Lithium-ion battery fires present increasing safety engineering challenges, with U.S. incident rates rising 86% between 2020 and 2023, particularly in micromobility devices and urban environments. We analyzed 148 lithium-ion battery fire incidents documented through the Massachusetts State Fire Marshal’s specialized checklist program, employing logistic regression for charging-related risks, spatial clustering for geographic patterns, and time-series analysis for temporal trends. Consumer electronics showed significantly lower odds of charging-related fires (OR = 0.125–0.148, p < 0.05), while micromobility devices had the highest injury rate (IRR = 2.98, 95% CI: 0.837–10.615). Charging was involved in 40.5% of cases, and online purchases were associated with greater risk (OR = 1.87, 95% CI: 1.23–2.84, p = 0.003). Significant urban clustering was observed (Moran’s I = 0.28, p = 0.003) with three metropolitan hotspots. Device-specific risk profiles demonstrate the effectiveness of existing consumer electronics safety standards and highlight critical intervention points for emerging high-risk devices, particularly in dense urban areas where targeted protection strategies are most needed.

Using a cone calorimeter for small-scale tests as a radiant heat source, the influence of compacting fuel beds on their flammability and combustibility for three different types of dry vegetation (Pinus halepensis and Pinus pinaster needles, and Wheat straw sticks) was experimentally investigated for a wide range of compactness (the degree of densification of the fuel bed) from $$\:3$$ to $$\:50\:\%$$ . While the flaming duration increases monotonically with packing ratio (a quantitative measure of this compactness), ignition time shows at least one minimum value for the fuels studied. Using the mean free path of radiation as the controlling parameter instead of the packing ratio the range with minimum ignition time is significantly narrowed down to a few millimeters, which indicates the importance of radiation in the flammability process as expected for such a mainly radiative heating process. For Pinus halepensis needles, two minimum ignition times for values of packing ratio around 12.6% and 34% were identified both when the fuel bed thickness is varied or maintained constant. For low compactness, before ignition, the mass loss decreases linearly with time with a rate slightly affected by the packing ratio. After ignition, the flame spreads quickly to cover the entire fuel bed (fully developed flame) at the growth time. This marks the beginning of a sharp decrease in the mass corresponding to a sharp increase in the mass loss rate (MLR) towards a maximum value. For high compactness, the linear decrease of the mass still holds before ignition, followed by a long slightly non-linear trend corresponding to the slow flame spreading to cover the whole surface of the bed at the growth time (fully developed flame). This also marks the begining of a sharp mass decrease (MLR increase). The duration between ignition time and growth time is then very short for low compactness, and becomes very large for high compactness and corresponds to a plateau of MLR. The peak MLR is followed by a slow decrease until extinction (decay phase). To analyze the compactness induced combustion, the MLR curve was divided into two widths: the upper width is the Full Width at Half Maximum (FWHM), and the lower width is the duration ( $$\:{x}_{t}$$ ) between extinction time and growth time. The peak MLR, and the FWHM were found insensitive to the compactness (constant behavior within statistical errors for all compactness) whereas the $$\:{x}_{t}$$ was found to decrease for high compactness.

Lithium-ion battery (LiB) powered devices are in use every day and function as designed, however there have been reports of fatal fires involving LiB powered micro-mobility vehicles from around the globe. When a LiB fails and starts a fire, it is typically the result of the battery suffering thermal runaway. Failure of LIBs in micro-mobility vehicles has been shown to create a rapidly growing ignition source that is capable of igniting nearby combustible materials within the room of origin and forcing the room to flashover in less than a minute. The impact of such rapid-fire growth has been reported in the media around the world. This type of rapid-fire growth is almost unprecedented in residential buildings and calls into question: can residential sprinklers control such a rapidly developing fire? This study investigates the impact of such rapid-fire growth in a residential building with both full-scale bedroom and living room fires started from the thermal runaway of a LiB in a sit-on e-scooter. Results from this study quantify the impact of residential sprinklers and clearly show the effectiveness of residential fire sprinklers on fires resulting from thermal runaway of sit-on e-scooters.