Exposure to ambient air pollution and onset of Parkinson’s disease in a large cohort study

This population-based longitudinal cohort study examines the association between ambient air pollution (PM_2.5 and NO₂) and Parkinson's disease (PD) using a 28% representative sample of Northern Ireland's population (2009-2016). We matched complete address records to annual average PM_2.5 and NO₂ concentrations at a 1 km grid level and tracked PD onset via first receipt of PD medication. After controlling for confounding factors at individual, household, and neighbourhood levels, we found no association between medium-term PM_2.5 or NO₂ exposure and PD onset in the overall cohort, over-50s, or sex-stratified samples. However, a positive association was observed between PM_2.5 exposure and PD onset in those under 50 in 2011, with weaker evidence for NO₂. We discuss potential etiological and non-etiological explanations for this age-related difference.