Multi-Year Datasets of PM1 Chemical Composition and Organic Aerosol Sources at Various French Urban and Suburban Areas
HASNA CHEBAICHEB, Olivier Favez, Joel Brito, Florian Couvidat, Augustin Colette, Caroline Marchand, Veronique Riffault,
Laboratoire Central de Surveillance de la Qualité de l’Air Abstract Number: 441
Working Group: Urban Aerosols
AbstractIn France, exposure to fine particles (PM) is responsible for 48000 premature deaths per year. PM concentrations exceed the annual PM2.5 concentration of 5 µg.m-3 recommended by the WHO (EEA, 2021). In this context, more than 12 ACSMs (Aerosol Chemical Speciation Monitor) and aethalometers (AE33) have been operating quasi-continuously since 2015 at different French urban sites. The objective is to provide a long-term dataset of the chemical composition of PM1 particles and to study the sources of organic aerosols (OA) by applying the rolling Positive Matrix Factorization method. This approach, based on relevant constraints and criteria, has the advantage of capturing potential temporal changes in source profiles within multi-year datasets.
The results of this study first confirm that OA is the main component of submicron aerosol in many French cities (40-60% of PM1). Spatial variability in the chemical composition and OA sources is also observed. Primary factors are mainly related to combustion processes. In particular, hydrocarbon-type OA (related to traffic, HOA) and that from biomass combustion (BBOA) are present at all sites. The HOA factor shows a fairly constant contribution to the OA throughout the period while the BBOA factor varies with a peak in winter due to increased emissions from residential wood burning. Other site-specific primary sources were also resolved, including those related to cooking, as well as port and/or industrial emissions. Oxygenated factors were distinguished between their less and more oxidized fractions (LO-OOA and MO-OOA, respectively). These oxygenated factors dominate the OA at all sites, with an average contribution of 74%, suggesting a very strong contribution from aging and secondary formation processes. Comparison with the CHIMERE model and with filter-based aerosol tracers is also considered to improve our knowledge of OA sources in France and may help improve the accuracy of air quality models.
Acknowledgments
This work was supported by the French Ministry of Environment, through the CARA program. It is also part of the Labex CaPPA project (ANR-11-LABX-0005-01), and the CLIMIBIO project, both also funded by the Regional Council “Hauts-de-France” and the European Regional Development Fund (ERDF).
References
[1] European Environment Agency, Air quality in Europe 2021 — European Environment Agency: https://www.eea.europa.eu/publications/air-quality-in-europe-2021.