ARD Aerosol Research Discussions ARD Aerosol Research Discuss. Göttingen, Germany 10.5194/ar-2026-35 Chemical Speciation and Source Apportionment of PM<sub>2.5</sub> in Greek Urban and Suburban Areas: Insights from the PANACEA Initiative Papagiannis Stefanos https://orcid.org/0009-0001-4996-4500 1 2 Diapouli Evangelia https://orcid.org/0000-0002-8244-2018 1 Vasilatou Vasiliki https://orcid.org/0000-0002-1707-8133 1 Gini Maria 1 Kourtidis Konstantinos https://orcid.org/0000-0002-5753-7074 3 Kaltsonoudis Christos https://orcid.org/0000-0001-8654-185X 4 Tsagkaraki Maria 5 Grivas Georgios 6 Liakakou Eleni 6 Bougiatioti Αikaterini 6 Mihalopoulos Nikolaos 5 6 Eleftheriadis Konstantinos https://orcid.org/0000-0003-2265-4905 1 Environmental Radioactivity & Aerosol Technology for atmospheric & Climate Impact Lab, INRaSTES, NCSR Demokritos, 15341 Athens, Greece Department of Materials Science & Engineering, University of Ioannina, Ioannina, 45110, Greece Department of Environmental Engineering, Democritus University of Thrace, Xanthi, 67100, Greece Institute of Chemical Engineering Sciences, ICE-HT, Patras, 26504, Greece Department of Chemistry, University of Crete, Heraklion,70013, Greece Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Penteli, 15236, Greece 07 10 2026 2026 1 38 Copyright: © 2026 Stefanos Papagiannis et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://ar.copernicus.org/preprints/ar-2026-35/ The full text article is available as a PDF file from https://ar.copernicus.org/preprints/ar-2026-35/ar-2026-35.pdf

This study, conducted under the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA), examines PM₂.₅ chemical speciation and source apportionment across five Greek cities (Athens, Ioannina, Patras, Volos, and Xanthi) representing urban background, urban, and rural environments. Sampling was conducted during summer (June to August 2019) and winter (December 2019 to February 2020), complemented by an earlier campaign at Athens Thissio (December 2018 to August 2019), yielding over 545 24-hour PM₂.₅ samples. Filters were analyzed for major and trace elements, water-soluble ions, organic carbon (OC), and elemental carbon (EC). Positive Matrix Factorization (PMF) was applied separately for each site using a harmonized protocol. Seven source categories were identified across the network: biomass burning (16.2 % to 50.9 %), heavy oil combustion (2.5 % to 15.1 %), industrial emissions (3.3 % to 14.4 %), mineral dust (4.8 % to 16.4 %), sea salt (1.6 % to 11.7 %), secondary sulfates and organics (7.1 % to 33.0 %), and vehicular traffic (9.7 % to 27.6 %). Campaign-average PM₂.₅ concentrations in Ioannina and Volos remained above 25 &mu;g m⁻&sup3;, pointing to severe air pollution burdens and a high risk of non-compliance with European standards. The high spatial and temporal variation in source contributions reveals that while regional background pollution strongly influences PM₂.₅ levels, localized anthropogenic activities, and particularly wintertime biomass burning for residential heating, remain a critical driver of urban air quality degradation in Greece.

 European Commission MIS 5021516 MIS 5002799