The Fire Hazards of Insulation Materials

Insulation materials are widespread in the modern built environment. They have, particularly in recent years, been a major focus of fire safety research. That focus has been enhanced by the tragic Grenfell Tower Fire that resulted in the death of 72 people. This work aims to understand and quantitatively assess the fire hazards presented by modern insulation materials. 14 materials were selected for analysis, including 7 PIR foams, 4 phenolic foams and 3 mineral wool materials. These materials were tested for their elemental composition, fire toxicity, and reaction-to-fire properties. The data generated was then used to calculate the maximum safe loadings of the insulation materials. The methodology had originally only been used with estimated values based on Euroclass data. In order to practically apply the method, the cone calorimeter was used to generate the mass loss per unit area data, rather than SBI test data or estimated values. Fire toxicity data was generated using the ISO/TS 19700 Steady State Tube Furnace. Additional maximum safe loading values were calculated using material-IC50 values, as incapacitation is arguably a more important end point in fire toxicity assessment. The maximum safe loading values calculated were comparable to the estimated values outlined in the original methodology. This methodology could be used to provide quick estimations of the safe loading of insulation materials in construction, allowing for informed decision making in building design without an overwhelming amount of data for non-fire experts to consider. The results of this work demonstrate significant differences between the 3 types of insulation material. The mineral wool materials (both glass wool and stone wool) were of low toxicity and flammability. The foam insulation materials (PIR and phenolic) produced high yields of toxic gases in under-ventilated conditions, and had relatively high flammability. The PIR foams, in particular, had the highest toxicity due to the high yields of HCN produced during under-ventilated flaming, which has been linked to their nitrogen content and chemical composition. The phenolic foams lacked the high yields of HCN due to their low nitrogen content, but still produced high quantities of asphyxiating CO, like the PIR foams. Both types of foam insulation also produced hydrogen chloride gas during combustion, which would have a strongly irritating effect on exposed persons, potentially hindering their escape. FED analysis has demonstrated that the PIR foams increased toxicity is largely the result of the high toxicity of HCN. 1 kg of any of the 7 PIR samples burning in under-ventilated conditions is capable of producing enough HCN to create a lethal atmosphere in 50 m3. The maximum safe loading values calculated showed that, on average, phenolic foams present ~50 to 100x higher fire hazard than the mineral wool materials, and the average PIR foam presented a potential fire hazard ~1.5 to 2.5x higher than the average phenolic foam. Additional work was performed to optimise a method for the quantification of HCN in fires – the chloramine-T/isonicotinic acid method from ISO 19701. HCN is a highly toxic product of the combustion of nitrogen containing materials. As such, it was important to ensure sampling and analysis was both accurate and reliable. Analysis was performed to understand sample and standard stability, optimal time to analysis, analytical variation, and potential interferences as a result of commonly encountered acid gases in fire effluent. The cone calorimeter and SBI apparatus were also assessed for their viability in fire toxicity assessment, potentially negating the need to use the ISO/TS 19700 Steady State Tube Furnace. However, the resulting data demonstrated that both tests are inadequate due to their inability to recreate the more toxic fire condition – under-ventilated burning. This emphasises the need for dedicated fire toxicity tests, as most fire tests are well-ventilated reaction-to-fire tests, despite the fact that fire toxicity results in at least 50% of UK fire deaths

Quantification of Hydrogen Cyanide in Fire Effluent

Hydrogen Cyanide (HCN) is often the most toxicologically significant component in fire effluents from nitrogen-containing materials. Unlike the other major asphyxiant, carbon monoxide, sensors for continuous HCN quantification, at and above dangerous concentrations, are not commercially available. This paper investigates the analysis of fire effluent captured in bubbler solutions, by colorimetric quantification of HCN using chloramine-T/isonicotinic acid. The bubbler samples were mixed with colorimetric reagents to give a blue dye in response to cyanide ions. A novel reaction scheme accounting for the formation of the blue dye from cyanide ions is presented. Dilute, standard cyanide solutions were found to be stable after storage for up to one year. Alkaline bubbler solutions, through which the fire effluent has passed, showed consistent cyanide concentrations, for samples stored between 5°C and 35°C, for up to 31 days after sampling. The effect of other common ions likely to be present in fire effluent solution samples (CO32-, SO32-, SO42-, NO2- and NO3-) was investigated for their potential interference. The most significant interference was sulphite which reduced the apparent cyanide concentration by 13% at 10 mg L-1 SO32- concentration

Burning behaviour of rainscreen façades

Four reduced-height (5 m) BS 8414-1 façade flammability tests were conducted, three having mineral-filled aluminium composite material (ACM-A2) with polyisocyanurate (PIR) and phenolic (PF) foam and stone wool (SW) insulation, the fourth having polyethylene-filled ACM (ACM-PE) with PIR insulation. Each façade was constructed from a commercial façade engineer’s design, and built by practising façade installers. The ACM-PE/PIR façade burnt so ferociously it was extinguished after 13.5 min, for safety. The three ACM-A2 cladding panels lost their structural integrity, and melted away from the test wall, whereupon around 40% of both the combustible PIR and PF insulation burnt and contributed to the fire spread. This demonstrates why all façade products must be non-combustible, not just the outer panels. For the three ACM-A2 tests, while the temperature in front of the cavity was independent of the insulation, the temperatures within it varied greatly, depending on the insulation. The system using PF/A2 allowed fire to break through to the cavity first, as seen by a sharp increase in temperature after 17 min. For PIR/A2, the temperature increased sharply at 22 minutes, as the panel started to fall away from the wall. For SW/A2, no rapid temperature rise was observed

Flame retardants in UK furniture increase smoke toxicity more than they reduce fire growth rate

This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuries, and the importance of upholstered furniture and bedding on fatalities from unwanted fires. The aim was to compare the fire hazards (fire growth and smoke toxicity) using different upholstery materials. Four compositions of sofa-bed were compared: three meeting UK Furniture Flammability Regulations (FFR), and one using materials without flame retardants intended for the mainland European market. Two of the UK sofa-beds relied on chemical flame retardants to meet the FFR, the third used natural materials and a technical weave in order to pass the test. Each composition was tested in the bench-scale cone calorimeter (ISO 5660) and burnt as a whole sofa-bed in a sofa configuration in a 3.4 × 2.25 × 2.4 m3 test room. All of the sofas were ignited with a No. 7 wood crib; the temperatures and yields of toxic products are reported. The sofa-beds containing flame retardants burnt somewhat more slowly than the non-flame retarded EU sofa-bed, but in doing so produced significantly greater quantities of the main fire toxicants, carbon monoxide and hydrogen cyanide. Assessment of the effluents' potential to incapacitate and kill is provided showing the two UK flame retardant sofa-beds to be the most dangerous, followed by the sofa-bed made with European materials. The UK sofa-bed made only from natural materials (Cottonsafe®) burnt very slowly and produced very low concentrations of toxic gases. Including fire toxicity in the FFR would reduce the chemical flame retardants and improve fire safety. [Abstract copyright: Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Fire behaviour of modern façade materials – Understanding the Grenfell Tower fire

The 2017 Grenfell Tower fire spread rapidly around the combustible façade system on the outside of the building, killing 72 people. We used a range of micro- and bench-scale methods to understand the fire behaviour of different types of façade product, including those used on the Tower, in order to explain the speed, ferocity and lethality of the fire. Compared to the least flammable panels, polyethylene-aluminium composites showed 55x greater peak heat release rates (pHRR) and 70x greater total heat release (THR), while widely-used high-pressure laminate panels showed 25x greater pHRR and 115x greater THR. Compared to the least combustible insulation products, polyisocyanurate foam showed 16x greater pHRR and 35x greater THR, while phenolic foam showed 9x greater pHRR and 48x greater THR. A few burning drips of polyethylene from the panelling are enough to ignite the foam insulation, providing a novel explanation for rapid flame-spread within the facade. Smoke from polyisocyanurates was 15x, and phenolics 5x more toxic than from mineral wool insulation. 1kg of burning polyisocyanurate insulation is sufficient to fill a 50m3 room with an incapacitating and ultimately lethal effluent. Simple, additive models are proposed, which provide the same rank order as BS8414 large-scale regulatory tests

Gene content evolution in the arthropods

Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods. Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception. These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity

A Picture of the Research Field of Doctoral Education from the Students’ Perspectives : Studies Using Questionnaires and Scales

Peer reviewe

Allele-Specific HLA Loss and Immune Escape in Lung Cancer Evolution

Immune evasion is a hallmark of cancer. Losing the ability to present neoantigens through human leukocyte antigen (HLA) loss may facilitate immune evasion. However, the polymorphic nature of the locus has precluded accurate HLA copy-number analysis. Here, we present loss of heterozygosity in human leukocyte antigen (LOHHLA), a computational tool to determine HLA allele-specific copy number from sequencing data. Using LOHHLA, we find that HLA LOH occurs in 40% of non-small-cell lung cancers (NSCLCs) and is associated with a high subclonal neoantigen burden, APOBEC-mediated mutagenesis, upregulation of cytolytic activity, and PD-L1 positivity. The focal nature of HLA LOH alterations, their subclonal frequencies, enrichment in metastatic sites, and occurrence as parallel events suggests that HLA LOH is an immune escape mechanism that is subject to strong microenvironmental selection pressures later in tumor evolution. Characterizing HLA LOH with LOHHLA refines neoantigen prediction and may have implications for our understanding of resistance mechanisms and immunotherapeutic approaches targeting neoantigens. Video Abstract [Figure presented] Development of the bioinformatics tool LOHHLA allows precise measurement of allele-specific HLA copy number, improves the accuracy in neoantigen prediction, and uncovers insights into how immune escape contributes to tumor evolution in non-small-cell lung cancer

BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes