Chemical components of electric vehicle and internal combustion engine vehicle fire smoke and their mutagenic effects.

Lithium-ion (Li-ion) batteries have become the primary power source for electric vehicles (EVs) around the world. However, this technology comes with important risks during EV fires if the batteries are damaged, improperly overcharged, or overheated, leading to intense heat and considerable amounts of smoke, which may have different properties than those from fires in internal combustion engine vehicles (ICEVs). Chemical components of smoke emissions from EV fires and their potential health risks are not fully understood. In this study, full-scale fire tests of six EVs and two ICEVs were conducted to simulate real-world fire scenarios. Respirable particulate matter (PM) in the smoke emissions was collected for chemical analyses and mutagenicity tests using the Ames assay. Results showed that the EV smoke PM contained more metals than the ICEV smoke samples, but the mass fractions of the PM varied depending on vehicle models. While Li, Mn, Co, and Ni were the predominant metals of the EV fire smoke emissions, Zn was a primary contributor to the total metal content of the ICEV fire smoke PM. In addition, fluoride was strongly enriched in the EV fire smoke samples. On an equal mass basis, most EV fire smoke PM induced more substantial mutagenic potencies compared to the ICEV fire smoke samples. These findings provide an initial understanding of the chemistry and potential health effects associated with EV fire smoke exposures and could inform protective strategies for emergency responders to EV fire events.