Pollutant-specific pathways linking gaseous air pollution to adolescent depressive symptoms: Direct and...

This study aimed to examine associations between multiple gaseous air pollutants across different developmental periods and depressive in late adolescence. We also investigated the mediating role of sleep duration.

This population-based longitudinal cohort study consisted of 10,859 adolescence Taiwan followed up to 2 years. The exposures consisted of residential concentrations of sulfur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), and nitrogen dioxide (NO₂), estimated using a hybrid kriging-land use regression framework with machine learning models and expressed as daily averages across three periods: current (2015-2017), early adolescence (2012-2014), and lifetime cumulative (2000-2017). Depressive symptoms were assessed via five CES-D-based items at ages 16 and 18. Scores from both time points were averaged to generate a continuous composite score, with higher values reflecting greater severity of depressive symptoms.

A total of 10,859 adolescents were included. After adjustment for demographic, health, and other pollutant factors, higher exposure to CO and NO₂ was consistently associated with greater depressive symptoms across current (CO β = 0.083; P = 0.001; NO₂ β = 0.002; P = 0.038), early adolescence (CO β = 0.058; P = 0.011; NO₂ β = 0.003; P = 0.005), and cumulative (CO β = 0.054; P = 0.028; NO₂ β = 0.002; P = 0.034) exposure periods. SO₂ and O₃ were not directly associated with depressive symptoms but showed significant indirect effects through sleep duration (SO₂ indirect β = 0.005; 95% CI, 0.001-0.010; O₃ indirect β = -0.002; 95% CI, -0.003 to -0.001).

Adolescents exposed to higher levels of CO and NO₂ showed greater depressive symptoms during late adolescence. Sleep duration mediated the associations of SO₂ and O₃ with depression, suggesting pollutant-specific pathways linking air pollution to mental health outcomes in adolescents.