URBAN AIR-POLLUTION AND EMERGENCY ADMISSIONS FOR ASTHMA IN 4 EUROPEANCITIES - THE APHEA PROJECT

Background - A study was undertaken to assess the combined association between urban air pollution and emergency admissions for asthma durin g the years 1986-92 in Barcelona, Helsinki, Paris and London. Methods - Daily counts were made of asthma admissions and visits to the emerge ncy room in adults (age range 15-64 years) and children (<15 years). C ovariates were short term fluctuations in temperature and humidity, vi ral epidemics, day of the week effects, and seasonal and secular trend s. Estimates from all the cities were obtained for the entire period a nd separately by warm or cold seasons using Poisson time-series regres sion models. Combined associations were estimated using meta-analysis techniques. Results - Daily admissions for asthma in adults increased significantly with increasing ambient levels ofnitrogen dioxide (NO2) (relative risk (RR) per 50 mu g/m(3) increase 1.029, 95% CI 1.003 to 1 .055) and non-significantly with particles measured as black smoke (RR 1.021, 95% CI 0.985 to 1.059). The association between asthma admissi ons and ozone (O-3) was heterogeneous among cities. In children, daily admissions increased significantly with sulphur dioxide (SO2) (RR 1.0 75, 95% CI 1.026 to 1.126) and non-significantly with black smoke (RR 1.030, 95% CI 0.979 to 1.084) and NO2, though the latter only in cold seasons (RR 1.080, 95% CI 1.025 to 1.140). No association was observed for O-3. The associations between asthma admissions and NO2 in adults and SO2 in children were independent of black smoke. Conclusions - Th e evidence of an association between air pollution at current urban le vels and emergency room visits for asthma has been extended to Europe. In addition to particles, NO2 and SO2 - by themselves or as a constit uent of a pollution mixture - may be important in asthma exacerbations in European cities.