Combustion aerosols from mineral oil industrial fires: Physicochemical characterization and toxicity in bronchial epithelial cells at the air-liquid interface.

Industrial fires involving petroleum-based materials are episodic but can be major sources of atmospheric pollution, releasing complex combustion aerosols into the atmosphere, raising concerns about potential health effects for nearby populations and firefighters. However, the hazard assessment of such emissions remains challenging due to their chemical complexity. In this context, the aim of this study was to combine physico-chemical characterization, controlled aerosol exposure at the air-liquid interface, and biological responses to assess the hazards of combustion aerosols generated from mineral oils, with and without engine lubricant additives, following an industrial fire scenario. Comprehensive targeted and untargeted chemical analyses revealed shared polycyclic aromatic hydrocarbon (PAH) signatures alongside specific tracers found in aerosols generated from mineral oils containing additives, including sulfur-containing compounds previously detected in environmental samples following a fire event. Microphysical characterization showed that soot particles remained in the nanoscale range and exhibited distinct deposition efficiencies under air-liquid interface (ALI) exposure conditions. This enabled controlled exposure of bronchial epithelial cells (Beas-2B) to environmentally relevant concentrations observed during industrial fire events. Interestingly, aerosols generated from mineral oils containing additives induced lower cytotoxicity, which may be related to compositional differences, including the presence of antioxidant compounds. The relatively low intrinsic potential of the particulate fraction suggests that direct redox activity may not be the primary driver of toxicity. Instead, cytotoxicity effects may involve metabolic activation of organic compounds, such as PAH, or inflammatory signaling pathways. Overall, this study highlights the relevance of a multidisciplinary approach for better assessing the potential health hazards associated with industrial fire emissions.