Fine and coarse particulate air pollution and out-of-hospital cardiac arrest onset: a nationwide case-crossover study in China

Out-of-hospital cardiac arrest (OHCA) is a global public health concern. Nationwide studies on the effects of short-term exposure to particulate matter (PM) on OHCA risk are rare in regions with high PM levels, and evidence for coarse PM (PM2.5-10) is limited and inconsistent. To evaluate the associations between fine PM (PM2.5) and PM2.5-10 and OHCA onset, a time-stratified case-crossover study was conducted on 77,261 patients with cardiac OHCA in 26 cities across China in 2020. Daily PM2.5 and PM2.5-10 concentrations were assessed with high-resolution and full-coverage PM estimations. Conditional logistic regression models were applied in analyses. Each interquartile range of PM increase in 3-day moving average was associated with an increased risk of cardiac OHCA onset of 2.37% (95% CI, 1.20-3.56%) for PM2.5 and 2.12% (95% CI, 0.70-3.56%) for PM2.5-10. Stratified analyses showed higher susceptibility in patients over 75 years for PM2.5 exposure and with diabetes for PM2.5-10. This first nationwide study in region with high PM levels and great PM variability found not only PM2.5 but also PM2.5-10 were associated with a higher risk of OHCA onset, which could add powerful epidemiological evidence to this field and provide new evidence for the formulation of air quality guidelines.