Smoke Toxicity Research Articles

Flame‐retarded rigid polyurethane foam conferred by an amino trimethylphosphonate iron and expandable graphite compound flame retardant

AbstractFlame‐retarded rigid polyurethane foam (RPUF) conferred by an amino trimethylphosphonate iron (Fe2+‐ATMP) and expandable graphite (EG) compound flame retardant has been successfully fabricated by one‐step all‐water foaming method. The combustion characteristics of the RPUFs and the synergistic effect of Fe2+‐ATMP and EG on RPUF have been studied based on limiting oxygen index (LOI), smoke toxicity analysis, cone calorimeter (CONE), thermogravimetric (TG) analysis and thermal decomposition kinetics analysis. The current results indicated that the flame retardancy and thermal stability of the RPUFs modified by Fe2+‐ATMP and EG had been improved obviously and the contents of smoke toxic gases had been significantly reduced. When the ratio of Fe2+‐ATMP to EG was 1:5, LOI of the modified RPUF was the highest (27.1%). And its peak heat release rate (PHRR) and total heat release (THR) were the lowest, which were 135 kW/m2 and 15.7 MJ/m2, respectively, and were 40.5% and 17.8% lower than RPUF‐0. It also showed that the modified RPUF with a Fe2+‐ATMP to EG ratio of 1:5 had the best flame retardancy, smoke suppression, and thermal stability. The present work can provide some reference and guidance for flame retardant modification of polyurethane foam.

Core-Shell ZIF67@ZIF8 Modified with Phytic Acid as an Effective Flame Retardant for Improving the Fire Safety of Epoxy Resins.

Despite many important industrial applications, epoxy resin (EP) suffers from high flammability and toxicity emission, extremely hampering their applications. To circumvent the problem, core–shell structured ZIF67@ZIF8 is successfully synthesized and further functionalized with phytic acid (PA) to obtain PA-ZIF67@ZIF8 hybrids. Then, it is used as an efficient flame retardant to reduce the fire risk of EP. The fire test results show a significant reduction in heat and smoke production. Compared with EP, incorporating 5.0 wt % PA-ZIF67@ZIF8 into EP, the peak heat release rate, total heat release, and peak carbon monoxide production are dramatically reduced by 42.2, 33.0, and 41.5%, respectively. Moreover, the EP/PA-ZIF67@ZIF8 composites achieve the UL-94 V-0 rating and the limiting oxygen index increases by 29.3%. These superior fire safety properties are mainly attributed to the excellent dispersion and the catalytic effect of metal oxide and phosphorus-containing compounds. This work provides an efficient strategy for preparing a promising ZIF-based flame retardant for enhancing flame retardancy and smoke toxicity suppression of EP.

Fire Behaviour of Insulation Panels Commonly Used in High-Rise Buildings

The energy efficiency of buildings drives the replacement of traditional construction materials with lightweight insulating materials. However, energy-efficient but combustible insulation might contribute to the building’s fire load. Therefore, it is necessary to analyse the reaction-to-fire properties of various insulating materials to provide a better understanding of designing a fire-safe structure. In this study, reaction-to-fire tests were carried out to assess the fire behaviour of lightweight polystyrene insulating panels commonly employed in high-rise buildings. The flammability characteristics of expanded polystyrene (EPS) and extruded polystyrene (XPS) were determined using a cone calorimeter under two distinct external irradiance regimes, 35 kW/m2 and 50 kW/m2, to approximate small to medium fire exposure situations. To investigate the effect of a fire-rated (FR) foil layer on a sandwich panel, three distinct test configurations were used: (i) sample without FR layer (standard sample), (ii) sample with FR layer (FR foil), and (iii) damaged layer (foil and vent) for EPS. Except for the smoke toxicity index (STI), the overall fire performance of EPS is superior to that of XPS. The findings of this study are useful in analysing fire performance and fire safety design for lightweight insulation panels.

Breath Carbon Monoxide Levels in Different Forms of Smoking

Bidi, cigarette, hookah and chillum are common modes of tobacco smoking in India. Many people consider hookah and chillum smoking less toxic because smoke is filtered through water or wet cloth. We evaluated the toxicity of tobacco smoking by measuring end-tidal carbon monoxide (eCO) levels after various modes of smoking. Eighteen healthy smokers who smoked bidi, cigarette, hookah and chillum on six days were studied. They smoked one bidi, one cigarette, five minutes hookah, one serve (15 minutes) hookah, five minutes chillum and one serve (15 minutes) chillum on six days randomly. The eCO values were measured before initiation of smoking and for a period of one hour after the smoking session. Increase in eCO values in comparison to baseline after different modes of smoking was compared. In comparison to baseline, mean eCO levels were raised by 4.94 (0.96) parts per million (ppm) immediately and 4.17 (1.07) ppm 60 minutes after cigarette smoking. Bidi smoking caused slightly less increase in mean eCO levels (3.17 [0.82]). One serve of hookah and chillum smoking caused elevation of mean eCO values by almost eight-folds higher than that of cigarette smoking. Five minutes of smoking with hookah (22.18 [5.29]) and one serve of hookah (33.0 [8.76]) and chillum (40.14 [12.73]) caused significantly higher values of mean increase in eCO in comparison to cigarette smoking (p<0.001). With regard to eCO levels, hookah and chillum smoking are much more toxic than cigarette smoking.

Assessment of inhalation toxicity of cigarette smoke and aerosols from flavor mixtures: 5-week study in A/J mice.

Most flavors used in e‐liquids are generally recognized as safe for oral consumption, but their potential effects when inhaled are not well characterized. In vivo inhalation studies of flavor ingredients in e‐liquids are scarce. A structure‐based grouping approach was used to select 38 flavor group representatives (FGR) on the basis of known and in silico‐predicted toxicological data. These FGRs were combined to create prototype e‐liquid formulations and tested against cigarette smoke (CS) in a 5‐week inhalation study.Female A/J mice were whole‐body exposed for 6 h/day, 5 days/week, for 5 weeks to air, mainstream CS, or aerosols from (1) test formulations containing propylene glycol (PG), vegetable glycerol (VG), nicotine (N; 2% w/w), and flavor (F) mixtures at low (4.6% w/w), medium (9.3% w/w), or high (18.6% w/w) concentration or (2) base formulation (PG/VG/N). Male A/J mice were exposed to air, PG/VG/N, or PG/VG/N/F‐high under the same exposure regimen. There were no significant mortality or in‐life clinical findings in the treatment groups, with only transient weight loss during the early exposure adaptation period. While exposure to flavor aerosols did not cause notable lung inflammation, it caused only minimal adaptive changes in the larynx and nasal epithelia. In contrast, exposure to CS resulted in lung inflammation and moderate‐to‐severe changes in the epithelia of the nose, larynx, and trachea. In summary, the study evaluates an approach for assessing the inhalation toxicity potential of flavor mixtures, thereby informing the selection of flavor exposure concentrations (up to 18.6%) for a future chronic inhalation study.

A review of the characteristic properties of selected tobacco chemicals and their associated etiological risks.

Despite the quantum of research findings on tobacco epidemic, a review on the formation characteristics of nicotine, aldehydes and phenols, and their associated etiological risks is still limited in literature. Accordingly, knowledge on the chemical properties and free radical formation during tobacco burning is an important subject towards unravelling the relationship between smoking behaviour and disease. This review investigates how scientific efforts have been advanced towards understanding the release of molecular products from the thermal degradation of tobacco, and harm reduction strategies among cigarette smokers in general. The mechanistic characteristics of nicotine and selected aldehydes are critically examined in this review. For the purpose of this work, articles published during the period 2004-2021 and archived in PubMed, Google Scholar, Medley, Cochrane, and Web of Science were used. The articles were selected based on the health impacts of cigarette smoking, tobacco burning kinetics, tobacco cessation and tobacco as a precursor for emerging diseases such as Covid-19. The toxicity of cigarette smoke is directly correlated with its chemical composition derived from the pyrolysis of tobacco stem and leaves. Most of the harmful toxic substances are generated by pyrolysis during smoking and depends on pyrolysis conditions. Detailed studies have been conducted on the kinetics of nicotine by use of robust theoretical models in order to determine the rate constants of reactions in nicotine and those of nicotine dissociation via C-C and C-N scission, yielding pyridinyl and methyl radicals, respectively. Research has suggested that acetaldehyde enhances the effect of nicotine, which in turn reinforces addiction characteristics whereas acrolein and crotonaldehyde are ciliatoxic, and can inhibit lung clearance. On the other hand, phenol affects liver enzymes, lungs, kidneys, and the cardiovascular system while m-cresol attacks the nervous system. The characteristics of chemical release during tobacco burning are very important in the tobacco industry and the cigarette smoking community. Understanding individual chemical formation from cigarette smoking will provide the necessary information needed to formulate sound tobacco reform policies from a chemical standpoint. Nonetheless, intense research is needed in this field in order to prescribe possible measures to deter cigarette smoking addiction and ameliorate the grave miseries bedevilling the tobacco smoking community.

Synergistic effect of combining amino trimethylphosphonate calcium and expandable graphite on flame retardant and thermal stability of rigid polyurethane foam

Amino trimethylphosphonate calcium (Ca-ATMP) has been synthesized and applied to rigid polyurethane foam (RPUF). Synergistic effect of Ca-ATMP and expandable graphite (EG) on flame retardant and thermal stability of RPUFs has been investigated by using the limiting oxygen index (LOI) method, smoke toxicity analysis, Cone calorimeter analysis (CONE), and thermogravimetric analysis (TGA). The experimental results indicated that LOI of the RPUF was 26.3% when the ratio of Ca-ATMP and EG was 1:5. And the peak heat release rate (PHRR) of this proportion of RPUF decreased by 52.4% compared with that of RPUF without flame retardant. In addition, this modified RPUF possessed the maximum apparent activation energy (E) and produced the least toxic gas. On the basis the above data, it can be found that the synergistic effect of Ca-ATMP and EG on flame retardant and thermal stability of RPUFs has the most significant effect when the addition amount of Ca-ATMP and EG is 1:5, which is helpful for improving flame retardation of the RPUF.

The influence of poorly-/well-dispersed organo-montmorillonite on interfacial compatibility, fire retardancy and smoke suppression of polypropylene/intumescent flame retardant composite system

A novel linear polymeric charring agent (PEPAPC) was synthesized via the nucleophilic substitution reaction, and then embedded into polypropylene (PP) substrate to improve the fire retardancy and anti-dripping performance. Unfortunately, the opposite polarity between intumescent flame retardant (IFR) and polymer-matrix could seriously deteriorate the interfacial compatibility, harmful to the flame-retardant efficiency and smoke toxicity suppression of PP/IFR composites. For the foregoing reasons, flame retardant PP/IFR/Organo-montmorillonite (OMMT) nanocomposites with the combination of maleic anhydride-grafted PP as compatibilizer have been prepared via melt intercalation technique. When 2 wt% well-dispersed OMMT were incorporated, it showed a significant reduction in peak heat release rate and total heat release (90.5 and 62.7%) compared with pristine PP, and an achievement in limiting oxygen index value of 32% from 18.5% for pristine PP, which can be attributed to the nano-barrier and catalytic carbonization effect of well-dispersed OMMT within the polymer-matrix. More importantly, the well-dispersed OMMT displays significant smoke toxicity suppression, toughening and strengthening effect on PP/IFR system. The peak CO release and total smoke production for PP-6 were decreased by 89.8 and 64.7%, respectively. This work may provide an effective approach towards fabricating high-performance polymeric materials on organic/inorganic hybrid nanocomposites with homogenous dispersion, thereby effectively reducing the fire hazard risk.

ZIF-8@Co-doped boronate ester polymer core-shell particles: Catalytically enhancing the nonflammability and smoke suppression of epoxy resin

Starting from a typical metal-organic framework (MOF) ZIF-8, a core-shell flame retardant named ZIF-8@BP-Co was synthesized by using ZIF-8 as the core and boronate ester polymer (BP) doped with Co2+ as the shell. The thermal stability and possible thermal degradation pathways of ZIF-8@BP-Co were characterized by TG and Py-GC/MS. ZIF-8@BP-Co was introduced into epoxy resin (EP) to reduce the flammability and smoke toxicity of EP nanocomposites. At the same time, the EP/ZIF-8@BP-Co achieved a V-0 rating in the UL-94 test, and its mechanical properties were also enhanced. Compared with EP, the peak heat release rate (pHRR), total heat release (THR), peak of smoke production rate (pSPR) and total smoke production (TSP) of EP/ZIF-8@BP-Co decrease by 51.3%, 13.2%, 37.2% and 20.9%, respectively. This work may be of interest in the design of multi-element flame retardant particles, especially in improving the compatibility between MOFs and polymer matrix.

Rigid polyurethane foam composites based on bivalent metal phytate: thermal stability, flame retardancy, and fire toxicity

ABSTRACT As the main form of phosphorus in plant seeds, phytic acid has potential value in flame retardant field. In this study, a series of bivalent metal phytate (PA-M) flame retardants were prepared using phytic acid and divalent metal salts as raw materials. FTIR, SEM-EDS, XRD, and TG tests confirmed that copper phytate (PA-Cu), zinc phytate (PA-Zn), cobalt phytate (PA-Co) and nickel phytate (PA-Ni) were successfully synthesized. Furthermore, flame retardant rigid polyurethane foam (RPUF/PA-M) composites were prepared by one-step water-blown technology using PA-M as flame retardant. TG test results showed that RPUF/PA-Cu30 had the highest char residue at 700 C, which was 26.2 wt%, significantly higher than 12.4 wt% of RPUF. Cone calorimetry, smoke density test, and TG-FTIR analysis confirmed that RPUF/PA-Co30 composite exhibited excellent smoke suppression and toxicity reduction performance when 30 phr PA-Co was added. Compared with RPUF, the THR, TSR, and SDR of RPUF/PA-Co30 were decreased by 13.9%, 27.3% and 43.9%, respectively, and the release of toxic gases (isocyanate compounds, aromatic compounds, CO and HCN) and combustible gases (hydrocarbons and esters) were significantly reduced. The analysis of char residues of RPUF/PA-M composites suggested that PA-M could promote the formation of dense carbon layer with high graphitization degree and improved the fire resistance of composites. This work provided a new way for fabricating fire safety RPUF composites.

From laboratory to industrialization: Eco‐friendly flame retardant endowing epoxy resin with excellent flame retardancy, transparency, and mechanical properties

AbstractTo eliminate the fire safety hazards (flammability and smoke toxicity) of epoxy resins (EP), while reaching industrial production of flame retardants, we proposed a facile strategy to successfully synthesize an industrially scalable phosphorus‐nitrogen flame retardant (named FNU) by the substitution reaction of 2‐(2‐aminoethylamino) ethanol and 9,10‐dihydro‐9‐oxo‐10‐phosphofi‐10‐oxide. FNU was synthesized in a simple and heat‐free step with room temperature stirring, and such process optimizations facilitate industrially scalable. As expected, FNU endowed EP with excellent flame retardancy and smoke suppression properties. EP mixing with 10 phr of FNU reached the highest limiting oxygen index value of 44.5%, UL‐94 reached V‐0 level, total smoke production and total heat release were reduced by 15.5% and 19.8% compared with pure EP. Residual carbon analysis showed that the presence of FNU could promote to form dense and continuous carbon layer. Thermogravimetric analysis‐infrared spectrometry results demonstrated a significant reduction in the pyrolysis products, especially in the yield of CO. Moreover, the structure of FNU contained aromatic rigid and reactive amine groups that significantly improved the mechanical properties of EP without affecting its transparency, retaining its value for applications in optical materials.

Comparative Study on the Chronic Vascular Responses Induced by Regular Versus Occasional Waterpipe Smoke Inhalation in Mice.

Waterpipe smoke (WPS) is the second most prevalent form of smoking in the world. There are ample evidences about the vascular alterations caused by regular WPS (Reg-WPS). Nonetheless, comparison of the chronic vascular response induced by regular versus occasional WPS (Occ-WPS) exposure is very scarce. We investigated, in BALB/c mice, the effects of Occ-WPS (30 minutes/day, 1 day/week) versus Reg-WPS (30 minutes/day, 5 days/week) for 6 months on thrombogenicity and platelet aggregation in vivo and in vitro. Moreover, various markers of endothelial integrity, inflammation and oxidative stress were assessed by enzyme-linked immunosorbent assay and colorimetric assay. Control mice were exposed to air. Our results showed that either Occ-WPS or Reg-WPS exposure shortened the thrombotic time in pial microvessels in vivo. Moreover, in pial venules, this effect was more marked in Reg-WPS group (-47%) compared with Occ-WPS (-34%). Similarly, exposure to either Occ-WPS or Reg-WPS reduced the prothrombin time and activated partial thromboplastin time. Platelet count was increased only in Reg-WPS exposure. Exposure to either Occ-WPS or Reg-WPS induced platelet aggregation in vitro. In addition, there was a statistically significant difference between Occ-WPS and Reg-WPS groups in platelet count and aggregation. Plasma concentration of tissue factor (+98%), P-selectin (+14%) and E-selectin (+16%) were significantly increased in Occ-WPS group compared with air exposed group. Likewise, compared with air group Reg-WPS caused an increase in concentration of tissue factor (+193%), P-selectin (+21%) and E-selectin (+42%). Nevertheless, only Reg-WPS induced a decrease (-38%) in the plasma concentration of tissue plasminogen activator. Notably, our results showed a statistically significant difference between Occ-WPS and Reg-WPS groups in the concentration of tissue factor. Erythrocyte numbers, hemoglobin concentration, hematocrit and lactate dehydrogenase activity were augmented only in Reg-WPS group compared with either control or Occ-WPS groups. Likewise, only Reg-WPS induced an increase in proinflammatory cytokines, tumor necrosis factor-α and interleukin-1β compared with either control or Occ-WPS groups. However, markers of oxidative stress including 8-isoprostane and total antioxidants were enhanced in both Occ-WPS and Reg-WPS compared with control group. Our data confirm the vascular toxicity of the chronic Reg-WPS exposure and shows that even occasional chronic exposure to WPS caused thrombosis, platelet aggregation, endothelial alterations and oxidative stress. The latter findings are an additional cause of concern about the long-term toxicity of occasional waterpipe smoking.

Facile Synthesis of a Novel Bio-Based P-N Containing Flame Retardant for Effectively Reducing the Fire Hazards of Epoxy Resin

In this work, a bio-based flame retardant (Cy-HEDP) was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression performance. The product Cy-HEDP was well characterized by FTIR, 1 H and 31P NMR and SEM tests. On the basis of the results, by adding 15 wt% Cy-HEDP, the EP15 can pass UL-94 V-0 rating, and the total smoke production (TSP) as well as total heat release (THR) can be decreased by 61.05% (from 22.61 to 8.7 m2 /m2 ) and 39.44% (from 103.19 to 62.50 MJ/m2 ) in comparison to the unfilled EP, reflecting the attenuated smoke toxicity and impeded heat generation. According to the analysis results of residual char, it can be concluded that Cy-HEDP possessed the ability to promote the formation of continuous and dense char layers, which would be a physical barrier to insulate oxygen and prevent heat feedback during the combustion of EP. This work provide inspiration towards developing bio-based flame retardant, probably extending the prospects to other polymeric material system.

Transcriptome Analysis of Rat Lungs Exposed to Moxa Smoke after Acute Toxicity Testing.

The increasing use of moxibustion has led to a debate concerning the safety of this treatment in human patients. Inhalation of cigarette smoke induces lung inflammation and granulomas, the proliferation of alveolar epithelial cells, and other toxic effects; therefore, it is important to assess the influence of inhaled moxa smoke on the lungs. In the present study, a novel poisoning cabinet was designed and used to assess the acute toxicity of moxa smoke in rats. We evaluated pathological changes in rat lung tissue and analyzed differentially expressed genes (DEGs) using RNA-seq and transcriptomic analyses. Our results show that the maximum tolerable dose of moxa smoke was 290.036 g/m³ and LC50 was 537.65 g/m³. Compared with that of the control group, the degree of inflammatory cell infiltration in the lung tissues of group A rats (all dead group) was increased, while that in group E rats (all live group) remained unchanged. GO and KEGG enrichment analyses showed that the DEGs implicated in cell components, binding, and cancer were significantly enriched in the experimental groups compared with the profile of the control group. The expressions of MAFF, HSPA1B, HSPA1A, AOC1, and MX2 determined using quantitative real-time PCR were similar to those determined using RNA-seq, confirming the reliability of RNA-seq data. Overall, our results provide a basis for future evaluations of moxibustion safety and the development of moxibustion-based technology.

Smoking and pregnancy

Smoking is one of the most harmful habits among adults. During pregnancy, the adverse effects go beyond the organism of the mother and it is considered to be a risk factor for miscarriage, stillbirth, placental abruption, preterm birth, low birthweight, morbidity and mortality. Through its numerous and dangerous compounds, tobacco smoking influence proteins and is leading to despaired fetal nourishment. Cigarette smoke toxicity is mainly driven by carbon monoxide, tar and nicotine. Carcinogens have a high negative impact, causing both maternal and fetal anemia, as well as abnormal fetal growth and development, pathology that by itself is associated with an additional risk of preterm delivery and low birthweight. Having the capability to cross the placenta, nicotine along with the other compounds, can be fetotoxic, neurologic teratogen and impact brain development. Smoking cessation outside or during pregnancy should be encouraged. Various medication and procedures have been proposed including in gestation. Some have proved to have positive effects, while others are not recommended during pregnancy or didn’t show promising outcome. Still, pregnant women should be informed upon general and fetal risk that are associated with smoking and pregnancy need additional medical care due to related smoking complications.

Toward an In‐Depth Fire Hazard and Resistance Diagnosis of Flame Retarded Liquid Electrolytes for Safer Lithium‐Ion Batteries

AbstractGrowing reports of fire incidents originating from lithium‐ion batteries have led to a quest for safer lithium‐ion batteries. Although the commercial success of the lithium‐ion batteries owes a great debt to the liquid electrolyte as much as the electrodes, the liquid electrolyte is considered the most flammable component of the battery. Flame retardant additives offer a promising solution to alleviate electrolyte flammability since they are added in minute quantities. However, the fire resistance and hazard diagnosis of the flame retardant containing liquid electrolyte remains a challenge due to the lack of reliable characterization technology. Herein, a stainless steel sample holder is custom‐designed and integrated into the cone calorimeter, enabling a precise and reliable technique for diagnosing the fire resistance efficiency and hazards of flame retarded liquid electrolytes. This integration allows for real‐time analysis of key fire behavior parameters of the flame retarded electrolytes such as time to ignition, heat release rate, fire growth rate index, smoke toxicity index, carbon monoxide, and smoke produced. Most of the fire test results show high reproducibility with less than 10% error. This study indicates that the modified cone calorimetry is a promising technology for diagnosing flame retarded liquid electrolyte fire resistance and hazard.

Chemistry, lung toxicity and mutagenicity of burn pit smoke-related particulate matter

BackgroundOpen burning of anthropogenic sources can release hazardous emissions and has been associated with increased prevalence of cardiopulmonary health outcomes. Exposure to smoke emitted from burn pits in military bases has been linked with respiratory illness among military and civilian personnel returning from war zones. Although the composition of the materials being burned is well studied, the resulting chemistry and potential toxicity of the emissions are not.MethodsSmoke emission condensates from either flaming or smoldering combustion of five different types of burn pit-related waste: cardboard; plywood; plastic; mixture; and mixture/diesel, were obtained from a laboratory-scale furnace coupled to a multistage cryotrap system. The primary emissions and smoke condensates were analyzed for a standardized suite of chemical species, and the condensates were studied for pulmonary toxicity in female CD-1 mice and mutagenic activity in Salmonella (Ames) mutagenicity assay using the frameshift strain TA98 and the base-substitution strain TA100 with and without metabolic activation (S9 from rat liver).ResultsMost of the particles in the smoke emitted from flaming and smoldering combustion were less than 2.5 µm in diameter. Burning of plastic containing wastes (plastic, mixture, or mixture/diesel) emitted larger amounts of particulate matter (PM) compared to other types of waste. On an equal mass basis, the smoke PM from flaming combustion of plastic containing wastes caused more inflammation and lung injury and was more mutagenic than other samples, and the biological responses were associated with elevated polycyclic aromatic hydrocarbon levels.ConclusionsThis study suggests that adverse health effects of burn pit smoke exposure vary depending on waste type and combustion temperature; however, burning plastic at high temperature was the most significant contributor to the toxicity outcomes. These findings will provide a better understanding of the complex chemical and combustion temperature factors that determine toxicity of burn pit smoke and its potential health risks at military bases.

The Effect of Accelerated Ageing on Reaction-to-Fire Properties–Composite Materials

As material age, the durability, strength, and other mechanical properties are impacted. The lifespan of a material generally decreases when exposed to weathering conditions such as wind, temperature, humidity, and light. It is important to have knowledge of how materials age and how the material properties are affected. Regarding materials´ fire behaviour and the effect of ageing on these properties, the knowledge is limited. The research questions of the current work are: Are the fire properties of composite materials affected by ageing? And if so, how is it affected? The study is on material at Technology Readiness Level 9 (TRL). In this study, three composite fibre laminates developed for marine applications were exposed to accelerated ageing. Two different ageing conditions were selected, thermal ageing with an increased temperature of 90°C and moisture ageing in a moderately increased temperature of 40°C and a relative humidity of 90%. Samples were collected after one, two and four weeks of ageing. The reaction-to-fire properties after ageing was evaluated using the ISO 5660–1 cone calorimeter and the EN ISO 5659–2 smoke chamber with FTIR gas analysis. The test results showed that the fire behaviour was affected. Two of the composite laminates, both phenolic/basalt composites, showed a deteriorated fire behaviour from the thermal ageing and the third composite laminate, a PFA/glass fibre composite, showed an improved fire behaviour both for thermal and moisture ageing. The smoke toxicity was affected by the accelerated ageing, especially for the PFA/glass fibre composite that showed a higher production of CO and HCN, both for the thermal aged and the moisture aged samples.

Cigarette Smoke Extract Produces Superoxide in Aqueous Media by Reacting with Bicarbonate.

The toxicity of cigarette smoke (CS) is largely attributed to its ability to generate reactive oxygen species (ROS). Reportedly, CS generates superoxide in cell culture systems by stimulating the cells to produce superoxide and through direct chemical reactions with components of the culture media. In this study, we investigated CS-induced superoxide formation in biocompatible aqueous media and its characteristics. Cigarette smoke extract (CSE) and total particulate matter (TPM) were prepared from the mainstream smoke of 3R4F reference cigarettes. CSE and TPM generated superoxide in Hank’s balanced salt solution (HBSS), Dulbecco’s modified Eagle media (DMEM), and blood plasma, but not in distilled water and phosphate-buffered saline. Each constituent of HBSS in solution was tested, and bicarbonate was found to be responsible for the superoxide generation. More than half of the superoxide formation was abolished by pretreating CSE or TPM with peroxidase, indicating that the substrates of peroxidase, presumably peroxides and peroxy acids, mainly contributed to the superoxide production. In conclusion, the presence of bicarbonate in experimental conditions should be considered carefully in studies of the biological activity of CS. Furthermore, the local amount of bicarbonate in exposed tissues may be a determinant of tissue sensitivity to oxidative damage by CS.

Conditioned Media of Adipose-Derived Stem Cells Suppresses Sidestream Cigarette Smoke Extract Induced Cell Death and Epithelial-Mesenchymal Transition in Lung Epithelial Cells.

The role of the epithelial–mesenchymal transition (EMT) in lung epithelial cells is increasingly being recognized as a key stage in the development of COPD, fibrosis, and lung cancers, which are all highly associated with cigarette smoking and with exposure to second-hand smoke. Using the exposure of human lung cancer epithelial A549 cells and non-cancerous Beas-2B cells to sidestream cigarette smoke extract (CSE) as a model, we studied the protective effects of adipose-derived stem cell-conditioned medium (ADSC-CM) against CSE-induced cell death and EMT. CSE dose-dependently induced cell death, decreased epithelial markers, and increased the expression of mesenchymal markers. Upstream regulator analysis of differentially expressed genes after CSE exposure revealed similar pathways as those observed in typical EMT induced by TGF-β1. CSE-induced cell death was clearly attenuated by ADSC-CM but not by other control media, such as a pass-through fraction of ADSC-CM or A549-CM. ADSC-CM effectively inhibited CSE-induced EMT and was able to reverse the gradual loss of epithelial marker expression associated with TGF-β1 treatment. CSE or TGF-β1 enhanced the speed of A549 migration by 2- to 3-fold, and ADSC-CM was effective in blocking the cell migration induced by either agent. Future work will build on the results of this in vitro study by defining the molecular mechanisms through which ADSC-CM protects lung epithelial cells from EMT induced by toxicants in second-hand smoke.