Effect of long-term exposure to air pollution on anxiety and depression in adults: A cross-sectional study

Background: The association between exposure to air pollutants and mental disorders among adults has been suggested, although results are not consistent. Objective: To analyze the association between long-term exposure to air pollution and history of anxiety and depression disorders and of medication use (benzodiazepines and antidepressants) in adults living in Barcelona. Methods: A total of 958 adults (45-74 years old) residents in Barcelona, most of them having at least one of their parents diagnosed with dementia (86%), and participating in the ALFA (Alzheimer and Families) study, were included. We used Land Use Regression (LUR) models to estimate long-term residential exposure (period 2009-2014) to PM2.5, PM2.5 absorbance (PM2.5 abs), PM10, PM coarse, NO2 and NOx. Between 2013 and 2014 participants self-reported their history of anxiety and depression disorders and related medication use. The analysis was focused on those participants reporting outcome occurrence from 2009 onwards (until 2014). Results: We observed an increased odds of history of depression disorders with increasing concentrations of all air pollutants [e.g. an increased odds of depression of 2.00 (95% CI; 1.37, 2.93) for each 10μg/m3 NO2 increase]. Such associations were consistent with an increased odds of medication use in relation to higher concentrations of air pollutants [e.g. an increased odds of antidepressants use of 1.23 (1.04, 1.44) for each 20μg/m3 NOx increase]. Associations regarding anxiety disorders did not reach statistical significance. Conclusions: Our study shows that increasing long-term exposure to air pollution may increase the odds of depression and the use of antidepressants and benzodiazepines. Further studies are needed to replicate our results and confirm this association.