Background: Stroke, a leading cause of mortality and disability worldwide, is influenced by both nonmodifiable and modifiable risk factors, including air pollution. Arak, Iran, is one of the country’s most industrialized and polluted cities. This study investigates the association between short-term and longterm exposure to major air pollutants—PM2.5, PM₁₀, O₃, SO₂, and NO₂—and stroke morbidity.
Methods: This prospective cohort study included all stroke patients registered in Arak between 2019 and 2022. Air pollutant concentrations were obtained from four monitoring stations, with short-term exposures defined as 1 week, 1 month, 3 months, and 6 months, and long-term exposures as 9, 12, 18, and 24 months. Data were analyzed using a time-series zero-inflated negative binomial regression model, adjusting for confounders including smoking and opium use.
Results: Short-term (3-month) exposure to NO₂, O₃, and SO₂ was significantly associated with increased stroke incidence, while short-term (1-week) exposure to these pollutants showed a negative association. PM₁₀ and O₃ (6 months) and SO₂ (1–3 months) also demonstrated significant associations. Long-term (2-year) exposure to PM₁₀, NO₂, and SO₂ was strongly associated with stroke morbidity, whereas O₃ exposure showed an inverse relationship. PM2.5 was not significantly associated in the short term but showed a positive, though nonsignificant, association in the long term.
Conclusion: Both short-term and long-term exposure to certain air pollutants are associated with stroke morbidity, with varying effects by pollutant and lag period. Reducing chronic exposure to PM₁₀, NO₂, and SO₂ may help lower the incidence of stroke in high-pollution settings.