Ambient Air Pollution and Out-of-Hospital Cardiac Arrest in Beijing, China

Air pollutants are associated with cardiovascular death; however, there is limited evidence of the effects of different pollutants on out-of-hospital cardiac arrests (OHCAs) in Beijing, China. We aimed to investigate the associations of OHCAs with the air pollutants PM(2.5–10) (coarse particulate matter), PM(2.5) (particles ≤2.5 μm in aerodynamic diameter), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), carbon monoxide (CO), and ozone (O(3)) between 2013 and 2015 using a time-stratified case-crossover study design. We obtained health data from the nationwide emergency medical service database; 4720 OHCA cases of cardiac origin were identified. After adjusting for relative humidity and temperature, the highest odds ratios of OHCA for a 10 μg/m(3) increase in PM(2.5) were observed at Lag Day 1 (1.07; 95% confidence interval (CI): 1.04–1.10), with strong associations with advanced age (aged ≥70 years) (1.09; 95% CI: 1.05–1.13) and stroke history (1.11; 95% CI: 1.06–1.16). PM(2.5–10) and NO(2) also showed significant associations with OHCAs, whereas SO(2), CO, and O(3) had no effects. After simultaneously adjusting for NO(2) and SO(2) in a multi-pollutant model, PM(2.5) remained significant. The effects of PM(2.5) in the single-pollutant models for cases with hypertension, respiratory disorders, diabetes mellitus, and heart disease were higher than those for cases without these complications; however, the differences were not statistically significant. The results support that elevated PM(2.5) exposure contributes to triggering OHCA, especially in those who are advanced in age and have a history of stroke.