Analysis of major pollutants and physico-chemical characteristics of PM2.5 at an urban site in Rome.

Air quality data from a one year study at an urban roadside location in Rome are reported for major pollutants. Continuous concentration data of carbon monoxide, ozone, nitrogen dioxide, aromatic hydrocarbons and natural radioactivity were measured in the urban air of Rome from January 2016 to January 2017. Moreover, PM2.5 mass concentration and physico-chemical characteristics of single constituent particles are herein reported. Gaseous pollutants, except ozone, and PM2.5 showed maximum concentrations in December due to high atmospheric stability. O3 and NO2 trend analysis showed photochemical smog episodes in June and September. In September, during a photochemical smog episode the aromatic hydrocarbons contribution to ozone formation was experimentally proven. Pearson's coefficient among aromatic hydrocarbons and the ratio Toluene/Benzene (T/B) showed that pollutants were under the influence of vehicular traffic. Physico-chemical characterization of PM2.5 single particles, carried out by field emission scanning electron microscope combined with energy dispersive X-ray spectroscopy, displayed the presence of particle diversity from natural and anthropogenic origin. Four principal components in the PM2.5 were identified: carbonaceous particles, Ca-sulphates, soil dust and building structure particles, metal particles. The principal source of carbonaceous particles in this urban area consists of the motor vehicle exhausts and the heating systems in winter. Traces of S and sometimes S, Na, K were detected on varying percentages of carbonaceous particles. These data suggested that the carbonaceous particles act as vehicles for strong acids, prevalently H2SO4 and alkaline metal sulphates. A Saharan dust contribution to PM2.5 was found in different periods. Metal particles included iron oxide particles, metals oxide particles and Fe-rich metal compounds. The identification of chemical composition of individual particles provide useful information to determine their origin and formation processes.

Two-years of fine and ultrafine particles measurements in Rome, Italy.

Long-term aerosol measurements have been conducted at two sites in Rome, Italy, April 2001 through March 2003, in a traffic-oriented site, and at an urban background site, close to the city center. The main objective was to establish validated and consistent data sets of particle number concentrations (PNC) in Rome to be used for epidemiological analyses of cardiovascular health effects. Particle number concentrations were measured by a condensation particle counter (CPC 3022A, TSI). Other pollutants (PM10, PM2.5, CO, NO2, NO, NOx, O3) were simultaneously measured at the traffic-oriented site. During the study period, the mean (standard deviation) 24-h PNC values were 4.69 x 10(4) (1.99 x 10(4)) cm(-3) and 2.46 x 10(4) (1.10 x 10(4)) cm(-3), respectively, at the traffic-oriented site and at the urban background site. Mean (standard deviation) 24-h mass concentration of PM2.5 was 23.1 (11.9) microg m(-3), while for PM10 it was 41.3 (17.9) microg m(-3). Higher values for all the pollutants, except ozone, were recorded during the winter period in comparison with the summer period, and a higher variability of the results was also observed during cold months. The comparison between the daily PNC measured at the two sites showed a good correlation (r = .74). CO (r = .77), NO (r = .82), and NOx (r = .83) were all highly correlated with PNC (simultaneous obs. number 576). The diurnal and seasonal pattern of PNC can be attributed to the combined effect of motor vehicle emissions and meteorological conditions.