Chemical composition of indoor and outdoor PM2.5 in three schools in the city of Rome

It is well known that children are more sensitive than adults to the adverse health effects of air pollution. Since in Italy children spend up to 30% of their time in school institutions, the evaluation of indoor air quality in schools constitutes a necessary step forward in the direction of child health protection. In this study, we investigated the chemical composition of atmospheric particulate matter below 2.5 ?m (PM2.5) collected simultaneously indoor and outdoor in three primary schools in Rome, Italy. Seasonal variations between winter and spring/summer were evaluated, as well as the role of the main macro-sources of PM (soil, sea, traffic, secondary inorganics and organics). During winter periods, characterized by strong atmospheric stability, indoor PM concentrations were higher than the values recommended by the international guidelines. The analysis of PM composition showed that the main contributors were organics (up to 52% of the total PM2.5 mass) and combustion products (domestic heating and traffic-related components). Spring/summer period was characterized by very low outdoor concentration (on average, about 12 ?g/m3) and by a more balanced contribution of organic, traffic and secondary inorganic components. Indoor, the contribution of soil-related species from re-suspension of settled dust and secondary inorganic species from outdoor photochemical reactions became significant.