ObjectiveTo investigate the association between ambient air pollution and stroke morbidity in different subgroups and seasons.MethodsWe performed a time-series analysis based on generalised linear models to study the short-term exposure–response relationships between air pollution and stroke hospitalisations, and conducted subgroup analyses to identify possible sensitive populations.ResultsFor every 10 µg/m3increase in the concentration of air pollutants, across lag 0–3 days, the relative risk of stroke hospitalisation was 1.029 (95% CI 1.013 to 1.045) for PM2.5, 1.054 (95% CI 1.031 to 1.077) for NO2and 1.012 (95% CI 1.002 to 1.022) for O3. Subgroup analyses showed that statistically significant associations were found in both men and women, middle-aged and older populations, and both cerebral infarction and intracerebral haemorrhage. The seasonal analyses showed that statistically significant associations were found only in the winter.ConclusionsOur study indicates that short-term exposure to PM2.5, NO2and O3may induce stroke morbidity, and the government should take actions to mitigate air pollution and protect sensitive populations.