Associations of outdoor fine particulate matter (PM2.5) air pollution and symptoms of depression in the Prospective Urban Rural Epidemiology (PURE) study

Abstract

Background/Aim: Emerging evidence suggests that outdoor fine particulate matter (PM2.5) exposure may be a risk factor for major depressive disorder (MDD). The Prospective Urban Rural Epidemiology (PURE) study provides the opportunity to assess this association using a large global cohort with comprehensive covariate data. Within this cohort, long-term PM2.5 exposure has been linked to cardiovascular disease, and increased risk of cardiovascular disease has been linked to having depressive symptoms. We built on this work by evaluating associations between outdoor PM2.5 and depressive symptoms at cohort baseline, across countries of different levels of economic development. Methods: In the PURE study, adults aged 35-70 from 21 high-, middle-, and low-income countries were assigned 3-year rolling mean outdoor PM2.5 estimates, based on their community of residence. Estimates were derived from ground monitoring, satellite retrievals, and chemical transport models. Participants completed the Short-Form Composite International Diagnostic Interview (CIDI-SF), for which validation studies indicate that reporting ≥ 4 of 7 symptoms is predictive of MDD. Multivariate regression models will be used to estimate associations between PM2.5 concentrations and CIDI-SF scores. Results: Of 202,131 participants that enrolled in the PURE study (01/2003 – 07/2018), 155,447 had complete information on exposures, covariates, and depressive symptoms. The mean (SD) age was 50.9 (9.7) years, and 59.1% participants were female. The mean (SD) 3-year outdoor PM2.5 concentration at baseline was 47.5 μg/m³ (32.6), ranging from 6 μg/m³ in Vancouver, Canada to 140 μg/m³ in Jaipur, India. 19.5% of participants reported feeling sad, blue, or depressed for two weeks or longer in the past year, and 12.2% reported ≥ 4 depressive symptoms. Conclusions: The findings of this project can help evaluate the association between outdoor PM2.5 exposure and MDD on a multinational scale, and further establish the roles of related risk factors. Keywords: Ambient air pollution, mental health, depression