Fire

Ammonia (NH₃) is a promising zero-carbon fuel to eliminate carbon footprint while the high autoignition temperature and low combustion rate of NH₃ remain challenging for practical implementation. Using dimethyl ether (DME) as pilot ignition fuel can substantially promote the reactivity of NH₃, thus paving the way for a widespread application of NH₃. In this study, the ignition process and nitrogen oxides (NO_x) emissions of the NH₃ liquid spray ignited by liquid DME spray were numerically investigated using Converge software. The ambient temperatures (T_amb) ranging from 900 K to 1100 K were used to mimic the in-cylinder temperature typically encountered in turbocharger engines. The effect of ammonia energy ratio (AER) and fuel injection timing was examined as well. It is found that only half of NH₃ is consumed at T_amb = 900 K while 97.4% of NH₃ is burned at T_amb = 1100 K. Nitric oxide (NO) and nitrogen dioxide (NO₂) formation also have strong correlation with T_amb and NO₂ is usually formed around the periphery of NO through these two channels HO₂ + NO = NO₂ + OH and NO + O(+M) = NO₂(+M). Extremely high nitrous oxide (N₂O, formed by NH + NO = H + N₂O) and carbon monoxide (CO) are produced with the presence of abundant unburned NH₃ at T_amb = 900 K. Additionally, increasing AER from 60% to 90% results in slightly declined combustion efficiency of NH₃ from 98.7% to 94%. NO emission has a non-monotonical relationship with AER owing to the ‘trade-off’ relationship between HNO concentration and radical pool at varying AERs. A higher AER of 95% leads to failed ignition of NH₃. Advancing DME injection not only increases combustion efficiency, but also reduces NO_x and CO emissions. Full article

Leadership is context-dependent in its influence on various employee attitudes and behaviors, particularly in high-risk environments. Despite this, few studies have explored the role of leadership in shaping safety-related outcomes within high-risk public sector settings. This study posits that leadership’s impact may differ in high-risk contexts such as firefighting, where safety is of utmost importance. Using survey data collected from firefighters in Gyeonggi-do, the largest province in South Korea, this study examines the relationship between transformational leadership, perceived accident likelihood, and three safety-related attitudes: safety motivation, safety compliance, and safety participation. With sample sizes for the three dependent variables ranging from 1502 to 1504, the ordinary least squares (OLS) regression results indicate that transformational leadership is positively associated with all three safety attitudes. However, perceived accident likelihood shows a positive relationship with only one of the safety-related attitudes: safety motivation. More importantly, perceived accident likelihood moderates the relationship between transformational leadership and safety attitudes; as perceived accident likelihood increases, the positive impact of transformational leadership on these attitudes diminishes. These findings underscore the contextual nature of leadership effectiveness in high-risk settings and highlight the importance of contextual factors in understanding leadership styles. Full article

Aircraft cargo compartment fires represent a major threat to aviation safety due to their rapid development, concealment, and the challenges associated with suppression in confined spaces. This study analyzes the 2019 A330 cargo compartment fire at Beijing Capital International Airport as a representative case. Based on flight crew statements, ECAM alerts, surveillance footage, and firefighting records, the event timeline was reconstructed and the emergency response process examined. The analysis identified four defining characteristics of cargo fires: rapid escalation, interacting hazards, restricted accessibility, and prolonged suppression duration. To address these challenges, a three-stage investigation framework—comprising timeline reconstruction, evidence analysis, and experimental verification—is proposed to systematically determine the causes of fires. In addition, a portable penetrating fire-suppression device was designed and experimentally validated. Results confirm its effectiveness in achieving rapid agent delivery, enhanced structural cooling, and prevention of re-ignition. The findings demonstrate that comprehensive cargo fire investigations require the integration of multi-source data and experimental validation, while tactical and equipment innovations are critical for improving suppression efficiency in confined environments. This research provides practical insights for optimizing cargo fire investigation methodologies and emergency response strategies, thereby contributing to the advancement of aviation safety management systems. Full article

Post-disaster support is critical for responders’ well-being who navigate the physical, mental, and emotional challenges of crisis intervention. The January 2025 Eaton Fire destroyed structures and disproportionately impacted Black and Latino neighborhoods. AltaMed deployed approximately 230 staff members to serve as frontline responders, providing medical and psychosocial support to evacuees at the Pasadena Convention Center. AltaMed frontline responders were invited to participate in a four-phase support initiative that included on-site peer-led debriefings, a needs and experiences survey, resilience-building workshops, and formal recognition of their contributions. A mixed-methods analysis was conducted on quantitative and qualitative survey data to assess well-being. Survey participants (n = 113) were highly motivated by community service, with 93% reporting a desire to contribute during crisis response. In addition, 53% identified the emotional impact as challenging, and 56% expressed interest in additional training. Peer support and reflection activities were cited as protective factors. Responders requested additional trauma-informed resources and infection prevention training. AltaMed’s support initiative successfully addressed the stressors of disaster response. Structured recognition, resilience-building, and professional development can promote long-term workforce well-being. These findings offer scalable strategies for Federally Qualified Health Centers and health systems supporting frontline workers during emergencies exacerbated by climate change and systemic disparities. Full article

In this study, we evaluate a phosphorus-based fire retardant (HR Prof) on Norway spruce using Simultaneous Thermal Analysis (STA: TG/DTG/DSC), Gas Chromatography–Mass Spectrometry (GC–MS), and bench-scale mass-loss measurements. Relative to the untreated reference, HR Prof re-routes decomposition toward earlier dehydration and transient char, simplifies the evolved gas mixture in the 150–250 °C range, and reduces burning intensity during 600 s of radiant exposure. Across 150/200/250 °C, identified components fell from 20/24/51 (reference) to 5/9/9 (HR Prof); no phosphorus-containing volatiles were detected in this window. Mass-loss tests showed a lower average burning rate (0.107 vs. 0.156%·s⁻¹) and a smaller cumulative loss at 600 s (64.2 ± 9.5% vs. 93.7 ± 2.1%; one-way ANOVA, p < 0.05 for percentage loss). STA was conducted in air; the transient char formed at an intermediate temperature is oxidized near ~600 °C, explaining the low final residue despite earlier charring. A count-based Poisson model corroborated the significant reduction in volatile component richness for HR Prof (p < 0.001). The cross-method correspondences—earlier condensed-phase dehydration/char → leaner volatile pool → lower and flatter burning-rate profiles—support a condensed-phase-dominated protection mechanism within the conditions studied. Full article

Vegetation fires are among the most common natural disasters, posing significant threats to people and the natural environment worldwide. Density-based clustering methods can be used to identify geospatial clustering patterns of fire points. It further helps reveal the spatial distribution characteristics of wildfires, which are crucial for regional-specific fire mapping, prediction, mitigation, and protection. DBSCAN (density-based spatial clustering of applications with noise) is widely used for clustering spatial objects. It needs two user-determined threshold values: the local radius and the minimum number of neighboring points for core points, which require user expertise and background information. This work proposes a dual-population genetic optimization to determine threshold values of DBSCAN for clustering vegetation fire points in western China. By constructing randomly generated threshold populations, optimized threshold values are obtained through crossover, mutation, and inter-population exchange, measured by multiple clustering metrics. Focusing on vegetation wildfires in western China during 2016–2022, the results reveal that vegetation wildfires can be divided into eight regions, each exhibiting distinct spatiotemporal patterns and geographic contexts. Full article

In order to improve the fluidity, pumpability, and strength of separation-layer grouting fire-protecting filling material and reliability with multiple parameters and factors in traditional orthogonal tests, the coupling theory of the response surface-satisfaction function is applied to optimize the ratio of separation-layer grouting fire-protecting filling material. Cement content, the ash–gangue ratio, slurry concentration, and admixture were selected as the influencing factors for the ratio optimization of separation-layer grouting fire-protecting filling material and slump, with the bleeding rate and compressive strength selected as the evaluation indexes of material properties. The Box–Behnken experimental design method was applied to conduct 25 groups of experiments with different material ratios, and the response surface functions of various material performance evaluation indexes were constructed. The relationship between the influencing factors of fire protecting and filling material ratios and the target responsiveness was studied, as well as the optimal ratio of separation-layer grouting fire-protecting filling materials under multi-objective conditions. The results show that the influence of the slurry concentration and cement content on the degree of collapse is significant. The cement content and slurry concentration had significant influence on the compressive strength. The ash–gangue ratio has a significant impact on bleeding rate. Meanwhile, the interaction of the ash–gangue ratio, slurry concentration, and cement content also has a significant impact on the bleeding rate. For waste rock cementation abscission-layer grouting fire protecting and filling material, the optimal ratio is an ash and gangue ratio of 1:2, the cement content is 12.12%, the admixture is 1.49%, and the slurry concentration is 52%. The ratio of the corresponding response under the condition of prediction result is a slurry slump of 28.5 cm, bleeding rate of 2.36%, and filling body strength of 4.62 MPa, which basically coincide with the experimental results and verification and provide evidence for the abscission layer grouting field industrial test. Full article

This study investigates post-fire vegetation transitions and spectral responses in the Snowstorm Fire (2017) and South Sugarloaf Fire (2018) in Nevada using Landsat 8 Operational Land Imager (OLI) surface reflectance imagery and unsupervised ISODATA classification. By comparing pre-fire and post-fire conditions, we have assessed changes in vegetation composition, spectral signatures, and the emergence of novel land cover types. The results revealed widespread conversion of shrubland and conifer-dominated systems to herbaceous cover with significant reductions in near-infrared reflectance and elevated shortwave infrared responses, indicative of vegetation loss and surface alteration. In the South Sugarloaf Fire, three new spectral classes emerged post-fire, representing ash-dominated, charred, and sparsely vegetated conditions. A similar new class emerged in Snowstorm, highlighting the spatial heterogeneity of fire effects. Class stability analysis confirmed low persistence of shrub and conifer types, with grassland and herbaceous classes showing dominant post-fire expansion. The findings highlight the ecological consequences of high-severity fire in sagebrush ecosystems, including reduced resilience, increased invasion risk, and type conversion. Unsupervised classification and spectral signature analysis proved effective for capturing post-fire landscape change and can support more accurate, site-specific post-fire assessment and restoration planning. Full article

Building-Integrated Photovoltaics (BIPV), which are used for building exteriors such as walls, roofs, balconies, and awnings, play a significant role in reducing greenhouse gas emissions. However, since the back sheet, sealant, junction box, and cable of BIPV modules are made of flammable plastic materials, fire protection technologies are needed to ensure fire safety. The aim of this work is to evaluate the fire safety performance of BIPV modules coated with fire-resistant (FRs) and flame-retardant (FRt) materials. The test results show that the performance of the FRs coating was excellent in terms of fire blocking, physical properties, and durability, compared to the FRt coating. Surface damage, such as cracks and blisters, was observed on the FRt coating during the impact and acid resistance tests, whereas the FRs coating demonstrated superior durability without any defects. Specifically, aluminum hydroxide (ATH, 5–10 wt%) added to the FRs coating promoted an endothermic reaction that lowered the flame temperature, released H₂O, and stably formed an Al₂O₃ heat-shielding layer. Due to this reaction, the suppression of the fire spread by the BIPV modules was the best compared to that of Mg, Ti, and Si-based additives. Full article

This study investigates the minimum ignition temperature of smoldering paper scraps with varying bulk densities and lengths under different external airflow rates. Paper scraps of different lengths were compressed to modify the bulk density within the smoldering fuel bed. The ignition tests were performed using a rod-heater with a controlled temperature range of 340–460 °C. Once the rod-heater reached the preset temperature, the current was turned off, and the rod-heater was inserted into the center of the vertically oriented combustion chamber filled with paper scraps. By recording the temperature variations at different locations within the combustion chamber, the ignition limits of smoldering paper scraps with varying bulk densities under different external airflow rates were determined. The results showed that in the absence of external airflow and with a fixed paper scrap length, the ignition limit of smoldering paper scrap exhibits a clear U-shaped trend as bulk density increases. Furthermore, we found that in the absence of external airflow, the length of paper scraps had no significant effect on the ignition limit in the low bulk density range. However, in the high bulk density range, the ignition limit increased with scrap length. As for cases with external air flows, the ignition limit of paper scrap smoldering combustion once again exhibits a U-shaped trend with varying bulk density. Compared with the condition without forced airflow, however, the inflection point of the U-shaped curve shifts toward the higher-density region. Moreover, within the range of externally forced airflow rates examined in the present study, the length of paper scraps had no significant effect on the smoldering ignition limit. Full article

In this study, thermogravimetric analysis (TGA) was coupled with Fourier-transform infrared (FTIR) spectroscopy to systematically investigate the pyrolysis characteristics and mechanisms of cement fiberboard across varying heating rates. Experimental findings demonstrated that the thermal degradation process occurs in four distinct phases. Overlapping decomposition peaks in DTG curves were successfully resolved using a double-Gaussian deconvolution algorithm. A comprehensive kinetic analysis was conducted by integrating model-free iso-conversional methods (Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose analysis) with a model-fitting technique (Coats–Redfern approximation) to determine the activation energies for each degradation stage. A subsequent FTIR spectroscopic analysis revealed that the evolution of gaseous products follows the sequence CO₂ > H₂O > CH₄. The CO₂ release was found to originate from multiple pathways, including the decomposition of organic components and high-temperature inorganic reactions. Notably, while the heating rate had a negligible impact on product speciation, it exhibited a statistically significant influence on CO₂ emission intensities. Finally, mechanistic interpretations integrating Arrhenius parameters with time-resolved infrared spectral features were proposed for each thermal decomposition stage. Full article

The present study investigates the influence of atomizing air-to-liquid mass ratio (ALR) on the near-field spray characteristics and stability of a novel twin-fluid injector that integrates bubble-bursting for primary atomization and shear-induced secondary atomization. Unlike conventional injectors, the novel design generates ultra-fine sprays at the exit with low sensitivity to liquid properties. The previous version improved secondary atomization even for highly viscous liquids, showing strong potential in hydrogel-based fire suppression. The current design improves primary atomization, leading to more stable and finer sprays. The near-field spray characteristics are quantified using a high-speed shadowgraph across ALRs ranging from 1.25 to 2.00. This study found that stable and finely atomized sprays are produced across all the tested ALRs. Increasing ALR reduces droplet size, while the spray is the widest at 1.25. Sauter Mean Diameter (SMD) contours show larger droplets at the edges and smaller ones toward the center, with ALR 2.00 yielding the most uniform size distribution. As per the atomization efficiency, ALR of 1.25 shows the best performance. Overall, an optimum ALR of 1.75 is identified, offering balanced droplet size distribution, stability, and atomization efficiency, making the injector potentially suitable for fire suppression and liquid-fueled gas turbines requiring high stability and fuel flexibility. Full article

Pyrolysis of 24 samples of foliage from three U.S. regions with frequent wildland fires (Southeastern U.S., northern Utah and Southern California) was studied in a fuel-rich flat-flame burner system at 765 °C (for Southeastern U.S. samples) and 725 °C (for northern Utah and Southern California species), with a heating rate of approximately 180 °C/s. These conditions were selected to mimic the conditions of wildland fires. Individual plant samples were introduced to the high temperature zone in a flat-flame burner and pyrolysis products were collected. Tar was extracted and later analyzed by GC/MS. Light gases were collected and analyzed by GC/TCD. The estimated range for the average yields of tar and light gases were 48 to 62 wt% and 18 to 31 wt%, respectively. Apart from Eastwood’s manzanita (Arctostaphylos glandulosa Eastw.), aromatics were the major constituents of tar. The variations in the concentrations of tar compounds likely resulted from differences in biomass composition and physical characteristics of the foliage. The four major components of light gases from pyrolysis (wt% basis) were CO, CO₂, CH₄ and H₂. Tar contributed more than 82% of the high heating value of volatiles. These data can be used to improve physical-based fire propagation models. Full article

Fires remain a critical threat to the resilience and safety of the built environment, yet current research is often fragmented across building types, technologies, and functions. This study investigates typology-specific gaps in fire safety by conducting a scientometric review of peer-reviewed articles published between 2010 and 2025. Following a PRISMA-guided protocol, a total of 83 studies indexed in the Web of Science were systematically screened and analyzed using VOSviewer (v1.6.19) and the R-based Bibliometrix package (version 4.2.1). The dataset was classified according to building typologies, fire safety functions—detection, suppression, and evacuation—and applied technologies such as BIM, simulation platforms, and AI-based models. The results show a strong research bias toward evacuation modeling in high-rise and general-purpose buildings, while critical typologies including healthcare facilities, heritage structures, and informal settlements remain underexplored. Suppression systems and real-time detection technologies are rarely integrated, and technological applications are often fragmented rather than interoperable. A conceptual matrix is proposed to align tools with typology-specific risk profiles, highlighting mismatches between research priorities and building functions. These findings emphasize the need for integrated, data-driven, and context-sensitive fire safety strategies that bridge methodological innovation with practical application, offering a roadmap for advancing resilient and adaptive fire safety in diverse urban settings. Full article

State-of-the-art historical global burned area (BA) products largely rely on MODIS data, offering long temporal coverage but limited spatial resolution. As a result, small fires and complex landscapes remain underrepresented in global fire history reconstructions. By contrast, Landsat provides the only continuous satellite record extending back to the 1980s, with substantially finer resolution. However, its use at a global scale has long been hindered by infrequent revisit times, cloud contamination, massive data volumes, and processing demands. We compared MODIS FireCCI51 with the only existing Landsat-based global product, GABAM, in a mountainous region characterized by frequent, small-scale fires. GABAM detected a higher number of burn scars, including small events, with higher Producer’s Accuracy (0.68 vs. 0.08) and similar User’s Accuracy (0.85 vs. 0.83). These results emphasize the value of Landsat for reconstructing past fire regimes in complex landscapes. Crucially, recent advances in cloud computing, data cubes, and processing pipelines now remove many of the former barriers to exploiting the Landsat archive globally. A more systematic integration of Landsat data into MODIS-based routines may help produce more complete and accurate databases of historical fire activity, ultimately enabling improved understanding of long-term global fire dynamics. Full article

This study develops an explainable machine learning framework for wildfire prediction across Australia, integrating region-specific models and feature attribution to identify key environmental drivers. Three wildfire indicators, Estimated Fire Area (FA), Mean Fire Brightness Temperature (FBT), and Fire Radiative Power (FRP), were modeled using Lasso, Random Forest, LightGBM, and XGBoost. Performance metrics (RMSEC, RMSECV, RMSEP) confirmed strong calibration and generalization, with Tasmania and Queensland achieving the lowest prediction errors for FA and FRP, respectively. Feature importance and SHAP analyses revealed that soil moisture, solar radiation, precipitation, and humidity variability are dominant predictors. Extremes and variance-based measures proved more influential than mean climatic values, indicating that fire dynamics respond non-linearly to environmental fluctuations. Lasso models captured stable linear dependencies in arid regions, while ensemble models effectively represented complex interactions in tropical climates. The results highlight a hierarchical process where cumulative soil and radiation stress establish fire potential, and short-term meteorological variability drives ignition and spread. Projected climate shifts, declining soil water and increased radiative load, are likely to intensify these drivers. The framework supports interpretable, region-specific mitigation planning and paves the way for incorporating generative AI and multi-source data fusion to enhance real-time wildfire forecasting. Full article

This paper presents a validated computational workflow for simulating the fire-induced collapse of steel moment-resisting frames, comparing static general and dynamic explicit analysis procedures. Whereas most existing studies employ dynamic explicit analysis for collapse validation, this work evaluates the capability of the static general approach as a viable alternative. Finite element models developed with beam and shell elements capture both global instability and local failure modes. The results show that the static general procedure effectively reproduces quasi-static post-buckling behaviour and predicts the critical failure temperature within 2–3% of experimental results, similar to the dynamic explicit method. For the dynamic explicit procedure, sensitivity analyses are conducted to optimise time scaling, mesh refining, and ensure realistic physical response while maintaining computational efficiency. The study demonstrates that, along with dynamic explicit analysis, static general procedure also offers a practical and reliable alternative for simulating fire-induced structural collapse, reducing computational time by up to eighteen times for beam models and around six times for shell models, while maintaining reliable accuracy. Full article

Rigid polyurethane foams (RPUFs) are essential polymeric materials, prized for their low density, high mechanical strength, and superior thermal insulation, making them indispensable in construction, refrigeration, and transportation. Despite these advantages, their highly porous, carbon-rich structure renders them intrinsically flammable, promoting rapid flame spread, intense heat release, and the generation of toxic smoke. Traditional strategies to reduce flammability have primarily focused on incorporating additive or reactive flame retardants into the foam matrix, which can effectively suppress combustion but often compromise mechanical integrity, suffer from migration or compatibility issues, and involve complex synthesis routes. Despite recent progress, the long-term stability, scalability, and durability of surface flame-retardant coatings for RPUFs remain underexplored, limiting their practical application in industrial environments. Recent advances have emphasized the development of surface-engineered flame-retardant coatings, including intumescent systems, inorganic–organic hybrids, bio-inspired materials, and nanostructured composites. These coatings form protective interfaces that inhibit ignition, restrict heat and mass transfer, promote char formation, and suppress smoke without altering the intrinsic properties of RPUFs. Emerging deposition methods, such as layer-by-layer assembly, spray coating, ultraviolet (UV) curing, and brush application, enable precise control over thickness, uniformity, and adhesion, enhancing durability and multifunctionality. Integrating bio-based and hybrid approaches further offers environmentally friendly and sustainable solutions. Collectively, these developments demonstrate the potential of surface-engineered coatings to achieve high-efficiency flame retardancy while preserving thermal and mechanical performance, providing a pathway for safe, multifunctional, and industrially viable RPUFs. Full article

Firefighters wear bunker gear for protection against thermal hazards during firefighting. Bunker gear are fabricated from superior-performance fibers and enhanced by chemical flame retardants to increase fire resistance. However, brominated flame retardants (BFRs), which are widely used, have been associated with health and environmental toxicity risks. Despite the concerns, toxic BFRs continue to find application in consumer products, including in firefighter bunker gear. This study investigated the possibility of volatilization of BFRs from firefighter bunker gear during thermal exposure. Five different bunker gear samples were subjected to 3–8 kW/m² thermal conditions in a cone calorimeter, and polyurethane foam disks were used to capture the volatilizing effluents. The samples were analyzed for brominated diphenyl ether (BDE) congeners (-28, -47, -99, -100, -154, and -209) using gas chromatography–mass spectrometry. BDE-28, -47, and -99 were detected in all five samples, with concentrations ranging from 0.02 to 0.1 ng/g, 0.03 to 0.34 ng/g and 0.18 to 0.86 ng/g, respectively. BDE-100 and -154 were detected in 80% and -209 was below the limit of detection. BDE-99 was the most abundant congener detected, followed by BDE-47. The results confirm the volatilization of BFRs from bunker gear during firefighting, which can expose firefighters to toxic flame retardants. Full article