MILAN WITHOUT DIESEL: HOW WOULD THE AIR QUALITY IMPROVE?

Abstract

The "Road transport" sector represents 74% of the nitrogen oxides emissions in the Municipality of Milan, with 93% of these emissions produced by diesel-powered vehicles. To estimate the impact of the emissions from these vehicles circulating in the urban area, simulations were conducted using a complex modelling system that takes into account the dispersion of the pollutants emitted and the chemical transformations which take place in the atmosphere according to meteorology. Road traffic emissions that persist over Milan urban area were estimated by using the official European COPERT 5 methodology and the traffic data provided by the Environment and Territory Mobility Agency (AMAT) of the Municipality of Milan. Two simulations were therefore carried out corresponding respectively to the 2017 “ex-ante” emission framework and excluding from it the emissions deriving from all diesel-powered vehicles circulating on the municipal road network of Milan (scenario "NO Diesel"). In this scenario, public transport and vehicles circulating on motorways and ring roads are not involved. The results from the "ex-ante" scenario show average annual NO₂ concentrations above the annual limit value (40 µg m^-3) in a major part of the urban area (about 75%) and higher values along the ring roads north of the city centre. In the "NO Diesel" scenario, NO₂ concentrations above the limit value remain only along the ring roads to the east and north of the urban area. Starting from these results, the percentage increase in the portion of the Milan territory that would respect the limit values was also estimated for traffic restrictions progressively involving increasing categories of diesel-powered vehicles