The activities conducted in 2023 are aimed at making the HAM modelling chain more applicable to planning needs and improving its practical usability. The simplified SIMBAD emission-concentration model is able to replicate the spatial and temporal resolution of the CAMx reference model. This is particularly useful for energy and air quality policy planning, especially considering the European Union’s new proposed directives to reduce air pollution, which require more stringent air quality standards and effective tools for predicting exceedances.

An analysis of the performance of SIMBAD compared to CAMx showed that SIMBAD is effective in reconstructing also daily average concentrations of PM10 and PM2.5, but may slightly underestimate the number of exceedance days compared to CAMx, although the relative error remains small. Evaluations of the scenarios show that significant emission reductions allow compliance with the limits proposed by the new directive, while less incisive scenarios are ineffective in reducing exceedances.

A simplified methodology was implemented and tested to take into account the evolution of the scenarios’ starting points over time, considering the emission reduction measures currently planned to improve air quality. A preliminary study simulated year 2030, with emissions variations based on GAINS projection data, to obtain the concentration fields to be used in the simplified model as base case for scenarios. SIMBAD was then applied using the sensitivity coefficients calculated in the current context, showing satisfactory performance for a primary pollutant such as elemental carbon, but significant differences for secondary pollutants such as NO2 and PM10.

It is therefore necessary to recalculate sensitivities also in future simulations by applying the DDM algorithm. Improvements were made to the SIMBAD-HAM web application, including the enhancement of the user management system and the possibility of making scenarios public or private. In addition, an offline version of the tool was introduced that allows multiple scenarios to be run simultaneously and the results saved for further processing. These changes increase the usability and flexibility of the web interface, allowing users to more efficiently manage and analyse scenarios of interest.

The Report is available on the Italian site