Introduction: Accumulating evidence has shown the elevated risk for cardiovascular diseases (CVD) with exposure to air pollution, such as fine particles <2.5μm in aerodynamic diameter (PM2.5). A bi-directional relationship exists between air pollution and traditional CV risk factors like obesity, diabetes, and hypertension. However, little is known about the effect of age and sex on association between ambient air pollution and out-of-hospital cardiac arrest (OHCA).
Purpose: This study aimed to identify sex and age differences in the associations between exposure to PM2.5 and OHCA in Japan.
Methods: A case-crossover design was used to determine the odds ratio (OR) of OHCA across Japan with daily PM2.5 exposure on the day of the arrest or 1–3 days before it (lag 0–3). OHCA cases were identified through the All-Japan Utstein registry of the Fire and Disaster Management Agency from January 1, 2014 to December 31, 2015. OHCAs were investigated by conditional logistic regression adjusted for daily temperature and relative humidity with stratification by sex and age.
Results: A total of 249,372 OHCAs were included during study period. Their mean age was 75 years and 57% were male. Each 10 μg/m3 increase in daily PM2.5 exposure over 4 days was associated with all cause OHCA risk for male (lag 0: OR 1.022, 95% confidence interval (CI) 1.013, 1.031; lag 1: OR 1.016, 95% CI 1.007, 1.025; lag 2: OR 1.016, 95% CI 1.007, 1.026; lag 3: OR 1.017, 95% CI 1.008, 1.027; lag 0–1: OR 1.025, 95% CI 1.015, 1.036). Increased risk in OHCA was also found with lag 1 to lag 3 PM2.5 exposure among women. Lag 0 to lag 3 PM2.5 exposures were significantly associated with OHCA among patients older than 65 years. Among 35 to 64 years, only lag 3 PM2.5 exposure was associated with an increased risk in OHCA. No significant association was observed between PM2.5 exposure and OHCA among patients less than 35 years.
Conclusions: Short-term exposure to PM2.5 is associated with an increased risk of OHCA in both sexes. Patients older than 65 years were more susceptible to PM2.5 exposure than younger age group.