Association between ambient ozone and health outcomes in Prague

Though numerous studies investigating ambient ozone (O-3) effects on human health were published, such a study for Central Europe is still lacking. We have investigated the association between ozone (O-3) levels and hospital admissions and mortality due to cardiovascular and respiratory diseases for Prague inhabitants for summer months (April-September) over the 5-year period 2002-2006. Our hypothesis was that ambient O-3 levels in Prague resulted in adverse health outcomes and were associated with increased mortality and hospital admissions. The effect of O-3 on mortality and hospital admissions was investigated using the negative binomial regression after controlling for the influence of meteorological factors (air temperature and relative humidity) and calendar effects (seasonal patterns, long-term trends and day of week). We found a statistically significant association between O-3 levels and daily mortality from respiratory diseases. Relative risk of 1.080 (95% CI: 1.031-1.132) was observed for mortality from respiratory diseases per 10 mu g m(-3) increase in 1-day lagged daily mean O-3 concentration. No statistically significant association was detected between O-3 concentrations and daily mortality from all causes, daily mortality from cardiovascular diseases and hospital admissions for respiratory and cardiovascular diseases. The O-3 effects differed in men and women, nevertheless, the results were ambiguous with respect to used lag and O-3 metrics. No significant confounding effects of PM10 on the investigated association were observed. O-3 exposure in Prague, though lower as compared to many other cities in Europe, is high enough to cause adverse health effects.