The modeling chain developed in the previous research period is refined in some aspects, with special emphasis on the simulation of meteorological variables that play a key role in the reconstruction of dispersion processes at the urban scale. The effort to develop a hybrid quality model at the urban scale must be combined with a better reconstruction of the small-scale meteorological processes that result from the complexity of the urban fabric; this will be the focus of research in the next two years of the PTR (Regional Territorial Plan).

The main results of this study are the analysis of two mobility scenarios with different incidence for the city of Milan and their impact on road traffic emissions and air pollutant concentrations. The first scenario involves a zero-emission zone (ZEZ) in the center of Milan, while the second, called Phase Out, assumes a total transition to electric mobility.

The ZEZ scenario results in a 19% reduction in NOx emissions and a 6% reduction in PM10 emissions, while the Phase Out scenario completely eliminates NOx emissions and reduces PM10 emissions by 18%. In terms of air quality impacts, the reduction estimates suggest that while the impact of mobility scenarios focused on replacing the current vehicle fleet can bring significant benefits for nitrogen oxides, the impact of such policies is not as strong for PM fractions. This result can be explained in part by the fact that while electric mobility eliminates the contribution of combustion emissions, it has an impact on brake and tire wear emissions.

The study is complemented by work on the assessment of the environmental benefits of sustainable urban mobility policies, which was carried out using a methodology complementary to deterministic atmospheric modeling. An approach was developed that can provide a faster alternative for reconstructing atmospheric processes and analyzing the impact of scenarios to enable preliminary screening of a wide range of sustainable mobility solutions. This approach was applied to the case study of the city of Milan, with the aim of verifying its effectiveness in assessing the impact of mobility policies applied at different spatial scales and to different types of vehicles.