Association between ambient air pollution and out-of-hospital cardiac arrest: are there potentially susceptible groups?

This study aimed to examine the association between air pollution and out-of-hospital cardiac arrest (OHCA), and the effects of underlying diseases. Between January 2015 and December 2016, data on particulate matter (PM)2.5 and other air pollutants in Kaohsiung City were collected, and an emergency medical service database was used for information on patients who experienced OHCA. Overall, 3566 patients were analyzed and subgroup analyses by sex, age, and preexisting morbidities were performed. Interquartile increments in PM2.5, PM10, and O3 levels on lag 1 and NO2 level on lag 3 were associated with increments of 10.8%, 11.3%, 6.2%, and 1.7% in OHCA incidence, respectively. Subgroup analyses showed that patients with diabetes (1.363; interaction p = 0.009), heart disease (1.612; interaction p = 0.001), and advanced age (≥70 years, 1.297; interaction p = 0.003) were more susceptible to NO2 on lag 3. Moreover, patients were more susceptible to O3 during the cold season (1.194; interaction p = 0.001). We found that PM2.5, PM10, NO2, and O3 may play an important role in OHCA events, and the effects vary by underlying condition, age and season.