County-Level Air Pollution and Its Unequal Impact on Ischemic Stroke Mortality in Elderly Americans

Introduction: Air pollution is a known risk factor for cardiovascular diseases, including ischemic stroke. This study examines the impact of county-level air pollution on ischemic stroke mortality among U.S. individuals aged 65 and older, emphasizing racial and socioeconomic disparities.

Methods: Using data from the Center for Disease Control Interactive Atlas of Heart Disease and Stroke, we analyzed county-level ischemic stroke mortality rates for elderly residents between 2016 and 2020. County-level air pollution, measured by common air pollutant PM2.5 levels, were sourced from the CDC, and multivariable regression models were employed to assess the relationship between PM2.5 levels and stroke mortality.

Results: County-level analysis revealed a significant correlation (R = 0.68, R² = 0.48, P < 0.001) between PM2.5 levels and overall stroke mortality. For every 1 µg/m³ increase in PM2.5, there was an increase of 1.89 ischemic stroke deaths per 100,000 residents. Racial and socioeconomic disparities were evident. Counties with predominantly Black populations exhibited a stark disparity, with each 1 µg/m³ increase in PM2.5 correlating with a significant rise in mortality, amounting to 5.81 additional deaths per 100,000 residents. Persistently poor counties displayed vulnerability, experiencing a 4.01 increase in ischemic stroke deaths per 100,000 residents for every 1 µg/m³ increase in PM2.5 levels. Conversely, in counties without a Black majority and counties without a persistent state of poverty, the associated increases in stroke mortality per 100,000 residents for every 1 µg/m³ rise in county-level PM2.5 were 1.77 and 1.67, respectively.

Conclusion : This study underscores the detrimental impact of county-level air pollution, particularly PM2.5, on ischemic stroke mortality among elderly U.S. residents. Black-majority and persistently poor counties experience disproportionately higher mortality rates in response to elevated PM2.5 levels. Urgent and targeted interventions and policies aimed at reducing air pollution are imperative, especially in vulnerable communities, to promote equitable public health outcomes.