To evaluate the relationship between short-term increases in air pollutants—ozone and fine particulate matter (PM_2.5)—and stroke incidence, type, and severity in Camden, New Jersey between 2022-2023.

Air pollution is a recognized cerebrovascular risk factor, potentially exacerbating oxidative stress, endothelial dysfunction, and systemic inflammation that precipitate ischemic and hemorrhagic events. Although long-term exposure to particulate matter contributes to stroke risk, the impact of short-term fluctuations, particularly during extreme pollution events such as wildfires, on stroke severity and etiology remains poorly defined.

We conducted a retrospective study using the Cooper Observational Acute Stroke and Thrombectomy Registry, including all ischemic and hemorrhagic strokes between January 2022 through December 2023. Daily mean PM_2.5 and ozone levels were obtained from EPA air quality monitors in Camden, NJ. Each stroke was linked to pollutant concentrations from the same day and the preceding 1–2 days to account for lag effects. Primary outcome was stroke incidence while secondary outcomes included stroke type, etiology, and severity (length of stay [LOS], NIHSS, and change in mRS). Mann-Whitney U, Kruskal-Wallis, and Spearman correlation tests were applied.

Among 1,200 patients, presentation on high PM_2.5 days was associated with greater stroke severity, including higher initial NIHSS (9.90 vs. 8.37; p=0.013) and greater functional decline by discharge (ΔmRS 2.56 vs. 2.07; p=0.03). Hemorrhagic stroke was more frequent on high PM_2.5 days (p=0.024), while overall ischemic stroke incidence did not differ. Large-artery atherosclerotic ischemic strokes was more common during high PM_2.5 exposure (adjusted OR 1.45; 95% CI 1.08–1.86). Lagged analyses demonstrated significant associations at two days for ischemic stroke incidence, NIHSS, and ΔmRS (all p<0.05). Ozone was not associated with stroke outcomes.

Short-term PM_2.5 elevations, particularly during wildfire smoke episodes, were associated with increased stroke severity and large-artery atherosclerotic ischemic stroke, with effects persisting up to 48 hours after exposure.