Decontamination Time Research Articles

Evaluation method investigation of public decontamination time in off-site nuclear emergency under the influence of human factors

Decontamination is an important means to reduce the personnel radioactive contamination under sever nuclear accidents. Public decontamination time estimation with the process simulation is helpful for emergency organizations to improve efficiency. To date, most studies focus on improving personal decontamination technology and decontamination strategies, while research on the overall decontamination process and time estimating is limited. Due to the complex population structure, the unknown contaminated proportion and the complicated psychological emotions, it is hard to quantify the decontamination process and calculate the decontamination time with numerous procedures and diverse facility configurations. Combined with public contaminated proportion, crowd structure and waiting psychology, a public decontamination model based on queuing theory and system dynamics method is established for offsite nuclear emergency to simulate the decontamination process and give an estimate of decontamination time. A hypothetical nuclear leakage accident of Changjiang Nuclear Power Plant in Hainan, China is conducted to simulate the established model. The results show the working status of different facilities at different stages and the changes in waiting queues at different times, which can effectively calculate the duration time of each link and the overall public decontamination progress. A plan for adding devices is provided to meet the decontamination time requirements and control the number of waiting queues within the specified threshold efficiently. The method proposed in this paper could help nuclear emergency decision-makers estimate the public decontamination time, optimize site configuration plans, give guidance on public decontamination procedures and prepare for the subsequent nuclear emergency evacuation.

Dynamic impacts of short-term bath administration of enrofloxacin on juvenile black seabream Acanthopagrus schlegelii

Dynamic impacts of short-term enrofloxacin (ENR) exposure on juvenile marine fish are not well understood, and the underlying mechanisms remain unclear. We therefore investigated the accumulation and elimination of ENR in the liver of juvenile black seabream Acanthopagrus schlegelii. Meanwhile, the dynamic alterations of biochemical parameters and liver transcriptomes after short-term bath immersion and withdrawal treatment were explored. The results indicated that the contents of ENR in the liver were significantly increased after bath administration for 24 h, and then quickly declined to very low concentrations along with the decontamination time increasing. Judging from the changes in biochemical indicators and liver transcriptomic alterations, 0.5 and 1 mg/L ENR exposure for 24 h triggered oxidative stress, impairment of immune system, as well as aberrant lipid metabolism via differential molecular pathways. Interestingly, biochemical and transcriptome analysis as well as integrated biomarker response (IBR) values showed that more significant changes appeared in 1 mg/L ENR group at decontamination periods, which indicated that the impact of high dose ENR on juvenile A. schlegelii may persist even after depuration for 7 days. These results revealed that the risk of short-term bath of 1 mg/L ENR should not be overlooked even after depuration period. Therefore, attention should be paid to the dosage control when administering the drug to juvenile A. schlegelii, and the restoration of physiological disturbance may be an important factor in formulating a reasonable treatment plan.

Influence of decontamination process parameters on ultrasonic decontamination efficiency of pipeline

Many radioactive pollutants will be deposited inside the nuclear power plant pipelines after long-term service, which will form radioactive hot spots and increase the radiation dose rate level of operators. The ultrasonic decontamination efficiency was studied through the establishment of ultrasonic decontamination dynamic test bench, under different decontamination process parameters. It has also been applied in the engineering filed. The results show that: Ultrasonic decontamination efficiency increases with the increase of decontamination power, and the maximum decontamination efficiency of pollutants is up to 62.69%. The main reason is that the mechanical effect and cavitation effect of ultrasonic are significant with the increase of power, which is conducive to the removal of pollutants in the pipeline. When the decontamination time is 60min, the ultrasonic decontamination efficiency is more than 90%. Meanwhile, after ultrasonic decontamination of the pipeline hot spots, the contact dose rate at the pipeline hot spots is reduced by 75.20% at the highest, and the environmental dose rate is reduced by more than 90%, which reduces the collective dose level of operators working near the pipeline hot spot greatly, and ensures the health of the operators and environmental safety.

The effect of pore-scale contaminant distribution on the reactive decontamination of porous media

AbstractA porous material that has been contaminated with a hazardous chemical agent is typically decontaminated by applying a cleanser solution to the surface and allowing the cleanser to react into the porous material, neutralising the agent. The agent and cleanser are often immiscible fluids and so, if the porous material is initially saturated with agent, a reaction front develops with the decontamination reaction occurring at this interface between the fluids. We investigate the effect of different initial agent configurations within the pore space on the decontamination process. Specifically, we compare the decontamination of a material initially saturated by the agent with the situation when, initially, the agent only coats the walls of the pores (referred to as the ‘agent-on-walls’ case). In previous work (Luckins et al., European Journal of Applied Mathematics, 31(5):782–805, 2020), we derived homogenised models for both of these decontamination scenarios, and in this paper we explore the solutions of these two models. We find that, for an identical initial volume of agent, the decontamination time is generally much faster for the agent-on-walls case compared with the initially saturated case, since the surface area on which the reaction can occur is greater. However for sufficiently deep spills of contaminant, or sufficiently slow reaction rates, decontamination in the agent-on-walls scenario can be slower. We also show that, in the limit of a dilute cleanser with a deep initial agent spill, the agent-on-walls model exhibits behaviour akin to a Stefan problem of the same form as that arising in the initially saturated model. The decontamination time is shown to decrease with both the applied cleanser concentration and the rate of the chemical reaction. However, increasing the cleanser concentration is also shown to result in lower decontamination efficiency, with an increase in the amount of cleanser chemical that is wasted.

Experimentation and optimization of laser waterless decontamination rate of residual organic solvents

Laser waterless decontamination is a widely researched area for the high pollution issue of residual organic solvents in industry and agriculture. In this research, a nanosecond pulsed laser was used to conduct waterless decontamination studies on organic solvent residues on the surface of optical glass. A single-factor test was designed using the decontamination rate (Y) as the response value and the laser power (X1), scanning speed (X2), and decontamination times (X3) as the influencing variables. The Raman spectrum reflected the decontamination effect of organic solvent decontamination using a waterless laser. The Box-Behnken response surface method (RSM) was used to design the experiments. The developed RSM was used to determine the link between laser parameters and decontamination rate, and optimum decontamination parameters were determined. In addition, the mathematical model and regression equation were established using Design-Expert. The findings demonstrate that residual solvent may be removed at a rate of up to 95.22%. Optimum values for laser power, scanning speed, and decontamination times are 130 W, 381 mm/s, and 10 times respectively.

Optimized cleaning of conveyor belts using plasma-processed water assisted by optical detection of food residues

As food of animal and plant origin is prone to microbial spoilage, its production must be monitored and conducted safely to avoid consumer hazards. At the same time, environmental and sustainability aspects are becoming increasingly important. In this study, washing of food conveyor belts at ambient temperature was performed with plasma-processed water (PPW) and an optical detector to monitor the cleaning success. The microbial plate counts could be reduced with pressurized water, foam and PPW by >3 log10 CFU/cm2, similar to the standard industrial washing with amine-based disinfectant (Neoseptal®, Dr. Weigert, Germany). However, PPW degrades to naturally occurring substances, and the inactivation time was reduced from 15 to 1 min. The optical detector could mostly distinguish between uncleaned and cleaned belts. The fast, precise and easy applicable measurement could be integrated into the production line for automated monitoring, which could result in cleaning cycles based on demand. Industrial relevanceAn on-demand cleaning process with less need for chemicals would save time and money plus protect the environment. Plasma-processed water is as effective as a chemical disinfectant combined with a reduced decontamination time (from 15 to 1 min) and free of complex chemical compounds. The optical detector can be used inline, fast and easy for automated hygiene monitoring in the food production.

Escherichia coli Disinfection with Ag+ in the Recycled Flow Ultrasonic Reactor

After the recent pandemic process, disinfection/sterilization methods used for the control of infectious diseases have gained even more importance. The alternative disinfection studies like ultrasound (US) have been developing due to the various shortcomings of microbial inactivation processes such as chlorine application, ozone and ultraviolet radiation, which are widely applied for the prevention of epidemic diseases caused by pathogenic microorganisms. Within the scope of this study, disinfection treatments were carried out in recycled flow ultrasonic reactors operated at 22kHz, 36kHz and 833kHz ultrasonic frequencies using Escherichia coli bacteria indicated fecal contamination in the water sources. In this article, the combined usage of silver ions (0.1mM, 0.01 mM and 0.005 mM Ag+) and US (22 kHz, 36 kHz and 833 kHz ultrasonic frequencies) were mainly investigated using initial Escherichia coli bacteria concentration of 1x104 CFU/mL. As a result of the study, Escherichia coli was inactivated obtaining 4-log reduction with 22 kHz ultrasonic frequency with the minimum Ag+ concentrations. To conclude, the disinfection was effectively achieved with US and Ag+ methods, and higher Escherichia coli inactivation rate were obtained in US-Ag+ dual processes with faster decontamination time and lower Ag+ concentration due to their synergistic effects.

Review on Public Health Effects of Aflatoxins in Milk and Milk-Based Foodstuffs of Dairy Cow

Aflatoxins are toxigenic metabolites that are definitely occurring by lethal strains of Aspergillus parasiticus and Aspergillus flavus that commonly dwell and colonize in feed components and various nutritive foodstuffs particularly milk and milk based products. This Review has three main objectives; those are causes of aflatoxin, effects and methods of control in milk and milk products. Drinking of cow milk polluted with aflatoxin may overwhelm immunity and subsidize to stunting in young children, as the young children are not immune-competent during early stage. It has been internationally assessed that aflatoxin is possibly accountable for 30% of the annual cases of liver cancer. Generally, control approaches of aflatoxin can be applied during pre-harvest, cautious management in the time of harvest and postharvest decontamination. Moreover, choosing breed for aflatoxin impervious crop diversities, prevention of aflatoxin production through biological decontamination by microorganisms and their metabolites, rejection of aflatoxin by physical means in addition to inactivation by chemicals are the typical approaches that have been described in different studies. For the reason that cow milk is the most important and principal diet of children, but the risk of exposed to the cancer are more in infants. In addition, according to various investigations it also well thought that young animals are also found to be more vulnerable to aflatoxin than adults. Thus; the contamination of cow milk and milk products by AFM1 should understood as undesirable for young human and animals.

Laboratory evaluation of the efficacy of Liastene application in complex therapy of multiresistant pulmonary tuberculosis

OBJECTIVE. Evaluating according to laboratory tests the effectiveness of Liasten in the treatment of patients with multidrug-resistant pulmonary tuberculosis (MDR-TB).
 MATERIALS AND METHODS. Evaluation of the effectiveness of etiotropic and etiopathogenetic therapy in 57 patients with MDR-TB was performed. According to the treatment schemes, patients were divided into groups. The control group (n=22) received individualized antimycobacterial therapy (AMBT) regimens. The experimental group (n=35) received AMBT in combination with Liasten. Evaluation of the effectiveness of treatment regimens was performed on the basis of indicators of general clinical blood tests, immunological and bacteriological studies.
 RESULTS AND DISCUSSION. In patients of the experimental group, compared with the control in 1.5 times more often found positive changes in the hemogram of blood and ESR (p<0.05-0.001), the establishment of a dynamic balance between the pools of lymphocyte cells CD4+ and СD8+ (immunoregulatory index, p<0.05), an increase in the number of phagocytosis active cells (phagocytic index, p<0.05), the content of cationic lysosomal proteins of granulocyte leukocytes (p<0.05), a 1.4-fold decrease in the cytochemical coefficient of neutrophils (p<0.05), the number of proliferated under the action of PPD-L lymphocytes (p<0.05), normalization of phagocytic counts and total redox activity of neutrophils (p<0.05), increase in frequency and reduction of anesthesia was stated.
 CONCLUSIONS. Restoration of the body’s immune status, blood hemogram, increase in frequency and reduction of the time of decontamination were more active and occurred 1.5 times more often in patients receiving a complex combination of AMBT with Liasten.

A bioinspired cercosporin/polymethylmethacrylate photocatalyst with high efficiency for decontamination of pharmaceuticals and pathogens

Pharmaceuticals have seriously contaminated aquatic environments and resulted in the formation of drug-tolerant bacteria owing to continuous release and accumulation. Therefore, the development of new methods to simultaneously decompose drugs and disinfect pathogens in an environmental-friendly manner with high efficiency is still in great demand. Bioinspired by the great photosensitivity of natural product cercosporin with the ability to efficiently generate reactive oxygen species (ROS) under natural sunlight and its antibacterial activity, here a novel cercosporin/polymethylmethacrylate (CP/PMMA) photocatalyst was rationally developed by incorporating and restricting cercosporin in a “green” macroporous resin PMMA, which greatly improved the ROS generation efficiency and displayed 97.2–100% photodegradation for broad-spectrum pharmaceuticals, including fluoroquinolones, trimethoprim and chloroquine phosphate, upon 15 W compact fluorescent lamp irradiation. More importantly, this decontamination efficiency was greatly improved, and the decontamination time was substantially shortened in a large-scale assay under natural sunlight. Furthermore, it could inactivate the pathogen Staphylococcus aureus. Overall, this work provides new insight into how a multifunctional photocatalyst could be designed using a natural product and macroporous resins for environmental remediation.

N95 respirator decontamination: a study in reusability

The coronavirus disease 2019 (COVID-19) pandemic had caused a severe depletion of the worldwide supply of N95 respirators. The development of methods to effectively decontaminate N95 respirators while maintaining their integrity is crucial for respirator regeneration and reuse. In this study, we systematically evaluated five respirator decontamination methods using vaporized hydrogen peroxide (VHP) or ultraviolet (254 nm wavelength, UVC) radiation. Through testing the bioburden, filtration, fluid resistance, and fit (shape) of the decontaminated respirators, we found that the decontamination methods using BioQuell VHP, custom VHP container, Steris VHP, and Sterrad VHP effectively inactivated Cardiovirus (3-log10 reduction) and bacteria (6-log10 reduction) without compromising the respirator integrity after 2–15 cycles. Hope UVC system was capable of inactivating Cardiovirus (3-log10 reduction) but exhibited relatively poorer bactericidal activity. These methods are capable of decontaminating 10–1000 respirators per batch with varied decontamination times (10–200 min). Our findings show that N95 respirators treated by the previously mentioned decontamination methods are safe and effective for reuse by industry, laboratories, and hospitals.

The stability and decontamination of surface radioactive contamination of biomass-based antifreeze foam

Conventional water-based foam decontaminants used for the removal of radionuclides lose their efficacy in winter at temperatures below 0 °C. To address this problem, an antifreeze foam, with characteristics of good stability, high decontamination efficiency, less liquid waste generation, and excellent biodegradability, was developed using a biomass-based surfactant, a polysaccharide foam stabilizer, and an antifreeze agent. Furthermore, the surface tension, solution viscosity, foam stability, and decontamination of simulated radionuclides on different plates of a xanthan gum (XG)-stabilized antifreeze foam at temperatures ranging from −10 °C to 10 °C were investigated. Especially, the bulk-phase performance and stabilizing mechanism of the antifreeze foam were analyzed. Compared with the antifreeze foam without stabilizer, the half-life of the XG-stabilizing foam increases from 30.5 min to 2785 min, and the initial drainage time increases from 5 min to 383.5 min at −10 °C, which considerably extends the decontamination time and is conducive to improving the decontamination efficiency. Furthermore, the foam stability and bulk viscosity of the foam solution at a low shear rate exhibited a significant positive correlation. As a result, with decreasing the temperature, the viscosity of the XG-stabilized antifreeze foam solution increased leading to a better stability of foam at a lower temperature. The stabilizing mechanism of the XG stabilizer would possibly be the rigid chain structure of the XG molecule, which could lightly resist the contraction and bending of the molecular chain caused by Na+ originated from the surfactant sodium alpha-olefin sulfonate (AOS) and H+ originated from acidic chelator citric acid (CA) in the decontamination foam. Another probable stabilizing mechanism would be that the electrostatic repulsion generated by the negatively charged groups on the XG molecular chains could prevent the molecular aggregation and precipitation. Moreover, surface decontamination results revealed that the XG-stabilized antifreeze foam can remove >90% of the radionuclide contamination physically attached to surfaces of glass, stainless steel, white paint, green paint, and tile plate below 0 °C. Therefore, the antifreeze foam detergent exhibits good application potential for the decontamination of surface radioactive contamination in winter due to its excellent stability, high decontamination efficiency, and biodegradability.

Health Hazards and Protocol for Management of Used Facemasks Outside Hospitals during SARCOV-2 Pandemic

Background: SARS-CoV-2 is highly infectious pathogenic disease leading to infection and death of millions of people all over the world till the date according to the data provided by John Hopkins University. Peoples have started using various types of mask to protect themselves from getting infected from the deadly corona virus. There has also been large amount of confusion in general public about disposal of the mask as most of them are using for first time in their life. Even healthcare professionals may be unaware of the methods of disposal of the masks outside their hospitals. This mask may carry infections from asymptomatic, SARS-CoV-2 patients that if it comes in contact with other peoples and animals may have severe bio health hazards. Observation & Management of facemasks: Since the SARS-COV-2 pandemic outbreak since March 2020, personally, we found out that peoples a carelessly throwing masks everywhere including streets, parking lots, beaches, building complexes, sewages and homes. These masks may have been used by asymptomatic carriers or have got infected with these viruses is hazardous not only to the health of the public but also for the household waste collectors, pet animals and marine animals. Disinfecting with sodium hypochlorite * decontaminating methods like washing facemasks and drying in sunlight, pressure cooker sterilisation method, boiling, by using laundry detergent and hot dryer and cleaning in washing machine, etc. Conclusion & Relevance: The objective of these articles is to alert the public & health care professionals to understand the hazards of throwing the facemasks at public places and preventive measure to be taken during this pandemic time and various methods of decontamination, pre-treatment and disposal of facemask avoiding severe health hazards.

The Importance of Atmospheric Microbial Contamination Control in Dental Offices: Raised Awareness Caused by the SARS-CoV-2 Pandemic

Background: In the context of the Sars-CoV-2 pandemic that started in 2020, more attention is being paid to the air quality in medical offices. The medical, economic and social implications of this crisis are unprecedented. Dental offices, particularly, were significantly affected by this pandemic due to the high exposure of dental workers, limited availability of personal protective equipment (PPE) and serious financial problems. Methods: Four different procedures were compared regarding their effectiveness in air contamination reduction, both from a biological point of view and from a management point of view: Fogging, Ultraviolet C (UVC) lamps, UVC air circulation units and natural ventilation. A total of 56 Petri dishes were used to evaluate air contamination. Results: All four procedures offered good results but the decontamination time and overall effect varied depending on the chosen method. Fogging was the only method that managed to remove all the identifiable pathogens. Conclusions: Fogging proved to be superior from a medical point of view, while the UVC air circulation unit proved to be more efficient from a management point of view.

Active and Strippable PVA/Borax/NaBO3 Hydrogel for Effective Containment and Decontamination of Chemical Warfare Agents.

Active gels present unique potential for the decontamination of chemical warfare agents (CWAs) as they strongly adhere to surfaces, thus allowing prolonged decontamination time. Herein, we present a decontamination hydrogel based on polyvinyl alcohol/borax, which contains sodium perborate (NaBO3), as an in situ source of the active ingredient hydrogen peroxide. Developed as a binary formulation, this gel instantly forms and effectively sticks when sprayed on various matrices, including porous and vertically positioned matrices. The gel efficiently detoxified the CWAs sarin (GB), O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate (VX), and sulfur mustard (HD) in test tubes (2 μL CWA/0.5 mL gel) to provide nontoxic products with reaction half-lives of <3, 45 and 113 min, respectively. The gel was also shown to efficiently decontaminate surfaces contaminated with VX (5–7 mg, 8–12 mL of gel, i.e., >99%) and to prevent GB evaporation, as proven by laboratory wind tunnel experiments. The universal decontamination abilities of this mild hydrogel, as well as its facile application and removal processes suggest that it holds high potential for future development as a new CWA decontamination tool.

Propellant Off-Gassing and Implications for Triage and Rescue.

INTRODUCTION: Hypergolic propellants can be released in large amounts during space launch contingencies. Whether propellant-contaminated suit fabric poses a significant risk to rescue crews, due to off-gassing, has not been explored in detail. In this study, we addressed this issue experimentally, exposing space suit fabric to propellants (dinitrogen tetroxide [N₂O₄] and monomethyl hydrazine [MMH]).METHODS: The NASA Space Shuttle Program Advanced Crew Escape System II (ACES II) is similar to the NASA Orion Crew Survival System (OCSS) and was utilized here. Suit fabric was placed and sealed into permeation cells. Fabric exterior surface was exposed to constant concentrated hypergolics, simulating permeation and leakage. Fabric was rinsed, and permeation and off-gassing kinetics were measured. Experimental parameters were selected, simulating suited flight crewmembers during an evacuation transport without cabin air flow.RESULTS: The fabric allows for immediate permeation of liquid or vaporized MMH and N₂O₄. NO₂ off-gassing never exceeded the AEGL-1 8-h level (acute exposure guideline level). In contrast, MMH off-gassing levels culminated in peak levels, approaching AEGL-2 10-min levels, paralleling the drying process of the fabric layers. DISCUSSION: Our findings demonstrate that MMH off-gassing is promoted by the drying of suit material in a delayed fashion, resulting in MMH concentrations having the potential for adverse health effects for flight and rescue crews. This indicates that shorter decontamination times could be implemented, provided that suit material is either kept moist to prevent off-gassing or removed prior to medical evacuation. Additional studies using OCSS or commercial crew suits might be needed in the future.Schwertz H, Roth LA, Woodard D. Propellant off-gassing and implications for triage and rescue. Aerosp Med Hum Perform. 2020; 91(12):956961.

UV-C tower for point-of-care decontamination of filtering facepiece respirators

BackgroundFiltering facepiece respirators (FFR) are critical for protecting essential personnel and limiting the spread of disease. Due to the current COVID-19 pandemic, FFR supplies are dwindling in many health systems, necessitating re-use of potentially contaminated FFR. Multiple decontamination solutions have been developed to meet this pressing need, including systems designed for bulk decontamination of FFR using vaporous hydrogen peroxide or ultraviolet-C (UV-C) radiation. However, the large scale on which these devices operate may not be logistically practical for small or rural health care settings or for ad hoc use at points-of-care.MethodsHere, we present the Synchronous UV Decontamination System, a novel device for rapidly deployable, point-of-care decontamination using UV-C germicidal irradiation. We designed a compact, easy-to-use device capable of delivering over 2 J cm2 of UV-C radiation in one minute.ResultsWe experimentally tested Synchronous UV Decontamination System' microbicidal capacity and found that it eliminates near all virus from the surface of tested FFRs, with less efficacy against pathogens embedded in the inner layers of the masks.ConclusionsThis short decontamination time should enable care-providers to incorporate decontamination of FFR into a normal donning and doffing routine following patient encounters.

Development of a prototype dry decontamination method for particulate contamination: The DryCon system.

This article describes the development of a prototype dry decontamination system (DryCon) for use in the event of a contamination incident involving a particulate contaminant. Disrobing and showering is currently recommended almost exclusively in mass decontamination, although it may not be feasible when water is scarce, in cold weather environments, or when there may be compliance issues with the requirement to disrobe, ie, unwillingness to disrobe. During disrobing, dust particles could also re-aerosolize, leading to inhalation of contaminants. The DryCon prototype uses air jets for dry decontamination. The system is portable and can run on building-supplied 220-V power or generator power. Multiple contaminated persons can be treated rapidly, one after the other, using this system. We tested DryCon in a controlled environment, using a manikin and three different types of fabric squares to investigate its effectiveness, with a decontamination time of 60 seconds. At the higher airflow tested, ie, 90 percent of full blower speed or approximately 540 cfm (15 m3/minute), mean decontamination efficiencies of 56.8 percent, 70.3 percent, and 80.7 percent were measured for firefighter (FF) turnout fabric, cotton denim, and polyester double knit fabric, respectively. Removal of this easily re-aerosolized fraction of the contaminants helps protect contaminated people, as well as healthcare providers they come in contact with, from the potential risk of further inhalation exposures from the re-aerosolization caused by doffing clothing. The results demonstrate the promise of the DryCon system for use where water is not available, as a first step prior to wet decontamination, or in an industrial setting for post-work-shift decontamination. Further lab and field research will be necessary to prove the effectiveness of this technique in real-world applications and to determine if respiratory protection or other personal protective equipment (PPE) is needed during use of the DryCon system.

A predictive model of the temperature-dependent inactivation of coronaviruses.

The COVID-19 pandemic has stressed healthcare systems and supply lines, forcing medical doctors to risk infection by decontaminating and reusing single-use personal protective equipment. The uncertain future of the pandemic is compounded by limited data on the ability of the responsible virus, SARS-CoV-2, to survive across various climates, preventing epidemiologists from accurately modeling its spread. However, a detailed thermodynamic analysis of experimental data on the inactivation of SARS-CoV-2 and related coronaviruses can enable a fundamental understanding of their thermal degradation that will help model the COVID-19 pandemic and mitigate future outbreaks. This work introduces a thermodynamic model that synthesizes existing data into an analytical framework built on first principles, including the rate law for a first-order reaction and the Arrhenius equation, to accurately predict the temperature-dependent inactivation of coronaviruses. The model provides much-needed thermal decontamination guidelines for personal protective equipment, including masks. For example, at 70 °C, a 3-log (99.9%) reduction in virus concentration can be achieved, on average, in 3 min (under the same conditions, a more conservative decontamination time of 39 min represents the upper limit of a 95% interval) and can be performed in most home ovens without reducing the efficacy of typical N95 masks as shown in recent experimental reports. This model will also allow for epidemiologists to incorporate the lifetime of SARS-CoV-2 as a continuous function of environmental temperature into models forecasting the spread of the pandemic across different climates and seasons.

High‐Efficiency Particulate Air Filters in the Era of COVID‐19: Function and Efficacy

Aerosol-generating procedures in the office represent a major concern for health care-associated infection of patients and health care providers by SARS-CoV-2, the causative agent for coronavirus disease 2019 (COVID-19). Although the Centers for Disease Control and Prevention has not yet provided any recommendations for the use of portable air purifiers, air purifiers with high-efficiency particulate air (HEPA) filters have been discussed as an adjunctive means for decontamination of SARS-CoV-2 aerosols in health care settings. This commentary discusses HEPA filter mechanisms of action, decontamination time based on efficiency and flow rate, theoretical application to SARS-CoV-2, and limitations. HEPA filter functionality and prior guidance from the Centers for Disease Control and Prevention for SARS-CoV-1 suggest theoretical efficacy for HEPA filters to decontaminate airborne SARS-CoV-2, although direct studies for SARS-CoV-2 have not been performed. Any portable HEPA purifier utilization for SARS-CoV-2 should be considered an adjunctive infection control measure and undertaken with knowledge of HEPA filter functionality and limitations in mind.