RI-URBANS: Source apportionment of different pollutants in urban Europe

RI-URBANS (Research Infrastructures Services Reinforcing Air Quality (AQ) Monitoring Capacities in European Urban & Industrial AreaS) is a research project supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-GD-2020 (grant 10103624) that connects the atmospheric observation expertise from Aerosols, Clouds and Trace gases Research InfraStructure (ACTRIS), with the urban air quality observation capacities of the regulatory air quality monitoring networks. It is specifically connected to the new European AQ Directive (NAQD) 2024/2881/CE published on 20 November 2024.

RI-URBANS focuses on the infrastructures to measure emerging pollutants for AQ and the well-being of the citizens. Particularly, service tools (STs) for novel pollutants, such as ultrafine particles (UFP), UFP-number size distribution (PNSD), black carbon (BC), as well as ammonia (NH3) and numerous volatile organic compounds (VOCs), and measurements of tracers of potential toxicity of PM (oxidative potential (OP) of particulate matter PM), are provided for urban supersites in order to support scientific understanding of their effects on health and the environment. The NAQD has been introduced in Art. 10 the measurements of these new pollutants in a new network of AQ supersites.

In essence, these STs are guidance documents that RI-URBANS have reviewed, in some cases developed, tested, and recommended for advanced AQ assessment in urban areas. Two of these STs focus on the source apportionment of PM based on receptor modelling with offline and online PM speciation (ST10) and on UFP-PNSD, BC, VOCs and OP of PM. The electronic files of the guidance documents of ST10 and ST11 can be downloaded at https://riurbans.eu/project/#service-tools

PMF is used in most cases (PM, VOCs, UFP-PNSD), and it is coupled with multi-linear regression for (OP), and aethalometer source apportionment for BC.

Here we present the results from the application of these source apportionment tools to datasets of PM speciation, UFP-PNSD, VOCs, BC and OP data available in urban Europe. The results have a high interest for AQ policy (identifying major sources contributing to air quality impairment, but also identifying measures needed and evaluating the impact of policy actions), evaluation of the health outcomes, and identifying the source contributions with higher toxicity potential.

The creation of the European network of AQ supersites by the European NAQD will provide very valuable datasets for source apportionment receptor modelling of a number of pollutants, however the required PM speciation in the NAQD is quite limited for obtaining detailed source apportionment results. It is important to intensify the source apportionment studies to support the need of more tracers of PM to be included in the supersites in the next review of the Directive, which will take place in five years.