Sources-attributed contributions to health risks associated with PM_2.5-bound polycyclic aromatic hydrocarbons during the warm and cold seasons in an urban area of Eastern Asia

Despite the well-established recognition of the health hazards posed by PM_2.5-bound PAHs, a comprehensive understanding of their source-specific impact has been lacking. In this study, the health risks associated with PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) and source-specific contributions were investigated in the urban region of Taipei during both cold and warm seasons. The levels of PM_2.5-bound PAHs and their potential health risks across different age groups of humans were also characterized. Diagnostic ratios and positive matrix factorization analysis were utilized to identify the sources of PM_2.5-bound PAHs. Moreover, potential source contribution function (PSCF), concentration-weighted trajectory (CWT) and source regional apportionment (SRA) analyses were employed to determine the potential source regions. Results showed that the total PAHs (TPAHs) concentrations ranged from 0.08 to 2.37 ng m^-3, with an average of 0.69 ± 0.53 ng m^-3. Vehicular emissions emerged as the primary contributor to PM_2.5-bound PAHs, constituting 39.8 % of the TPAHs concentration, followed by industrial emissions (37.6 %), biomass burning (13.8 %), and petroleum/oil volatilization (8.8 %). PSCF and CWT analyses revealed that industrial activities and shipping processes in northeast China, South China Sea, Yellow Sea, and East China Sea, contributed to the occurrence of PM_2.5-bound PAHs in Taipei. SRA identified central China as the primary regional contributor of ambient TPAHs in the cold season and Taiwan in the warm season, respectively. Evaluations of incremental lifetime cancer risk demonstrated the highest risk for adults, followed by children, seniors, and adolescents. The assessments of lifetime lung cancer risk showed that vehicular and industrial emissions were the main contributors to cancer risk induced by PM_2.5-bound PAHs. This research emphasizes the essential role of precisely identifying the origins of PM_2.5-bound PAHs to enhance our comprehension of the related human health hazards, thus providing valuable insights into the mitigation strategies.