Short‐Term Exposure to Fine Particulate Matter Air Pollution Is Preferentially Associated With the Risk of ST‐Segment Elevation Acute Coronary Events

BACKGROUND: Air pollution is associated with greater cardiovascular event risk, but the types of events and specific persons at risk remain unknown. This analysis evaluates effects of short‐term exposure to fine particulate matter air pollution with risk of acute coronary syndrome events, including ST‐segment elevation myocardial infarction, non–ST‐segment elevation myocardial infarction, unstable angina, and non–ST‐segment elevation acute coronary syndrome. METHODS AND RESULTS: Acute coronary syndrome events treated at Intermountain Healthcare hospitals in urban areas of Utah's Wasatch Front were collected between September 1993 and May 2014 (N=16 314). A time‐stratified case‐crossover design was performed matching fine particulate matter air pollution exposure at the time of each event with referent periods when the event did not occur. Patients served as their own controls, and odds ratios were estimated using nonthreshold and threshold conditional logistic regression models. In patients with angiographic coronary artery disease, odds ratios for a 10‐μg/m(3) increase in concurrent‐day fine particulate matter air pollution >25 μg/m³ were 1.06 (95% CI 1.02–1.11) for all acute coronary syndrome, 1.15 (95% CI 1.03–1.29) for ST‐segment elevation myocardial infarction, 1.02 (95% CI 0.97–1.08) for non–ST‐segment elevation myocardial infarction, 1.09 (95% CI 1.02–1.17) for unstable angina, and 1.05 (95% CI 1.00–1.10) for non–ST‐segment elevation acute coronary syndrome events. Excess risk from fine particulate matter air pollution exposure was not observed in patients without angiographic coronary artery disease. CONCLUSIONS: Elevated fine particulate matter air pollution exposures contribute to triggering acute coronary events, especially ST‐segment elevation myocardial infarction, in those with existing seriously diseased coronary arteries but not in those with nondiseased coronary arteries.