The temporal pattern of mortality responses to ambient ozone in the APHEA project

The temporal pattern of effects of summertime ozone (O(3)) in total, cardiovascular and respiratory mortality were investigated in 21 European cities participating in the APHEA-2 (Air Pollution and Health: a European Approach) project, which is fundamental in determining the importance of the effect in terms of life loss.

Data from each city were analysed separately using distributed lag models with up to 21 lags. City-specific air pollution estimates were regressed on city-specific covariates to obtain overall estimates and to explore sources of possible heterogeneity.

Stronger effects on respiratory mortality that extend to a period of 2 weeks were found. A 10 microg/m(3) increase in O(3) was associated with a 0.36% (95% CI -0.21% to 0.94%) increase in respiratory deaths for lag 0 and with 3.35% (95% CI 1.90% to 4.83%) for lags 0-20. Significant adverse health effects were found of summer O(3) (June-August) on total and cardiovascular mortality that persist up to a week, but are counterbalanced by negative effects thereafter.

The results indicate that studies on acute health effects of O(3) using single-day exposures may have overestimated the effects on total and cardiovascular mortality, but underestimated the effects on respiratory mortality.