How were the sources of air pollution related mortality estimated?

The contributions of each of the emission sources to the concentrations of pollutants were estimated using the Screening for High Emission Reduction Potentials for Air quality (SHERPA) tool, a software developed by the Joint Research Centre (JRC), which applies, in a simplified way, the principles of the so-called chemical transport models. These models take into account factors such as meteorology and chemical transformations to simulate the concentration of pollutants in the atmosphere. The research team divided the surface area of the European cities into 36 km² grids. Using SHERPA, they estimated the changes in atmospheric concentrations of PM_2.5 and NO₂ that would occur if emissions were reduced in each of the grids on the map and calculated the relative contributions of each of the pollution sources.

Finally, a comparative risk assessment was carried out to estimate the mortality attributable to each air pollution source, using the relative changes in pollutant concentrations that would result from reducing each emission source.