Abstract
BACKGROUND: It is common to protect people from air pollution by wearing masks, but how much of its health effect on cardiovascular diseases (CVDs) is unknown. This study aimed to determine whether the mask intervention associated with decrease in stroke morbidity and mortality. METHODS: We conducted a retrospective cohort study comprising 7.8 million residents in Weifang, China from 2016 to 2022. The primary outcome was the daily stroke morbidity and mortality. An interrupted time series analysis, adjusting for underlying secular trends, seasonal patterns, air pollution, meteorological factors, health services utilization and road lockdowns, was performed to assess the immediate and gradual changes of stroke morbidity and mortality after the implementation of mask-wearing regulations. RESULTS: During the study period, 400,245 incident cases and 64,719 deaths of stroke were identified. Findings indicated a 5.5% (95% confidence interval (CI): 0.8%-10.0%) immediate and a 14.3% annual gradual (95% CI: 12.7%-15.8%) reduction were observed in stroke morbidity after the implementation of the regulations, which resulted in an overall reduction of 38.6% (95% CI: 34.1%-43.2%) within 33 months of follow-up. Similarly, there was the gradual decrease in stroke mortality. It resulted in an overall post-intervention decrease of 8.4% (95% CI, 1.6%-15.1%). The subgroup analyses indicated that overall post-regulation reductions in stroke morbidity were observed across all age groups, genders, and subtypes. However, the overall reduction in stroke mortality among male and those with hemorrhagic stroke was not statistically significant. CONCLUSION: These findings have implications for policy makers and public health experts seeking to reduce burden of stroke morbidity and mortality at the population level through personal protection measure in regions with severe air pollution.