(HealthDay News) – There is an increased risk of out-of-hospital cardiac arrest (OHCA) with higher levels of exposure to fine particulate matter (PM2.5) and ozone, according to a study published online Feb. 13 in Circulation.

To examine the correlation between OHCA and air pollution concentrations in the hours or days before onset, Katherine B. Ensor, PhD, from Rice University in Houston, and colleagues used data from 11,677 emergency medical service-logged OHCA events from 2004–2011 in Houston.

The researchers observed an increased risk of OHCA with an average increase of 6µg/m³ in PM2.5 two days before onset (1.046; 95% confidence interval [CI], 1.012–1.082). There was an increased risk of OHCA with a 20 parts per billion (ppb) ozone increase for the eight-hour average daily maximum on the day of the event (1.039; 95% CI, 1.005–1.073). For each 20ppb increase in ozone in the previous one–three hours there was an increased risk of OHCA (1.044; 95% CI, 1.004–1.085). Men, African-Americans, and those aged >65 years had higher relative risk estimates.

“While this study identifies an association between PM2.5 and ozone air pollution and OHCA, future research to better define the exposure time period associated with triggering an OHCA is needed,” the authors write.

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