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 (PM_2.5) and temperature (TM) with the ACS onset. The ACS onset risks increased by 0.38% for each 10 μg/m³ increment in PM_2.5 concentration, and an inverse U-shaped curve of TM and risk of ACS onset was observed. The associations of PM_2.5 with the ACS onset were greater on colder days. The jointly attributable fractions (AF) of PM_2.5 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 PM_2.5 and moderate cold TM may substantially increase the onset of ACS. Furthermore, there are synergistic interactions among higher PM_2.5 and lower TM peaks on the ACS onset.