Evaluation of the temporal variation of air quality in Rome, Italy from 1999 to 2008

Summary. The main objective of this study was to asses the temporal variation (1999 trough 2008) of air quality in Rome, focusing on airborn concentration of selected pollutants (PM 10 and PM 2.5 mass concentration and particle number concentration, PNC, carbon monoxide, CO, nitrogen oxides, NO and NO 2 ) used for health effects assessment in epidemiological analyses. Time series analysis using Seasonal Kendall test has been applied. A statistically significant decreasing trend was found for primary gaseous pollutants and total particle number concentrations. Moreover a decreasing trend was assessed for PM 10 , PM 2.5 and NO 2 measured at traffic oriented sites even if the estimated reduction was lower compared with NO, CO and PNC. The urban background PM 10 and NO 2 concentrations seem to be practically unchanged since 1999 as no statistically significant trends were found. All the pollutants show higher slope of the estimated trend line at traffic oriented sites compared with those observed at the urban background. Thus a reduction of the intra-city concentration variability throughout the years occurred.