DUST GENERATION AND DISPERSION (PM10 AND PM2.5) IN THE AOSTA VALLEY: ANALYSIS WITH THE FARM MODEL

Abstract: The aim of this work is to analyze the origin and the dispersion of the particulate matter (PM10 and PM2.5) in a mountainous region: the Aosta Valley. To meet this goal, different simulations were performed, using the flexible air quality regional model (FARM), to study two scenarios: winter and summer situations. To evaluate the performance of the FARM model in order to simulate the air quality situation of the selected periods, a comparison of modelled results against observed air quality data was carried out for both primary pollutants and particulate matter next to the measurement stations. Farm performed well in simulating especially ozone (O3) and nitrogen dioxide (NO2) concentrations, showing a good reproduction of both daily peaks and their daytime variations. PM model results revealed the tendency to under-predict the observed values, so we tried to use a different emission factor for the road traffic (Lohmeyer factor). The new results were good for the urban and suburban areas, but they give over-predictions close to highways. The PM characterisation provided by the model gives good results: in some different points of the analysis domain (mountain, plain and urban points) we found PM profiles wich reproduce expected values. Key words: Air quality modelling, urban and rural air pollution, traffic emission, chemical characterisation of PM10