Air pollution exposure and mental health disorders in Catalonia: A population-based cross-sectional study

Introduction: Air pollution is a global health threat increasingly linked to mental disorders. Exposure to particulate matter (PM₁₀), nitrogen dioxide (NO₂), and ozone (O₃) has been linked to higher risk of these conditions. Evidence is strongest for NO₂, while findings for PM₁₀ and O₃ remain inconsistent, particularly in Southern Europe. Methods: We conducted a cross-sectional study geolinking 2019 mental health diagnoses from the PADRIS-PRESTO cohort (n = 1,415,944) with air pollution data from 30 health districts in Catalonia, Spain. Annual mean concentrations of NO₂, O₃, and PM₁₀ were estimated. Logistic regression models, adjusted for age, sex, socioeconomic status, and health district, examined associations between pollutant exposure tertiles and the prevalence of major depressive disorder (MDD), anxiety disorder (AD), bipolar disorder, schizophrenia (SCZ), attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD). Results: NO₂ exposure showed the strongest associations, including a moderate effect for ADHD (OR = 2.04, 95%CI: 1.94–2.15) and small positive associations with ASD, SCZ, and AD (OR range: 1.27–1.31). O₃ demonstrated a small positive association with ADHD (OR = 1.41, 95%CI: 1.36–1.46) but showed no substantive associations with other disorders. PM₁₀ showed mostly null or inverse associations, including a small inverse association with ADHD (OR = 0.76, 95%CI: 0.73–0.79). Conclusions: This large population-based study found consistent associations between NO₂ exposure and neurodevelopmental and psychotic disorders, whereas O₃ and PM₁₀ showed weaker or inconsistent relationships. These findings highlight the need for longitudinal research to clarify causality.