Source attribution of fine particulate matter in European cities for different meteorological years

Ambient fine particulate matter (PM2.5) poses a significant risk to health in Europe, where many cities are exposed to levels above World Health Organization guidelines. To support the implementation of optimal PM2.5 reduction policies, air quality models are necessary. In such context, source-receptor relationships (SRRs) are models that can be used to replace fully-fledged Chemical Transport models, and save significant computation time when simulating various emission reduction scenarios. They allow calculating the relative potential of a given source at a receptor, i.e. the share of PM2.5 concentration at a given receptor that results from the complete removal of the emissions from that source. Here, we use the SRR model SHERPA, based on the EMEP Chemical Transport Model for four different meteorological years (2015, 2017, 2019 and 2021), to evaluate relative potentials for 150 European cities. These potentials are evaluated for five different emission precursors, twelve emission sectors, and four reduction scopes (city core, commuting zone, remaining national territory and rest of Europe). Results show that relative potentials vary little between meteorological years for most cities. The industry, transport and residential sectors generally bear the highest values of relative potential for most cities through emissions of primary particulate matter. Cities near important ports where the shipping sector exhibits high values through sulfur oxides. High potentials are observed for agriculture at the national and international scales. Cities in Southern Europe have low reduction potentials due to high PM2.5 levels originating from natural sources. Smaller cities have a higher relative potential for national and international emissions, while larger cities have high relative potentials for city core emissions. Relative potentials are generally low for commuting zones. These results underline the reliability of SRRs in guiding targeted air quality interventions, thereby helping to reduce PM2.5 exposure effectively across diverse urban settings in Europe.