It's not the heat, it's the humidity: Effectiveness of a rice cooker-steamer for decontamination of cloth and surgical face masks and N95 respirators

Evaluation of steam heat as a decontamination approach for SARS-CoV-2 when applied to common transit-related materials

AIMS

The purpose of this study was to evaluate the efficacy of steam heat for inactivation of SARS-CoV-2 when applied to materials common in mass transit installations.

METHODS AND RESULTS

SARS CoV-2 (USA-WA1/2020) was resuspended in either cell culture media or synthetic saliva, inoculated (∼1 × 106 TCID50) onto porous and nonporous materials and subjected to steam inactivation efficacy tests as either wet or dried droplets. The inoculated test materials were exposed to steam heat ranging from 70°C to 90°C. The amount of infectious SARS-CoV-2 remaining after various exposure durations ranging from 1 to 60 s was assessed. Higher steam heat application resulted in higher inactivation rates at short contact times. Steam applied at 1-inch distance (∼90°C at the surface) resulted in complete inactivation for dry inoculum within 2 s of exposure (excluding two outliers of 19 test samples at the 5-s duration) and within 2-30 s of exposure for wet droplets. Increasing the distance to 2 inches (∼70°C) also increased the exposure time required to achieve complete inactivation to 15 or 30 s for materials inoculated with saliva or cell culture media, respectively.

CONCLUSIONS

Steam heat can provide high levels of decontamination (>3 log reduction) for transit-related materials contaminated with SARS-CoV-2 using a commercially available steam generator with a manageable exposure time of 2-5 s.

Conservation Practices for Personal Protective Equipment: A Systematic Review with Focus on Lower-Income Countries

During the start of the COVID-19 pandemic, shortages of personal protective equipment (PPE) necessitated unprecedented and non-validated approaches to conserve PPE at healthcare facilities, especially in high income countries where single-use disposable PPE was ubiquitous. Our team conducted a systematic literature review to evaluate historic approaches for conserving single-use PPE, expecting that lower-income countries or developing contexts may already be uniquely conserving PPE. However, of the 50 included studies, only 3 originated from middle-income countries and none originated from low-income countries. Data from the included studies suggest PPE remained effective with extended use and with multiple or repeated use in clinical settings, as long as donning and doffing were performed in a standard manner. Multiple decontamination techniques were effective in disinfecting single use PPE for repeated use. These findings can inform healthcare facilities and providers in establishing protocols for safe conservation of PPE supplies and updating existing protocols to improve sustainability and overall resilience. Future studies should evaluate conservation practices in low-resource settings during non-pandemic times to develop strategies for more sustainable and resilient healthcare worldwide.

Decontamination of disposable respirators for reuse in a pandemic employing in-situ-generated peracetic acid

BACKGROUND

During shortages of filtering face pieces (FFP) in a pandemic, it is necessary to implement a method for safe reuse or extended use. Our aim was to develop a simple, inexpensive and ecological method for decontamination of disposable FFPs that preserves filtration efficiency and material integrity.

MATERIAL AND METHODS

Contamination of FFPs (3M Aura 9320+) with SARS-CoV-2 (1.15 × 10⁴ PFUs), Enterococcus faecium (>10⁶ CFUs), and physiological nasopharyngeal flora was performed prior to decontamination by submersion in a solution of 6 % acetic acid and 6 % hydrogen peroxide (6%AA/6%HP solution) over 30 minutes. Material integrity was assessed by testing the filtering efficiency, loss of fit and employing electron microscopy.

RESULTS AND DISCUSSION

Decontamination with the 6%AA/6%HP solution resulted in the complete elimination of SARS-CoV-2, E. faecium and physiological nasopharyngeal flora. Material characterization post-treatment showed neither critical material degradation, loss of fit or reduction of filtration efficiency. Electron microscopy revealed no damage to the fibers, and the rubber bands' elasticity was not affected by the decontamination procedure. No concerning residuals of the decontamination procedure were found.

CONCLUSION

The simple application and widespread availability of 6%AA/6%HP solution for decontaminating disposable FFPs make this solution globally viable, including developing and third world countries.

Effectiveness of N95 Masks against SARS-CoV-2: Performance Efficiency, Concerns, and Future Directions

The coronavirus disease 2019 (COVID-19) epidemic, which is caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has continued to spread around the world since December 2019. Healthcare workers and other medical first responders in particular need personal protective equipment to protect their respiratory system from airborne particulates, in addition to liquid splashes to the face. N95 respirator have become a critical component for reducing SARS-CoV-2 transmission and controlling the scale of the COVID-19 pandemic. However, a major dispute concerning the protective performance of N95 respirators has erupted, with a myriad of healthcare workers affected despite wearing N95 masks. This article reviews the most recent updates about the performance of N95 respirators in protecting against the SARS-CoV-2 virus in the present pandemic situation. A brief overview of the manufacturing methods, air filtration mechanisms, stability, and reusability of the mask is provided. A detailed performance evaluation of the mask is studied from an engineering point of view. This Review also reports on a comparative study about the protective performance of all commercially available surgical and respiratory masks used to combat the spread of COVID-19. With the aim of protecting healthcare providers more efficiently, we suggest some potential directions for the development of this respiratory mask that improve the performance efficiency of the mask.

Effect of dry heat treatment between room temperature and 160 °C on surgical masks

The Covid-19 crisis has led to a high demand and use of surgical masks worldwide, causing risks of shortages and pollution. Therefore, decontamination of surgical masks could be an opportunity to reduce these risks. In our study, we applied dry heat to the masks for 15 min at different temperatures and studied the consequences of heat on surface chemistry and fiber morphology. We focus here on the effects of dry heat treatment on the masks and not on the verification of mask disinfection, which has been thoroughly studied in existing literature. The masks that were heated to 70 °C, 100 °C, 130 °C, 140 °C, 150 °C did not show significant changes at the nanometric scale and the standard deviation of the surface temperature of the worn masks is similar to that of the unheated control mask. However we show a slight heating altered the hydrophobicity of the surface, and induced a significative modification of the wetting angle of water droplets. The mask heated to 157 °C has a higher surface temperature standard deviation and fused fibers are observed by scanning electron microscopy. The mask heated to 160 °C melted and then hardened as it cooled making it completely unusable.

What We Are Learning from COVID-19 for Respiratory Protection: Contemporary and Emerging Issues

Infectious respiratory diseases such as the current COVID-19 have caused public health crises and interfered with social activity. Given the complexity of these novel infectious diseases, their dynamic nature, along with rapid changes in social and occupational environments, technology, and means of interpersonal interaction, respiratory protective devices (RPDs) play a crucial role in controlling infection, particularly for viruses like SARS-CoV-2 that have a high transmission rate, strong viability, multiple infection routes and mechanisms, and emerging new variants that could reduce the efficacy of existing vaccines. Evidence of asymptomatic and pre-symptomatic transmissions further highlights the importance of a universal adoption of RPDs. RPDs have substantially improved over the past 100 years due to advances in technology, materials, and medical knowledge. However, several issues still need to be addressed such as engineering performance, comfort, testing standards, compliance monitoring, and regulations, especially considering the recent emergence of pathogens with novel transmission characteristics. In this review, we summarize existing knowledge and understanding on respiratory infectious diseases and their protection, discuss the emerging issues that influence the resulting protective and comfort performance of the RPDs, and provide insights in the identified knowledge gaps and future directions with diverse perspectives.

Reusing and/or reprocessing the N95 face respirator mask or equivalent: An integrative review

OBJECTIVE

to analyze the scientific evidence available on the different reprocessing methods and the necessary conditions for reuse of the N95 face respirator mask or equivalent.

METHOD

an integrative literature review. The PICO strategy was used to elaborate the question. The search was conducted in four databases: PubMed, SciVerse Scopus, WebofScience and EMBASE, considering any period of time.

RESULTS

a total of 32 studies were included from the 561 studies identified, and they were presented in two categories: "Conditions for reuse" and "Reprocessing the masks". Of the evaluated research studies, seven(21.8%) addressed the reuse of the N95 face respirator mask or equivalent and 25(78.1%) evaluated different reprocessing methods, namely: ultraviolet germicidal irradiation(14); hydrogen peroxide(8); vapor methods(14); using dry heat(5) and chemical methods(sodium hypochlorite[6], ethanol[4] and sodium chloride with sodium bicarbonate and dimethyldioxirane[1]). We emphasize that different methods were used in one same article.

CONCLUSION

no evidence was found to support safe reprocessing of face respirator masks. In addition, reuse is contraindicated due to the risk of self-contamination and inadequate sealing.

Impact of ultraviolet germicidal irradiation on new silicone half-piece elastometric respirator (VJR-NMU) performance, structural integrity and sterility during the COVID-19 pandemic

Since the innovation of our new half-piece elastometric respirator, this type of filtering facepiece respirator (FFR) has been used widely in Thailand. Decontamination methods including ultraviolet C (UVC) germicidal irradiation and 70% alcohol have been implemented to decontaminate these respirators. We then examined the inactivation potential of different decontamination processes on porcine epidemic diarrhea virus (PEDV) and numerous bacterial strains, most of which were skin-derived. To enable rigorous integrity of the masks after repeated decontamination processes, fit tests by the Bitrex test, tensile strength and elongation at break were also evaluated. Our results showed that UVC irradiation at a dose of 3 J/cm2 can eradicate bacteria after 60 min and viruses after 10 min. No fungi were found on the mask surface before decontamination. The good fit test results, tensile strength and elongation at break were still maintained after multiple cycles of decontamination. No evidence of physical degradation was found by gross visual inspection. Alcohol (70%) is also an easy and effective way to eradicate microorganisms on respirators. As the current pandemic is expected to continue for months to years, the need to supply adequate reserves of personnel protective equipment (PPE) and develop effective PPE reprocessing methods is crucial. Our studies demonstrated that the novel silicone mask can be safely reprocessed and decontaminated for many cycles by UVC irradiation, which will help ameliorate the shortage of important protective devices in the COVID-19 pandemic era.

Decontaminating N95/FFP2 masks for reuse during the COVID-19 epidemic: a systematic review

BACKGROUND

With the current COVID-19 pandemic, many healthcare facilities have been lacking a steady supply of filtering facepiece respirators. To better address this challenge, the decontamination and reuse of these respirators is a strategy that has been studied by an increasing number of institutions during the COVID-19 pandemic.

METHODS

We conducted a systematic literature review in PubMed, PubMed Central, Embase, and Google Scholar. Studies were eligible when (electronically or in print) up to 17 June 2020, and published in English, French, German, or Spanish. The primary outcome was reduction of test viruses or test bacteria by log3 for disinfection and log6 for sterilization. Secondary outcome was physical integrity (fit/filtration/degradation) of the respirators after reprocessing. Materials from the grey literature, including an unpublished study were added to the findings.

FINDINGS

Of 938 retrieved studies, 35 studies were included in the analysis with 70 individual tests conducted. 17 methods of decontamination were found, included the use of liquids (detergent, benzalkonium chloride, hypochlorite, or ethanol), gases (hydrogen peroxide, ozone, peracetic acid or ethylene oxide), heat (either moist with or without pressure or dry heat), or ultra violet radiation (UVA and UVGI); either alone or in combination. Ethylene oxide, gaseous hydrogen peroxide (with or without peracetic acid), peracetic acid dry fogging system, microwave-generated moist heat, and steam seem to be the most promising methods on decontamination efficacy, physical integrity and filtration capacity.

INTERPRETATION

A number of methods can be used for N95/FFP2 mask reprocessing in case of shortage, helping to keep healthcare workers and patients safe. However, the selection of disinfection or sterilization methods must take into account local availability and turnover capacity as well as the manufacturer; meaning that some methods work better on specific models from specific manufacturers.

SYSTEMATIC REGISTRATION NUMBER

CRD42020193309.

Research on Dry Microwave Heating Infectious Aerosols or Droplets on Respirators

Dramatic shortages of filtering facepiece respirator supplies generally occur following the outbreak of a pandemic such as COVID-19. Here, the decontamination and reuse of respirators are considered. Among decontamination methods, microwave irradiation has great potential because of easy access of microwave ovens. However, can a respirator be heated in a microwave oven for a certain time and then be reused? Herein, we demonstrate that dry microwave irradiation cannot heat infectious aerosols or droplets up to their deactivation temperature. The microwave absorption performance of a single aerosol or droplet was analyzed theoretically. The multiphysics simulation results indicate that a single aerosol or droplet can be barely heated under dry microwave irradiation. Experiments were carried out using a traveling wave system to verify the simulation. Following this, we simulated multiple aerosols and droplets on a respirator material, with the results indicating that the aerosols and droplets were at the same temperature as that of the respirator. Experimental measurements using a microwave oven demonstrated that the temperature increase of an N95 respirator under dry heating is less than 10 °C, which is far less than the temperature required to deactivate the COVID-19 virus. Although dry microwave heating cannot be used to heat the aerosols or droplets, microwave-generated steam has proved effective in deactivating infectious biological organisms. Therefore, to successfully decontaminate a used respirator in a microwave oven, a reservoir with a small amount of water beneath the respirator (or a steam bag to accommodate it) is essential to the decontamination process.

Mask decontamination methods (model N95) for respiratory protection: a rapid review

BACKGROUND

N95 respiratory protection masks are used by healthcare professionals to prevent contamination from infectious microorganisms transmitted by droplets or aerosols.

METHODS

We conducted a rapid review of the literature analyzing the effectiveness of decontamination methods for mask reuse. The database searches were carried out up to September 2020. The systematic review was conducted in a way which simplified the stages of a complete systematic review, due to the worldwide necessity for reliable fast evidences on this matter.

RESULTS

A total of 563 articles were retrieved of which 48 laboratory-based studies were selected. Fifteen decontamination methods were included in the studies. A total of 19 laboratory studies used hydrogen peroxide, 21 studies used ultraviolet germicidal irradiation, 4 studies used ethylene oxide, 11 studies used dry heat, 9 studies used moist heat, 5 studies used ethanol, two studies used isopropanol solution, 11 studies used microwave oven, 10 studies used sodium hypochlorite, 7 studies used autoclave, 3 studies used an electric rice cooker, 1 study used cleaning wipes, 1 study used bar soap, 1 study used water, 1 study used multi-purpose high-level disinfection cabinet, and another 1 study used chlorine dioxide. Five methods that are promising are as follows: hydrogen peroxide vapor, ultraviolet irradiation, dry heat, wet heat/pasteurization, and microwave ovens.

CONCLUSIONS

We have presented the best available evidence on mask decontamination; nevertheless, its applicability is limited due to few studies on the topic and the lack of studies on real environments.

Face masks against COVID-19: Standards, efficacy, testing and decontamination methods

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the novel coronavirus disease 2019 (COVID-19), has caused a global pandemic on a scale not seen for over a century. Increasing evidence suggests that respiratory droplets and aerosols are likely the most common route of transmission for SARS-CoV-2. Since the virus can be spread by presymptomatic and asymptomatic individuals, universal face masking has been recommended as a straightforward and low-cost strategy to mitigate virus transmission. Numerous governments and public health agencies around the world have advocated for or mandated the wearing of masks in public settings, especially in situations where social distancing is not possible. However, the efficacy of wearing a mask remains controversial. This interdisciplinary review summarizes the current, state-of-the-art understanding of mask usage against COVID-19. It covers three main aspects of mask usage amid the pandemic: quality standards for various face masks and their fundamental filtration mechanisms, empirical methods for quantitatively determining mask integrity and particle filtration efficiency, and decontamination methods that allow for the reuse of traditionally disposable N95 and surgical masks. The focus is given to the fundamental physicochemical and engineering sciences behind each aspect covered in this review, providing novel insights into the current understanding of mask usage to curb COVID-19 spread.

The COVID-19 pandemic and N95 masks: reusability and decontamination methods

BACKGROUND

With the current SARS-CoV-2 pandemic, many healthcare facilities are lacking a steady supply of masks worldwide. This emergency situation warrants the taking of extraordinary measures to minimize the negative health impact from an insufficient supply of masks. The decontamination, and reuse of healthcare workers' N95/FFP2 masks is a promising solution which needs to overcome several pitfalls to become a reality.

AIM

The overall aim of this article is to provide the reader with a quick overview of the various methods for decontamination and the potential issues to be taken into account when deciding to reuse masks. Ultraviolet germicidal irradiation (UVGI), hydrogen peroxide, steam, ozone, ethylene oxide, dry heat and moist heat have all been methods studied in the context of the pandemic. The article first focuses on the logistical implementation of a decontamination system in its entirety, and then aims to summarize and analyze the different available methods for decontamination.

METHODS

In order to have a clear understanding of the research that has already been done, we conducted a systematic literature review for the questions: what are the tested methods for decontaminating N95/FFP2 masks, and what impact do those methods have on the microbiological contamination and physical integrity of the masks? We used the results of a systematic review on the methods of microbiological decontamination of masks to make sure we covered all of the recommended methods for mask reuse. To this systematic review we added articles and studies relevant to the subject, but that were outside the limits of the systematic review. These include a number of studies that performed important fit and function tests on the masks but took their microbiological outcomes from the existing literature and were thus excluded from the systematic review, but useful for this paper. We also used additional unpublished studies and internal communication from the University of Geneva Hospitals and partner institutions.

RESULTS

This paper analyzes the acceptable methods for respirator decontamination and reuse, and scores them according to a number of variables that we have defined as being crucial (including cost, risk, complexity, time, etc.) to help healthcare facilities decide which method of decontamination is right for them.

CONCLUSION

We provide a resource for healthcare institutions looking at making informed decisions about respirator decontamination. This informed decision making will help to improve infection prevention and control measures, and protect healthcare workers during this crucial time. The overall take home message is that institutions should not reuse respirators unless they have to. In the case of an emergency situation, there are some safe ways to decontaminate them.

Efficacy of Face Masks Used in Uganda: A Laboratory-Based Inquiry during the COVID-19 Pandemic

With shortages of face masks being reported worldwide, it is critical to consider alternatives to commercially manufactured face masks. This study aimed to test and compare the efficacy of various makes of locally made or homemade cloth face masks obtained from face-mask vendors in Kampala, Uganda, during the COVID-19 pandemic. The testing was performed to assess the bacterial filtration efficiency (BFE), breathability, distance-dependent fitness, and reusability of the locally made or homemade cloth face masks, while considering the most commonly used non-published face-mask decontamination approaches in Uganda. During laboratory experimentation, modified protocols from various face-mask testing organizations were adopted. Ten different face-mask types were experimented upon; each face-mask type was tested four times for every single test, except for the decontamination protocols involving washing where KN95 and surgical face masks were not included. Among the locally made or homemade cloth face masks, the double-layered cloth face masks (described as F) had better BFE and distance-dependent fitness characteristics, they could be reused, and had good breathability, than the other locally made or homemade cloth face masks. Despite these good qualities, the certainty of these face masks protecting wearers against COVID-19 remains subject to viral filtration efficiency testing.

Validation of N95 Filtering Facepiece Respirator Decontamination Methods Available at a Large University Hospital

BACKGROUND

Due to unprecedented shortages in N95 filtering facepiece respirators, healthcare systems have explored N95 reprocessing. No single, full-scale reprocessing publication has reported an evaluation including multiple viruses, bacteria, and fungi along with respirator filtration and fit.

METHODS

We explored reprocessing methods using new 3M 1860 N95 respirators, including moist (50%-75% relative humidity [RH]) heat (80-82°C for 30 minutes), ethylene oxide (EtO), pulsed xenon UV-C (UV-PX), hydrogen peroxide gas plasma (HPGP), and hydrogen peroxide vapor (HPV). Respirator samples were analyzed using 4 viruses (MS2, phi6, influenza A virus [IAV], murine hepatitis virus [MHV)]), 3 bacteria (Escherichia coli, Staphylococcus aureus, Geobacillus stearothermophilus spores, and vegetative bacteria), and Aspergillus niger. Different application media were tested. Decontaminated respirators were evaluated for filtration integrity and fit.

RESULTS

Heat with moderate RH most effectively inactivated virus, resulting in reductions of >6.6-log₁₀ MS2, >6.7-log₁₀ Phi6, >2.7-log₁₀ MHV, and >3.9-log₁₀ IAV and prokaryotes, except for G stearothermohphilus. Hydrogen peroxide vapor was moderately effective at inactivating tested viruses, resulting in 1.5- to >4-log₁₀ observable inactivation. Staphylococcus aureus inactivation by HPV was limited. Filtration efficiency and proper fit were maintained after 5 cycles of heat with moderate RH and HPV. Although it was effective at decontamination, HPGP resulted in decreased filtration efficiency, and EtO treatment raised toxicity concerns. Observed virus inactivation varied depending upon the application media used.

CONCLUSIONS

Both moist heat and HPV are scalable N95 reprocessing options because they achieve high levels of biological indicator inactivation while maintaining respirator fit and integrity.

Validation of N95 Filtering Facepiece Respirator Decontamination Methods Available at a Large University Hospital

BACKGROUND

Due to unprecedented shortages in N95 filtering facepiece respirators, healthcare systems have explored N95 reprocessing. No single, full-scale reprocessing publication has reported an evaluation including multiple viruses, bacteria, and fungi along with respirator filtration and fit.

METHODS

We explored reprocessing methods using new 3M 1860 N95 respirators, including moist (50%-75% relative humidity [RH]) heat (80-82°C for 30 minutes), ethylene oxide (EtO), pulsed xenon UV-C (UV-PX), hydrogen peroxide gas plasma (HPGP), and hydrogen peroxide vapor (HPV). Respirator samples were analyzed using 4 viruses (MS2, phi6, influenza A virus [IAV], murine hepatitis virus [MHV)]), 3 bacteria (Escherichia coli, Staphylococcus aureus, Geobacillus stearothermophilus spores, and vegetative bacteria), and Aspergillus niger. Different application media were tested. Decontaminated respirators were evaluated for filtration integrity and fit.

RESULTS

Heat with moderate RH most effectively inactivated virus, resulting in reductions of >6.6-log10 MS2, >6.7-log10 Phi6, >2.7-log10 MHV, and >3.9-log10 IAV and prokaryotes, except for G stearothermohphilus. Hydrogen peroxide vapor was moderately effective at inactivating tested viruses, resulting in 1.5- to >4-log10 observable inactivation. Staphylococcus aureus inactivation by HPV was limited. Filtration efficiency and proper fit were maintained after 5 cycles of heat with moderate RH and HPV. Although it was effective at decontamination, HPGP resulted in decreased filtration efficiency, and EtO treatment raised toxicity concerns. Observed virus inactivation varied depending upon the application media used.

CONCLUSIONS

Both moist heat and HPV are scalable N95 reprocessing options because they achieve high levels of biological indicator inactivation while maintaining respirator fit and integrity.

Decontamination and Reuse of N95 Filtering Facepiece Respirators: Where Do We Stand?

The coronavirus disease 2019 (COVID-19) pandemic created an extraordinary demand for N95 and similarly rated filtering facepiece respirators (FFR) that remains unmet due to limited stock, production constraints, and logistics. Interest in decontamination and reuse of FFR, a product class designed for single use in health care settings, has undergone a parallel surge due to shortages. A worthwhile decontamination method must provide effective inactivation of the targeted pathogen(s), and preserve particle filtration, mask fit, and safety for a subsequent user. This discussion reviews the background of the current shortage, classification, structure, and functional aspects of FFR, and potentially effective decontamination methods along with reference websites for those seeking updated information and guidance. The most promising techniques utilize heat, hydrogen peroxide, microwave-generated steam, or ultraviolet light. Many require special or repurposed equipment and a detailed operational roadmap specific to each setting. While limited, research is growing. There is significant variation between models with regard to the ability to withstand decontamination yet remain protective. The number of times an individual respirator can be reused is often limited by its ability to maintain a tight fit after multiple uses rather than by the decontamination method itself. There is no single solution for all settings; each individual or institution must choose according to their need, capability, and available resources. As the current pandemic is expected to continue for months to years, and the possibility of future airborne biologic threats persists, the need for plentiful, effective respiratory protection is stimulating research and innovation.

Máscaras caseiras na pandemia de COVID-19: recomendações, características físicas, desinfecção e eficácia de uso

Resumo Objetivo Descrever as recomendações, características físicas, métodos de desinfecção e eficácia de uso de máscaras caseiras na redução da transmissão da COVID-19. Métodos Realizou-se busca nas bases de dados MEDLINE, SciELO e Google Scholar, além das recomendações oficiais de uso. Resultados Foram incluídas 31 referências. A capacidade de filtração de tecidos variou entre 5% e 98%. Tecidos 100% algodão em duas ou três camadas apresentaram eficácia de filtração entre 70% e 99% em estudos in vitro. Máscaras caseiras, cirúrgicas e respiradores apresentaram respirabilidade entre 2,2 e 3,0 Pascal. A capacidade de redução da propagação de microrganismos por pessoas usando máscaras caseiras foi três vezes menor do que usando máscaras cirúrgicas, embora tenha sido superior ao não uso de máscaras. Conclusão A respirabilidade de máscaras caseiras mostrou-se adequada, enquanto a capacidade de filtração parece ser inferior à das máscaras cirúrgicas, mas superior a não se usar máscara. Não há evidências que respaldem a eficácia e efetividade das máscaras caseiras.

Use, re-use or discard? Quantitatively defined variance in the functional integrity of N95 respirators following vaporized hydrogen peroxide decontamination during the COVID-19 pandemic

BACKGROUND

Coronavirus disease 2019 has stretched the ability of many institutions to supply needed personal protective equipment, especially N95 respirators. N95 decontamination and re-use programmes provide one potential solution to this problem. Unfortunately, a comprehensive evaluation of the effects of decontamination on the fit of various N95 models using a quantitative fit test (QNFT) approach is lacking.

AIMS

To investigate the effects of up to eight rounds of vaporized hydrogen peroxide (VHP) decontamination on the fit of N95 respirators currently in use in a hospital setting, and to examine if N95 respirators worn by one user can adapt to the face shape of a second user with no compromise to fit following VHP decontamination.

METHODS

The PortaCount Pro+ Respirator Fit Tester Model 8038 was used to quantitatively define functional integrity, measured by fit, of N95 respirators following decontamination with VHP.

FINDINGS

There was an observable downward trend in the functional integrity of Halyard Fluidshield 46727 N95 respirators throughout eight cycles of decontamination with VHP. Functional integrity of 3M 1870 N95 respirators was reduced significantly after the respirator was worn, decontaminated with VHP, and then quantitatively fit tested on a second user. Furthermore, inconsistencies between qualitative fit test and QNFT results were uncovered that may have strong implications on the fit testing method used by institutions.

CONCLUSIONS

The data revealed variability in the functional integrity of different N95 models after VHP decontamination, and exposed potential limitations of N95 decontamination and re-use programmes.

Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators (FFRs) with moist heat generated by a multicooker

Decontamination of N95 filtering facepiece respirators (FFRs) is a crisis capacity strategy allowed when there are known shortages of FFRs. The application of moist heat is one decontamination method that has shown promise and is the approach approved in the Steris Steam Emergency Use Authorization (EUA). This effort examines the use of multicookers to apply moist heat, as they are available in retail stores and more affordable than methods requiring more sophisticated equipment. Four of five multicooker models examined met the acceptance criteria for the test and one model was selected for inactivation testing. Tests were performed on four different FFR models with SARS‐CoV‐2 suspended in culture media, simulated saliva or simulated lung fluid. Moist heat treatment reduced recoverable titres of SARS‐CoV‐2 virus to levels below the limit of detection in all tests. Furthermore, these four FFR models showed no loss in collection efficiency, inhalation resistance or visual damage after up to 10 decontamination cycles. Two (2) FFR models showed a slight change in strap elasticity (<9%). These data show that moist heat treatment using a multicooker is a viable option for FFR decontamination in a crisis capacity strategy.

Gravity steam reprocessing in healthcare facilities for the reuse of N95 respirators

BACKGROUND

Coronavirus disease 2019 (COVID-19) has significantly impacted the health of millions of people around the world. The shortage of personal protective equipment, including N95 respirators, in hospital facilities has put frontline healthcare professionals at high risk for contracting this virus.

AIM

To develop a reproducible and safe N95 respirator reprocessing method that satisfies all presented regulatory standards and that can be directly implemented by hospitals using existing available equipment.

METHODS

A non-toxic gravity steam reprocessing method has been developed for the reuse of N95 respirators consisting of 30 min of steam treatment at 121°C followed by 30 min of heat drying. Samples of model number 1860, 1860s, 1870+, and 9105 N95 respirators were either collected from hospitals (for microbiology testing) or purchased new (for functionality testing), with all functionality tests (i.e. filter efficiency, fit evaluation, and strap integrity) performed at the Centers for Disease Control and Prevention using standard procedures established by the National Institute for Occupational Safety and Health.

FINDINGS

All tested models passed the minimum filter efficiency of 95% after three cycles of gravity steam reprocessing. The 1870+ N95 respirator model is the most promising model for reprocessing based on its efficient bacterial inactivation coupled with the maintenance of all other key functional respirator properties after multiple reprocessing steps.

CONCLUSIONS

The gravity steam method can effectively reprocess N95 respirators over at least three reprocessing cycles without negatively impacting the functionality requirements set out by regulators. Enabling the reuse of N95 respirators is a crucial tool for managing both the current pandemic and future healthcare crises.

Exploring options for reprocessing of N95 Filtering Facepiece Respirators (N95-FFRs) amidst COVID-19 pandemic: A systematic review

BACKGROUND

There is global shortage of Personal Protective Equipment due to COVID-19 pandemic. N95 Filtering Facepiece Respirators (N95-FFRs) provide respiratory protection against respiratory pathogens including SARS-CoV-2. There is scant literature on reprocessing methods which can enable reuse of N95-FFRs.

AIM

We conducted this study to evaluate research done, prior to COVID-19 pandemic, on various decontamination methods for reprocessing of N95-FFRs.

METHODS

We searched 5 electronic databases (Pubmed, Google Scholar, Crossref, Ovid, ScienceDirect) and 1 Grey literature database (OpenGrey). We included original studies, published prior to year 2020, which had evaluated any decontamination method on FFRs. Studies had evaluated a reprocessing method against parameters namely physical changes, user acceptability, respirator fit, filter efficiency, microbicidal efficacy and presence of chemical residues post-reprocessing.

FINDINGS AND CONCLUSIONS

Overall, we found 7887 records amongst which 17 original research articles were finally included for qualitative analysis. Overall, 21 different types of decontamination or reprocessing methods for N95-FFRs were evaluated. Most commonly evaluated method for reprocessing of FFRs was Ultraviolet (Type-C) irradiation (UVGI) which was evaluated in 13/17 (76%) studies. We found published literature was scant on this topic despite warning signs of pandemic of a respiratory illness over the years. Promising technologies requiring expeditious evaluation are UVGI, Microwave generated steam (MGS) and based on Hydrogen peroxide vapor. Global presence of technologies, which have been given Emergency use authorisation for N95-FFR reprocessing, is extremely limited. Reprocessing of N95-FFRs by MGS should be considered for emergency implementation in resource limited settings to tackle shortage of N95-FFRs.

SYSTEMATIC REVIEW IDENTIFIER

PROSPERO, PROSPERO ID: CRD42020189684, (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020189684).

Dry Heat as a Decontamination Method for N95 Respirator Reuse

A pandemic such as COVID-19 can cause a sudden depletion of the worldwide supply of respirators, forcing healthcare providers to reuse them. In this study, we systematically evaluated dry heat treatment as a viable option for the safe decontamination of N95 respirators (1860, 3M) before their reuse. We found that the dry heat generated by an electric cooker (100 °C, 5% relative humidity, 50 min) effectively inactivated Tulane virus (TV, >5.2-log10 reduction), rotavirus (RV, >6.6-log10 reduction), adenovirus (AdV, >4.0-log10 reduction), and transmissible gastroenteritis virus (TGEV, >4.7-log10 reduction). The respirator integrity (determined on the basis of the particle filtration efficiency and quantitative fit testing) was not compromised after 20 cycles of a 50 min dry heat treatment. On the basis of these results, dry heat decontamination generated by an electric cooker (e.g., rice cookers, instant pots, and ovens) could be an effective and accessible decontamination method for the safe reuse of N95 respirators. We recommend users measure the temperature during decontamination to ensure the respirator temperature can be maintained at 100 °C for 50 min.

Factors associated with the use and reuse of face masks among Brazilian individuals during the COVID-19 pandemic

Objective

to identify the factors associated with the use and reuse of masks among Brazilian individuals in the context of the COVID-19 pandemic.

Method

cross-sectional study conducted in the five Brazilian regions, among adult individuals, via an electronic form disseminated in social media, addressing general information and the use of masks. Bivariate analysis and binary logistic regression were used to identify the factors associated with the use and reuse of masks.

Results

3,981 (100%) individuals participated in the study. In total, 95.5% (CI 95%: 94.8-96.1) reported using masks. Fabric masks were more frequently reported (72.7%; CI 95%: 71.3-74.1), followed by surgical masks (27.8%; CI 95%: 26.5-29.2). The percentage of reuse was 71.1% (CI 95%: 69.7-72.5). Most (55.8%; CI 95%: 51.7-60.0) of those exclusively wearing surgical masks reported its reuse. Being a woman and having had contact with individuals presenting respiratory symptoms increased the likelihood of wearing masks (p≤0.001). Additionally, being a woman decreased the likelihood of reusing surgical masks (p≤0.001).

Conclusion

virtually all the participants reported the use of masks, most frequently fabric masks. The findings draw attention to a risky practice, that of reusing surgical and paper masks. Therefore, guidelines, public policies, and educational strategies are needed to promote the correct use of masks to control and prevent COVID-19.

Recharging and rejuvenation of decontaminated N95 masks

N95 respirators comprise a critical part of the personal protective equipment used by frontline health-care workers and are typically meant for one-time usage. However, the recent COVID-19 pandemic has resulted in a serious shortage of these masks leading to a worldwide effort to develop decontamination and re-use procedures. A major factor contributing to the filtration efficiency of N95 masks is the presence of an intermediate layer of charged polypropylene electret fibers that trap particles through electrostatic or electrophoretic effects. This charge can degrade when the mask is used. Moreover, simple decontamination procedures (e.g., use of alcohol) can degrade any remaining charge from the polypropylene, thus severely impacting the filtration efficiency post-decontamination. In this report, we summarize our results on the development of a simple laboratory setup allowing measurement of charge and filtration efficiency in N95 masks. In particular, we propose and show that it is possible to recharge the masks post-decontamination and recover filtration efficiency.

Last-resort strategies during mask shortages: optimal design features of cloth masks and decontamination of disposable masks during the COVID-19 pandemic

Face masks and respirators are the most widely used intervention measures for respiratory protection. In the wake of COVID-19, in response to shortages and lack of availability of surgical masks and respirators, the use of cloth masks has become a research focus. Various fabrics have been promoted with little evidence-based foundation and without guidelines on design principles for optimal performance. In these circumstances, it is essential to understand the properties, key performance factors, filter mechanisms and evidence on cloth masks materials. The general community might also need to decontaminate and reuse disposable, single-use devices as a last resort. We present an overview of the filter materials, filter mechanisms and effectiveness, key performance factors, and hydrophobicity of the common disposable masks, as well as cloth masks. We also reviewed decontamination methods for disposable respiratory devices. As an alternative to surgical masks and respirators, we recommend a cloth mask made of at least three layers (300-350 threads per inch) and adding a nylon stocking layer over the mask for a better fit. Water-resistant fabrics (polyesters/nylon), blends of fabrics and water-absorbing fabrics (cotton) should be in the outside layer, middle layer/layers and inside layer, respectively. The information outlined here will help people to navigate their choices if facing shortages of appropriate respiratory protection during the COVID-19 pandemic.

Dry heat and microwave-generated steam protocols for the rapid decontamination of respiratory personal protective equipment in response to COVID-19-related shortages

BACKGROUND

In the wake of the SARS-CoV-2 pandemic and unprecedented global demand, clinicians are struggling to source adequate access to personal protective equipment. Respirators can be in short supply, though are necessary to protect workers from SARS-CoV-2 exposure. Rapid decontamination and reuse of respirators may provide relief for the strained procurement situation.

METHOD

In this study, we investigated the suitability of 70°C dry heat and microwave-generated steam (MGS) for reprocessing of FFP2/N95-type respirators, and Type-II surgical face masks. Staphylococcus aureus was used as a surrogate as it is less susceptible than enveloped viruses to chemical and physical processes.

RESULTS

We observed >4 log10 reductions in the viability of dry S. aureus treated by dry heat for 90 min at 70°C and >6 log10 reductions by MGS for 90 s. After 3 reprocessing cycles, neither process was found to negatively impact the bacterial or NaCl filtration efficiency of the respirators that were tested. However, MGS was incompatible with Type-II surgical masks tested, as we confirmed that bacterial filtration capacity was completely lost following reprocessing. MGS was observed to be incompatible with some respirator types due to arcing observed around some types of metal nose clips and by loss of adhesion of clips to the mask.

CONCLUSION

Considering the advantages and disadvantages of each approach, we propose a reprocessing personal protective equipment/face mask workflow for use in medical areas.

Rapid Review of SARS-CoV-1 and SARS-CoV-2 Viability, Susceptibility to Treatment, and the Disinfection and Reuse of PPE, Particularly Filtering Facepiece Respirators

In the COVID-19 pandemic caused by SARS-CoV-2, hospitals are often stretched beyond capacity. There are widespread reports of dwindling supplies of personal protective equipment (PPE), particularly N95-type filtering facepiece respirators (FFRs), which are paramount to protect frontline medical/nursing staff, and to minimize further spread of the virus. We carried out a rapid review to summarize the existing literature on the viability of SARS-CoV-2, the efficacy of key potential disinfection procedures against the virus (specifically ultraviolet light and heat), and the impact of these procedures on FFR performance, material integrity, and/or fit. In light of the recent discovery of SARS-CoV-2 and limited associated research, our review also focused on the closely related SARS-CoV-1. We propose a possible whole-of-PPE disinfection solution for potential reuse that could be rapidly instituted in many health care settings, without significant investments in equipment.

Use, reuse or discard: quantitatively defined variance in N95 respirator integrity following vaporized hydrogen peroxide decontamination during the COVID-19 pandemic

BACKGROUND

COVID-19 has stretched the ability of many institutions to supply needed personal protective equipment, especially N95 respirators. N95 decontamination and reuse programs provide one potential solution to this problem. Unfortunately, a comprehensive evaluation of the effects of decontamination on the integrity of various N95 models using a quantitative fit test (QTFT) approach is lacking.

AIMS

1) To investigate the effects of up to eight rounds of vaporized H2O2 (VHP) decontamination on the integrity of N95 respirators currently in use in a hospital setting. 2) To examine if N95 respirators worn by one user can adapt to the face shape of a second user with no compromise of integrity following VHP decontamination.

METHODS

The PortaCount Pro+ Respirator Fit Tester Model 8038 was used to quantitatively define the integrity, measured by fit, of N95 respirators following decontamination with VHP.

FINDINGS

There was an observable downward trend in the integrity of Halyard Fluidshield 46727 N95 respirators throughout eight cycles of decontamination with VHP. The integrity of 3M 1870 N95 respirators was significantly reduced after the respirator was worn, decontaminated with VHP, and then quantitatively fit tested on a second user. Furthermore, we uncovered inconsistencies between qualitative fit test and QTFT results that may have strong implications on the fit testing method used by institutions.

CONCLUSIONS

Our data revealed variability in the integrity of different N95 models after VHP decontamination and exposed potential limitations of N95 decontamination and reuse programs.

Face Masks and Respirators in the Fight against the COVID-19 Pandemic: A Review of Current Materials, Advances and Future Perspectives

The outbreak of COVID-19 has spread rapidly across the globe, greatly affecting how humans as a whole interact, work and go about their daily life. One of the key pieces of personal protective equipment (PPE) that is being utilised to return to the norm is the face mask or respirator. In this review we aim to examine face masks and respirators, looking at the current materials in use and possible future innovations that will enhance their protection against SARS-CoV-2. Previous studies concluded that cotton, natural silk and chiffon could provide above 50% efficiency. In addition, it was found that cotton quilt with a highly tangled fibrous nature provides efficient filtration in the small particle size range. Novel designs by employing various filter materials such as nanofibres, silver nanoparticles, and nano-webs on the filter surfaces to induce antimicrobial properties are also discussed in detail. Modification of N95/N99 masks to provide additional filtration of air and to deactivate the pathogens using various technologies such as low- temperature plasma is reviewed. Legislative guidelines for selecting and wearing facial protection are also discussed. The feasibility of reusing these masks will be examined as well as a discussion on the modelling of mask use and the impact wearing them can have. The use of Artificial Intelligence (AI) models and its applications to minimise or prevent the spread of the virus using face masks and respirators is also addressed. It is concluded that a significant amount of research is required for the development of highly efficient, reusable, anti-viral and thermally regulated face masks and respirators.

Selection of parameters for thermal coronavirus inactivation - a data-based recommendation

Background: Healthcare workers and large parts of the population are currently using personal protective equipment, such as face masks, to avoid infections with the novel coronavirus SARS-CoV-2. This equipment must be sterilized as gently as possible before reuse. One possibility is thermal inactivation, but professional autoclaves with their high temperatures are often not available or suitable. If the inactivation period is long enough, coronavirus inactivation can also be carried out at relatively low temperatures. The required duration was determined in this study. Material and methods: Data from published thermal inactivation studies on coronaviruses were applied to determine the temperature dependence of the rate constant k(T) for each coronavirus by employing Arrhenius models. Results: The data obtained exhibit large variations, which appear to be at least partially caused by different sample properties. Samples with high protein content or samples in dry air sometimes seem to be more difficult to inactivate. Apart from this, the Arrhenius models describe the thermal inactivation properties well and SARS-CoV and SARS-CoV-2 can even be represented by a combined model. Furthermore, the available data suggest that all samples, including critical ones, can be mathematically included by a worst-case Arrhenius model. Conclusion: Coronaviruses can already be inactivated at relatively low temperatures. For most samples, application times of approximately 32.5, 3.7, and 0.5 minutes will be sufficient at 60°C, 80°C, and 100°C, respectively, for a 5 log-reduction. For difficult conditions, the worst-case model provides significantly longer application times of 490, 55, and 8 minutes for the temperatures mentioned.

Elective, Non-urgent Procedures and Aesthetic Surgery in the Wake of SARS-COVID-19: Considerations Regarding Safety, Feasibility and Impact on Clinical Management

BACKGROUND

The worldwide spread of a novel coronavirus disease (COVID-19) has led to a near total stop of non-urgent, elective surgeries across all specialties in most affected countries. In the field of aesthetic surgery, the self-imposed moratorium for all aesthetic surgery procedures recommended by most international scientific societies has been adopted by many surgeons worldwide and resulted in a huge socioeconomic impact for most private practices and clinics. An important question still unanswered in most countries is when and how should elective/aesthetic procedures be scheduled again and what kind of organizational changes are necessary to protect patients and healthcare workers when clinics and practices reopen. Defining manageable, evidence-based protocols for testing, surgical/procedural risk mitigation and clinical flow management/contamination management will be paramount for the safety of non-urgent surgical procedures.

METHODS

We conducted a MEDLINE/PubMed research for all available publications on COVID-19 and surgery and COVID-19 and anesthesia. Articles and referenced literature describing possible procedural impact factors leading to exacerbation of the clinical evolution of COVID-19-positive patients were identified to perform risk stratification for elective surgery. Based on these impact factors, considerations for patient selection, choice of procedural complexity, duration of procedure, type of anesthesia, etc., are discussed in this article and translated into algorithms for surgical/anesthesia risk management and clinical management. Current recommendations and published protocols on contamination control, avoidance of cross-contamination and procedural patient flow are reviewed. A COVID-19 testing guideline protocol for patients planning to undergo elective aesthetic surgery is presented and recommendations are made regarding adaptation of current patient information/informed consent forms and patient health questionnaires.

CONCLUSION

The COVID-19 crisis has led to unprecedented challenges in the acute management of the crisis, and the wave only recently seems to flatten out in some countries. The adaptation of surgical and procedural steps for a risk-minimizing management of potential COVID-19-positive patients seeking to undergo elective aesthetic procedures in the wake of that wave will present the next big challenge for the aesthetic surgery community. We propose a clinical algorithm to enhance patient safety in elective surgery in the context of COVID-19 and to minimize cross-contamination between healthcare workers and patients. New evidence-based guidelines regarding surgical risk stratification, testing, and clinical flow management/contamination management are proposed. We believe that only the continuous development and broad implementation of guidelines like the ones proposed in this paper will allow an early reintegration of all aesthetic procedures into the scope of surgical care currently performed and to prepare the elective surgical specialties better for a possible second wave of the pandemic.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Face Masks in the New COVID-19 Normal: Materials, Testing, and Perspectives

The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health. Routes of transmission differ, but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse, while being amenable to prevention by the humble face mask. Different types of masks give different levels of protection to the user. The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them, driving individuals to self-produce masks from household items. At the same time, research has been accelerated towards improving the quality and performance of face masks, e.g., by introducing properties such as antimicrobial activity and superhydrophobicity. This review will cover mask-wearing from the public health perspective, the technical details of commercial and home-made masks, and recent advances in mask engineering, disinfection, and materials and discuss the sustainability of mask-wearing and mask production into the future.