[Occurrence of metals in various size fractions of particulate matter]

Size distributions of trace metals of specific health concern (Pb, Cd, Cr, Ni, Cd, V, Zn and Fe) in the fine (PM2.5) and coarse (PM2.5-10) fractions of suspended particulate matter were evaluated. Samples were collected through a year in three sites (traffic oriented and urban background in the urban area of Rome, and remote, in the Regional Park of Simbruini Mountains). Mean concentrations never exceeded the values recommended by WHO and EU. During winter season, levels of Cr, Cd, Pb and Zn resulted higher than in summer, in both fine and coarse fractions. The series of Pb, Cd, and V concentrations clearly showed a predominant fine-particle distribution, whereas Cr, Mn and Ni were more equally distributed between the coarse and fine fractions. Fe prevailed in the coarse mode at the urban sites. At the urban sites mean concentrations of the different metals were from 4 to 22 times higher than at the remote site. For various metals the distribution mode, as well as the seasonal trends of the concentrations, showed significant differences between urban and remote site. In busy and densely populated urban areas, without relevant industrial emissions, anthropogenic sources of metallic species seem still to give a contribution to air pollution, though a trend downwards, compared to previous surveys, was observed, particularly for Pb.