In March 1995 a measurement campaign of atmospheric aerosol in the urban area of Bologna was carried out by the Institute for Radioprotection in the Environment Department of ENEA. Two standards, total suspended particles (TSP) and a particle fraction with a diameter smaller than 10 μm (PM10 fraction), were measured with a Total Filter of cellulose triacetate and with a PM10 Dichotomous Sampler, respectively. A cascade impactor was also used. Its sampling inlet and its first-stage plate showed the same aerodynamic cutoff as the PM10 sampler: this enabled a mass granulometric distribution of PM10 fraction to be obtained. Using aerosol size distribution data from the cascade impactor, the deposited mass on the respiratory tract was evaluated for a standard exposure by means of the deposition model proposed by the International Commission on Radiological Protection in the general model of the human respiratory tract for radiological protection. TSP and PM10 time-series analysis reveals that, on average, TSP concentration data are 20% higher than PM10 data. The pulmonary deposition assessments show that the fraction of accumulation mode mass deposited in the alveolar-interstitial region is less than the fraction of Aitken mode mass, but the values of the deposited mass are greater because of the higher concentration of the accumulation mode obtained during the measurement campaign.

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