Objective: the relationship between air pollution and mortality has been well established in national and international scientific literature. This study reports the results of the EpiAir Project relative to the effect of air pollution on mortality in 10 Italian cities during 2001-2005. The association between particulate matter (PM10) and gases (nitrogen dioxide, NO2, and ozone, O3), and all natural mortality, as well as cardiac, cerebrovascular and respiratory mortality, is presented. Specific issues have been investigated, such as the latency of the air pollution-mortality effects and the identification of individual demographic characteristics and clinical conditions that result in greater susceptibility to the effects of particulate matter.
Methods: the study population consisted of 276,205 subjects aged 35+ years old, resident in one of the 10 Italian cities studied, which died in the city between 2001-2005. For each subject, information was collected on cause of death, location of death, demographical variables and hospital discharge diagnoses in the previous 2-year period. The statistical analysis was adjusted for the relevant temporal and meteorological factors using the case-crossover approach. The results for ozone are limited to the warm semester (April through September). An analysis of the association between air pollution and mortality was conducted for each city, and the city-specific estimates were meta-analyzed on a second level to obtain a pooled result, and reported inter-city heterogeneity.
Results: a short-term effect of PM10 on mortality has been detected for all the groups of causes considered, with latencies ranging from lag 0 for cerebrovascular mortality to lag 0-3 for respiratory mortality. The association between NO2 and mortality displays strong and similar effects for all death causes, with prolonged effects (lag 0-5) for all groups of causes. The results for O3 are similar to those found for NO2, with prolonged latency (lag 0-5) for all causes of death with the exception of cerebrovascular mortality, for which a delayed effect (lag 3-5) was identified. Individual susceptibility factors of the PM10-natural mortality association include age, as elderly subjects are especially vulnerable to the effects of particles.
Conclusions: the main results of the study suggest that the air pollution originated by vehicular traffic is the most relevant environmental problem in Italian cities from a public health viewpoint.