Background: Although ozone has been associated with cardiovascular morbidity and mortality, the effects of ozone on out-of-hospital cardiac arrest (OHCA) has rarely been addressed and studies investigating the link between OCHA and air pollution have presented inconsistent findings. Aim: The objective of this study is to investigate the effects of short-term exposure to air pollution, including ozone on OHCA and effect modification by season, age, and gender. Methods: A total of 5973 OHCA Emergency Medical Service-assessed cases in Stockholm County 2000-2010 were obtained from the Swedish cardiac arrest register. The urban background 03 level was on average 51.2μg/m~3 during the study period. A time-stratified case-crossover design was used to analyze exposure to air pollution and the risk of OHCA. Moving 2-h, 24-h and 3-day averages for urban background O3, PM2.5, NO2, and NOx were constructed from hourly means preceding the event and control time points. We adjusted for temperature and relative humidity. Results: Ozone levels were associated with increased risk of OHCA, for 2-h, 24-h and 3-d exposure windows. The respective odds ratio (OR; confidence interval) for a 10 μg/m3 increase were 1.02 (1.00-1.05), 1.04 (1.01-1.08) and 1.05 (1.01-1.09). The association with 2-h ozone was stronger for events that occurred outdoors compared to indoor events: 1.13 (1.06-1.21) vs 1.02 (0.99-1.04; p value for interaction = 0.05). We saw no effects for other pollutants and no effect modification by age, gender or season. Conclusion: Elevated levels of ozone are associated with risk of OHCA.
展开▼
