Pulmonary Toxicity of Particulate-Phase Combustion Byproducts from Lithium-Ion Battery Fires

The frequency of lithium-ion battery (LIB) fires is increasing globally, creating new challenges for firefighters and growing public safety concerns from smoke and intense heat. However, the health effects from exposure to LIB fires are not well understood. We collected soot and smoke particulate matter (PM) from LIB thermal runaway events (10 and 2 fire tests for soot and PM samples, respectively), filtered them to remove non-inhalable particles (>10 μm), analyzed for chemical composition and assessed for lung toxicity and pulmonary function in mice at 4 h and 24 h post exposure to 100 μg of the sample. Chemical and biological results were analyzed using a computational approach to identify hazardous chemical components that were potentially responsible for toxicity outcomes. Computational findings were further compared to those produced by other sources of air pollution. The soot sample contained more carbon species than the smoke PM sample (37% vs. 18%), whereas anions were higher in the PM sample (12% vs. 6%), and concentrations of inorganic elements were similar (23% vs. 28%). Fluoride particulate was found to account for up to 5% of the mass of each sample. Only soot significantly increased ventilatory timing and peak expiratory flow in mice and decreased relaxation time, while both samples caused significant increases in inflammatory responses. Soot and PM exhibited similar lung inflammatory outcomes relative to those caused by previously reported combustion-related air pollution sources. Computational analysis indicated that fluoride, Al, Fe, Ni, and Li from both samples were significantly associated with the lung toxicity responses (p < 0.05). The findings indicate that LIB fire soot and PM that contain hazardous metals and fluoride elicit pulmonary toxicity responses comparable to other sources of air pollution, increasing the need for awareness of potential strategies to mitigate public health impacts.