Association of ambient air pollution with risk of out of hospital cardiac arrest in the United States

OBJECTIVE: We assessed the association of acute exposure to ambient air particulate matter < 2.5 μm (PM(2.5)) and Ozone with risk of out of hospital cardiac arrest (OHCA). METHODS: We used data from the Cardiac Arrest Registry to Enhance Survival (CARES), a prospective multicenter registry of patients with OHCA in the U.S. Environmental data was obtained from publicly available data and linked with each patient. A case-crossover design was used to estimate association of acute exposure to ambient air PM(2.5) and Ozone with risk of OHCA. Case day was defined as the day of the OHCA, and control days were same days of the week from preceding two weeks. RESULTS: Of 187,047 patients with OHCA, mean age was 61.5 ± 19.9 years, 59.7 % were males and 47.1 % were of White race. Mean daily PM(2.5) concentration on case day was 9.2 ± 4.9 μg/m(3) and mean averaged 8-hour Ozone concentration was 36.9 ± 12.1 ppb. Each 5 μg/m(3) increase in PM(2.5) concentration (case day vs. control day) was not associated with risk of OHCA (OR 0.99 [95 % CI 0.998, 1.017] p = 0.72). In contrast, there was an association of exposure to Ozone with risk of OHCA with every 12 ppb increase in Ozone associated with a higher risk for OHCA on case day (OR 1.011 [95 % CI 1.003, 1.019] p = 0.01). CONCLUSION: In the U.S., higher exposure to Ozone was associated with increased risk of OHCA.