Application of Advanced Particulate Matter Source Apportionment Techniques in the Northern Italy Basin

Abstract

This work describes the results of the CAMx modelling system application aimed at reconstructing the particulate matter concentration over the Northern Italy basin and analysing the role played by the main emission sources on the pollution levels. Simulations have been performed on yearly basis in the frame of two different modelling exercises. The present analysis has been performed taking into account an overlapping period, covering February 2004. As a first step, CAMx results have been compared to a considerable data set of observed concentrations of NO₂ and PM₁₀. Model has been able to correctly reproduce the daily evolution and spatial variability of NO₂, while some underestimations of PM₁₀ concentrations have been highlighted. Then the Particulate Source Apportionment tool (PSAT) has been applied, in order to discriminate the contribution of several key emission sectors such as transport, domestic heating and power plants, in relation to three emission areas. Road transport appears to be the most responsible sector of PM₁₀ concentration, especially in the area between Milan and Turin. The urban area of Milan is characterised by high PM₁₀ concentration with an important contribution by road transport and domestic heating. The analysis has also pointed out the increasing relevance of the emissions coming from areas outside the city during critical pollution episodes, when severe stagnant conditions emphasise the role of secondary particulate matter. Finally, the comparison between the two PSAT applications has put in evidence, as a whole, quite coherent distributions of the relative contribution to PM₁₀ concentration, thus proving the robustness of the source apportionment results. The main differences concerned domestic heating contribution, clearly related to the discrepancies in the emission inventories.