Chemical compounds in PM10 as a tool for source apportionment

Volatile chemical products (VCPs) represent an emerging and under-recognised source of semi-volatile organic compounds in urban air, contributing to the chemical complexity and secondary formation potential of PM 10 . Despite growing awareness of their role in atmospheric chemistry and exposure, real-world data on VCP-derived species in ambient particles remain scarce. This study provides the first integrated characterisation of VCP-related compounds in PM 10 for Central Europe. PM 10 samples were collected from Ústí nad Labem, Zdiby, Mělník between November 2022 and April 2023 and analysed using TD-GC/MS. A total of 157 compounds were classified, 106 of which were uniquely associated with product emissions. VCP markers accounted for 0.59–2.11% of all identified organics, equivalent to 0.05–0.43 µg/m 3 . Among conventional sources, traffic and biomass burning dominated over coal, while biogenic markers were regionally variable. Plasticisers were pervasive: phthalate esters (PAEs) and non-phthalate plasticisers (NPPs) occurred at most sites. Given EU restrictions on cosmetic PAEs, their ambient levels (ΣPAE 18–54 ng/m 3 ) mainly reflect polymer and plastic emissions rather than personal-care sources. ΣNPP 6–14 ng/m 3 were ubiquitous but source-ambiguous; therefore, the ΣNPP/ΣPAE ratio is introduced as a new diagnostic indicator of phthalate substitution, revealing a clear regional gradient (Ústí 2.6>Mělník 1.1>Zdiby 0.3). Fragrance-related terpenes showed stronger product than biogenic signatures, and significant fragrance-PAE correlation (r=0.67) indicates functional coupling in emissions. Overall, concentrations were comparable to or below urban levels reported elsewhere, confirming that Central Europe is undergoing an early yet measurable chemical transition in PM 10 composition driven by consumer-product and polymer-related emissions. • Chemical compounds from VCPs contribute to 12% of PM 10 pollutants. • A total of 106 compounds derived from VCPs were identified in PM 10 particles. • VCP markers formed 0.6–2.1% of organics in Central European PM 10 • TD-GC/MS was used for the detailed identification of VCP-related pollutants in PM 10 . • Phthalates and non-phthalate plasticisers in PM 10 may pose a health risk.