Long-Term Exposures to Air Pollution and the Risk of Atrial Fibrillation in the Women’s Health Initiative Cohort

BACKGROUND: Atrial fibrillation (AF) is associated with substantial morbidity and mortality. Short-term exposures to air pollution have been associated with AF triggering; less is known regarding associations between long-term air pollution exposures and AF incidence. OBJECTIVES: Our objective was to assess the association between long-term exposures to air pollution and distance to road on incidence of AF in a cohort of U.S. women. METHODS: We assessed the association of high resolution spatiotemporal model predictions of long-term exposures to particulate matter ([Formula: see text] and [Formula: see text]), sulfur dioxide ([Formula: see text]), nitrogen dioxide ([Formula: see text]), and distance to major roads with incidence of AF diagnosis, identified through Medicare linkage, among 83,117 women in the prospective Women’s Health Initiative cohort, followed from enrollment in Medicare through December 2012, incidence of AF, or death. Using time-varying Cox proportional hazards models adjusted for age, race/ethnicity, study component, body mass index, physical activity, menopausal hormone therapy, smoking, diet quality, alcohol consumption, educational attainment, and neighborhood socioeconomic status, we estimated the relative risk of incident AF in association with each pollutant. RESULTS: A total of 16,348 incident AF cases were observed over 660,236 person-years of follow-up. Most exposure–response associations were nonlinear. [Formula: see text] was associated with risk of AF in multivariable adjusted models [[Formula: see text]; 95% confidence interval (CI): 1.13, 1.24, comparing the top to bottom quartile, [Formula: see text]]. Women living closer to roadways were at higher risk of AF (e.g., [Formula: see text]; 95% CI: 1.01, 1.13 for living within [Formula: see text] of A3 roads, compared with [Formula: see text] , [Formula: see text]), but we did not observe adverse associations with exposures to [Formula: see text] , [Formula: see text] , or [Formula: see text]. There were adverse associations with [Formula: see text] (top quartile [Formula: see text]; 95% CI: 1.05, 1.16, [Formula: see text]) and [Formula: see text] (top quartile [Formula: see text]; 95% CI: 1.03, 1.14, [Formula: see text]) in sensitivity models adjusting for census region. DISCUSSION: In this study of postmenopausal women, [Formula: see text] and distance to road were consistently associated with higher risk of AF. https://doi.org/10.1289/EHP7683