SHERPA (Screening for High Emission Reduction Potential on Air) is a Python tool, which allows for a rapid exploration of potential air quality improvements resulting from national/regional/local emission reduction measures. The tool has been developed with the aim of supporting national, regional and local authorities in the design and assessment of their air quality plans. The tool is based on the relationships between emissions and concentration levels, and can be used to answer the following type of questions:

• What is the potential for local action in my domain?
• What are the priority activity, sectors and pollutants on which to take action?
• What is the optimal dimension that my policy action domain (city, region…) should have to be efficient?

The SHERPA tool is distributed with EU-wide data on emissions and source-receptor models (spatial resolution of roughly 6x6 km2, reference year for emissions at 2019), so that it is very easy to start working on any region/local domain in Europe.

More specifically, SHERPA logical pathway is implemented through the following steps:

• Source allocation: to understand how the air quality in a given area is influenced by different sectoral or geographical sources;
• Scenario analysis: - Scenario analysis: to simulate the impact on air quality of a specific emission reduction scenario (defined also through the previous two steps)