Introduction: the relationship between air pollution and hospital admissions has been well studied. In this study, the results of the Italian EpiAir Project are reported on the effect of air pollution on hospital admissions in 9 Italian cities during 2001-2005. The association between particulate matter (PM10) and gases (NO2 and O3) and hospital admissions for cardiac, cerebrovascular, respiratory conditions, pulmonary embolism and diabetes has been evaluated.
Material and methods: The study population consists of 701,902 hospital admissions of subjects residents in nine Italian cities and hospitalized in the city in the period 2001- 2005. We used a case-crossover approach and the statistical analysis considered the relevant temporal and meteorological factors for confounding adjustment. The results for ozone refer to the warm semester. The analysis of the association between air pollution and admissions was conducted for each city, and the city-specific estimates were meta-analyzed to obtain pooled results.
Results: we found an immediate effect of PM10 and NO2 (lag 0) for cardiac diseases as a group and for specific conditions (coronary syndrome and heart failure). No effect of ozone was observed. For cerebrovascular diseases we did not observe a positive effect of the three pollutants. An effect of NO2 on pulmonary embolism was detected. The association between air pollutants and hospitalization for respiratory diseases (respiratory infections, COPD and asthma) showed different lags for the three pollutants: the effect of PM10 was immediate at lag 0-1 while the effects of NO2 and ozone were prolonged at lag 0-5. The strongest association was between NO2 and asthma admissions, especially in children. No effects on diabetes were found.
Conclusions: the main results of the present study confirm the deleterious short term impact of air pollution on cardiovascular and respiratory morbidity in Italian cities.