Evaluation of organic micropollutants and fine particles in vehicle exhausts and in ambient air

The incredible increasing of the number of vehicles circulating in the Italian cities, occurred in the last fifteen years, is the main reason for still considering the traffic as the most important source of gaseous and particle pollutants in the urban atmosphere. The large volume of on road vehicles balances and deletes the positive effects in terms of exhaust emissions coming from the recent technological improvements regarding the engine combustion efficiency, the fuel quality and the after-treatment device performances. The urban air quality, in fact, is still greatly influenced by the elevated traffic volume, whose negative effects on the air pollution are made worse by the type of driving pattern enforced to the vehicle in a congested traffic situation. The most critical pollutant are represented by particulate matter and organic compounds, generally indicated as organic volatile compounds, which include carcinogenic species. Due to very dangerous effects of such pollutants for human health and environment, it is very important both to characterise the pollution source in terms of quantity and quality of emissions at the exhaust of the several in-use vehicle technologies and to establish the real contribution of road traffic to ambient air pollutant concentrations. This experimental work is aimed to carry out a comprehensive characterisation of volatile organic compounds and fine particles (in terms of mass, number and PAHs content) at the vehicle exhaust and in the ambient air, and to find a correlation between the exhaust pollution source and the air pollution in several traffic urban sites in Napoli. The methodology applied to realize this research plan involved two parallel experimental programmes: one aimed to measure exhaust emissions and the other to evaluate ambient air concentrations. Vehicle exhaust emission factors were evaluated by executing experimental tests on chassis dynamometer on a fleet including 20 in use vehicles, each characterised by a different engine technology and type approval ...