PM2.5 components mixture and atherosclerotic cardiovascular disease mortality: a national analysis of Medicare enrollees

Fine particulate matter (PM2.5) exposure is adversely linked to atherosclerotic cardiovascular disease (ASCVD). However, most studies focused on PM2.5 mass rather than its chemical composition. PM2.5’s individual chemical components can have distinct, cumulative, and potentially synergistic health impacts. We investigated the associations of PM2.5’s composition and sources with ASCVD mortality, considering the combined associations and regional variations in the US. We used data from the Centers for Medicare and Medicaid Services, (65,838,403 person-years) from 2000 to 2016. We estimated PM2.5 exposure using machine-learning models and attributed components to five source categories. We used Poisson survival models to assess the associations with the source categories. Higher ASCVD mortality risk (RR [95% CI] per interquartile range increase) was associated with oil combustion (1.050[1.049;1.051]), industrial (1.054[1.052;1.056]), coal/biomass burning (1.064[1.062;1.067]), and traffic sources (1.044[1.042;1.046]). Comparing source-specific effects within each region, oil combustion effects were more pronounced in the East and Midwest, and coal/biomass burning effects were more pronounced in the West and Southwest. In conclusion, we found higher ASCVD mortality risk associated with PM2.5, with differential effects across sources and US regions. These associations persisted even after limiting our sample to ZIP code-years with PM2.5 <9 μg/m3 - the National Ambient Air Quality Standards (NAAQS). This highlights the importance of consideration of local population characteristics and exposure patterns when assessing health risks associated with PM2.5. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by the HERCULES Center (P30 ES019776), the Mount Sinai transdisciplinary center on early environmental exposures (P30 ES023515 and P30 AG021342), the National Institute on Aging (NIA/NIH R01 AG074357), the National Institute of Environmental Health Sciences (R21 ES032606, R01 ES032242, 5U2CES026555-03, R01 ES013744, P30 ES000002, R01 ES032418, and UL1TR004419), and the United States Environmental Protection Agency (US EPA) (RD-83587201). Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the US EPA. Furthermore, the US EPA does not endorse the purchase of any commercial products or services mentioned in the publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Center for Medicare and Medicaid Services (CMS) approved this study under the data use agreement (#RSCH-2020-55,733), the Institutional Review Board of Emory University (#STUDY00000316), and the Institutional Review Board of Mount Sinai (STUDY 20-01344). Additionally, a waiver of informed consent was granted. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Restrictions apply to the availability of these data, which were used under license for this study.