280 Impact of ozone air pollution on ischemic cerebral and cardiac events in Dijon, France

BackgroundThere is strong evidence that short-term exposure to ozone (O3) is associated with respiratory disease and death, but the effects of short-term exposure to ozone on ischemic heart and cerebrovascular disease have not been clearly established.MethodsDaily levels of urban O3 pollution, the incidence of first-ever, recurrent, fatal and non-fatal ischemic cerebro-vascular events (ICVE) and myocardial infarction (MI) were compared using a bi-directional case-crossover design analysis. We analysed 1 574 ICVE and 913 MI that occurred in Dijon, France from 2001 to 2007. Sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), particulate matter with an aerodiameter of 10μg/m3 (PM10) were used to create bi-pollutant models. Using the adjusted Odd Ratios (OR), the effects of O3 exposure were calculated for every 10 μg/m3 increase in pollutants in multivariate logistic models adjusted for all possible confounders.ResultsWe found a statistically significant association between even low-levels of O3 and recurrent ICVE with a 3-day lag (OR = 1.115; 95% CI: 1.027–1.209). The association was marginally significant for recurrent MI with 1-day lag (OR = 1.147; 95% CI: 0.999–1.318). For incident events, we detected no significant association. In stratified analysis by vascular risk factors, we observed for ICVE an association with each vascular risk factor (OR = 1.523; 95% CI: 1.149–2.018) while for MI, an association with O3 was found when hypercholesterolemia was present (OR = 1.111; 95%: 1.020–1.211). Moreover, we noted an increase in the strength of association with an increasing number of combined factors.ConclusionFrom this population-based study, recurrent ICVE and MI could be triggered by short-term exposure to even low levels of O3, especially among subjects with severe vascular risk factors. As a result, preventive strategies could be designed for such subjects