Clean Heating Renovation Differentially Reduces Nitro-PAH and Nitrated Phenol Exposure: Implications from Real-World Personal Monitoring and NF-κB-Based Toxicological Assessment

Abstract

Nitrogen-containing organic compounds (NOCs) are key characteristic components in particulate matter (PM) from household solid fuel combustion, yet their personal exposure and class-dependent toxicity remain poorly characterized. We compared size-resolved personal exposure to particulate nitrated phenols (NPs) and nitro-PAHs (n-PAHs) among rural users of clean coal (CC), raw coal chunk (RCC), and biomass (BB), and evaluated representative compounds in A549 cells. Biomass users had the highest PM2.5-bound n-PAH exposure (up to 11.5-fold above clean coal), while NPs varied little across fuel groups (≤1.3-fold); CC and RCC users showed comparable PM2.5-bound NPs concentrations (64.0 ± 12.1 vs 57.4 ± 25.8 ng m–3, P = 0.545). n-PAHs exhibited greater cytotoxicity with lower IC50 values, whereas NPs produced stronger NF-κB activation by larger increases in p-IκB-α and COX-2 expression. Physicochemical descriptor analysis and molecular docking suggested that divergent biological responses may be partly attributable to differing hydrophobicity and protein interaction modes: hydrophobic contacts for n-PAHs, polar and hydrogen-bonding interactions for NPs. These results demonstrate clean heating transitions better mitigate n-PAH than NP exposure. NPs and n-PAHs differ substantially in cytotoxicity and NF-κB-mediated inflammation, providing a case study linking real-world personal exposure monitoring to molecular toxicology for health-risk-based prioritization of combustion-derived PM constituents.