Abstract 12409: Ambient Fine Particulate Matter and Ozone Air Pollution Are Differentially Associated With Hospitalization for Unstable Angina and Acute Myocardial Infarction During Wildfire and Inversion Seasons

Abstract

Background: Short-term increases (days to weeks) in fine particulate matter (PM 2.5 ) air pollution are associated with hospitalization for acute coronary syndromes (ACS). A changing climate is shifting sources of PM 2.5 toward summer wildfires in the western US. This study evaluated if short-term increases in PM 2.5 and ozone were associated with ACS risks in wildfire (June-October) and winter inversion (Nov.-March) seasons. Methods: Case-crossover analyses examined N=21,414 subjects with emergency or inpatient hospitalization at 11 Intermountain hospitals for ACS, including the primary diagnosis of myocardial infarction (AMI, n=20,287) or unstable angina (USA, n=1,127). PM 2.5 data were collected in January 1, 1999 to March 31, 2022 (ozone: 2006-2022) from community monitors on Utah’s Wasatch Front. Odds ratios (OR) and 95% confidence intervals (CI) were computed by Poisson regression with adjustment for weather data. Results: Subjects averaged 66±14 years of age and 31.0% were female. Overall PM 2.5 increases were associated with concurrent day (lag 0 days) ACS hospitalizations (OR=1.024 per +10 μg/m 3 , CI: 1.004, 1.043, p=0.019), driven by AMI (OR=1.025 per +10 μg/m 3 , CI: 1.004, 1.045, p=0.017). USA admissions were delayed to the second week [lag moving average (mAvg) days 7-13] after PM 2.5 increases (OR=1.090 per +10 μg/m 3 , CI: 1.024, 1.159, p=0.007) and PM 2.5 associations with USA were strengthened by adjustment for ozone. Analyzed by wildfire and inversion seasons, PM 2.5 associations differed for AMI and USA (Figure). Short-term increases in ozone in wildfire season were associated with lower USA risk at lag 1, lag 2, 3-day mAvg 0-2, and 1-week mAvg 0-6 and lower AMI risk at mAvg 7-13, but not with inversion season risks. Conclusions: Short-term increases in PM 2.5 air pollution were associated with ACS hospitalizations for AMI and USA, with patterns of risk differing between wildfire and inversion seasons. Ozone increases were not associated with greater risk.