Various ambient air pollutants, residential greenness, and risk of substance use disorders: a population-based cohort study

Abstract Background Air pollution is a recognized contributor to the global burden of disease, but its association with incident substance use disorders (SUD) remains poorly characterized. Whether residential greenness modifies this association is also unclear. We addressed both questions in a large prospective cohort. Methods We analyzed 247,138 UK Biobank participants without SUD at baseline. Five ambient air pollutants (PM 2.5 , PM 2.5−10 , PM 10 , NO 2 , NO X ) and three measures of 300-m residential greenness (green space, domestic garden, natural environment) were modelled using Land Use Regression and the 2005–2007 Land Cover Map. Cox proportional hazards models estimated hazard ratios with 95% confidence intervals. Effect modification by greenness was tested using cross-product terms and likelihood-ratio tests. Sensitivity analyses restricted to long-term residents, used alternative outcome definitions (F10-F19 and F11-F19), and recomputed greenness at a 1000-m buffer. Results Over a median follow-up of 10.9 years, 4,982 participants developed SUD. All five air pollutants were positively associated with incident SUD in fully adjusted models. PM 2.5 showed the strongest effect (HR = 1.111, 95% CI: 1.081–1.142), followed by PM 10 (HR = 1.070, 95% CI: 1.054–1.086). Green space (HR = 0.997, 95% CI: 0.996–0.998) and natural environment (HR = 0.997, 95% CI: 0.995–0.998) were inversely associated. Domestic garden attenuated the pollutant associations in the high-exposure subgroup, with cross-product terms of 0.979 (95% CI: 0.963–0.996) for PM 2.5 and 0.987 (95% CI: 0.980–0.995) for PM 10 . The positive air-pollution associations were strongest among males, participants aged ≥ 65 years, and individuals with a history of smoking. Conclusion Long-term exposure to ambient air pollutants was associated with a higher risk of incident SUD, and residential greenness showed protective associations. These patterns were most pronounced in older males and in individuals with a smoking history. The findings support integrating greenness exposure into environmental frameworks for SUD prevention. Clinical trial number Not applicable.