How do emission reductions of individual national and local measures impact street-level air quality in a neighbourhood of Madrid, Spain?

This paper aims to assess the impact of individual measures for NOx emission reduction on NO₂ concentrations at very high spatial resolution in an urban district of Madrid City (Spain). A methodology based on a set of Computational Fluid Dynamics simulations for 16 meteorological scenarios combined with the CHIMERE model for background pollution is used to obtain annual NO₂ concentration maps. Two scenarios included in the Spanish National Air Pollution Control Programme are investigated: NOx emission reductions from the installation of more efficient boilers for domestic heating (ECOBOIL) and from the partly substitution of passenger cars with combustion engines by electric cars (EC). This analysis is extended to 9 additional scenarios of more ambitious implementation of electric vehicles in order to determine what the NOx emission reduction required for the annual mean NO₂ concentration EU limit value not being exceeded is. The ECOBOIL scenario has a very weak impact on the NO₂ concentrations. However, the EC scenario implies a more significant reduction of the NO₂ concentrations, but not enough to fully remove NO₂ limit value exceedances in the study area. A small additional (compared with the EC scenario) implementation of electric vehicles seems to fulfil that the spatially averaged NO₂ concentration be lower than the EU limit value, but the area with exceedances is still very large. However, stronger traffic emission reductions (80%) corresponding to the most ambitious scenarios are needed in order to reach that at least 95% of the domain is free of EU limit value exceedances.