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[Simulation of children exposure to NO2 and pm10 in the urban area of Bologna (Italy)].

OBJECTIVE
To estimate exposure to NO2 and PM10 of children living in a central area of the city of Bologna, Italy.


DESIGN
Mean personal exposure was estimated for 333 school children as weighted average of the individual hourly exposure levels during the period 1.06.2004-31.05.2005. Four microenvironments (home indoor, school indoor, traffic, home outdoor) and three typical days (school day, holidays in schooling period, and summer holidays) has been considered in the model.


MAIN OUTCOME MEASURES
Annual mean exposure to NO2 and PM10.


RESULTS
Exposure levels in the sample were lower than mean concentrations recorded by the monitoring station located in the study area. During the school period, mean exposures to NO2 and to PM10 were respectively 20% and 40% higher than in holidays during school period and 30% and 50% higher than during summer holidays. Exposures of the most exposed children were 39 mg/m3 for NO2 and 18 mg/m3 for PM10, i.e. roughly 50% higher than the least exposed children. During the school period, the most important contributions to total exposure were those of the indoor and school micro-environments.


DISCUSSION AND CONCLUSIONS
Compared to ambient levels measured at traffic oriented monitoring stations, exposures of school children are influenced by the length of time spent in the traffic microenvironment, as well as by the protection given by the time spent at school and at home. Exposure modelling can be used in order to estimate the consequences of policy options on exposure. However, a detailed empirical validation of the exposure model is needed.