Unveiling emerging polycyclic aromatic compounds in the urban atmospheric particulate matter

Despite the ubiquity and complexity of atmospheric polycyclic aromatic compounds (PACs), many of these compounds are largely unknown and lack sufficient toxicity data for comprehensive risk assessments. In this study, nontarget screening assisted by in-house and self-developed spectra databases was, therefore, employed to identify PACs in atmospheric particulate matter collected from multiple outdoor settings. Additionally, absorption, distribution, metabolism, excretion, and toxicity properties were evaluated to indicate PAC's overall abilities to cause adverse outcomes and incorporated into a novel health risk assessment model to assess their inhalation risks. Here, except for target PACs, 98 PAC analogues across eight categories were identified in the outdoor samples of atmospheric particulate matter. Their concentrations were source-specific and correlated to that of the total 16 priority polycyclic aromatic hydrocarbons (PAHs). Virtual high-throughput screening results suggested that metabolism disruption and endocrine disruption might be significant non-carcinogenic effects caused by the PACs. However, PAHs and oxygenated PAHs exhibited stronger overall abilities to induce non-carcinogenic adverse outcomes in human body when compared to the other PACs. Among PACs, total PAHs exhibited the highest carcinogenic and non-carcinogenic risks, while emerging PAHs accounted for 47% and 27% of total carcinogenic and non-carcinogenic risks, respectively. This study advances our understanding of the potential harmful effects of PACs and provides insights into mitigating the inhalation risks from complex PAC exposures based on classified risk levels. © 2025 The Author(s).