PM emissions in an urban context

Within a urban environment, three different sources of particulate matter should be considered: heating plants using different combustibles (natural gas, gas oil, fuel oil, wood), industrial plants placed in the surrounding area, traffic. While the effects of the first two origins can be easily calculated on the basis of existing emission factors, the PM emissions from traffic are of two types, exhaust and non-exhaust. The latter type of emission is due to vehicle components’ wear (tyres, brakes), road abrasion and dust re-suspension and its quantification is not straightforward, as the variability of the corresponding emission factors found in literature demonstrates. In this paper we tried to calculate the total PM emission factors due to traffic by means of the measured PM concentrations for a 50,000 inhabitants town in NW Italy. At the same time we tried to assess the different contributions to the air quality of the town due to the other emission sources, namely heating and industrial plants, in order to understand who is the main responsible of the existing critical situation and to get some general information on the positive effect obtainable through different intervention policy.