Measurements of ultrafine particle size distribution near Rome

This paper presents the results of an experimental investigation into the particle number concentration and size distribution of ultrafine particles (UFPs) near the city of Rome. Measurements were made using Scanning Mobility particle Sizer System (SMPS), at Montelibretti station in October and November, 2007. The major focus of this study was the evaluation of aerosol size distribution from 4 to 70 nm using scanning mobility particle size with a high resolution Nano Differential Mobility Analyzer (DMA). Cluster analysis and factor analysis were used to analyze the correlation of different diameter particle fractions with related gaseous pollutants and meteorological parameters. The results obtained showed that over the measurements period the daily average particle total number concentration was 19,000 cm− 3. There was a weekly cycle which makes it evident that the values on workdays were higher than the values on the weekends by a factor of around 1.3. The cluster analysis and factor analysis conducted with an hourly data set suggest that the N30–50 (number concentration of particles with diameter between 30 and 50 nm) and the N50–70 closely correlated to NOx and relative humidity, while the N4–10, N10–30 and N4–70 consort with solar radiation, temperature and wind speed.