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/m³ and mean averaged 8-hour Ozone concentration was 36.9 ± 12.1 ppb. Each 5 μg/m³ 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.