Fire Smoke Research Articles

A new strategy for constructing ZIF-67@PBA core-shell 3D cross-heterostructures for improving fire safety of TPU at ultra-low addition amount

Thermoplastic polyurethane (TPU) has an extensive application in many different industries. However, serious fire hazards and smoke toxicity have been the main reason limiting its wide application. Therefore, it is necessary and urgent to perform flame retardant and smoke suppression treatment for TPU. In recent years, metal-organic framework compounds (MOFs) have very promising application prospects in the fields of flame-retardant polymer composites. However, there is a problem of low flame-retardant efficiency for the original MOFs alone in polymer composites. It is reported the multi-level and multi-structured flame-retardant system has better flame-retardant efficiency than the traditional structures. So, the dual MOF core-shell heterostructure may have more effective heat reduction and smoke suppression than any single component. In this paper, a core-shell 3D cross-heterostructures nanohybrid (ZIF-67H@PBA) was prepared using ZIF-67H as the host MOF and Prussian blue nanocubes (PBA) as the guest MOF. It has been found that TPU/ZIF-67H@PBA composites with ultra-low additions have excellent fire safety. Compared with those of pure TPU, the peak heat release rate (PHRR), total smoke release (TSP), and smoke factor (SF) of the samples with 0.5wt% ZIF-67H@PBA were reduced by 33.6 %, 47 %, and 61 %, respectively. At the same time, a cone calorimeter (CCT), a homemade soot sampling device and a gas chromatography-mass spectrometry (GC–MS) coupling with each other were constructed and used to demonstrate the most realistic effects of flame retardants in terms of smoke suppression and toxicity reduction. This work provides a new strategy to design TPU flame retardants.

Evidence for Wildland Fire Smoke Transport of Microbes From Terrestrial Sources to the Atmosphere and Back

AbstractSmoke from wildland fires contains more diverse, viable microbes than typical ambient air, yet little is known about the sources and sinks of smoke‐borne microorganisms. Data from molecular‐based surveys suggest that smoke‐borne microorganisms originate from material associated with the vegetation and underlying soils that becomes aerosolized during combustion, however, the sources of microbes in smoke have not yet been experimentally assessed. To elucidate this link, we studied high‐intensity forest fires in the Fishlake National Forest, Utah, USA and applied source‐sink modeling to assemblages of 16S ribosomal RNA (rRNA) gene sequences recovered from samples of smoke, vegetation, and soil. Our results suggest that 70% of the bacterial taxa in smoke originated from the local aspen (Populus tremuloides) (33%) and soil (37%) communities. In comparison, 42% of bacteria in air sampled prior to the fires could be attributed to these terrestrial sources. When the bacterial assemblages in smoke were modeled as sources to the local communities, they contributed an average of 25% to the terrestrial sinks versus an estimated contribution of <4% from ambient air. Our results provide support for the role of wildland fire in bacterial dispersal and the working hypothesis that smoke is an environmental reservoir of microbes for receiving ecosystems.

Simulation on passenger evacuation of metro train fire in the tunnel

The metro tunnel space is relatively closed, it is difficult to rescue after the metro train fire accident, which causes heavy casualties and property losses. Studying the safe evacuation of passengers under fire smoke spread has important significance. The numerical simulation methods are used to analyze the reliability of passenger evacuation in metro train fire scenarios. Firstly, the required safety evacuation time (RSET) calculation methods in short-distance and long-distance tunnels are developed combining the pre-action time and train response time. Then, a passenger evacuation model in metro trains is established in Pathfinder software to simulate the evacuation process under different passenger loads, carriage layouts, evacuation strategies, and train locations. The simulation results show that the RSET is affected by passenger load, seat arrangement, evacuation strategies and train locaitons. The critical point calculation method effectively finds out the critical point of the train location, which guides emergency evacuation strategies in fire scenarios.

Multi-Objective Real-Time Planning of Evacuation Routes for Underground Mine Fires

When a fire occurs underground, pre-existing emergency escape routes may become ineffective. Such scenarios necessitate the real-time planning of escape routes that consider evolving conditions and prioritize safety. This paper proposes a multi-objective real-time search method for emergency escape routes using dynamic programming to address these challenges. Firstly, this paper discusses how the evacuation of an underground mine fire caused by external factors depends on the fire monitoring system, personnel positioning system, and emergency evacuation system, as well as the modeling and solution methods of evacuation route planning. Then, based on fire smoke, CO, and temperature sensor data from the mine ventilation network structure and monitoring system, the possible smoke spread in the event of an underground fire was calculated. The objectives are to optimize both the shortest equivalent length of the path and the shortest time to walk through the smoke flow while ensuring that temporary escape time does not exceed the rated protection time of the self-rescuer. A mathematical model for emergency escape route planning is established under these conditions. A labeling algorithm based on dynamic programming is employed to find the Pareto optimal solution set of emergency evacuation routes that meet emergency requirements. Finally, two path evaluation indicators, namely “escape target priority” and “personnel temporary escape time”, are introduced to re-rank the solutions in the Pareto optimal set, thereby obtaining disaster evacuation routes with different priorities. Example verification shows that the algorithm can quickly solve the disaster evacuation routes that meet the actual disaster evacuation needs in complex networks. Example verification shows that the algorithm can quickly solve the emergency escape routes in complex networks that meet actual emergency escape needs.

SmokeFireNet: A Lightweight Network for Joint Detection of Forest Fire and Smoke

In recent years, forest fires have been occurring frequently around the globe, affected by extreme weather and dry climate, causing serious economic losses and environmental pollution. In this context, timely detection of forest fire smoke is crucial for realizing real-time early warning of fires. However, fire and smoke from forest fires can spread to cover large areas and may affect distant areas. In this paper, a lightweight joint forest fire and smoke detection network, SmokeFireNet, is proposed, which employs ShuffleNetV2 as the backbone for efficient feature extraction, effectively addressing the computational efficiency challenges of traditional methods. To integrate multi-scale information and enhance the semantic feature extraction capability, a feature pyramid network (FPN) and path aggregation network (PAN) are introduced in this paper. In addition, the FPN network is optimized by a lightweight DySample upsampling operator. The model also incorporates efficient channel attention (ECA), which can pay more attention to the detection of forest fires and smoke regions while suppressing irrelevant features. Finally, by embedding the receptive field block (RFB), the model further improves its ability to understand contextual information and capture detailed features of fire and smoke, thus improving the overall detection accuracy. The experimental results show that SmokeFireNet is better than other mainstream target detection algorithms in terms of average APall of 86.2%, FPS of 114, and GFLOPs of 8.4, and provides effective technical support for forest fire prevention work in terms of average precision, frame rate, and computational complexity. In the future, the SmokeFireNet model is expected to play a greater role in the field of forest fire prevention and make a greater contribution to the protection of forest resources and the ecological environment.

Experimental Study on Early Fire Smoke Characteristics in a High-Volume Space: A Fire Detection Perspective

Experimental Study on Early Fire Smoke Characteristics in a High-Volume Space: A Fire Detection Perspective

Study on the variation law of smoke layer thickness with ceiling structure height in long-narrow space with one end opening

The ceiling structure in a long-narrow space has a significant impact on the thickness of the fire smoke layer. This paper mainly studies the influence of the height of the ceiling structure on the thickness of the smoke layer before the ceiling structure. Firstly, a theoretical analysis is conducted on the relationship between the critical thickness that affects the smoke flow state and the smoke layer thickness directly below the ceiling structure, and a formula for calculating the smoke layer thickness under gradient flow conditions is derived. Then a small-scale experimental platform was built to study the deviation of actual fire smoke relative to theoretical calculations. Experimental results show that due to the smoke cannot maintain gradient flow when crossing the ceiling structure, there is difference with theoretical calculations in the smoke layer thickness directly below the ceiling structure and some distance before the ceiling structure (which may be of greater concern for personnel evacuation). The gradient flow coefficient and thickness coefficient are defined to represent the above differences. After analysis, it was found that the gradient flow coefficient and thickness coefficient showed different linear variation patterns when the height of the ceiling structure was longer than 35 cm or shorter than 30 cm. Through numerical analysis, this study suggests that the main reason for the change in this linear pattern is whether the potential energy conversed from kinetic energy of the thin layer close to the ceiling structure can directly make the smoke to cross the ceiling structure. The research conclusions of this paper can assist in the engineering design of building smoke control and personnel evacuation.

Ventilation heterogeneity is increased in adults exposed to coal mine fire-related PM2.5.

The Hazelwood Health Study was set up to study long-term health effects of a mine fire that blanketed residents of the Latrobe Valley with smoke for 45 days in 2014. The Respiratory Stream specifically assessed the impact of fine particulate matter <2.5 μm diameter (PM2.5) exposure from mine fire smoke on lung health. The multiple breath nitrogen washout (MBW) test assesses ventilation heterogeneity, which may detect sub-clinical airways dysfunction not identified using standard tests such as spirometry. This analysis assessed the association of PM2.5 exposure with measures of ventilation heterogeneity. Exposed (Morwell) and unexposed (Sale) participants were recruited 3.5-4 years after the fire from those who had participated in an Adult Survey. MBW was performed to measure lung clearance index (LCI), functional residual capacity (FRC), acinar (Sacin) and conductive (Scond) ventilation heterogeneity. PM2.5 exposure was estimated with emission and chemical transport models. Multivariable linear regression models were fitted controlling for confounders. We recruited 519 participants. MBW tests were conducted on 504 participants with 479 acceptable test results (40% male; 313 exposed, 166 unexposed). Exposure to mine fire-related PM2.5 was associated with increasing Scond (β = 1.57/kL, 95%CI: 0.20-2.95, p = 0.025), which was comparable to the estimated effect on Scond of 4.7 years of aging. No other MBW outcomes were statistically different. Increasing exposure to PM2.5 was associated with increased ventilation heterogeneity in the conductive region of the lungs 4 years after the event.

Wildfire-smoke-precipitation interactions in Siberia: Insights from a regional model study

Powerful wildfires occurring in Siberia each summer emit large amounts of smoke aerosol that, according to studies of the environmental impacts of biomass burning (BB) aerosol in different regions of the world, can affect precipitation and other weather parameters and induce feedback on fires. However, the knowledge of smoke-weather interactions and fire-weather feedback in Siberia is presently limited. To advance this knowledge, we performed coupled-meteorology-chemistry simulations of aerosols and weather in a Siberian region covering taiga and tundra using the CHIMERE chemistry-transport model and the WRF meteorological model. We addressed a monthly period of July 2016 and considered several modeling scenarios in which aerosol-radiation interaction (ARI) and aerosol-cloud interaction (ACI) were taken into account jointly or separately. The simulation results were combined with emission and precipitation data retrieved from satellite observations. The joint analysis of the simulated precipitation fields and satellite-observation-based data revealed that in the taiga, the inhibiting effect of Siberian smoke on precipitation induced a significant positive feedback on BB aerosol emissions that, according to our estimates, enhanced by 27 (±7) % respective to a hypothetical situation in which smoke-weather interactions were absent. At the same time, an increase of precipitation over active fire spots due to ACI and ARI in tundra led to the formation of a negative feedback loop between fire emissions and BB smoke, resulting in a reduction of BB aerosol emissions there by 14 (±6) %. Hence, this study revealed evidence for significant feedback of smoke-induced precipitation changes on fire emissions in Siberia. Given the global importance of Siberia as a major carbon sink, this feedback needs to be studied further and accurately taken into account in projections of climate change both on regional and global scales.

Pregnancy Exposure to PM2.5 from Wildland Fire Smoke and Preterm Birth in California

Pregnancy Exposure to PM2.5 from Wildland Fire Smoke and Preterm Birth in California

The Use of Fire Dynamics System (NIST) in Determining The Architecture of Educational Spaces for Children and Young People

Objective: This study aims to investigate the potential of the Fire Dynamics Simulator (FDS) software, developed by the National Institute of Standards and Technology (NIST), as a tool to assess and improve Fire Safety (FS) in educational environments, specifically in the classrooms of CEFET in Araxá (MG), Brazil. Theoretical Framework: The research is based on the importance of fire safety in educational environments, highlighting the vulnerability of children and young people. Concepts of fire behavior, smoke propagation, and thermal conditions in buildings are addressed. Method: The methodology adopted for this research involves detailed computer simulations using FDS to analyze different fire scenarios. The simulation results were validated with the PyroSim software. Data collection was conducted through these simulations, generating robust empirical data that support the review and development of specific regulations. Results and Discussion: The results indicate that FDS is an important ally in promoting fire safety in educational buildings. The simulations showed the effectiveness of FDS in predicting fire behavior, smoke propagation, and thermal conditions, helping to prevent and minimize potential damages. The discussion contextualizes these results, highlighting the need for accurate empirical data to strengthen Brazilian fire safety legislation. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the results can be applied to positively influence legislation, optimize architectural designs, and promote safety guidelines in educational institutions in Brazil. Originality/Value: This study significantly contributes to the advancement of knowledge and practices in FS. The originality of the research lies in the application of FDS for simulations in educational environments, offering a robust tool for evaluating and improving fire safety.

The Camp fire and perinatal health: An example of the generalized synthetic control method to identify susceptible windows of exposure.

The November 2018 Camp fire was the most destructive wildfire in California history, but its effects on reproductive health are not known. We linked California birth records from 2017-2019 to daily smoke levels using U.S. EPA Air Quality System (AQS) PM2.5 data and NOAA Hazard Mapping System smoke plume polygons during the Camp fire. In the main analysis, pregnancies were considered exposed if they had median AQS PM2.5 levels above 50 μg/m3 for at least 7 days during November 8-22, 2018. We calculated rates of preterm birth and the infant sex ratio based on week of conception and used the generalized synthetic control method to estimate the average treatment effect on the treated and to propose a novel approach to identify potential critical weeks of exposure during pregnancy. We found associations between Camp fire-related smoke exposure and rates of preterm birth, with a risk difference (RD) = 0.005, 95% CI 0.001, 0.010. Exposure during week 10 of pregnancy was consistently associated with increased preterm birth (RD = 0.030, 95% CI 0.004, 0.056). We did not observe differences in the infant sex ratio. Camp fire smoke exposure was associated with increased rates of preterm birth, with sensitive windows in the first trimester.

RELATIVE IMPORTANCE INDEX OF LEADING INDICATORS FIRE PROTECTION SYSTEMS IN HIGHER EDUCATION BUILDINGS IN KOTA BANDA ACEH

Fire can cause material loss and also cause physical disabilities and even fatalities for building users. Fires that occur as a result of human activity must be overcome by increasing human awareness themselves. However, fires caused by natural factors or errors in the electrical system can be overcome by having a fire prevention system or safety system. The aim of the research is to identify the main indicators of fire protection systems in educational buildings in Banda Aceh City. A closed questionnaire and Likert scale survey of respondents using educational buildings was conducted to collect data. Next, the data is processed using the frequency index analysis method and the Relative Importance Index (RII). The results of the frequency index analysis provide an overview of the percentage level of occurrence of the fire protection system variable, namely the acid detector, at 91.294%. Based on the results of the RII analysis, five main indicators were found that influence the safety system, namely light fire extinguishers (0.929), smoke detectors (0.913), water transmitters (0.911), standpipes (0.894), and fire hydrant systems (0.892). Meanwhile, the main variable for the fire protection system is the active protection system with a RII value of 0.889.

Flame retardant and smoke suppression properties of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide derivative/zinc molybdate sepiolite modified acrylate emulsion

AbstractAcrylate emulsion is widely used in various industrial fields and is an important polymer emulsion. However, the high flammability limits its application. Besides, acrylate emulsion generally releases a large amount of smoke during combustion. To improve the fire resistance and smoke suppression properties of acrylate emulsions, methyl methacrylate‐butyl acrylate copolymer P(MMA‐BA)/DOPO‐based polymerizable monomer (HEPO)/zinc molybdate sepiolite (Mo‐Sep) composite emulsion was prepared by emulsion polymerization, and the effect of Mo‐Sep content on the flame‐retardant performance, thermal stability, and smoke suppression performance of the composite emulsion was studied. Through microcalorimeter and smoke density meter tests, it was found that the heat release rate (HRR) of the composite emulsion, added with 30% HEPO/3% Mo‐Sep, was reduced by 63.3%, and the peak heat release rate (PHRR) was reduced by 72.1%. The total heat release (THR) is reduced by 49.0%, while the peak‐specific optical density is reduced by 48.0%. It shows that the composite emulsion has excellent flame‐retardant and smoke suppression properties compared to pure MAA‐BA emulsion. In addition, scanning electron microscope (SEM) images show that the addition of Mo‐Sep increases the density of carbon residue. This composite emulsion may have potential application scenarios in the field of flame‐retardant coatings.

Study on Fire Smoke Movement Characteristics and Their Impact on Personal Evacuation in Curved Highway Tunnels

In the existing research on tunnel fires, researchers primarily focus on straight tunnels, neglecting the impact of curved sidewalls in curved tunnels. Based on the theory of smoke diffusion, a series of CFD numerical simulations was conducted using the Fire Dynamics Simulator to investigate the characteristics of smoke distribution in a curved highway tunnel. The results indicated that distinct smoke distribution characteristics were observed when a fire occurred in a curved tunnel compared with those observed in straight tunnels, with significant differences particularly evident for the radius of curvature of the tunnel below 1000 m. By comparing the smoke distribution characteristics from various fire source locations, the most unfavorable fire source locations within a curved tunnel were determined. High-temperature fire smoke bounds between the inner and outer walls of the tunnel, leading to the formation of multiple high-temperature zones in proximity to the fire source, rather than diffusing directly towards the exit in a linear tunnel. Additionally, based on an analysis of temperature, visibility, and CO concentration at characteristic heights, suitable locations for pedestrian crossings within the tunnel were deduced and an evacuation strategy for persons within the core fire area was proposed. The results can provide a reference for personal evacuation strategies in curved highway tunnel fire scenarios and the design of an adit for people passing in such tunnels.

Estimating spatially varying health effects of wildland fire smoke using mobile health data

Abstract Wildland fire smoke exposures are an increasing threat to public health, highlighting the need for studying the effects of protective behaviours on reducing health outcomes. Emerging smartphone applications provide unprecedented opportunities to deliver health risk communication messages to a large number of individuals in real-time and subsequently study the effectiveness, but also pose methodological challenges. Smoke Sense, a citizen science project, provides an interactive smartphone app platform for participants to engage with information about air quality, and ways to record their own health symptoms and actions taken to reduce smoke exposure. We propose a doubly robust estimator of the structural nested mean model that accounts for spatially and time-varying effects via a local estimating equation approach with geographical kernel weighting. Moreover, our analytical framework also handles informative missingness by inverse probability weighting of estimating functions. We evaluate the method using extensive simulation studies and apply it to Smoke Sense data to increase the knowledge base about the relationship between health preventive measures and health-related outcomes. Our results show that the protective behaviours’ effects vary over space and time and find that protective behaviours have more significant effects on reducing health symptoms in the Southwest than the Northwest region of the U.S.

Climate-adaptive fire smoke ventilation strategies for atrium-type metro stations: A NSGA-II multi-objective optimisation study

This study explores the impact of climate variability on the operation of sustainable ventilation systems in urban infrastructure, with a focus on smoke movement in metro stations under varied external climatic conditions. Smoke characteristics and ventilation strategies in an atrium-type metro station are investigated using numerical simulations. The simulations reveal the influence of external climate on smoke movement through the atrium and roof windows, with particular attention to outdoor temperature and wind velocity. The study designs different ventilation strategies for smoke control that incorporate meteorological data, evaluating smoke visibility, CO distribution, and smoke extraction efficiency. The findings indicate that under severe external climates of low temperatures and high wind velocities, smoke extraction from roof window outlets is challenging. The adverse effects of external climate decrease the natural smoke extraction efficiency, increase the CO concentration, and reduce the safe visibility area. However, improved ventilation measures, such as the platform make-up air system and roof mechanical extraction system, can significantly enhance smoke control performance and facilitate safe evacuation. The study also employs the NSGA-II multi-objective optimisation method to obtain optimal ventilation strategies for different climates, balancing three optimisation objectives of operating energy consumption, safe visibility area, and smoke extraction efficiency. The outcomes show that the recommended values of Vp are 20%–30 % (0 °C ≤ To≤40 °C) and 40 % (−40 °C ≤ To<0 °C), vr are 0.3 (10 °C ≤ To≤40 °C) and 0.4 (−40 °C ≤ To < −10 °C), and Vc are all lower than 4 %. As wind velocity increases, the recommended values need to be enhanced. This research contributes to sustainable urban development by offering a framework for managing public safety and energy efficiency in the context of climate variability.

Large-scale experimental study on the average temperature distribution model of fire smoke under mechanical ventilation in the flat space

Mechanical ventilation is essential to ensure the safety of persons, equipment, and structures in cruise ship fire incidents. The mass loss rate, smoke temperature, and comprehensive heat transfer coefficient during large-scale fire experiments are researched in cruise ship flat space. The results indicate that the mass loss rate of four pool fires with different sizes presents different rules in mechanical ventilation conditions compared with open conditions. In addition, the vertical distribution of temperature appears to be stratification, which aligns with the “dual-zone model”. The horizontal distribution of the temperature has a “mutation point”. With the mutation point as the boundary, the temperature drops rapidly from the fire source to the mutation point and decreases more slowly. Furthermore, the distribution model of comprehensive heat transfer coefficient and average temperature are established. The comprehensive heat transfer coefficient is in direct proportion to the 1.00 power of heat release rate and inversely in proportion to the 0.69 power of the number of mechanical ventilation. However, the average temperature is in direct proportion to the 0.52 power of heat release rate and inversely in proportion to the 1.40 power of the number of mechanical ventilation.

Imaging sensor band comparison for situational awareness in wildfires

In recent decades, wildfires have become increasingly widespread and hazardous. Dryer, hotter weather combined with more frequent heat waves leave forest areas susceptible to sudden, intense, and fast-growing forest fires. To protect private property and mitigate the damage, Hotshot firefighters are deployed into these dangerous situations. Extensive satellite and aerial platforms possess optical techniques for monitoring wildfire risks and boundary tracking. Small unmanned aerial system (sUAS)-based EO/IR systems provide a solution for real-time, high resolution, targeted response to acquire information critical to the safety and efficacy of wildfire mitigation. Real-time imagery from a sUAS of the position of Hotshots and the progression of the fire boundary would be easily obtained and offer a method of ensuring safe deployment. An ideal sensor system for situational awareness in this environment would be able to image the ambient terrain and firefighters with good contrast while also detecting fire signatures and imaging through the smoke. Longer wavelength infrared bands have demonstrated imaging through the smoke of forest fires. However, near the wildfire where the Hotshots work, they also receive strong radiometric signals from the temperature of the smoke. The emitted signal of the smoke can obscure the line of sight similarly to the scattering effect of wildfire smoke in the visible spectrum. The reflective and emissive components of a wildfire scene are studied and compared in the visible (VIS, 0.4–0.7 µm), shortwave infrared (SWIR, 1.0–1.7 µm), extended SWIR (eSWIR, 2.0–2.5 µm), and longwave infrared (LWIR, 8–14 µm). Both a radiometric model and calibrated field measurements find a band that has the highest, to our knowledge, probability for a continuous line of sight for terrain, firefighters, and fire signatures in a wildfire scene.

Eco-Friendly Tourmaline@MOF Lignocellulose Aerogel with Favorable Fire Retardancy and Smoke Suppression for Insulation Materials

Eco-Friendly Tourmaline@MOF Lignocellulose Aerogel with Favorable Fire Retardancy and Smoke Suppression for Insulation Materials