Multilayer firefighter PPE as a reservoir for PAH contaminants after controlled pine-polystyrene smoke exposure

Combustion-derived polycyclic aromatic hydrocarbons (PAHs) are semi-volatile contaminants that remain on protective textiles after smoke exposure. In this study, a controlled laboratory method for smoke exposure was developed to assess the layer-specific accumulation and redistribution of PAHs in firefighter personal protective equipment (PPE). Multilayer assemblies comprising an outer shell (OS), a moisture barrier (MB), and a thermal liner (TL) were exposed to pine/polystyrene smoke generated in an atmosphere-controlled combustion chamber (50 kW m-2 heat flux, 20.95% O2, 35 min). Particle mass emissions were measured; soot-like deposits characterized by SEM and GC-MS were used to quantify EPA 16 PAHs. The mixed pine/polystyrene fuels produced substantially higher PAH loading than the biomass-only fuels. After a single exposure, the OS accumulated the highest total PAH mass, reaching 27.50 ± 0.47 μg/100 cm² (50/50 pine/PS), while repeated exposures (70/30 pine/PS) increased contamination across all layers, with the MB reaching 20.76 ± 0.36 μg/100 cm² and showing increased contributions from high-molecular-weight PAHs. After 7 days of storage, total PAHs decreased in the OS but increased in the inner layers (MB & TL), indicating redistribution of semi-volatile PAHs throughout the multilayer sample. Toxicity equivalent (TEQ) values were used as screening-level indicators of PAH hazard, not as direct estimates of exposure or health risk. Overall, these findings demonstrate that multilayer PPE is a dynamic reservoir for PAHs from combustion and a controlled standard for future studies on the persistence, transfer, and decontamination of PAHs.