Motorway pollution: evaluation of PM10 transport phenomena in the urban area of Perugia – Italy.

The pollution from total suspended particulate (TSP) and above all from PM10, i.e. the inhaling fraction of particulate matter with diameter less than 10 mm, constitutes a health hazard for the population. Specific weather conditions, for example thermal reversed gradient or absence of rain, contribute to worsen the pollution problem, since this hinders the dispersion of pollutants. In the present paper the TSP (total suspended particulate) and the PM10 (fraction of TSP with diameter less than 10 mm) concentration and the weather climate parameters were recorded, near polluting sources and a sensitive receiver. The measurements were used to assess a thermofluidodynamic model for evaluating the dispersion of the pollution in a commercial finite volumes calculation code called Fluent. In particular, the temperature, the relative humidity, the rain, the solar radiation, the direction and the speed of the wind were monitored in real time with a GSM telephone. The PM10 and the total suspended particulate concentration were obtained with the gravimetric method, employing a portable equipment. The main polluting sources in the area of study are a linear source coming highway and a point source, constituted of the end part of a 950 m long tunnel. The horizontal domain of study of the thermofluidodynamic model is an area of 85x85 m, in which the sources and the receiver are comprised. A numerical analysis with a model of dispersion of the pollution in a reference Lagrangian system was carried out. The results show that the model supplies mean values of TSP and PM10 in agreement with the values measured near the receiver.