Is ambient air pollution a risk factor for Parkinson's disease? A meta-analysis of epidemiological evidence.

Current evidence shows inconsistencies about ambient air pollution (AAP) exposure as a risk factor for Parkinson's disease (PD). We performed meta-analyses to estimate the pooled risk of PD due to AAP exposure. We performed a systematic search in PubMed, Google Scholar, The Cochrane Library, and J-GATEPLUS databases for peer-reviewed epidemiological studies reporting the risk of PD due to exposure to PM, PM, O, CO, NO, NO and SO; from the beginning until October 2021. The pooled odds ratio (OR) for the effect of NO (per 1 μg/m) and O (per 1 ppb) on PD was 1.01[95% CI: 1.00,1.02;  = 69% ( = .01)] and 1.01 [95% CI: 1.00,1.02;  = 66% ( = .03)], respectively. The ORs for the effects of PM (per 1 µg/m) and CO (per 1 ppm) on PD were 1.01 [95% CI: .99,1.03;  = 40%] and 1.64 [95% CI: .96,2.78;  = 75% (= .01)], respectively. The study showed the adverse roles of NO, O, PM and CO in increasing the risk for PD.