The Interactive and Joint Associations of Ambient PM2.5 and Temperature on the Onset of Acute Coronary Syndrome: Findings from The Chinese Cardiovascular Association (CCA) Database-Chest Pain Center Registry.

Environmental factors are important exposures that trigger acute coronary syndrome (ACS) onset. However, the interactive and joint associations of multiple exposures on ACS onset remain unknown. A time-stratified case-crossover study was conducted including 1,292,219 ACS patients who were selected from 1,895 districts/counties across China during 2015-2020. The ACS conditions included ST-segment-elevation myocardial infarction (STEMI), non-ST-segment-elevation myocardial infarction (NSTEMI), and unstable angina (UA). Conditional logistic regression models were applied to estimate the interactive and joint associations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) and temperature (TM) with the ACS onset. The ACS onset risks increased by 0.38% for each 10 μg/m3 increment in PM2.5 concentration, and an inverse U-shaped curve of TM and risk of ACS onset was observed. The associations of PM2.5 with the ACS onset were greater on colder days. The jointly attributable fractions (AF) of PM2.5 and nonoptimal TM was 9.93% in all ACS patients, 10.31% in females, 12.91% in patients aged ≥65 years, 17.54% in NSTEMI patients, and 12.43% in Southern China. This study suggested that joint short-term exposures to ambient PM2.5 and moderate cold TM may substantially increase the onset of ACS. Furthermore, there are synergistic interactions among higher PM2.5 and lower TM peaks on the ACS onset.