Hydrogen Cyanide Concentrations Research Articles

Quantification of Elevated Hydrogen Cyanide (HCN) Concentration Typical in a Residential Fire Environment Using Mid-IR Tunable Diode Laser.

A versatile portable tunable diode laser based measurement system for measuring elevated concentrations of hydrogen cyanide (HCN) in a time-resolved manner is developed for application in the fire environment. The direct absorption tunable diode laser spectroscopy (DA-TDLAS) technique is employed using the R11 absorption line centered at 3345.3 cm-1 (2989.27 nm) in the fundamental C-H stretching band (ν1) of the HCN absorption spectrum. The measurement system is validated using calibration gas of known HCN concentration and the relative uncertainty in measurement of HCN concentration is 4.1% at 1500 ppm. HCN concentration is measured with a sampling frequency of 1 Hz, in gas sampled from 1.5 m, 0.9 m, and 0.3 m heights in the Fireground Exposure Simulator (FES) prop at the University of Illinois Fire Service Institute, Champaign, Illinois. The immediately dangerous to life and health (IDLH) concentration of 50 parts per million (ppm) is exceeded at all the three sampling heights. A maximum concentration of 295 ppm is measured at the 1.5 m height. The HCN measurement system, expanded to measure HCN simultaneously from two sampling locations, is then deployed in two full-scale experiments designed to simulate a realistic residential fire environment at the Delaware County Emergency Services Training Center, Sharon Hill, Pennsylvania.

An Experimental and Theoretical Investigation of HCN Production in the Hadean Earth Atmosphere

A critical early stage for the origin of life on Earth may have involved the production of hydrogen cyanide (HCN) in a reducing, predominantly H$_2$ atmosphere. HCN is crucial for the origin of life as it is a possible precursor to several biomolecules that make up RNA and proteins including nucleobases, nucleotides, amino acids, and ribose. In this work, we perform an in depth experimental and theoretical investigation of HCN production in reducing atmospheric conditions (89-95% H$_2$) possibly representing the earliest stages of the Hadean eon, ~4.5-4.3 billion years ago. We make use of cold plasma discharges - a laboratory analog to shortwave UV radiation - to simulate HCN production in the upper layers of the atmosphere for CH$_4$ abundances ranging from 0.1-6.5%. We then combine experimental mass spectrum measurements with our theoretical plasma models to estimate the HCN concentrations produced in our experiments. We find that upper atmospheric HCN production scales linearly with CH$_4$ abundance with the relation [HCN] = 0.13 $\pm$ 0.01[CH$_4$]. Concentrations of HCN near the surface of the Hadean Earth are expected to be about 2-3 orders of magnitude lower. The addition of 1% water to our experiments results in a ~50% reduction in HCN production. We find that four reactions are primarily responsible for HCN production in our experiments: (i) $^4$N + CH$_3$ -> H$_2$CN + H -> HCN + H$_2$, (ii) $^4$N + CH -> CN + H followed by CN + CH$_4$ -> HCN + CH$_3$, (iii) C$_2$H$_4$ + $^4$N -> HCN + CH$_3$, and (iv) $^4$N + $^3$CH$_2$ -> HCN + H. The most prebiotically favorable Hadean atmosphere would have been very rich in CH$_4$ (> 5%), and as a result of greenhouse effects the surface would be likely very hot. In such a prebiotic scenario, it may have been important to incorporate HCN into organic hazes that could later release biomolecules and precursors into the first ponds.

Rapid measurements of hydrogen cyanide concentration in combustion gas via terahertz spectroscopy

The development of a real-time measurement system to determine the concentrations of combustion gases mixed with smoke particles in fire environments is an essential technical issue in the fire safety field. In this study, the absorption line for the J = 8–7 rotational transition at 708.9 GHz of hydrogen cyanide (HCN) produced by the combustion of silk is rapidly measured in a 1 m cell during repeat scans (seven times a minute) via terahertz spectroscopy. The obtained time profile of HCN concentrations agrees well with the time profile obtained via Fourier transform infrared (FT-IR) spectroscopy. The maximum concentrations derived via terahertz spectroscopy are consistent with those derived via FT-IR within an accuracy of 10%. The minimum sensitivity of HCN is 100 ppm as detected via terahertz spectroscopy. The repetition rate, the accuracy, and the sensitivity for the scans demonstrate the potential of terahertz spectroscopy to rapidly diagnose combustion gas flow concentrations in fire environments.

Groundwater quality assessments around acassava processing mill on the sedimentary terrain of Ilaro, South-western Nigeria

Groundwater quality assessments were carried out around a cassava processing mill within the Ilaro metropolis, South-western Nigeria using a hydro-chemical approach. Nineteen samples were obtained from proximate water wells which serve as sources of water for drinking, domestic, and irrigation activities. Twenty physicochemical parameters were analyzed, and the results were compared with the permissible limits of the world health organization (WHO) for drinking water. The pH values of the groundwater samples range between 4.60 and 7.65 which were not within the permissible limit and suggest the presence of contaminants in the water samples. The concentrations of electrical conductivity (EC), total dissolved solids (TDS), and total hardness (TH) in the groundwater samples were 100% compliance, while Hydrogen cyanide (HCN) concentrations in the groundwater samples were 0% compliance with standard permissible limit by WHO. All the Anions (Cl−, HCO3−, NO3−, SO42−) in the groundwater samples were 100% compliance except CO32-which is 79% compliance, and cations (Ca2+, Mg2+, Na+ and K+) concentrations were 100% compliance with the standard permissible limits. The concentrations of Fe, Cd, Mn, Pb, Zn, Cu in the samples were 0%, 0%, 31%, 36%, 100%, 100% in compliance respectively with standard permissible limits. The groundwater quality index (GWQI) and contamination index (CI) of the groundwater samples ranges from 527.24 to 699.16 and 24.03 to 38.80 respectively. The values of GWQI and CI of the groundwater samples were 0% compliance with recommended standard permissible limit for drinking and domestic purposes. The samples also showed moderate to high tendencies of aggressively corroding metals. The samples were unsuitable for irrigation and the concentrations of HCO3− and CO32− influenced the suitability of the samples. Strong direct relations exist between carbonate and electrical conductivity indicating freshwater status.

Simultaneous Quantitative Detection of HCN and C2H2 in Combustion Environment Using TDLAS

Emission of nitrogen oxides (NOx) and soot particles during the combustion of biomass fuels and municipal solid waste is a major environmental issue. Hydrogen cyanide (HCN) and acetylene (C2H2) are important precursors of NOx and soot particles, respectively. In the current work, infrared tunable diode laser absorption spectroscopy (IR-TDLAS), as a non-intrusive in situ technique, was applied to quantitatively measure HCN and C2H2 in a combustion environment. The P(11e) line of the first overtone vibrational band v1 of HCN at 6484.78 cm−1 and the P(27e) line of the v1 + v3 combination band of C2H2 at 6484.03 cm−1 were selected. However, the infrared absorption of the ubiquitous water vapor in the combustion environment brings great uncertainty to the measurement. To obtain accurate temperature-dependent water spectra between 6483.8 and 6485.8 cm−1, a homogenous hot gas environment with controllable temperatures varying from 1100 to 1950 K provided by a laminar flame was employed to perform systematic IR-TDLAS measurements. By fitting the obtained water spectra, water interference to the HCN and C2H2 measurement was sufficiently mitigated and the concentrations of HCN and C2H2 were obtained. The technique was applied to simultaneously measure the temporally resolved release of HCN and C2H2 over burning nylon 66 strips in a hot oxidizing environment of 1790 K.

Toxic Blood Hydrogen Cyanide Concentration as a Vital Sign of a Deceased Room Fire Victim-Case Report.

Carbon monoxide (CO) and hydrogen cyanide (HCN) are two common toxic products of combustion. HCN concentrations of fire victims are not routinely determined in most legal medicine services in Romania. We present the case of a room fire victim in which we evaluated the concentrations of HCN and carboxyhemoglobin (COHb), their contribution to the mechanism of death, and the possibility that HCN concentration can be interpreted as vital sign. COHb was determined by spectrophotometry. HCN was spectrophotometrically determined with ninhydrin in postmortem blood samples after its removal with 20% phosphoric acid and uptake into a solution of potassium carbonate. The presence of ethyl alcohol was determined by gas chromatography. The COHb concentration was 6.15%, while the blood HCN concentration was 1.043 µg × mL−1 and the total HCN was 1.904 µg × ml−1. A blood alcohol content of 4.36 g‰ and a urine alcohol content of 5.88 g‰ were also found. Although the fire produced a considerable amount of soot, and there were signs of inhalation of soot particles, the COHb level cannot be interpreted as a vital sign. Toxic concentrations of HCN and total HCN can be interpreted as a vital sign and indicates a contributive effect of HCN in the mechanism of death.

Genome-wide association study of cyanogenic glycosides, proline, sugars, and pigments in Eucalyptus cladocalyx after 18 consecutive dry summers.

Natural variation of cyanogenic glycosides, soluble sugars, proline, and nondestructive optical sensing of pigments (chlorophyll, flavonols, and anthocyanins) was examined in ex situ natural populations of Eucalyptus cladocalyx F. Muell. grown under dry environmental conditions in the southern Atacama Desert, Chile. After 18 consecutive dry seasons, considerable plant-to-plant phenotypic variation for all the traits was observed in the field. For example, leaf hydrogen cyanide (HCN) concentrations varied from 0 (two acyanogenic individuals) to 1.54 mg cyanide g-1 DW. Subsequent genome-wide association study revealed associations with several genes with a known function in plants. HCN content was associated robustly with genes encoding Cytochrome P450 proteins, and with genes involved in the detoxification mechanism of HCN in cells (β-cyanoalanine synthase and cyanoalanine nitrilase). Another important finding was that sugars, proline, and pigment content were linked to genes involved in transport, biosynthesis, and/or catabolism. Estimates of genomic heritability (based on haplotypes) ranged between 0.46 and 0.84 (HCN and proline content, respectively). Proline and soluble sugars had the highest predictive ability of genomic prediction models (PA=0.65 and PA=0.71, respectively). PA values for HCN content and flavonols were relatively moderate, with estimates ranging from 0.44 to 0.50. These findings provide new understanding on the genetic architecture of cyanogenic capacity, and other key complex traits in cyanogenic E. cladocalyx.

Hydrogen cyanide and carboxyhemoglobin assessment in an open space fire‐related fatality

Hydrogen cyanide (HCN) can be a major contributory factor in death from fire‐related inhalation injury. Although carbon monoxide (CO) is considered the lethal agent of smoke in fires, its liability as a cause of death is sometimes debatable. The purpose of this report is to present the case of an 80‐year‐old man with locomotor disabilities who died due to an open space fire of vegetation debris and household waste in his yard. We evaluated here the concentrations of HCN and carboxyhemoglobin (COHb) and their contribution to the mechanism of death. In addition, the risk factors and the contributing effect of the factors that compose the complex toxic environment that develops in fires were discussed. COHb was determined by spectrophotometry as recommended by Katsumata et al. in 1982. HCN was determined with ninhydrin in postmortem blood samples after removal with 20% phosphoric acid and capture in a potassium carbonate solution. A toxic concentration of 1.3 μg ml−1 HCN and a lethal COHb level of 73.7% were determined in the blood samples. Although death was mainly attributed to CO poisoning and extremely severe burns in this open space burning case, the additive effect of HCN in the mechanism of death was also highlighted. The results suggested the possibility that the man's clothing may have played an important role in the production of HCN in this open space fire, as well as other types of garbage that were burned.

Hydrogen cyanide and mycotoxins: Their incidence and dietary exposure from cassava products in Anyigba, Nigeria

While cassava products are important in addressing food security crises in Africa, they are not exempted from recurring food safety concerns. This research determined consumption, incidence, and concentrations of hydrogen cyanide (HCN), total aflatoxins (AFs), ochratoxin A (OTA) and fumonisins (FBs) in cassava product (casava flour, fufu and gari) among residents of Anyigba, Nigeria, and also estimated dietary exposure to the toxins from the foods. Consumption data from 82 households showed that 89%, 68% and 94% of the residents consume cassava flour, fufu, and gari, respectively. Average daily intake for individuals was 0.751, 0.111, and 0.120 kg of cassava flour, fufu, and gari respectively. The highest incidence and concentration of HCN were found in cassava flour, with %TDI (EDI) of 33.3% (0.03 mg/kg.bw/day). Weekly, residents are exposed to 0.0371, 0.0077 and 0.0224 μg/kg.bw of OTA, and daily to 0.0315, 0.0043, 0.0060 μg/kg.bw of AFs and 0.0000, 0.0025, 0.0004 μg/kg.bw of FBs from consumption of cassava flour, fufu, and gari, respectively. The mycotoxins also co-occurred in the food products.

Cometary Delivery of Hydrogen Cyanide to the Early Earth.

Delivery of water and organics by asteroid and comet impacts may have influenced prebiotic chemistry on the early Earth. Some recent prebiotic chemistry experiments emphasize hydrogen cyanide (HCN) as a feedstock molecule for the formation of sugars, ribonucleotides, amino acids, and lipid precursors. Here, we assess how much HCN originally contained in a comet would survive impact, using parametric temperature and pressure profiles together with a time-dependent chemistry model. We find that HCN survival mainly depends on whether the impact is hot enough to thermally decompose H2O into reactive radicals, and HCN is therefore rather insensitive to the details of the chemistry. In the most favorable impacts (low impact angle, low velocity, small radius), this temperature threshold is not reached, and intact delivery of HCN is possible. We estimate the global delivery of HCN during a period of Early and Late Heavy Bombardment of the early Earth, as well as local HCN concentrations achieved by individual impacts. In the latter case, comet impacts can provide prebiotically interesting HCN levels for thousands to millions of years, depending on properties of the impactor and of the local environment.

Effect of Sulfur and Urea Fortification of Fresh Cassava Root in Fermented Total Mixed Ration on the Improvement Milk Quality of Tropical Lactating Cows.

The aim of the present research was to determine the influence of sulfur and urea combined with fresh cassava root in fermented total mixed ration (FTMR) on digestibility, fermentation in the rumen, blood metabolite, milk yield, and milk quality in tropical lactating dairy cows. Four mid-lactation Thai Holstein–Friesian crossbred cows were studied. Pre-experiment milk yield was 12.7 ± 0.30 kg/day, and the body weight was 495 ± 40.0 kg. Animals were evaluated in a 2 × 2 factorial in a 4 × 4 Latin square design to receive diets followed by: factor A, which was a dose of sulfur inclusion at 1.0% and 2.0%, and factor B, which was level of urea inclusion at 1.25% and 2.5% DM in FTMR. The hydrogen cyanide (HCN) concentrations reduced 99.3% to 99.4% compared with fresh cassava root when FTMR was supplemented with 1.0% and 2.0% sulfur, respectively. Intake of crude protein was increased based on urea level addition (p < 0.05). Blood thiocyanate concentration was increased by 21.6% when sulfur was supplemented at 2.0% compared to 1.0% (p < 0.05). There was no difference in protozoal concentration, whereas bacterial populations at 4 h after feeding were significantly greater by 6.1% with the FTMR supplemented with 2.0% sulfur and 2.5% urea (p < 0.01). Allantoin concentrations, excretion, absorption, and microbial crude protein showed significant interactions between sulfur levels and urea levels in cows fed diets supplemented with 2.0% sulfur and 2.5% urea (p < 0.05). The molar ratios of the volatile fatty acid (VFA) profile were affected by dietary FTMR (p < 0.01). Furthermore, propionic acid increased by 4.6% when diets were supplemented by 2.5% sulfur (p < 0.01). Milk fat and total solids increased when feed was supplemented with 2.0% sulfur and 2.5% urea (p < 0.05). The diets supplemented with 2.0% sulfur levels resulted in greater concentrations of milk thiocyanate (p < 0.05). The somatic cell count was significantly reduced throughout the experiment with increasing sulfur supplementation (p < 0.05). Animals fed diets supplemented with 2.0% sulfur exhibited a decreased somatic cell count by 18.3% compared with those fed diets supplemented with 1.0% sulfur. Thus, inclusion of 2.0% sulfur with 2.5% urea in FTMR containing fresh cassava root improved digestibility, ruminal fermentation, microbial crude protein synthesis, and milk qualities in dairy cows.

The increased hydrocyanic acid in drought-stressed sorghums could be alleviated by plant growth regulators

Droughts not only reduce the biomass of sorghum (Sorghum bicolor (L.) Moench) but also increase the risk of hydrogen cyanide (HCN) toxicity to animals, mainly due to increased HCN content in drought-stressed plants. In the present study, the variations of HCN contents in 12 sorghum genotypes (10 sweet sorghum cultivars, one Sudangrass and one forage sorghum) were investigated at jointing, filling and ripening stages under rainfed conditions. Next, three genotypes – one sweet sorghum, one Sudangrass and one forage sorghum – were further selected to elucidate the physiological mechanisms of plant growth regulators (PGRs) (abscisic acid (ABA) and methyl jasmonate (MeJA)) in mitigating the concentrations of HCN in drought-stressed plants in a pot experiment. About 100 µg/L ABA and 100 µg/L MeJA were sprayed separately or together twice on drought-stressed (50 and 75% field water capacity) plant leaf. The drought lasted for 15 days. In the field experiment the HCN content in plants reduced from jointing to filling stages then increased from filling to ripening stages in several cultivars. In the pot experiment, drought increased the HCN accumulation and soluble protein content in leaves of all three genotypes. PGRs overall reduced the HCN contents in drought-stressed sweet sorghum and Sudangrass but not in forage sorghum (except in the ABA+MeJA treatment). However, the soluble protein contents were reduced by PGRs in drought-stressed forage sorghum but not in sweet sorghum (except in the ABA+MeJA treatment) and Sudangrass. Both ABA and MeJA increased the plant weights, whereas only MeJA enhanced net photosynthetic rate (PN) in all three genotypes. PGRs reduced release rate of superoxide and hydrogen peroxide and malondialdehyde in all drought-stressed plants, and reduced the activities of peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase in sweet sorghum but not in other two genotypes. These results suggest that exogenous ABA and MeJA could increase plant weight and reduce HCN content in drought-stressed sorghums, with varying physiological responsive mechanisms among sorghum genotypes.

Quantitative evaluation of hydrogen cyanide content, chemical and functional properties of gari from Akwanga, Nasarawa State, Nigeria

Ingestion of cyanohydrins has been linked to acute and chronic toxicities even death on several occasions in Nigeria. The need for periodic evaluation of cassava based food products to ensure compliance to standard specifications is therefore imperative. This study was conducted to investigate the concentration of hydrogen cyanide and other quality parameters of gari samples collected from Akwanga main market in the month of July, 2019. A total of 21 samples of gari (16 white and 5 yellow varieties) were collected using systematic random sampling techniques. Hydrogen cyanide, proximate compositions, physicochemical and functional properties were carried out following standard procedures. Results showed that white and yellow gari contained hydrogen cyanide in the range of 3.68–19.37 mg/kg and 13.32–16.17 mg/kg respectively. High moisture (11.38–16.74%) and crude fibre (1.51–3.44%) contents were recovered in some white gari and all the yellow gari samples. The results obtained for pH (4.44–5.95) and titratable acidity (0.11–0.67%) indicated low acid concentrations in both gari varieties. The bulk density, water absorption capacity, swelling index and least gelation capacity varied significantly in white and yellow gari samples as from 0.12–0.87 g/mL, 4.06–5.40 mL/g, 0.47–4.40 and 3.00–6.70% respectively. The concentrations of hydrogen cyanide in all the samples were higher than maximum value (2.0 mg/kg) considered as National Standard Specifications for gari coupled with high moisture contents above the safe level which might predispose them to mould growth that could render them unsafe for human consumption.

Evaluation of the disappearance of cyanogen and hydrogen cyanide in different soil types using gas chromatography–mass spectrometry

Cyanogen (C2N2) is a new soil fumigant being tested worldwide for soil fumigation or sterilization before planting. This study established a multi-fumigant detection method for C2N2 and its degradation product hydrogen cyanide (HCN) by gas chromatography–mass spectrometry (GC–MS). The GC–MS method was then applied to investigate the degradation of C2N2 and HCN in eight different agricultural soils. The optimal headspace sampling conditions using a Box–Behnken experimental design were an extraction temperature of 60 °C, an extraction time of 0.7 h, and a solvent volume of 35 mL (30% H2SO4). Under these conditions, the extraction rates of C2N2 and HCN were 89.22% ± 0.65% and 92.50% ± 0.63%, respectively. The limits of quantification for both target compounds were 0.001 mg·kg−1. The recoveries of C2N2 and HCN ranged from 84.7% to 102.9% and from 80.18% to 95.34%, respectively, at spiked levels of 0.05, 0.2, and 1.0 mg·kg−1 with relative standard deviation ≤2.2%. A residual dynamics experiment showed that C2N2 and HCN disappeared rapidly in the soils. The first-order double-exponential decay model best described the decline of C2N2 and HCN concentrations in soil. The half-lives of C2N2 and HCN in soil were 8.553–27.964 h and 11.823–35.674 h, respectively. The GC–MS method provides a simple, fast, and organic solvent-free procedure to analyze multiple fumigants in the soil matrix. The proposed method is therefore recommended as a screening tool for the field investigation of C2N2- and HCN-fumigated sites.

Origin of Life's Building Blocks in Carbon- and Nitrogen-Rich Surface Hydrothermal Vents.

There are two dominant and contrasting classes of origin of life scenarios: those predicting that life emerged in submarine hydrothermal systems, where chemical disequilibrium can provide an energy source for nascent life; and those predicting that life emerged within subaerial environments, where UV catalysis of reactions may occur to form the building blocks of life. Here, we describe a prebiotically plausible environment that draws on the strengths of both scenarios: surface hydrothermal vents. We show how key feedstock molecules for prebiotic chemistry can be produced in abundance in shallow and surficial hydrothermal systems. We calculate the chemistry of volcanic gases feeding these vents over a range of pressures and basalt C/N/O contents. If ultra-reducing carbon-rich nitrogen-rich gases interact with subsurface water at a volcanic vent they result in – concentrations of diacetylene (C4H2), acetylene (C2H2), cyanoacetylene (HC3N), hydrogen cyanide (HCN), bisulfite (likely in the form of salts containing HSO3−), hydrogen sulfide (HS−) and soluble iron in vent water. One key feedstock molecule, cyanamide (CH2N2), is not formed in significant quantities within this scenario, suggesting that it may need to be delivered exogenously, or formed from hydrogen cyanide either via organometallic compounds, or by some as yet-unknown chemical synthesis. Given the likely ubiquity of surface hydrothermal vents on young, hot, terrestrial planets, these results identify a prebiotically plausible local geochemical environment, which is also amenable to future lab-based simulation.

An inhalational swine model for the characterization of physiological effects and toxicological profile associated with cyanide poisoning

Cyanides are highly toxic compounds that have been used as weapons of terrorism throughout history. Cyanide (CN) is acutely toxic by all routes of administration; however, inhalation is the main exposure route. To adequately test effective countermeasures against inhalational CN threats, robust and well-characterized animal models are needed. This paper describes the initial development of a hydrogen cyanide (HCN) exposure swine model for documenting the physiological effects and toxicological profile during and after HCN inhalation exposure. Animals were implanted with telemetry transmitters for heart rate (HR), blood pressure, and electrocardiogram monitoring, and vascular access ports for serial blood collections. Nine female swine were exposed to HCN concentrations of 500 ± 6 ppm while breathing parameters were monitored real-time. Inhaled HCN doses ranged from 2.02 to 2.83 mg/kg. Clinical signs included vocalization, agitation, salivation, respiratory distress and apnea. After HCN exposure initiation, systemic arterial pressure fell dramatically with a concomitant increase in HR. Blood samples were collected to determine CN blood levels using LC-MS/MS and blood gas analysis. In summary, the developed HCN inhalation swine model permitted documentation of the physiological effects associated with CN poisoning. This model could be used to evaluate potential CN medical countermeasures in the event of a public health emergency stemming from inhalational CN threats.

Spatially and temporally resolved IR-DFWM measurement of HCN released from gasification of biomass pellets

For the first time, to the best of the authors’ knowledge, nonintrusive quantitative measurement of hydrogen cyanide (HCN) released during the devolatilization phase of straw pellets gasification is demonstrated with high spatial and temporal resolution. Mid-infrared degenerate four-wave mixing (IR-DFWM) measurements of HCN were performed by probing the interference-free P(20) line in the v1 vibrational band at around 3 µm and the IR-DFWM signal was detected with an upconversion-based detector, providing discrimination of thermal noise and increased sensitivity. A novel single-pellet setup consisting of a multi-jet burner was used to provide hot flue gas environments with an even and well-defined temperature distribution, for single straw pellet gasification at atmospheric pressure. The environments had temperatures of 1380 K, 1540 K and 1630 K with a constant oxygen concentration of 0.5 vol%. In order to quantify the amount of HCN released during the devolatilization of straw pellets, calibration measurements were performed in well-defined HCN gas flows. Selected hot water lines were probed with IR-DFWM in the interrogated volume to obtain the instantaneous temperature, which were used to correct the temperature effect. HCN concentrations up to 1500 ppm were detected during the devolatilization stage, and the results indicate a strong temperature dependence of the HCN release.

Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells

Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells

Airborne contaminants during controlled residential fires

ABSTRACTIn this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.

A global enhancement of hydrogen cyanide in the lower stratosphere throughout 2016

AbstractIn September–October 2015, El Niño‐driven weather conditions led to one of the most intense Indonesian peatland burning events in recent history. Consequently, an unprecedented amount of hydrogen cyanide (HCN) was emitted from Southeast Asia and transported into the upper troposphere and lower stratosphere, which was then transported by the general circulation from the tropics to polar latitudes. By early 2016, the daily mean concentrations of HCN in the lower stratosphere at all latitudes, as measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS) instrument, were the largest on record for the region, on the order of 40–90% greater than the climatological mean and ~40% greater than the 2007 El Niño‐driven values. By December 2016, levels of polar HCN in the lower stratosphere were still on the order 10–20% greater than the climatological mean. These ACE‐FTS measurements are thus vital for interpreting ground‐based and nadir satellite measurements of HCN made during 2016 and could be used to help validate tropospheric‐stratospheric exchange in climate models.