Associations of combined short-term exposures to ambient PM2.5 air pollution and noise annoyance on mental health disorders: a panel study of healthy college students in Tehran

Few studies have focused on the simultaneous effects of air pollution and noise annoyance on human mental health. Using a panel study design, we studied the concurrent effect of short-term exposure to PM2.5 and noise annoyance on mental health outcomes by recruiting a sample of 110 students from Tehran University of Medical Sciences. Mental health was evaluated in terms of depression, anxiety, and stress symptoms using validated, standardized DASS-21 questionnaires in three time periods. Average daily exposures over a 6-day period were assigned to participants based on the closest stationary monitor during hours spent on campus and in the dormitory. The noise annoyance was evaluated based on self-reported scale. We used random intercept mixed-effect model, adjusting for potential confounders. An increase in PM2.5 and noise annoyance was significantly associated with mental health outcomes in crude and adjusted analysis. For example, an IQR increase in PM2.5 was associated with a 2.57 point (95% CI: 1.40, 3.74) increase in depression score, 2.11 point (95% CI: 0.94, 3.28) increase in anxiety score, and 1.64 point (95% CI: 0.47, 3.04) increase in stress score. PM2.5 in crude analysis was also positively associated with all three-outcome adjusting for economic status, sex, and noise annoyance. Overall, our findings revealed evidence confirming an association between short-term exposure to environmental PM2.5 and noise annoyance increased outcomes of depression, stress, and anxiety.