higher stroke rate per day.
They also found that strokes on above-average ozone days had higher rates of hemorrhagic strokes and more aortic atherosclerosis and plaque buildup in major arteries.
For particulate matter levels, 38% of days were above average and 62% of days were below average. Researchers compared 39 strokes that occurred on days when particulate matter was above average to 83 strokes that occurred on days when particulate matter was below average. They found that above-average particulate matter was associated with longer hospital stays and higher scores on scales measuring stroke severity.
“While long-term air pollution is recognized as a risk factor for stroke, less is known about short-term exposure to wildfire smoke,” Celseo said. “Our study addresses a critical gap by providing more information about the neurological effects of wildfire smoke. Our findings can guide stroke prevention and highlight the need for public health interventions during wildfires.”
Celseo noted that the analysis focused on short wildfire periods, and the results provide an early indication, rather than a complete picture, of the association between wildfire smoke and stroke risk. He said future studies will look at longer time periods.
A limitation of this study was that it looked at average daily pollutants. Celseo said more subtle hour-by-hour measurements may also have an impact on stroke, but may not be reflected in the average value. Similarly, other weather variables such as humidity and pressure are not incorporated.
sauce:
American Academy of Neurology
Reference magazines:
https://aanfiles.blob.core.windows.net/aanfiles/d9f6b136-ebf6-4f86-8a96-39cd262367 02/2026%20AAN%20Annual%20Conference%20Summary%20-%20Ozone%20 and%20PM2.5%20During%20the%202023%20Canada%20Wildfires
