Modellizzazione e verifica della dispersione di inquinanti atmosferici in un ambiente urbano di particolare valore storico-culturale. II parte

An application of emission and dispersion models has been run in order to simulate the production and dispersion in the atmosphere of organic pollutants, which are the main cause of deterioration of monuments of high historical and cultural relevance in urban areas. This work is focused on the Particulate Matter (PM), whose organic components are considered as the essential cause of monument darkening. Road traffic is the most important source of PM in urban areas: for this reason, specific emission and dispersion models have been used, particularly tested for studying typical urban configurations such as broad arterial roads and street canyons. The selected area for this study was the city of Florence (Italy), considered as a reliable test bench for the whole question, both for the amount and importance of the architectural heritage and for the remarkable effect of pollution deriving from PM produced by road traffic. One specific part of the whole problem of PM generation due to vehicles in an urban area has been analysed. In particular, PM has been treated as a primary pollutant only, thereby overlooking secondary PM produced by chemical and photochemical reactions involving other species such as VOC, NOx, SOx. Moreover, deposition and lifting phenomena of particulates from road pavement produced by car brakes and tyres have been overlooked, too. With this purpose, specific emission and dispersion models related to this problem have been used: the COPERT model to calculate emissions, and the CALINE model to simulate pollutant dispersion. The PM concentrations estimated by the models have been compared to the PM concentration measurements, as well as related to the trend of some meteorological variables. Final results showed fair accuracy in concentrations predicted by models, which could be considered as a good starting point for future improvements, particularly when the other features of PM generation and dispersion will be taken into account.