Short- and medium-chain polychlorinated alkanes in PM_2.5 in Athens, Greece: Source apportionment and risk assessment

Existing literature provides scarce information on polychlorinated alkanes (PCAs) in PM_2.5 atmospheric particulate fraction, with limited data on medium-chain PCAs homologues (PCAs-C_14-17), absence of European measurement, and methodological inconsistencies that complicate inter-study comparison. This study aims to fill these gaps by (i) measuring short-chain PCAs (PCAs-C_10-13) and PCAs-C_14-17 in PM_2.5 in Athens city, Greece, (ii) evaluating seasonal patterns and links with meteorological parameters, (iii) investigating the contribution of possible emission sources using diagnostic ratios and Positive Matrix Factorization (PMF), and (iv) estimating the potential health risk via inhalation to different population groups. PM_2.5 samples from two campaigns were analyzed using UPLC-ESI-FT-ICR-MS, partly compared with GC-MS/MS. The concentrations of ΣPCAs-C_10-13 and ΣPCAs-C_14-17 ranged 0.17-8.14 ng m^-3 and 1.42-26.73 ng m^-3, respectively. Significant seasonal variation was observed for PCAs-C_10-13, whereas PCAs-C_14-17 remained relatively constant. The predominant of short-chain PCAs were C₁₀ in warm and C₁₁ in cold season, while C₁₄ dominated medium-chain PCAs in both seasons. ΣPCAs-C_10-13 showed a moderate positive correlation with temperature and a negative correlation with relative humidity. Diagnostic ratios and PMF pointed to a mixture of local and long-range atmospheric transport sources, as well as contribution from road dust resuspension. Finally, low health risk due to exposure to PCAs via inhalation was estimated for adults and children. These results provide first European data for short- and medium-chain PCAs in PM_2.5, and improve the evidence base for monitoring and policy implementation.