POLLUTANTS EMISSIONS IN A URBAN AREA: DEFINITION OF EMISSION FACTORS, ATMOSPHERIC DISPERSION MODELLING AND SUPPORT OF INTERVENTION POLICIES
Special Symposium - Environmental Protection & Sustainability
Environmental Protection & Sustainability - III
Keywords: Traffic, PM10, NOx, non-exhaust emissions, atmospheric model, street canyon, urban area, OSPM.
Within a urban environment air quality depends on pollutants emitted by three main sources: heating plants using different combustibles (natural gas, gas oil, fuel oil, wood), industrial plants placed in the surrounding area, traffic. Air quality is also strongly related to meteorological local conditions, urban structure of buildings and roads. The most important pollutants that should be studied and reduced in a urban context in order to ensure the sustainability of a metropolitan environment are NOx and PM10. On the basis of the emissive scenario of the studied area, atmospheric dispersion models can calculate pollutant concentrations at the ground level to be compared with existing measured values. The calibrated models can be used to define intervention policies or emission limitations on the different sources.
While the emission factors for NOx are well known for all the sources, the PM emission 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. Once all the emission factors have been defined and compared with other similar experience of Northern Europe (National Environmental Research Institute of Denmark, TNO, German UBA, Swedish model for vehicle-induced non-tailpipe emissions of particles) we tried to assess the different contributions to air quality due to the different emission sources in two medium towns of NW Italy, both for PM10 and NOx. An important effort has been made in order to define the background concentration due to stagnation phenomena of pollutants within the urban contexts and in particular in a street canyon.
As a result, the described approach should be applied in order to understand who is the main responsible of the existing critical situation of air quality and to get some general information on the positive effect obtainable through different intervention policy (traffic restrictions, cleaning of the street, change of combustibles for heating plants, different abatement techniques for the industrial activities, etc.).
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Presented Monday 17, 16:40 to 17:00, in session Environmental Protection & Sustainability - III (S-7C).
