Residential exposure to air pollution and incidence of Parkinson’s disease in a large metropolitan cohort

Abstract

Background: The literature on air pollution exposure and Parkinson’s disease (PD) reported controversial results. The aim of this study is to analyze the association of exposure to particulate matter (PM 10 , PM 2.5 , PM 2.5–10 , PM 2.5 absorbance), nitrogen oxides (NO 2 , NO x ), and ozone (O 3 ) with incidence of PD in a large administrative cohort. Methods: We followed 1,008,253 patients who are 50+-year-old residents in Rome (free from PD) from January 2008 to December 2013. We identified new cases of PD using data from several sources including drug prescriptions and hospital discharges. We estimated exposure at residence using land use regression models for particulate matter and nitrogen oxides, and a chemical dispersion model for summer ozone. We used Cox models (hazard ratio [HR]) to estimate the association between air pollution exposure and incidence of PD, adjusting for individual and contextual variables. Results: There were 13,104 new cases of PD during the follow-up. There was no evidence of a positive association between particulate matter exposure and PD. There was a negative association between PM absorbance, nitrogen oxides exposure, and incidence of PD with HR = 0.97 (95% confidence interval [CI] = 0.96, 0.99) per 10 μg/m 3 increase in NO 2 and HR = 0.97 (95% CI = 0.96, 0.98) per 20 μg/m 3 increase in NO x . Long-term exposure to ozone was positively associated with incidence of PD, HR = 1.02 (95% CI = 1.00, 1.05) per 10 μg/m 3 increase in summer ozone. Conclusions: Incidence of PD was not related to PM exposure in this study and a negative association was found for nitrogen oxides. The association found with ozone is new and should be further investigated.