Fire Safety Design

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.

This paper examines firefighter exposure to emissions during actual firefighting in building scenarios. The focus is on actual exposure, not small-scale lab tests, to identify research gaps in light of the International Agency for Research on Cancer (IARC) classification of firefighting as an occupation with a heightened risk for certain types of cancer. The work is based on a systematic literature review of all literature published up to 2025, including only studies that measured both emissions and firefighter exposures during actual structure fires. Of the 6860 articles identified from various databases and sources, 76 articles correspond to the inclusion criteria for this review, following a rigorous screening process. Our findings show that, although substantial research has been conducted over the past few decades, the majority of the studies were concentrated in the United States. Fewer studies were identified from Australia, Canada, and select European countries, while no studies identified originated from Africa. Female (women) firefighters were either entirely excluded or represented less than 10% of study cohorts. These findings underscore critical gaps in both geographic and demographic representation in the existing body of research. Additionally, firefighter exposure during overhaul operations and to ultra fine particles in fire emissions remain largely understudied.

Wood’s flammability, low dimensional stability, and poor fungal resistance limit its application. In this study, Scots pine sapwood ( Pinus sylvestris L .) was treated with a low-molecular-weight phenol–formaldehyde (PF) resin and a monoguanidine phosphate flame retardant (FR) to achieve multifunctional enhancement. Differential scanning calorimetry confirmed no interference of FR with PF curing, while SEM and cell wall bulking analysis demonstrated effective penetration. The treatment improved the modulus of elasticity and rupture, though impact bending strength slightly decreased. Fungal decay resistance reached durability class 1 (EN 350, 2016) based on white- and brown-rot tests (EN 113–2, 2021). Dynamic vapor sorption showed no increase in equilibrium moisture content below 70 % RH. Artificial and natural weathering tests confirmed good FR retention and weathering resistance. Thermogravimetric analysis showed enhanced thermal stability, with higher char residue than FR-only treatments. Cone calorimetry verified sustained flame retardancy even after weathering. This combined treatment offers a durable, multifunctional wood modification approach suitable for structural and outdoor applications. • PF resin and monoguanidine phosphate salt effectively penetrate wood cell walls. • Enhanced mechanical properties, fungal resistance (DC 1), and dimensional stability. • Maintained durability and strong flame retardancy under artificial and natural weathering.

An experimental study of smoke propagation from an apartment to an escape route corridor in a real-scale residential building is presented in this paper. The experiments were performed using the same experimental setup but with different ventilation and apartment door opening times. The setup consisted of a fire in a two-seater sofa in an apartment connected to a corridor and other apartments. A total of four scenarios are presented in this paper. The baseline scenario examines the smoke propagation from the apartment to the corridor during a ventilation-limited fire with a closed façade and door between the apartment and corridor opening after 5 min. In the other scenarios, the effect of closing the door, smoke permeability and ventilation openings in the façade are investigated. The results show the impact of ventilation and door opening time on the conditions in the corridor. Closing the door of the apartment has a significant impact on decreasing smoke propagation, for example carbon monoxide concentrations in the corridor are 15–26 times lower than the baseline scenario. Ventilation openings have less impact, for example carbon monoxide concentrations are 2.6–3.7 times lower than the baseline scenario when additional ventilation openings are used. Overall, the results demonstrate the reliability of the design and provide insights into smoke propagation in real-scale residential buildings.

Bracing systems in steel structures are crucial for providing stability and resistance against lateral forces such as wind and earthquakes. However, when steel structures are exposed to fire, the bracing systems can also play an important role in maintaining the structural integrity of the building. Under fire conditions, steel members may lose strength due to heating, which can lead to collapse if not properly braced. In this article the effect of different X-braces cross-section in a steel warehouse under fire is analyzed and discussed using a non-linear thermomechanical model. Three fire scenarios have been considered: standard ISO834 fire, wood fire and plastic fire to investigate the influence of different temperature time history curves on the thermomechanical behavior of the structure. It has been found that an increase in the stiffness of the braces leads to a corresponding increase in the stiffness of the frame modifying its structural behavior; furthermore, since the compressed braces reach their buckling load in the initial minutes of a fire, the structure must redistribute its loads accordingly.

Abstract In order to design an Oxygen Reduction System (ORS) the most important parameter is the limiting oxygen concentration (LOC). Currently there are a couple of different small scale test methods used to determine the LOC for specific materials. In small scale tests an external heat flux is applied, to account for parameters such as geometry that otherwise cannot be replicated, theoretically arriving at a sufficiently low LOC. Other methods have tried to take heat transfer and geometry into consideration to better replicate real world conditions. However, there are some discussions into the validity to some of these existing methods. To replicate real world conditions a large scale setup was designed and used to determine LOC for certain warehouse configurations. This large scale setup is costly to run and therefore there is a need to investigate the possibility of creating an intermediate scale setup that has the ability to make flame propagation assessments for varying fuels, geometries and ignition sources. In this paper a first attempt for an intermediate scale setup is examined, and preliminary findings are discussed.

If the people understand the imaging engineering principle of how electron microscope technologies develop its pictures of viral infections and interpret those images accordingly to the atomic physics level, they will avoid using the current multi-billion unlimited forms and shapes receptor puzzle theory to interpret and betting on the current Covid-19 pandemic technical issues. It’s time for the biomedical, virology and related professions to apply bio-Electron/Proton Magnetic Field (bio-EMF) atomic physics to redefine the meaning of viral infection into two specific stages. Scientifically further exploring the phenomenon of antigens and antibodies in more detail to understand the current mRNA vaccine technologies and to determine the ultimate origin of the airborne Covid-19 coated with human bio-EMF molecules, predict its virulence behaviors.

SummaryThis study experimentally investigates the radiation heat flux distribution received on the floor due to fire plume impinging upon an inclined ceiling, which has not been quantified previously. The radiation heat fluxes were measured on the floor for 160 experimental conditions, involving various fire source heat release rates, source‐ceiling heights, angles of ceiling inclination and dimensions (aspect ratios) of the rectangular sources. The main findings include that the declining rate of the radiation heat flux along with distance received by the downstream floor decreases, while that received by the upstream floor increases, with the increasing of ceiling inclination angle. The radiation heat flux received by the floor is higher as the ceiling inclination angle is smaller for the downstream side, while it is lower as the ceiling inclination angle is smaller for the upstream side. Both of these variations can be explained by change of the flow distribution as well as flame length due to combustion and heat released in the two directions beneath the inclined ceiling. Further, a model with various fire source heat release rates, source‐ceiling height, and ceiling inclination angles is proposed, to globally describe the radiation heat flux received by both the upstream and downstream floors.

SummaryNine participants, representing eight different Swedish fire consultancy firms participated in a Round Robin study where two different cases were simulated with the Fire Dynamics Simulator. The first case included a large open warehouse where the activation of a sprinkler system was to be studied. In the second case time to critical conditions in a theatre was to be calculated. The participants were given clear instructions on the building layout and heat release rate for the two cases. Still, the results demonstrate a significant variation in time to sprinkler system activation (range of 110 seconds) and available safe escape time (range of 60 seconds), between the participants. It is important to emphasise that some degree of variation is unavoidable, as engineers can model things differently without the modelling solution necessarily being incorrect. Even though it is hard to isolate and specific cause of the variation, some of the variation seen in this study is related to modelling choices that are questionable and consequently problematic for the reliability of the fire safety design.

The distance of sprinklers below ceiling is of fundamental importance since it has a great influence on activation time. Accepted distances are specified in different sprinkler standards such as NFPA 13, FM 2-0 and EN 12845 for different configurations. This distance is unambiguously defined for flat smooth ceilings, but for corrugated ceilings, such as corrugated metal deck ceilings found in many warehouses, the distance can be measured from either the top or the bottom of the deck. NFPA 13 states that it should be measured from the bottom if the thickness of the deck is below 75 mm and from the top if it is higher. The requirement in NFPA 13 has been adopted from the FM datasheets, but the authors have been unable to identify any background to this requirement.In this paper, the activation time of sprinkler heads at different distances below a corrugated ceiling with thickness of 125 mm was simulated using FDS 6.6.0 and compared to distances below a flat smooth ceiling. The case was based on a warehouse with 6-tier storage of Uncartoned Expanded Plastics (UEP) with a ceiling height of 11.2 m and clearance to storage of 2.6 meters. Only the activation of the first sprinkler was simulated since it was expected that the drag from droplets of previously activated sprinkler heads would thicken the ceiling jet, making the activation time of additional sprinkler less sensitive to the distance from ceiling.The results show that the corrugated ceiling has a large influence on the ceiling jet allowing sprinklers further from the ceiling to activate.In the case studied, the activation time of sprinklers below the corrugated ceiling more closely resembled those under a flat smooth ceiling when the distance below the corrugated ceiling was measured from the bottom of the deck. More simulations and experiments are however needed before any guidance on changes in sprinkler standards can be given.