Association of Long-term Exposure to Particulate Air Pollution with Cardiovascular Events in California

Abstract

Importance: Long-term exposure to fine particulate air pollution (PM2.5) is a known risk factor for cardiovascular events, but controversy remains as to whether the current National Ambient Air Quality Standard (12 μg/m3for 1-year mean PM2.5) is sufficiently protective. Objective: To evaluate the associations between long-term fine particulate air pollution and cardiovascular events using electronic health record and geocoded address data. Design, Setting, and Participants: This retrospective cohort study included adults in the Kaiser Permanente Northern California integrated health care system during 2007 to 2016 and followed for up to 10 years. Study participants had no prior stroke or acute myocardial infarction (AMI), and lived in Northern California for at least 1 year. Analyses were conducted January 2020 to December 2022. Exposure: Long-term exposure to PM2.5. Individual-level time-varying 1-year mean PM2.5exposures for every study participant were updated monthly from baseline through the end of follow-up, accounting for address changes. Main Outcomes and Measures: Incident AMI, ischemic heart disease (IHD) mortality, and cardiovascular disease (CVD) mortality. Cox proportional hazards models were fit with age as time scale, adjusted for sex, race and ethnicity, socioeconomic status, smoking, body mass index, baseline comorbidities, and baseline medication use. Associations below the current regulation limit were also examined. Results: The study cohort included 3.7 million adults (mean [SD] age: 41.1 [17.2] years; 1992058 [52.5%] female, 20205 [0.5%] American Indian or Alaskan Native, 714043 [18.8%] Asian, 287980 [7.6%] Black, 696796 [18.4%] Hispanic, 174261 [4.6%] multiracial, 1904793 [50.2%] White). There was a 12% (95% CI, 7%-18%) increased risk of incident AMI, a 21% (95% CI, 13%-30%) increased risk of IHD mortality, and an 8% (95% CI, 3%-13%) increased risk of CVD mortality associated with a 10 μg/m3increase in 1-year mean PM2.5. PM2.5exposure at moderate concentrations (10.0 to 11.9 μg/m3) was associated with increased risks of incident AMI (6% [95% CI, 3%-10%]) and IHD mortality (7% [95% CI, 2%-12%]) compared with low concentrations (less than 8 μg/m3). Conclusions and Relevance: In this study, long-term PM2.5exposure at moderate concentrations was associated with increased risks of incident AMI, IHD mortality, and CVD mortality. This study's findings add to the evidence that the current regulatory standard is not sufficiently protective..