The association of depressive symptoms in children with indoor and outdoor short-term exposure to particulate matter

BACKGROUND: Air pollutants have been reported to affect mental health. However, the results on the association between particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5) and depression have been inconsistent, and there have been relatively few studies conducted among children. METHODS: This study examined the association between PM2.5 exposure and depressive symptoms in 52 children (aged 9–10 years) with repeated assessments across three waves. The Children’s Depression Inventory (CDI) was used to evaluate depressive symptoms. Exposure to PM2.5 was estimated by combining measurements from indoor and outdoor settings where the participants spent time during the study period based on a time-activity diary. A generalized estimating equation model was constructed to estimate the association between PM2.5 and the children’s depressive symptoms after adjusting for potential confounders. RESULTS: Per 10 µg/m³ increase in 24-hour average personal PM2.5 exposure on the day of assessment (lag 0), no significant association was observed with the mean CDI score (β = 0.12, 95% CI: −1.02 ~ 1.27; Model 2). A statistically significant inverse association was observed at lag 2 (β = −0.80, 95% CI: −1.49 ~ − 0.11; Model 2). In sex-stratified analyses, associations differed by sex, with predominantly positive estimates among boys and negative estimates among girls across examined lags. CONCLUSION: Although the overall association between short-term PM2.5 exposure and depressive symptoms was not significant, a significant PM2.5-by-sex interaction suggested effect modification by sex. Further studies and efforts to reduce indoor and outdoor PM2.5 exposure are warranted. TRIAL REGISTRATION: Clinical Research Information Service KCT0004277(Registered Date: 2019/09/05).