Objective: to evaluate the relationship between air pollution and hospital admissions in 25 Italian cities that took part in the EpiAir (Epidemiological surveillance of air pollution effects among Italian cities) project.
Design: study of time series with case-crossover methodology, with adjustment for meteorological and time-dependent variables. The association air pollution hospitalisation was analyzed in each of the 25 cities involved in the study; the overall estimates of effect were obtained subsequently by means of a meta-analysis.