COMPLEMENTARY USE OF HIGH TIME RESOLUTION PARTICULATE-SAMPLING AND PIXE ANALYSIS IN THE STUDY OF A SEVERE POLLUTION EPISODE

In Milan recurrent episodes of severe and long-lasting pollution occur in winter in peculiar meteo-climatic conditions. During one of these episodes, in which the Municipality of Milan prohibited traffic circul ation for one day, a streaker total filter particulate sampler was ope rated for one week at the Brera Tower station, located 25 m above grou nd level in the centre of Milan. In addition gas pollutants and meteor ological parameters were also continuously monitored. PIXE analysis of the particulate matter deposit on Nuclepore filter, sampled in the 18 -25 January period, provided hourly concentrations of 21 elements. The analysis of time sequence patterns, daily temporal trends of element concentrations together with SPUR and correlation analysis proved effe ctive for the understanding of pollution buildup mechanisms as well as the short term contribution of different sources. In particular, phen omena related to local meteorology. as fumigation, were evidenced.