The association between fine particulate matter exposure and anxiety in US-based cohort Nurses’ Health Study II

Abstract

BACKGROUND AND AIM: A growing body of evidence has connected air pollution exposure to anxiety outcomes, but existing studies have only been cross-sectional. Previous studies have found associations of varying magnitude between both short- and long-term fine particulate matter (PM2.5) exposure and anxiety outcomes. Here, we focus on short-term exposure. We examined the association between one-month average PM2.5 exposure and high anxiety symptoms in a prospective nationwide US-based cohort study. METHODS: We included 58,615 participants of the Nurses’ Health Study II (NHSII) who had complete outcome and covariate data in the analysis. Anxiety symptoms (Crown Crisp Index (CCI) phobic anxiety subscale) were measured via questionnaires administered in 1993 and 2005. CCI score was dichotomized at a clinically relevant cutoff (CCI ≥ 6). We used spatiotemporal prediction models to estimate monthly levels of PM2.5 exposure at each participant’s residential address at the time of each questionnaire. We used generalized estimating equation (GEE) regression models to estimate multivariable-adjusted odds ratios (OR) and corresponding 95% confidence intervals (CIs). RESULTS:A total of 6610 participants met the clinical cutoff for anxiety in 1993, and 6727 in 2005. The average one-month PM2.5 exposure level in 1993 was 15.8 μg/m3 and in 2005 was 14.3 μg/m3. After adjusting for individual and neighborhood-level sociodemographic factors, the odds ratio for clinically relevant anxiety symptoms associated with each 10 μg/m3 increase in PM2.5 exposure was 1.07 (1.02, 1.07). CONCLUSIONS:In this prospective cohort of US women, we observed increased odds of phobic anxiety in association with an increase in PM2.5 exposure. Our results support the findings from cross-sectional studies indicating that air pollution exposure may be related to adverse mental health outcomes. KEYWORDS: air pollution, short-term exposure, particulate matter, mental health outcomes