The association between long-term exposure to PM_2.5 constituents and ischemic stroke in the New York City metropolitan area

Numerous studies linked fine particulate matter (PM_2.5) to ischemic stroke. However, only a few investigated the differential associations with specific PM_2.5 components and sources. We utilized electronic health records (EHR) from the Mount Sinai Health System in the New York City metropolitan area during 2011–2019 and assessed the associations of PM_2.5 components and sources with ischemic stroke. We used mixed-effect Poisson survival regressions to assess the single-exposure associations with the chemical components. We used multivariable regression to assess the simultaneous associations with source-apportioned PM_2.5 exposures estimated using non-negative matrix factorization. Then, we assessed the sensitivity of our results to different specifications of EHR data continuity: (1) using a less strict definition of censorship year, (2) adjusting the model for EHR data continuity index, a validated algorithm measuring EHR-data continuity based on indicators of primary care service utilization. We observed higher risks for ischemic stroke (Risk ratio [95 % confidence intervals] per interquartile range increase) associated with higher exposure to nickel (1.080 [1.045; 1.116]), vanadium (1.070 [1.033; 1.109]), zinc (1.076 [1.031; 1.122]), and nitrate (1.084 [1.039; 1.132]). In the multivariate models we found higher risk for ischemic stroke associated with exposure to oil combustion sourced PM_2.5 (1.061 [1.012; 1.113]). The results remained consistent under different model specifications accounting for EHR data continuity. In conclusion, we found an increased risk of ischemic stroke associated with specific PM_2.5 components and sources. These findings were robust to different specifications of EHR-data continuity. Our findings can inform policy and interventions aimed at reducing cardiovascular disease burden.