Integrated model for the estimation of annual, seasonal, and episode PM10 exposures of children in Rome, Italy

Population exposure assessment plays a central role in developing efficient policies to control the significant health impacts caused by ambient pollution. Policy development requires comparison of alternative control options, which by definition can only be conducted using models. The current work presents results from an integrated model developed for Rome, Italy, to estimate the exposure distributions of children. Spatial distribution of the hourly PM₁₀ levels in 2005 was modeled by a chemical transport model and the modeled concentrations were adjusted using a procedure based on the observed PM₁₀ concentrations at urban stations. The PM₁₀ exposures of children were then estimated accounting for: the time?Cactivity patterns in indoors, outdoors, and in traffic; adjusted ambient levels; and outdoor to indoor infiltration factors. The mean annual exposure level was 22???g/m³, compared to the mean observed ambient concentration at a central station of 48???g/m³, with higher seasonal levels estimated for spring and summer than for autumn and winter. The differences are caused by the longer time spent outdoors and higher residential ventilation rates during spring and summer. The highest integrated exposures took place in the northeasterly districts. Average exposure levels in almost the whole city exceeded 20???g/m³. Short-term exposures were also investigated during a winter PM₁₀ episode for which exposure levels in excess of 30???g/m³ were calculated. Cumulative distribution results for the children indicate that the 24-h limit of 50???g/m3 set for the protection of human health is not exceeded by the exposures of children during the episode. The results of this study are important for a correct interpretation of the epidemiological studies taking into account the relationship of exposures and ambient air quality and for the development of alternative policy options to reduce children??s exposures by lifestyle modification and interventions focused on the reduction of the infiltration of PM₁₀ into indoor environments.