Local air pollution and long–range mass transport of atmospheric particulate matter: A comparative study of the temporal evolution of the aerosol size fractions

Long-range transport of polluted air masses can significantly affect surface particulate matter levels. PM10 and PM2.5 daily-average ponderal values alone are not sufficient to investigate the occurrence of such phenomena and consequently do not give significant information for source apportionment. In this work, the analysis of aerosol size spectra and the study of the correlation of the fine and coarse modes of PM have been applied to individuate long- range transport episodes of polluted air masses. Dust-models and backward-trajectory analysis were supportive to local surface measurements of size distribution of PM in confirming the origins of remote sources of pollution. An application is discussed involving long range transport of desert dust over Italy that comparatively examined with a fine-PM pollution episode due to local sources. During the study, the atmospheric stability/unstability conditions were followed through the trend of the natural radioactivity considered as tracer of the Planetary Boundary Layer.