Cleaning Agents Research Articles

Experimental study on exploration of optimum extinguishing agent for 243 Ah lithium iron phosphate battery fires

Nowadays, an effective and clean extinguishing agent or technology is highly desirable for lithium-ion battery (LIB) fires. Herein, the physicochemical properties and extinguishing effects of various extinguishing agents on 243 Ah lithium iron phosphate (LFP) battery fires are investigated systematically. The extinguishing mechanisms are deeply analyzed and the performance is comprehensively evaluated from the aspects of thermal runaway (TR) and toxicity suppression, cooling and extinguishing efficiency. Compared with HFC-227ea, C6F12O can absorb more heat through vaporization, thereby improving extinguishing and cooling efficiency. The lack of chemical inhibition effect and the tiny droplet size make water mist unable to suppress the high-temperature jet fire, but it has the lowest toxicity and highest cooling efficiency of 54.6%. F-500 and FireIce can improve the extinguishing performance of the water mist by encapsulating and taking hydrocarbon fuel away from the fire zone and inhibiting free radicals in the flame, respectively. 3% F-500 has the extinguishing efficiency of 78.4% and TR efficiency of 64.1%, while maintaining the cooling performance well. In the future, a novel type of fire-extinguishing agent with high heat capacity and latent heat, excellent extinguishing performance, high wettability, low toxicity and insulating properties is expected to be developed for LIB fires.

A cleaner leather chemical from feather waste for reducing ammonia-nitrogen pollution and improving biological treatment efficiency of tannery wastewater

Feather waste is produced in millions of tons globally every year, resulting in a waste of biomass resources and even environmental pollution. A sustainable strategy for utilizing feather waste was proposed by preparing a clean deliming agent for ammonia-nitrogen (NH3–N) reduction in leather manufacture and biological treatment efficiency improvement of tannery wastewater. Briefly, chicken feather wastes were deeply hydrolyzed with sulfuric acid, and the optimized keratin hydrolysate (KHopt) that contained 53.6% crude protein and 41.2% amino acids, such as glutamic acid, serine, proline, leucine, phenylalanine, glycine, valine, and arginine, was obtained and used to delime limed cattle hides. The appropriate ratio of amino acids in KHopt gave KHopt a great pH-buffering capacity and maintained a stable float pH of approximately 9 throughout the deliming process. The isoelectric points of KHopt (3.8) and the limed hide (6.3) were both lower than the float pH, thereby bringing about an electrostatic repulsion between the KHopt and the hide surface, which is helpful for KHopt to penetrate and deswell the limed hide rapidly. Moreover, the KHopt deliming effectively removed calcium from the limed hide and achieved leather comparable to conventional leather for commercial applications. KHopt reduced the NH3–N concentrations of deliming effluent and tannery wastewater by 91.1% and 80.6%, respectively, compared with the conventional deliming agent (ammonium sulfate), and dramatically increased the biological treatment efficiency of tannery wastewater. The results showed that efficient and high-value use of feather waste was made by preparing KHopt for sustainable leather manufacturing.

Use of Alteromonas sp. Ni1-LEM Supernatant as a Cleaning Agent for Reverse-Osmosis Membranes (ROMs) from a Desalination Plant in Northern Chile Affected by Biofouling.

Biofouling refers to the undesirable growth of microorganisms on water-submerged surfaces. Microfouling, the initial state of biofouling, is characterized by aggregates of microbial cells enclosed in a matrix of extracellular polymeric substances (EPSs). In seawater desalination plants, filtration systems, such as reverse-osmosis membranes (ROMs), are affected by microfouling, which decreases their efficiency in obtaining permeate water. The existing chemical and physical treatments are expensive and ineffective; therefore, controlling microfouling on ROMs is a considerable challenge. Thus, new approaches are necessary to improve the current ROM cleaning treatments. This study demonstrates the application of Alteromonas sp. Ni1-LEM supernatant as a cleaning agent for ROMs in a desalination seawater plant in northern Chile (Aguas Antofagasta S.A.), which is responsible for supplying drinking water to the city of Antofagasta. ROMs treated with Altermonas sp. Ni1-LEM supernatant exhibited statistically significant results (p < 0.05) in terms of seawater permeability (Pi), permeability recovery (PR), and the conductivity of permeated water compared with control biofouling ROMs and those treated with the chemical cleaning protocol applied by the Aguas Antofagasta S.A. desalination plant.

Pembuatan dan Pemanfaatan Larutan Multiguna Eco Enzyme sebagai Upaya Reduksi Limbah Organik di Kampoeng Kuliner Makassar

Kampoeng Kuliner Makassar (KKM) is one of the MSMEs in the culinary field in Makassar. KKM produces about 25 kg/day of organic waste, mainly fruit and vegetable. This community partnership program is a form of transfer of knowledge and technology fermentation in organic waste treatment, which aims to assist KKM partners in processing fruit and vegetable peel waste into eco-enzyme which is then used as a multipurpose cleaning solution according to KKM needs. This activity consists of a focus discussion group (FGD), counseling, making and harvesting eco enzyme, and its application in the restaurant as a multipurpose cleaning solution. Paired t-test results of participants' pre-test and post-test showed a significant increase (p-value &lt; 0.001) in participants' knowledge about various aspects of eco-enzyme. The participants' skills are improved through independent practice so that all participants can produce good quality eco enzymes. Eco-enzyme has been used as a cleaning and disinfection agent, such as washing agents for food, tableware, and cooking utensils; kitchen and bathroom cleaners at KKM. After this community partnership program, it is hoped that KKM can become a place to promote a healthy lifestyle with minimal waste.

Inert gas discharge time effects on full and reduced scale wood crib extinguishing experiments

The 2012 edition of NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems, was revised to allow a maximum 2-min discharge duration for systems that protect class A fire hazards with inert gases. With this change, UL 2127 and FM 5600 also began testing and certifying systems over both 60- and 120-s discharge durations. This study analyzes the effect of the different discharge times of an inert agent on the extinction of a test article (wood crib) placed within an enclosure. This was done following the UL 2127 procedure, and a modified version of it that involved the use of a reduced-scale experimental setup. The enclosure was scaled based on the oxygen consumption of the wood crib. Observations and measurements included oxygen concentration within the enclosure, near-crib gas velocity and temperature, as well as wood crib mass. These quantities were used to study the extinguishment differences at the two discharge durations and support the validity of a novel ¼ reduced-scale crib and enclosure developed in this study. It was found that varying the discharge time will induce changes in the suppression dynamics, as the flow of agent and entrained air affect the time to reach extinction.

Job and exposure intensity among hospital cleaning staff adversely affects respiratory health.

Occupational exposure to various types of cleaning agents may increase the risk of adverse respiratory health among cleaners. This study investigated the relationship between exposure to cleaning and disinfecting agents, using a job-task and exposure intensity metric, and respiratory outcomes among cleaners. A sample of 174 cleaners was selected from three public hospitals in Durban. A questionnaire was used to collect demographic and occupational information, and spirometry, including post-bronchodilator measures, was conducted according to the American Thoracic Society guidelines and skin prick testing were performed. Exposure metrics for job tasks and chemical exposures were created using frequency and employment-lifetime duration of exposure. Multivariate analysis regression models used job task and exposure intensity metrics. Doctor-diagnosed asthma prevalence was 9.8%. Breathlessness with wheeze (22.4%) was the prevalent respiratory symptom. Positive responses to skin prick testing were seen in 74 (43.2%). There was a statistically significant increased risk for shortness of breath with exposure to quaternary ammonium compounds (odds ratio [OR]: 3.44; 95% confidence interval [CI]: 1.13-10.5) and breathlessness with exposure to multipurpose cleaner (OR: 0.34; CI: 0.12-0.92). The losses in percent-predicted forced expiratory volume in 1 s (FEV1) ranged from 0.3%-6.7%. Results among the bronchodilator-positive (8.6%) showed lung function losses twofold greater when compared to the total study population with percentage predicted FEV1 (-22.6 %; p < 0.000). Exposure to certain cleaning and disinfectant agents adversely affects respiratory health, particularly lung function. This effect, while seen generally among cleaning workers, is more pronounced among those with pre-existing reversible obstructive lung disease.

Experimental Assessment of the Acoustic Performance of Nozzles Designed for Clean Agent Fire Suppression

Discharge through nozzles used in gas-based fire protection of data centers may generate noise that causes the performance of hard drives to decay considerably; silent nozzles are employed to limit this harmful effect. This work focuses on proposing an experimental methodology to assess the impact of sound emitted by gaseous jets by comparing various nozzles under several operating conditions, together with relating that impact to design parameters. A setup was developed and repeatability of the experiments was evaluated; standard and silent nozzles were tested regarding the discharge of inert gases and halocarbon compounds. The ability of silent nozzles to contain the emitted noise—generally below the 110 dB reference threshold—was proven effective; a relationship between Reynolds number and peak noise level is suggested to support the reported increase in noise maxima as released flow rate increases. Hard drives with lower speed were the most affected. Spectral analysis was conducted, with sound at the higher frequency range causing performance decay even if lower than the acknowledged threshold. Independence of emitted noise from the selected clean agent was also observed in terms of released volumetric flow rate, yet the denser the fluid, the lower the generated noise under the same released mass flow rate.

A Novel Application of Risk-Risk Tradeoffs in Occupational Health: Nurses' Occupational Asthma and Infection Risk Perceptions Related to Cleaning and Disinfection during COVID-19.

Nurses face the risk of new onset occupational asthma (OA) due to exposures to cleaning and disinfection (C&D) agents used to prevent infections in healthcare facilities. The objective of this study was to measure nurses' preferences when presented with simultaneous OA and respiratory viral infection (e.g., COVID-19) risks related to increased/decreased C&D activities. Nurses working in healthcare for ≥1 year and without physician-diagnosed asthma were recruited for an online anonymous survey, including four risk-risk tradeoff scenarios between OA and respiratory infection with subsequent recovery (Infect and Recovery) or subsequent death (Infect and Death). Nurses were presented with baseline risks at hypothetical "Hospital 1", and were asked to choose Hospital 2 (increased OA risk to maintain infection risk), Hospital 3 (increased infection risk to maintain OA risk), or indicate that they were equally happy. Over 70% of nurses were willing to increase infection risk to maintain baseline OA risk if they were confident they would recover from the infection. However, even when the risk of infection leading to death was much lower than OA, most nurses were not willing to accept a larger (but still small) risk of death to avoid doubling their OA risk. Age, work experience, and ever having contracted or knowing anyone who has contracted a respiratory viral infection at work influenced choices. We demonstrate the novel application of a risk-risk tradeoff framework to address an occupational health issue. However, more data are needed to test the generalizability of the risk preferences found in this specific risk-risk tradeoff context.

Cerium Oxide on a Fluorinated Carbon-Based Electrode as a Promising Catalyst for Hypochlorite Production.

Sodium hypochlorite (NaOCl) is widely used as a disinfectant agent for water treatment and surface cleaning. A straightforward way to produce NaOCl is by the electrolysis of an aqueous sodium chloride (NaCl) solution. This process presents several side reactions decreasing its efficiency with hypochlorite reduction on the cathode surface being one of the main detrimental reactions. In this work, we have studied carbon-based electrodes modified with cerium oxide (CeO2), fluorine, and platinum nanoparticles as cathodes for hypochlorite production. Fluorination was carried out electrochemically; the polyol method was used to synthesize platinum nanoparticles; and the hydrothermal process was applied to form a CeO2 layer. Scanning electron microscopy, FTIR, and inductively coupled plasma (ICP) indicated the presence of cerium oxide as a film, fluorine groups on the substrate, and a load of 3.2 mg/cm2 of platinum nanoparticles and 2.7 mg/cm2 of CeO2. From electrochemical impedance spectroscopy, it was possible to demonstrate that incorporating platinum and fluorine decreases the charge transfer resistance by 16% and 28%, respectively. Linear sweep voltammetry showed a significant decrease in hypochlorite reduction when the substrate was doped with fluorine from −16.6 mA/cm2 at −0.6 V to −9.64 mA/cm2 that further reduced to −8.78 mA/cm2 with cerium oxide covered fluorinated electrodes. The performance of the cathode materials during hypochlorite production improved by 80% compared with pristine activated carbon cloth (ACC) electrodes. The improvement toward hindering NaOCl reduction is probably caused by the incorporation of a partial negative charge upon doping with fluorine.

(Invited) Fire-Extinguishing, Recyclable Liquefied Gas Electrolytes for Temperature-Resilience Lithium Metal Batteries

High energy density, improved safety, temperature resilience and sustainability are desirable properties for lithium battery electrolytes, yet these metrics are rarely achieved simultaneously. Inspired by the compositions of clean fire extinguishing agents, we demonstrate inherently safe liquefied gas electrolytes (LGE) based on 1,1,1,2-tetrafluoroethane (TFE) and pentafluoroethane (PFE) that maintain > 3 mS cm-1 ionic conductivity from –78 to +80 °C. As a result of beneficial solvation chemistry and a fluorine-rich environment, Li cycling at > 99% Coulombic efficiency for over 200 cycles at 3 mA cm-2 and 3 mAh cm-2 was demonstrated in addition to stable cycling of Li/NMC622 full batteries from –60 to +55 °C. Additionally, we demonstrate that the vapor pressure-temperature relationship unique to LGE systems allows for a one-step solvent recycling process, which promises sustainable operation at scale. This work provides a route to sustainable, temperature resilient lithium metal batteries with fire-extinguishing properties that maintain state-of-the-art electrochemical performance.

A high-efficient and low-consumption nanoimprint method to prepare large-area and high-quality Nafion array for the ordered MEA of fuel cell

Recently, the third-generation-ordered membrane electrode assembly (MEA) is widely researched, because it can simultaneously provide abundant and continuous ordered charge, proton, and mass transfer channels. However, the development of the ordered MEA is restricted by the preparation of the ordered channels. In this work, we developed a high-efficient (<1 min), contamination-free and low-consumption nanoimprint method to prepare large area (up to 1800 cm2) composite proton exchange membrane (PEM) with ordered Nafion array by repeatedly using porous anodic alumina oxide (AAO) template. Firstly, prepare the ordered Nafion nano-arrays by filling AAO template with low Nafion solution loading (only 0.75 g/m2). Secondly, imprint the ordered Nafion nano-arrays onto the commercial PEM under 140 °C to prepare the composite PEM with Nafion array. Thirdly, demold the composite PEM from the AAO template by using water as clean release agent. Lastly, recycle the AAO template to repeatedly prepare the composite PEM with Nafion array (at least 50 times). This nanoimprint method can prepare abundant composite PEMs by imprinting diverse ordered Nafion array structures on different commercial PEMs. In PEMFC, the composite PEM above has 1.6 times higher performance and one tenth lower hydrogen crossover than the corresponding commercial PEM. This nanoimprint method can be expanded to prepare the arrays on alkaline electrolyte membrane (AEM), PBI membrane and other electrolyte membranes. Furthermore, the application of these membranes can greatly promote the ordered MEA in PEMFC, AEM fuel cell, water electrolysis, and electrochemical synthesis, etc.

Study on the material compatibility of 2-bromo-3,3,3-trifluoropropene with the polymers used in built-in fire extinguishing system of aircraft

The seals are usually used to fill the gap between the storage containers and discharge pipes in the built-in fire extinguishing system of the aircraft. These seals inevitably touch the fire extinguishing agents, which may reduce the hermeticity of seals. In this paper, the compatibility experiment of 2-bromo-3,3,3-trifluoropropene, a new clean fire extinguishing agent, with fluorosilicone rubber and fluoro rubber was performed at 25 ℃, 0.1Mpa. The volume, weight, hardness, and mechanical properties of the sealings were tested, and the changes in cross-section and infrared spectrum were analyzed. The results show that during the contact with 2-bromo-3,3,3-trifluoropropene, fluoro rubber is damaged more severely than fluorosilicone rubber, the hardness measured directly and after drying decreased by 12.9 % and 17.6 % respectively, while the tensile strength decreased by 51.2 % and 86.1 % respectively. It is proved that 2-bromo-3,3,3-trifluoropropene have poor compatibility with the fluoro rubber and fluorosilicone rubber.

HERBAL CARE IN DENTISTRY- A REVIEW OF EMERGING TRENDS

Herbs are staging a comeback and herbal ‘renaissance’ is happening all over the globe. The herbal products, today, symbolize safety, in contrast to the synthetics that are regarded as unsafe to humans and the environment. An herb, botanically speaking, is any plant that lacks the woody tissue which is characteristic of shrubs or trees. More specifically, herbs are plants which are used medicinally or for their flavor or scent. Herbs with medicinal properties are a useful and an effective source of treatment for various disease processes. Herbal extracts have been successfully used in dentistry as tooth cleaning and antimicrobial plaque agents. The use of herbal medicines continues to expand rapidly across the world. Many people take herbal medicines or herbal products now for their health care in different national healthcare settings. Herbal extracts have been used in dentistry for reducing inflammation, as antimicrobial plaque agents, for preventing release of histamine and as antiseptics, antioxidants, antimicrobials, antifungals, antibacterials, antivirals and analgesics. They also aid in healing and are effective in controlling microbial plaque in gingivitis and periodontitis, thereby improving immunity.

Using Biosurfactants from Plants to Treat Chicken Feathers into a Green Oil Absorbent Material

While feathers are still commonly regarded in many places as waste, in many developed countries it has been considered a valuable by-product of the poultry industry. The poultry industry of Vietnam has achieved encouraging achievements in the past 10 years. The total flock of poultry from 100 million to now has reached nearly 467 million. Though light as a feather, with the vast quantities of chickens produced annually, the number of feathers produced is considerable. Research has shown that the feathers have hydrophobic properties and can therefore be used to make products that absorb oil. However, the use of large amounts of toxic detergents to clean chicken feathers in reported studies has reduced the environmental significance of agricultural waste reuse. In this study, we evaluated the possibility of replacing toxic cleaning agents with eco-friendly natural cleaners in the handling of chicken feathers. Water-based extracts of soapnuts and bo-ket fruits have been selected for our study due to their high saponin content - an effective cleaning agent, and have been used as a dishwashing liquid or shampoo for a long-time by local housewives. Our study showed that natural detergents derived from soapnuts have been shown the ability to remove lards on the plastic surface, and to clean chicken feathers, thereby increasing their capacity to absorb various oils including cooking oil, used cooking oil, and lubricant oil. We have also created an oil-absorbing pillow containing soapnut extract-treated chicken feathers with a maximum efficiency of 16.8 g/g in absorbing lubricant oil. Our research opens new avenues for the use and treatment of poultry feathers, contributing to the reduction of solid waste from the poultry industry by methods which is friendlier to the environment. The greenness of the created absorber is guaranteed.

Bacterial Disinfection of Polymethyl Methacrylate (PMMA) Resin Polymer Using Low Level Microwave Irradiation and Denture Cleaning Agent

The aim was to evaluate the disinfection of E. coli, S. aureus and S. mutans cultured on Polymethyl Methacrylate (PMMA) resin polymer using microwave disinfection and sodium perborate (DC). Biofilms of E. coli, S. aureus and S. mutans were cultured on the PMMA denture base for 24, 36, 48 and 96 h. Specimens were subjected to three disinfection protocols, including microwave disinfection in distilled water (MW-DW), sodium perborate (denture cleaning tablet) with distilled water (DC-DW) and a combination of MW-DC-DW for 1 to 5 min. Colony-forming units among the study groups were analyzed using Kruskal–Wallis and Mann–Whitney tests. For E. coli and S. aureus cultured on PMMA, the MW-DC-DW group displayed complete disinfection at 2 min of exposure. However, for both bacteria, the MW-DW disinfection group showed zero CFU at 3 min. DC disinfection for E. coli and S. aureus displayed zero CFU at 5 min of exposure (p ≤ 0.05). For S. mutans, MW-DC-DW and MW-DW displayed zero CFU count at 1 min and 2 min, respectively. In DC-treated samples, CFU were significantly zero at 4 min when compared with the control at each growth time. A combination of MW irradiation with DC (sodium perborate) showed higher disinfection percentage of bacterial species on PMMA polymer denture bases compared to MW and DC alone. PMMA disinfection using DC displayed a lower antimicrobial disinfection percentage than the combined use of MW and DC as well as MW alone at 1 min or 2 min disinfection for E. coli, S. aureus and S. mutans.

Characterization of Exposure to Cleaning Agents Among Health Workers in Two Southern African Tertiary Hospitals.

Whilst cleaning agents are commonly used in workplaces and homes, health workers (HWs) are at increased risk of exposure to significantly higher concentrations used to prevent healthcare-associated infections. Exposure assessment has been challenging partly because many are used simultaneously resulting in complex airborne exposures with various chemicals requiring different sampling techniques. The main objective of this study was to characterize exposures of HWs to various cleaning agents in two tertiary academic hospitals in Southern Africa. A cross-sectional study of HWs was conducted in two tertiary hospitals in South Africa (SAH) and Tanzania (TAH). Exposure assessment involved systematic workplace observations, interviews with key personnel, passive personal environmental sampling for aldehydes (ortho-phthalaldehyde-OPA, glutaraldehyde and formaldehyde), and biomonitoring for chlorhexidine. Overall, 269 samples were collected from SAH, with 62 (23%) collected from HWs that used OPA on the day of monitoring. OPA was detectable in 6 (2%) of all samples analysed, all of which were collected in the gastrointestinal unit of the SAH. Overall, department, job title, individual HW use of OPA and duration of OPA use were the important predictors of OPA exposure. Formaldehyde was detectable in 103 (38%) samples (GM = 0.0025 ppm; range: &lt;0.0030 to 0.0270). Formaldehyde levels were below the ACGIH TLV-TWA (0.1 ppm). While individual HW use and duration of formaldehyde use were not associated with formaldehyde exposure, working in an ear, nose, and throat ward was positively associated with detectable exposures (P-value = 0.002). Glutaraldehyde was not detected in samples from the SAH. In the preliminary sampling conducted in the TAH, glutaraldehyde was detectable in 8 (73%) of the 11 samples collected (GM = 0.003 ppm; range: &lt;0.002 to 0.028). Glutaraldehyde levels were lower than the ACGIH's TLV-Ceiling Limit of 0.05 ppm. p-chloroaniline was detectable in 13 (4%) of the 336 urine samples (GM = 0.02 ng/ml range: &lt;1.00 to 25.80). The study concluded that detectable exposures to OPA were isolated to certain departments and were dependent on the dedicated use of OPA by the HW being monitored. In contrast, low-level formaldehyde exposures were present throughout the hospital. There is a need for more sensitive exposure assessment techniques for chlorhexidine given its widespread use in the health sector.

Effects of various cleaning agents on polypropylene and copolyester thermoplastic orthodontic retainer materials

ObjectivesThis study aimed to evaluate and compare the effects of four cleaning agents on the flexural modulus and light transmittance properties of polypropylene and copolyester thermoplastic retainer materials after long-term exposure. MethodsA total of 120 pieces of standardized copolyester and polypropylene retainer materials were tested after being thermoformed. They were divided equally into six subgroups: as-received, artificial saliva, chlorhexidine, alcohol-based and alcohol-free mouthwashes, and Retainer Brite®. The pieces were subjected to a cleaning process involving 15 minute immersion three times weekly for 3 months. The flexural modulus and light transmittance were then measured for all specimens with three point bending tests and spectrophotometry, respectively. One-way ANOVA and independent samples t-test were applied to compare the means, and Tukey's post hoc test was used in cases of significant differences. The threshold for significance was 0.05. ResultsFor each retainer type, the statistical results revealed that the flexural modulus values of the copolyester retainer material significantly differed from those of polypropylene material under chlorhexidine mouthwash, alcohol-based mouthwash, and Retainer Brite® conditions. Copolyester and polypropylene showed significant differences in light transmittance under all conditions. No significant difference in flexural modulus values was observed among conditions, whereas significant differences in light transmittance were observed between alcohol-based mouthwash and the other conditions for copolyester material. ConclusionsAccording to our results, any cleaning agent can be safely used for both materials without affecting the elastic modulus. However, alcohol-based mouthwash decreases the light transmittance of copolyester retainer material.

The Efficacy of Common Household Cleaning Agents for SARS-CoV-2 Infection Control.

The COVID-19 pandemic caused by SARS-CoV-2 is having devastating effects on a global scale. Since common household disinfectants are often used to minimise the risk of infection in the home and work environment, we investigated the ability of some of these products to inactivate the virus. We tested generic brands of vinegar, bleach, and dishwashing detergent, as well as laboratory-grade acetic acid, sodium hypochlorite, and ethanol. Assays were conducted at room temperature (18–20 °C, 40% relative humidity), and two time points were used to reflect a quick wipe (30 s) and a brief soak (5 min). Vinegar, and its active ingredient, acetic acid, were completely ineffective at virus inactivation even when exposed to the virus at 90% v/v (a final concentration equivalent to 3.6% v/v acetic acid). In contrast, ethanol was capable of inactivating the virus at dilutions as low as 40% v/v. Dishwashing detergent effectively rendered SARS-CoV-2 inactive when diluted 100-fold (1% v/v). Bleach was found to be fully effective against SARS-CoV-2 at 0.21 g/L sodium hypochlorite after a 30 s exposure (1/200 dilution of commercial product). Given reports of infectious virus recovered from the surface of frozen packaging, we tested the persistence of infectiousness after multiple freeze-thaw cycles and found no change in infectious SARS-CoV-2 titre after seven freeze-thaw cycles. These results should help inform readers of how to effectively disinfect surfaces and objects that have potentially been contaminated with SARS-CoV-2 using common household chemicals.

An Overview of Cleaning Agents' Health Hazards and Occupational Injuries and Diseases Attributed to Them in Sweden.

Using data from the Swedish Products Register, hosted by the Swedish Chemicals Agency (KemI), national occupational injury and disease statistics, and call records from the Swedish Poisons Information Centre (PIC) we characterize health hazards of marketed cleaning products and recorded injuries, disease, and incidents linked to cleaning or disinfection agents. The results show that cleaning agents pose many kinds of health hazards, although corrosion and irritation hazards dominate, in particular for the eyes (54% of all included products). Few products were recognized as inhalation hazards. The nature of the health hazards is reflected in the occupational disease and injury statistics and PIC records for eyes and skin but not for the respiratory tract. Among occupational disease cases attributed to cleaning or disinfection agents, 61% concern skin and 26% the respiratory tract. Among occupational injury cases 64% concern chemical burns. However, only a small part (<0.5%) of all reported diseases and injuries were explicitly attributed to cleaning or disinfection agents. On average, there were 11 cases of disease attributed to cleaning or disinfection agents per million workers and year. For occupational injuries the corresponding number was 8. The data concern a broad range of sectors and occupations, but notable sectors were healthcare, accommodation and food service, and manufacturing. Women were more likely to suffer from disease, men and women equally likely to suffer from injury. PIC cases were evenly distributed between men and women, but the clear risk cases more frequently involved men. Occupational diseases increased many-fold in 2020 while injuries decreased, which could be due to COVID-19 changing use patterns of cleaning and disinfection agents at work. We conclude that cleaning agents pose a variety of risks to a large part of the workforce, although particular attention for preventive efforts may need to be directed to the healthcare, accommodation and food service, and manufacturing sectors.

Experimental study for the hold time of clean extinguishing agent interpreted as function of time

This paper proposes a new model to predict the hold time in enclosures protected with clean extinguishing agent (CEA). The limitations of three existing theoretical models are analyzed, and the proposed model is validated. Existing theoretical models employ the enclosure height as a variable in predicting the hold time of CEA; hence, the prediction of diffusion according to time change has limitation. In this study, a theoretical model is proposed in which species diffusion is defined as a function of time rather than elevation, based on the theory of diffusion in fluids. The proposed model was experimentally verified using five CEAs. The predicted hold time in each theoretical model was compared to the height-specific hold time measured in the test enclosure. Existing theoretical models, which are expressed as a function of elevation, will have varying errors between the predicted and measured hold times depending on the input parameters. Also, the maximum error range is approximately 46%. However, in the proposed model expressed as a function of time, the error of the hold time does not change. In addition, the maximum error range is approximately 16%, which increases the accuracy approximately 3 times compared to the existing theoretical model.