Ricerc@Sapienza

The main aim of this research effort is to assess the impact of the different circulating vehicle fleets on PM10 pollution, comparing the results from the ten most populated metropolitan cities in Italy. Circulating diesel vehicles have been categorized in different groups depending on the vehicle type (car or Light Commercial Vehicle - LCV) and European emission standard. The annual mileage and the total PM10 emission for each category has been determined based on several data sources. Estimated overall annual emissions of PM10 particles have been compared with PM10 concentration measurements from distributed ground monitoring stations. A new index, named SoP (Strength of Pollution), has been defined in order to quantify the contribution of each fleet category to the overall PM10 pollution. The index has been computed for the ten most populated Italian metropolitan cities, i.e. all cities with more than 300.000 inhabits: Rome, Milan, Naples, Turin, Palermo, Genoa, Bologna, Florence, Bari and Catania. Results in terms of SoP estimates for year 2018 reveal the presence in these Italian cities of emission clusters with heterogeneous characteristics, which impose the adoption of different PM10 pollution mitigation approaches in the different cities. For example, in Naples, Catania and Palermo, Euro 0 car fleets emit a total PM10 mass which is respectively 19, 10 and 5 times the mass emitted by Euro 6 vehicles, and consequently a reduction of this fleet is desirable for pollution mitigation purposes. Conversely, in Rome, Genoa and Bari, Euro 3 and 4 car fleets emit a total PM10 mass which is 3–6 times the one emitted by Euro 6 vehicles, which calls for a reduction of these fleets. Thus, the extension to the entire national territory of the results obtained in a specific metropolitan city may be strongly misleading and produce limited effects in terms of pollution mitigation.