Disinfection of N95 masks artificially contaminated with SARS-CoV-2 and ESKAPE bacteria using hydrogen peroxide plasma: Impact on the reutilization of disposable devices

Comparison of 2 methods for sterilization of filtering facepiece respirators worn for extended periods during the COVID-19 pandemic: An experimental laboratory study

BACKGROUND

During the COVID-19 pandemic, there was a shortage of filtering facepiece respirators (FFR), leading to prolonged use and reuse of FFRs.

METHODS

FFRs were collected in 3 hospitals after extended use (up to 15 or 30days). We assessed the physical characteristics and filtration levels of worn FFRs, before sterilization. Respirators that achieved at least 94% filtration of aerosol particles, nasal clip still attached, had no tears, had preserved elastic bands, and had no dirt were randomized to receive or not receive cleaning before being submitted to hydrogen peroxide plasma gas sterilization.

RESULTS

A total of 1,055 FFRs were collected. Over 85% of them exhibited secured nose clips, preserved strap elasticity, and no tears. However, more than 78% of samples contained dirt, leaving only 101 (19.6%) eligible to undergo sterilization. After sterilization, none of the FFRs in either group achieved minimum filtration, although 72% without cleaning and 80% with cleaning had filtration between 90.0% and 93.9%.

DISCUSSION

A large proportion of FFRs were ineligible for sterilization due to factors unrelated to health care (eg, dirt from makeup).

CONCLUSIONS

Prolonged reuse of FFRs significantly reduced aerosol filtration efficiency. Eligible FFRs did not maintain 94% filtration after sterilization with or without cleaning.

Design optimization and validation of UV-C illumination chamber for filtering facepiece respirators

In this study, we constructed an UV-C illumination chamber using commercially available germicidal lamps and other locally available low-cost components for general-purpose biological decontamination purposes. The illumination chamber provides uniform illumination of around 1 J/cm2 in under 5 min across the chamber. The control mechanism was developed to automate the on/off process and make it more secure minimizing health and other electrical safety. To validate the decontamination efficacy of the UV-C Illumination Chamber we performed the Geobacillus spore strip culture assay. Additionally, we performed the viral load measurement by identifying the COVID-19-specific N-gene and ORF1 gene on surgical masks. The gold standard RT-qPCR measurement was performed to detect and quantify the COVID-19-specific gene on the mask sample. The biochemical assay was conducted on the control and test group to identify the presence of different types of bacteria, and fungi before and after exposure under the illumination chamber. The findings of our study revealed satisfactory decontamination efficacy test results. Therefore, it could be an excellent device in healthcare settings as a disinfection tool for biological decontamination such as SAR-CoV-2 virus, personal protection equipment (PPE), (including n95, k95 respirators, and surgical masks), and other common pathogens.

Ultrafast inactivation of SARS-CoV-2 by 254-nm UV-C irradiation on porous and non-porous media of medical interest using an omnidirectional chamber

Covid-19 has spurred a renewed interest in decontamination techniques for air, objects and surfaces. Beginning in 2020, urgent effort was done to permit the reuse of UV-C for inactivating SARS-CoV-2. However, those studies diverged widely on the dose necessary to reach this goal; until today, the real value of the sensitivity of the virus to a 254-nm illumination is not known precisely. In this study, decontamination was performed in an original UV-C large decontamination chamber (UVCab, ON-LIGHT, France) delivering an omnidirectional irradiation with an average dose of 50 mJ/cm2 in 60 s. Viral inactivation was checked by both cell culture and PCR test. SARS-CoV-2 was inactivated by UV-C light within 3 s on both porous (disposable gown) and non-porous (stainless steel and apron) surfaces. For the porous surface, an irradiation of 5 min was needed to achieve a completely negative PCR signal. The Z value estimating the sensitivity of SARS-CoV-2 to UV-C in the experimental conditions of our cabinet was shown to be > 0.5820 m2/J. These results illustrate the ability of this apparatus to inactivate rapidly and definitively high loads of SARS-CoV-2 deposited on porous or non-porous supports and opens new perspectives on material decontamination using UV-C.

Recycling of disposable single-use face masks to mitigate microfiber pollution

The effectiveness of disposable masks in mitigating the transmission of COVID-19 infection increased the consumption of masks. The cheaper cost and easy accessibility resulted in massive consumption and disposal of non-woven masks. The improper disposal of mask emits microfiber into the environment upon weathering. This research mechanically recycled the disposed-of masks and developed fabric from reclaimed polypropylene (rPP) fibers. Obtained rPP fibers were blended with cotton in different proportions (50/50, 60/40, 70/30 cotton/rPP) to produce rotor-spun yarns and evaluated for their performance. The results of the analysis revealed that the developed blended yarns have enough strength; however, they are inferior to the 100% virgin cotton yarns. Based on its suitability, knitted fabrics were developed from 60/40 cotton/rPP yarn. Along with the physical properties, the microfiber release behavior of the developed fabric was analyzed at its different phases of the lifecycle (wearing, washing, degradation at disposal). The microfiber release was compared with the release characteristics of disposable masks. The results showed that recycled fabrics could release 2.32 microfiber/sq. cm during wearing, 4.91 microfiber/sq. cm in laundry, and 15.50 microfiber/sq. cm at the end-of-life disposal by weathering. In contrast, the mask can release 79.43, 96.07, and 223.66 microfiber/sq. cm, respectively, for use, immediate disposal, and long-term disposal by weathering. Approximately, an 83.17% reduction in the microfiber release was reported when the masks were recycled into fabrics. The compact structure of fabric where the fibers are made into yarn resulted in lesser fiber release. Mechanical recycling of disposable masks is simple, less energy-intensive, less expensive, and can be quickly adopted. However, a 100% elimination of microfiber release was not possible in this method due to the inherent nature of the textiles.

Disinfection efficacy of ozone on ESKAPE bacteria biofilms: Potential use in difficult-to-access medical devices

BACKGROUND

Medical devices can be reservoirs of multidrug-resistant bacteria that may be involved in the acquisition of infections since bacteria with the ability to form biofilms that are difficult to eradicate, mainly in mechanical ventilators. The aim of this work was to evaluate the efficacy of O₃ against biofilms of bacteria ESKAPE group through disinfection studies.

METHODS

The formation of biofilms of ESKAPE group bacteria was induced in vitro. O₃ was injected at different exposure times at a constant dose of 600 mg/h. The recovery of surviving bacteria after O₃ treatment was assessed by bacterial counts and biofilm disruption was analyzed. Finally, the viability and integrity of biofilms after O₃ treatment was determined by confocal laser scanning microscopy (CLSM).

RESULTS

O₃ showed bactericidal activity on biofilms from 12 min/7.68 ppm for A. baumannii and C. freundii. P. aeruginosa, K. pneumoniae and S. aureus were killed after 15 min/9.60 ppm. Correlation analyses showed inversely proportional relationships between the variables "disruption versus O₃". CLSM revealed that death was time-dependent of biofilms upon O₃ exposure. Orthogonal plane analysis showed that bacteria located in the outer region of the biofilms were the ones that initially suffered damage from O₃ exposure.

CONCLUSIONS

Our findings suggest that this method could be an alternative for the disinfection in mechanical ventilators colonized by bacteria biofilm forming.

Mask disinfection using atmospheric pressure cold plasma

OBJECTIVES

Mask usage has increased over the last few years due to the COVID-19 pandemic, resulting in a mask shortage. Furthermore, their prolonged use causes skin problems related to bacterial overgrowth. To overcome these problems, atmospheric pressure cold plasma was studied as an alternative technology for mask disinfection.

METHODS

Different microorganisms (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus spp.), different gases (nitrogen, argon, and air), plasma power (90-300 W), and treatment times (45 seconds to 5 minutes) were tested.

RESULTS

The best atmospheric pressure cold plasma treatment was the one generated by nitrogen gas at 300 W and 1.5 minutes. Testing of breathing and filtering performance and microscopic and visual analysis after one and five plasma treatment cycles, highlighted that these treatments did not affect the morphology or functional capacity of the masks.

CONCLUSION

Considering the above, we strongly believe that atmospheric pressure cold plasma could be an inexpensive, eco-friendly, and sustainable mask disinfection technology enabling their reusability and solving mask shortage.

Cold atmospheric plasma for addressing the COVID-19 pandemic

The coronavirus disease 2019 (COVID-19) pandemic has greatly stressed the global community, exposing vulnerabilities in the supply chains for disinfection materials, personal protective equipment, and medical resources worldwide. Disinfection methods based on cold atmospheric plasma (CAP) technologies offer an intriguing solution to many of these challenges because they are easily deployable and do not require resource-constrained consumables or reagents needed for conventional decontamination practices. CAP technologies have shown great promise for a wide range of medical applications from wound healing and cancer treatment to sterilization methods to mitigate airborne and fomite transfer of viruses. This review engages the broader community of scientists and engineers that wish to help the medical community with the ongoing COVID-19 pandemic by establishing methods to utilize broadly applicable CAP technologies.

A pandemic-induced environmental dilemma of disposable masks: solutions from the perspective of the life cycle

The coronavirus disease 2019 (COVID-19) has swept the world and still afflicts humans. As an effective means of protection, wearing masks has been widely adopted by the general public. The massive use of disposable masks has raised some emerging environmental and bio-safety concerns: improper handling of used masks may transfer the attached pathogens to environmental media; disposable masks mainly consist of polypropylene (PP) fibers which may aggravate the global plastic pollution; and the risks of long-term wearing of masks are elusive. To maximize the utilization and minimize the risks, efforts have been made to improve the performance of masks (e.g., antivirus properties and filtration efficiency), extend their functions (e.g., respiration monitoring and acting as a sampling device), develop new disinfection methods, and recycle masks. Despite that, from the perspective of the life cycle (from production, usage, and discard to disposal), comprehensive solutions are urgently needed to solve the environmental dilemma of disposable masks in both technologies (e.g., efficient use of raw materials, prolonging the service life, and enabling biodegradation) and policies (e.g., stricter industry criteria and garbage sorting).

Effect of five decontamination methods on face masks and filtering facepiece respirators contaminated with Staphylococcus aureus and Pseudomonas aeruginosa

Introduction. In the context of the global pandemic due to SARS-CoV-2, procurement of personal protective equipment during the crisis was problematic. The idea of reusing and decontaminating personal surgical masks in facilities was explored in order to avoid the accumulation of waste and overcome the lack of equipment.

Hypothesis. Our hypothesis is that this work will show the decontamination methods assessed are effective for bacteria, such as Staphylococcus aureus and Pseudomonas aeruginosa .

Aim. We aim to provide information about the effects of five decontamination procedures (UV treatment, dry heat, vaporized H2O2, ethanol treatment and blue methylene treatment) on S. aureus and P. aeruginosa . These bacteria are the main secondary bacterial pathogens responsible for lung infections in the hospital environment.

Methodology. The surgical masks and the filtering facepiece respirators were inoculated with two bacterial strains ( S. aureus ATCC 29213 and P. aeruginosa S0599) and submitted to five decontamination treatments: vaporized H2O2 (VHP), UV irradiation, dry heat treatment, ethanol bath treatment and blue methylene treatment. Direct and indirect microbiology assessments were performed on three positive controls, five treated masks and one negative control.

Results. The five decontaminations showed significant (P<0.05) but different degrees of reductions of S. aureus and P. aeruginosa . VHP, dry heat treatment and ethanol treatment adequately reduced the initial contamination. The 4 min UV treatment allowed only a reduction to five orders of magnitude for face mask respirators. The methylene blue treatment induced a reduction to two orders of magnitude.

Conclusions. The three methods that showed a log10 reduction factor of 6 were the dry heat method, VHP and ethanol bath treatment. These methods are effective and their establishment in the medical field are easy but require economic investment.

Ozone as an alternative decontamination process for N95 facemask and biosafety gowns

COVID-19 pandemic created a global shortage of medical protective equipment. Here, we considered ozone (O₃) a disinfectant alternative due to its potent oxidative activity against biological macromolecules. The O₃ decontamination assays were done using SARS-CoV-2 obtained from patients to produce artificial contamination of N95 masks and biosecurity gowns. The quantification of SARS-CoV-2 was performed before and after exposing the samples to different ozone gas concentrations for times between 5 and 30 min. Viral loads as a function of the O₃ exposure time were estimated from the data obtained by the RT-PCR technique. The genetic material of the virus was no longer detected for any tested concentrations after 15 min of O₃ exposure, which means a disinfection Concentration-Time above 144 ppm min. Vibrational spectroscopies were used to follow the modifications of the polymeric fibers after the O₃ treatment. The results indicate that the N95 masks could be safely reused after decontamination with treatments of 15 min at the established O₃ doses for a maximum of 6 cycles.

Face Mask Wastes as Cementitious Materials: A Possible Solution to a Big Concern

After more than two years wearing surgical masks due to the COVID-19 pandemic, used masks have become a significant risk for ecosystems, as they are producing wastes in huge amounts. They are a potential source of disturbance by themselves and as microplastic contamination in the water system. As 5500 tons of face masks are estimated to be used each year, there is an urgent need to manage them according to the circular economy principles and avoid their inadequate disposal. In this paper, surgical wear masks (WM), without any further pretreatment, have been introduced as addition to mortars up to 5% in the weight of cement. Mechanical and microstructural characterization have been carried out. The results indicate that adding MW to the cement supposes a decrease in the properties of the material, concerning both strength and durability behavior. However, even adding a 5% of WM in weight of cement, the aspect of the mortars is quite good, the flexural strength is not significantly affected, and the strength and durability parameters are maintained at levels that-even lower than the reference-are quite reasonable for use. Provided that the worldwide production of cement is around 4.1 Bt/year, the introduction of a 5% of WM in less than 1% of the cement produced, would make it possible to get rid of the mask waste being produced.

Review of aerosolized hydrogen peroxide, vaporized hydrogen peroxide, and hydrogen peroxide gas plasma in the decontamination of filtering facepiece respirators

BACKGROUND

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to over 170?million cases worldwide with over 33.2?million cases and 594,000 deaths in the US alone as of May 31st, 2021. The pandemic has also created severe shortages of personal protective equipment, particularly of filtering facepiece respirators (FFRs). The Centers for Disease Control and Prevention (CDC) has issued recommendations to help conserve FFRs, as well as crisis standards, including four criteria required for decontamination of the traditionally single use respirators. This review is designed to provide an overview of the current literature on vaporized hydrogen peroxide (vHP), hydrogen peroxide gas plasma (HPGP), and aerosolized hydrogen peroxide (aHP) with respect to each of the four CDC decontamination criteria.

METHODS

PubMed and Medrxiv were queried for relevant articles. All articles underwent a title and abstract screen as well as subsequent full text screen by two blinded reviewers if indicated.

RESULTS

Searches yielded 195 papers, of which, 79 were found to be relevant. Of those, 23 papers presented unique findings and 8 additional articles and technical papers were added to provide a comprehensive review. Overall, while there are potential concerns for all 3 decontamination methods, we found that vHP has the most evidence supporting its use in FFR decontamination consistent with CDC recommendation.

CONCLUSIONS

Future research is recommended to evaluate biological inactivation and real world fit failures after FFR reuse.

Reuse of medical face masks in domestic and community settings without sacrificing safety: Ecological and economical lessons from the Covid-19 pandemic

The need for personal protective equipment increased exponentially in response to the Covid-19 pandemic. To cope with the mask shortage during springtime 2020, a French consortium was created to find ways to reuse medical and respiratory masks in healthcare departments. The consortium addressed the complex context of the balance between cleaning medical masks in a way that maintains their safety and functionality for reuse, with the environmental advantage to manage medical disposable waste despite the current mask designation as single-use by the regulatory frameworks. We report a Workflow that provides a quantitative basis to determine the safety and efficacy of a medical mask that is decontaminated for reuse. The type IIR polypropylene medical masks can be washed up to 10 times, washed 5 times and autoclaved 5 times, or washed then sterilized with radiations or ethylene oxide, without any degradation of their filtration or breathability properties. There is loss of the anti-projection properties. The Workflow rendered the medical masks to comply to the AFNOR S76-001 standard as "type 1 non-sanitory usage masks". This qualification gives a legal status to the Workflow-treated masks and allows recommendation for the reuse of washed medical masks by the general population, with the significant public health advantage of providing better protection than cloth-tissue masks. Additionally, such a legal status provides a basis to perform a clinical trial to test the masks in real conditions, with full compliance with EN 14683 norm, for collective reuse. The rational reuse of medical mask and their end-of-life management is critical, particularly in pandemic periods when decisive turns can be taken. The reuse of masks in the general population, in industries, or in hospitals (but not for surgery) has significant advantages for the management of waste without degrading the safety of individuals wearing reused masks.

Removal effect of DNA contamination by hydrogen peroxide plasma compared to ethylene-oxide gas

We examined the ability of hydrogen peroxide plasma (HPP) to remove DNA contamination, to evaluate whether it is a suitable forensic-grade treatment under ISO 18385. HPP treatment was compared to ethylene-oxide gas (EOG) treatment, which is required by ISO 18385. For the evaluation, commercial control DNA solution and cultured cells sprinkled on Petri dishes were used, and the DNA fragments (214 and 80 bp autosomal DNA fragments and 75 bp Y chromosome fragment) were quantified. HPP treatment was performed up to four times and EOG treatment was performed once. Performing HPP treatment three times was as effective as EOG treatment, with all fragments decreasing to below 1/1,000 in DNA solution. With STR and Y-STR typing, no alleles were detected for three HPP treatments of control DNA using the original amount, i.e., 1 ng. Therefore, HPP appears useful for removing DNA contamination. For cells sprinkled on Petri dishes, the DNA degradation abilities of the HPP and EOG were comparable. However, less DNA was degraded with the HPP and EOG and neither met the ISO criteria. Although the current version of ISO 18385 recommends an evaluation method using cultured cells sprinkled on Petri dishes, it needs to be revised. These findings should be considered when revising ISO 18385.

Infectious Diseases Society of America Guidelines on Infection Prevention for Healthcare Personnel Caring for Patients with Suspected or Known COVID-19

BACKGROUND

Since its emergence in late 2019, SARS-CoV-2 continues to pose a risk to healthcare personnel (HCP) and patients in healthcare settings. Although all clinical interactions likely carry some risk of transmission, human actions like coughing and care activities like aerosol-generating procedures likely have a higher risk of transmission. The rapid emergence and global spread of SARS-CoV-2 continues to create significant challenges in healthcare facilities, particularly with shortages of personal protective equipment (PPE) used by HCP. Evidence-based recommendations for what PPE to use in conventional, contingency, and crisis standards of care continue to be needed. Where evidence is lacking, the development of specific research questions can help direct funders and investigators.

OBJECTIVE

Develop evidence-based rapid guidelines intended to support HCP in their decisions about infection prevention when caring for patients with suspected or known COVID-19.

METHODS

IDSA formed a multidisciplinary guideline panel including frontline clinicians, infectious disease specialists, experts in infection control, and guideline methodologists with representation from the disciplines of public health, medical microbiology, pediatrics, critical care medicine and gastroenterology. The process followed a rapid recommendation checklist. The panel prioritized questions and outcomes. Then a systematic review of the peer-reviewed and grey literature was conducted. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the certainty of evidence and make recommendations.

RESULTS

The IDSA guideline panel agreed on eight recommendations, including two updated recommendations and one new recommendation added since the first version of the guideline. Narrative summaries of other interventions undergoing evaluations are also included.

CONCLUSIONS

Using a combination of direct and indirect evidence, the panel was able to provide recommendations for eight specific questions on the use of PPE for HCP providing care for patients with suspected or known COVID-19. Where evidence was lacking, attempts were made to provide potential avenues for investigation. There remain significant gaps in the understanding of the transmission dynamics of SARS-CoV-2 and PPE recommendations may need to be modified in response to new evidence. These recommendations should serve as a minimum for PPE use in healthcare facilities and do not preclude decisions based on local risk assessments or requirements of local health jurisdictions or other regulatory bodies.

Disinfection methods against SARS-CoV-2: a systematic review

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, has caused millions of deaths worldwide. The virus is transmitted by inhalation of infectious particles suspended in the air, direct deposition on mucous membranes and indirect contact via contaminated surfaces. Disinfection methods that can halt such transmission are important in this pandemic and in future viral infections.

Aim

To highlight the efficacy of several disinfection methods against SARS-CoV-2 based on up-to-date evidence found in the literature.

Methods

Two databases were searched to identify studies that assessed disinfection methods used against SARS-CoV-2. In total, 1229 studies were identified and 60 of these were included in this review. Quality assessment was evaluated by the Office of Health Assessment and Translation's risk-of-bias tool.

Findings

Twenty-eight studies investigated disinfection methods on environmental surfaces, 16 studies investigated disinfection methods on biological surfaces, four studies investigated disinfection methods for airborne coronavirus, and 16 studies investigated methods used to recondition personal protective equipment (PPE).

Conclusions

Several household and hospital disinfection agents and ultraviolet-C (UV-C) irradiation were effective for inactivation of SARS-CoV-2 on environmental surfaces. Formulations containing povidone-iodine can provide virucidal action on the skin and mucous membranes. In the case of hand hygiene, typical soap bars and alcohols can inactivate SARS-CoV-2. Air filtration systems incorporated with materials that possess catalytic properties, UV-C devices and heating systems can reduce airborne viral particles effectively. The decontamination of PPE can be conducted safely by heat and ozone treatment.

Functionalized Masks: Powerful Materials against COVID-19 and Future Pandemics

The outbreak of COVID-19 revealed the vulnerability of commercially available face masks. Without having antibacterial/antiviral activities, the current masks act only as filtering materials of the aerosols containing microorganisms. Meanwhile, in surgical masks, the viral and bacterial filtration highly depends on the electrostatic charges of masks. These electrostatic charges disappear after 8 h, which leads to a significant decline in filtration efficiency. Therefore, to enhance the masks' protection performance, fabrication of innovative masks with more advanced functions is in urgent demand. This review summarizes the various functionalizing agents which can endow four important functions in the masks including i) boosting the antimicrobial and self-disinfectant characteristics via incorporating metal nanoparticles or photosensitizers, ii) increasing the self-cleaning by inserting superhydrophobic materials such as graphenes and alkyl silanes, iii) creating photo/electrothermal properties by forming graphene and metal thin films within the masks, and iv) incorporating triboelectric nanogenerators among the friction layers of masks to stabilize the electrostatic charges and facilitating the recharging of masks. The strategies for creating these properties toward the functionalized masks are discussed in detail. The effectiveness and limitation of each method in generating the desired properties are well-explained along with addressing the prospects for the future development of masks.

Personal protective equipment preservation strategies in the covid-19 era: A narrative review

BACKGROUND

The COVID-19 pandemic has led to personal protective equipment (PPE) supply concerns on a global scale. While efforts to increase production are underway in many jurisdictions, demand may yet outstrip supply leading to PPE shortages, particularly in low resource settings. PPE is critically important for the safety of healthcare workers (HCW) and patients and to reduce viral transmission within healthcare facilities. A structured narrative review was completed to identify methods for extending the use of available PPE as well as decontamination and reuse.

METHODS

Database searches were conducted in MEDLINE and EMBASE for any available original research or review articles detailing guidelines for the safe extended use of PPE, and/or PPE decontamination and reuse protocols prior to September 28, 2020. Grey literature in addition to key websites from the Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), Infection Prevention Association of Canada (IPAC), and the National Health Service (NHS) was also reviewed.

RESULTS

Extended use guidelines support co-locating patients with confirmed COVID-19 within specific areas of healthcare facilities to enable the use of PPE between multiple patients, and reduce PPE requirements outside these areas. Decontamination strategies for N95 respirators and face shields range from individual HCWs using conventional ovens and microwave steam bags at home, to large-scale centralized decontamination using autoclave machines, ultraviolet germicidal irradiation, hydrogen peroxide vapors, or peracetic acid dry fogging systems. Specific protocols for such strategies have been recommended by the US CDC and WHO and are being implemented by multiple institutions across North America. Further studies are underway testing decontamination strategies that have been reported to be effective at inactivating coronavirus and influenza, and on SARs-CoV-2 specifically.

CONCLUSIONS

This narrative review summarizes current extended use guidelines and decontamination protocols specific to COVID-19. Preserving PPE through the implementation of such strategies could help to mitigate shortages in PPE supply, and enable healthcare facilities in low resource settings to continue to operate safely for the remainder of the COVID-19 pandemic.

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.

Potential natural polymer-based nanofibres for the development of facemasks in countering viral outbreaks

The global coronavirus disease 2019 (COVID-19) pandemic has rapidly increased the demand for facemasks as a measure to reduce the rapid spread of the pathogen. Throughout the pandemic, some countries such as Italy had a monthly demand of ca. 90 million facemasks. Domestic mask manufacturers are capable of manufacturing 8 million masks each week, although the demand was 40 million per week during March 2020. This dramatic increase has contributed to a spike in the generation of facemask waste. Facemasks are often manufactured with synthetic materials that are non-biodegradable, and their increased usage and improper disposal are raising environmental concerns. Consequently, there is a strong interest for developing biodegradable facemasks made with for example, renewable nanofibres. A range of natural polymer-based nanofibres has been studied for their potential to be used in air filter applications. This review article examines potential natural polymer-based nanofibres along with their filtration and antimicrobial capabilities for developing biodegradable facemask that will promote a cleaner production.

Decontamination of respirators amid shortages due to SARS-CoV-2

The pandemic created by SARS-CoV-2 has caused a shortage in the supplies of N95 filtering facepiece respirators (FFRs), disposable respirators with at least 95% efficiency to remove non-oily airborne particles, due to increasing cases all over the world. The current article reviewed various possible decontamination methods for FFR reuse including ultraviolet germicidal irradiation (UVGI), hydrogen peroxide vapor (HPV), microwave-generated steam (MGS), hydrogen peroxide gas plasma (HPGP), and 70% or higher ethanol solution. HPV decontamination was effective against bacterial spores (6 log10 reduction of Geobacillus stearothermophilus spores) on FFRs and viruses (> 4 log10 reduction of various types of viruses) on inanimate surfaces, and no degradation of respirator materials and fit has been reported. 70% or higher ethanol decontamination showed high efficacy in inactivation of coronaviruses on inanimate surfaces (> 3.9 log10 reduction) but it was lower on FFRs which filtration efficiency was also decreased. UVGI method had good biocidal efficacy on FFRs (> 3 log10 reduction of H1N1 virus) combined with inexpensive, readily available equipment; however, it was more time-consuming to ensure sufficient reduction in SARS-CoV-2. MGS treatment also provided good viral decontamination on FFRs (> 4 log10 reduction of H1N1 virus) along with less time-intensive process and readily available equipment while inconsistent disinfection on the treated surfaces and deterioration of nose cushion of FFRs were observed. HPGP was a good virucidal system (> 6 log10 reduction of Vesicular stomatitis virus) but filtration efficiency after decontamination was inconsistent. Overall, HPV appeared to be one of the most promising methods based on the high biocidal efficacy on FFRs, preservation of respirator performance after multiple cycles, and no residual chemical toxicity. Nonetheless, equipment cost and time of the HPV process and a suitable operating room need to be considered.

Safety in the practice of decontaminating filtering facepiece respirators: A systematic review

BACKGROUND

Considering the new SARS-CoV-2 pandemic and the potential scarcity of material resources, the reuse of personal protective equipment such as filtering facepiece respirators (FFRs) for N95 filtering or higher is being discussed, mainly regarding the effectiveness and safety of cleaning, disinfection and sterilization processes.

AIM

To analyze the available evidence in the literature on the safety in processing FFRs.

METHODS

A systematic review conducted by searching for studies in the following databases: PubMed, CINAHL, LILACS, CENTRAL, EMBASE, Web of Science, and Scopus.

RESULTS

Forty studies were included in this review. The disinfectant/sterilizing agents most frequently tested at different concentrations and exposure periods were ultraviolet irradiation, vaporized hydrogen peroxide and steam sterilization. Microbial reduction was assessed in 21 (52.5%) studies. The only disinfectants/sterilizers that did not caused degradation of the material-integrity were alcohol, electric cooker, ethylene oxide, and peracetic acid fogging. Exposure to ultraviolet irradiation or microwave generated-steam resulted in a nonsignificant reduction in filter performance.

CONCLUSION

There is a complex relationship between the FFR raw materials and the cycle conditions of the decontamination methods, evidencing the need for validating FFRs by models and manufacturers, as well as the process. Some methods may require additional tests to demonstrate the safety of FFRs for use due to toxicity.

Applications of Cold Atmospheric Pressure Plasma Technology in Medicine, Agriculture and Food Industry

In recent years, cold atmospheric pressure plasma (CAPP) technology has received substantial attention due to its valuable properties including operational simplicity, low running cost, and environmental friendliness. Several different gases (air, nitrogen, helium, argon) and techniques (corona discharge, dielectric barrier discharge, plasma jet) can be used to generate plasma at atmospheric pressure and low temperature. Plasma treatment is routinely used in materials science to modify the surface properties (e.g., wettability, chemical composition, adhesion) of a wide range of materials (e.g., polymers, textiles, metals, glasses). Moreover, CAPP seems to be a powerful tool for the inactivation of various pathogens (e.g., bacteria, fungi, viruses) in the food industry (e.g., food and packing material decontamination, shelf life extension), agriculture (e.g., disinfection of seeds, fertilizer, water, soil) and medicine (e.g., sterilization of medical equipment, implants). Plasma medicine also holds great promise for direct therapeutic treatments in dentistry (tooth bleaching), dermatology (atopic eczema, wound healing) and oncology (melanoma, glioblastoma). Overall, CAPP technology is an innovative, powerful and effective tool offering a broad application potential. However, its limitations and negative impacts need to be determined in order to receive regulatory approval and consumer acceptance.

Repurposing of COVID-19 single-use face masks for pavements base/subbase

The coronavirus (COVID-19) pandemic has not only created a global health crisis, but it is also now threatening the environment. A multidisciplinary collaborative approach is required to fight against the pandemic and reduce the environmental risks associated with the disposal of used personal protective equipment (PPE). This paper explores an innovative way to reduce pandemic-generated waste by recycling the used face masks with other waste materials in civil constructions. In this research, for the first time, a series of experiments, including modified compaction, unconfined compression strength and resilient modulus tests, were conducted on the blends of different percentages of the shredded face mask (SFM) added to the recycled concrete aggregate (RCA) for road base and subbase applications. The experimental results show that RCA mixed with three different percentages (i.e., 1%, 2% and 3%) of SFM satisfied the stiffness and strength requirements for pavements base/subbase. The introduction of the shredded face mask not only increased the strength and stiffness but also improved the ductility and flexibility of RCA/SFM blends. The inclusion of 1% SFM to RCA resulted in the highest values of unconfined compressive strength (216 kPa) and the highest resilient modulus (314.35 MP). However, beyond 2%, increasing the amount of SFM led to a decrease in strength and stiffness.

Pulsed Broad-Spectrum UV Light Effectively Inactivates SARS-CoV-2 on Multiple Surfaces and N95 Material

The ongoing SARS-CoV-2 pandemic has resulted in an increased need for technologies capable of efficiently disinfecting public spaces as well as personal protective equipment. UV light disinfection is a well-established method for inactivating respiratory viruses. Here, we have determined that broad-spectrum, pulsed UV light is effective at inactivating SARS-CoV-2 on multiple surfaces in vitro. For hard, non-porous surfaces, we observed that SARS-CoV-2 was inactivated to undetectable levels on plastic and glass with a UV dose of 34.9 mJ/cm2 and stainless steel with a dose of 52.5 mJ/cm2. We also observed that broad-spectrum, pulsed UV light is effective at reducing SARS-CoV-2 on N95 respirator material to undetectable levels with a dose of 103 mJ/cm2. We included UV dosimeter cards that provide a colorimetric readout of UV dose and demonstrated their utility as a means to confirm desired levels of exposure were reached. Together, the results presented here demonstrate that broad-spectrum, pulsed UV light is an effective technology for the in vitro inactivation of SARS-CoV-2 on multiple surfaces.

Decontamination Strategies for Filtering Facepiece Respirators (FFRs) in Healthcare Organizations: A Comprehensive Review

Filtering facepiece respirators (FFRs) are made for one-time use. A massive shortage of FFRs is widespread during pandemic events and has forced many healthcare organizations to decontaminate them and re-use for a limited time. Many decontamination methods have been proposed for the decontamination of FFRs. This review highlights various aspects of decontamination methods available in the literature. Among various methods available, vaporized hydrogen peroxide, ultraviolet irradiation, and dry heat seem to be the most promising decontaminants for FFRs. On the other hand, microwave, bleach, ethylene oxide, alcohol, hydrogen peroxide liquid, sanitizing wipes, and soap and water are not recommended methods for FFR decontamination.

Technological Scenario for Masks in Patent Database During Covid-19 Pandemic

Since January 2020, the World Health Organization announces COVID-19 outbreak a case of public health emergency of international interest, and declaring it a pandemic on March. Due to the high transmission of this disease, rate precautions have been implemented, such as the use of masks by the population, personal protective equipment (PPE), and safety protocols, mainly to health workers. Thus, we performed a patent review to evaluate the current patents related to the protective mask. The review was carried out in the patent database in the period of May 2019 to May 2020. After the process of screening and eligibility, 563 patents were selected for our analysis according to the aim of the study which used masks such as a PPE against dust particles and pathogens, mostly when it is about airborne transmission, such as viruses and bacteria. Here, an overview of the main materials used in the mask manufacturing and their efficiency was described. The results of the review showed that most of the masks used cotton, nylon, silver fiber fabrics, among others as fabrics to develop the masks. It also makes an analysis of masks composed of nanotechnology which provide high filtration efficiency. Moreover, the review also brought possibilities of masking the population, which already have been done in countries such as China and Korea and ways of sterilization for reuse of PPE during COVID-19 outbreak. Thus, this review can further researchers in the developing of masks to decrease the spread of a pandemic disease. Graphical abstract.

Comparative evaluation of four hydrogen peroxide-based systems to decontaminate N95 respirators

Objective:

Protocols designed to facilitate N95 filtering facepiece respirator (FFR) decontamination by commercial sterilization devices do not recommend that operators verify the device’s performance against pathogens deposited on FFRs. Here, we compared the treatment efficacy of 4 hydrogen peroxide-based systems that were authorized for N95 decontamination during the COVID-19 pandemic.

Methods:

Suspensions prepared from S. aureus ATCC 29213 and 44300, B. subtilis ATCC 6633, a vancomycin-resistant E. faecium isolate (VRE), E. coli ATCC 25922, and P. aeruginosa ATCC 27853 colonies were inoculated onto nine 1-cm² areas on a 3M 1805, 1860, 1860S, 1870+, 8210, 8110S, or 9105S FFR. Contaminated respirators were treated according to protocols recommended by the STERRAD 100NX, Bioquell Z-2, Sterizone VP4, or Clēan Works Mini systems. Decontamination efficacy was determined by comparing colony counts cultured from excised segments of treated and untreated FFR.

Results:

All devices achieved a 6-log reduction in bacterial burden and met FDA sterilization criteria. The Bioquell Z-2 device demonstrated 100% efficacy against both gram-positive and gram-negative organisms with all FFRs tested. Colonies of S. aureus ATCC 29213 and 44300 and VRE were cultivable from up to 9 (100%) of 9 STERRAD 100NX– and Sterizone VP4–treated segments. Viable B. subtilis ATCC 6633 organisms were recovered from 76.0% of STERRAD 100NX–treated FFR segments.

Conclusions:

Variability in decontamination efficacy was noted across devices and FFR types. gram-positive organisms were more difficult to completely eliminate than were gram-negative organisms. Prior to initiating FFR decontamination practices, institutions should verify the effectiveness of their devices and the safety of treated FFR.

Decontamination of N95 respirators against SARS-CoV-2: A scoping review

OBJECTIVES

This scoping review aimed to map and compile the available evidence regarding the effectiveness of decontaminating N95 respirators against the novel coronavirus (SARS-CoV-2).

DATA

We selected studies written in English assessing or discussing the decontamination strategies of N95 respirators against SARS-CoV-2. Two independent researchers performed the search and study screening. A descriptive analysis was carried out considering the study design of the included studies.

SOURCES

PubMed, SCOPUS, and Preprint platforms (bioRxiv and medRxiv).

STUDY SELECTION

We included 55 reports from PubMed and SCOPUS. Nine articles were letters to the editors, 21 were in vitro studies, 16 were literature reviews, and 9 were classified as other study designs. We included 37 preprints. Two articles were letters to the editors, 24 were in vitro studies, 3 were literature reviews, and 8 were classified as other study designs. In general, vaporized hydrogen peroxide and ultraviolet irradiation were the strategies most cited and most promising. However, there is a lack of evidence and consensus related to the best method of N95 respirator decontamination.

CONCLUSION

The evidence regarding decontamination strategies of N95 respirators against SARS-CoV-2 remains scarce. Vaporized hydrogen peroxide and ultraviolet irradiation seem to be the current standard for N95 respirator decontamination.

CLINICAL SIGNIFICANCE

Vaporized hydrogen peroxide and ultraviolet irradiation appear to be the most promising methods for N95 respirator decontamination.

Methods to disinfect and decontaminate SARS-CoV-2: a systematic review of in vitro studies

BACKGROUND

Cleaning is a major control component for outbreaks of infection. However, for the SARS-CoV-2 pandemic, there is limited specific guidance regarding the proper disinfection methods that should be used.

METHODS

We conducted a systematic review of the literature on cleaning, disinfection or decontamination methods in the prevention of SARS-CoV-2.

RESULTS

A total of 27 studies were included, reporting a variety of methods with which the effectiveness of interventions were assessed. Virus was inoculated onto different types of material including masks, nasopharyngeal swabs, serum, laboratory plates and simulated saliva, tears or nasal fluid and then interventions were applied in an attempt to eliminate the virus including chemical, ultraviolet (UV) light irradiation, and heat and humidity. At body temperature (37°C) there is evidence that the virus will not be detectable after 2 days but this can be reduced to non-detection at 30 min at 56°C, 15 min at 65°C and 2 min at 98°C. Different experimental methods testing UV light have shown that it can inactivate the virus. Light of 254-365 nm has been used, including simulated sunlight. Many chemical agents including bleach, hand sanitiser, hand wash, soap, ethanol, isopropanol, guandinium thiocynate/t-octylphenoxypolyethoxyethanol, formaldehyde, povidone-iodine, 0.05% chlorhexidine, 0.1% benzalkonium chloride, acidic electrolysed water, Clyraguard copper iodine complex and hydrogen peroxide vapour have been shown to disinfect SARS-CoV-2.

CONCLUSIONS

Heating, UV light irradiation and chemicals can be used to inactivate SARS-CoV-2 but there is insufficient evidence to support one measure over others in clinical practice.

Decontaminating N95 respirators during the COVID-19 pandemic: simple and practical approaches to increase decontamination capacity, speed, safety and ease of use

Background

The COVID-19 pandemic has caused a severe shortage of personal protective equipment (PPE), especially N95 respirators. Efficient, effective and economically feasible methods for large-scale PPE decontamination are urgently needed.

Aims

(1) to develop protocols for effectively decontaminating PPE using vaporized hydrogen peroxide (VHP); (2) to develop novel approaches that decrease set-up and take-down time while also increasing decontamination capacity; (3) to test decontamination efficiency for N95 respirators heavily contaminated by make-up or moisturizers.

Methods

We converted a decommissioned Biosafety Level 3 laboratory into a facility that could be used to decontaminate N95 respirators. N95 respirators were hung on metal racks, stacked in piles, placed in paper bags or covered with make-up or moisturizer. A VHP® VICTORY™ unit from STERIS was used to inject VHP into the facility. Biological and chemical indicators were used to validate the decontamination process. Findings: N95 respirators individually hung on metal racks were successfully decontaminated using VHP. N95 respirators were also successfully decontaminated when placed in closed paper bags or if stacked in piles of up to six. Stacking reduced the time needed to arrange N95 respirators for decontamination by approximately two-thirds while almost tripling facility capacity. Make-up and moisturizer creams did not interfere with the decontamination process.

Conclusions

Respirator stacking can reduce the hands-on time and increase decontamination capacity. When personalization is needed, respirators can be decontaminated in labelled paper bags. Make up or moisturizers do not appear to interfere with VHP decontamination.

Désinfection à la chaleur humide des respirateurs N95, inactivation du SRAS-CoV-2 et effets sur les propriétés des respirateurs

CONTEXTE:

La demande sans précédent de respirateurs N95 durant la pandémie de maladie à coronavirus 2019 (COVID-19) a entraîné une pénurie mondiale. Nous avons validé un protocole de décontamination rapide et économique répondant aux normes réglementaires afin de permettre la réutilisation sûre de ce type de masque.

MÉTHODES:

Nous avons contaminé 4 modèles courants de respirateurs N95 avec le coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2) et avons évalué l’inactivation virale après une désinfection de 60 minutes à 70 °C et à une humidité relative de 0 %. De même, nous avons étudié l’efficacité de la désinfection thermique, à une humidité relative allant de 0 % à 70 %, de masques contaminés à Escherichia coli . Enfin, nous avons examiné des masques soumis à de multiples cycles de désinfection thermique: nous avons évalué leur intégrité structurelle à l’aide d’un microscope à balayage, et leurs propriétés protectrices au moyen des normes du National Institute for Occupational Safety and Health des États-Unis relatives à la filtration particulaire, à la résistance respiratoire et à l’ajustement.

RÉSULTATS:

Une seule désinfection thermique a suffi pour que le SRAS-CoV-2 ne soit plus décelable sur les masques étudiés. En ce qui concerne les masques contaminés à E. coli , une culture de 24 heures a révélé que la bactérie n’était pratiquement plus décelable sur les masques désinfectés à 70 °C et à une humidité relative de 50 %, contrairement aux masques non désinfectés (densité optique à une longueur d’onde de 600 nm : 0,02 ± 0,02 contre 2,77 ± 0,09; p < 0,001), mais qu’elle persistait sur les masques traités à une humidité relative moindre. Les masques ayant subi 10 cycles de désinfection avaient toujours des fibres de diamètre semblable à celui des fibres des masques non traités, et ils répondaient encore aux normes d’ajustement, de filtration et de résistance respiratoire.

INTERPRÉTATION:

La désinfection thermique a réussi à décontaminer les respirateurs N95 sans compromettre leur intégrité structurelle ni modifier leurs propriétés. Elle pourrait se faire dans les hôpitaux et les établissements de soins de longue durée avec de l’équipement facilement accessible, ce qui réduirait la pénurie de N95.

Effect of moist heat reprocessing of N95 respirators on SARS-CoV-2 inactivation and respirator function

BACKGROUND

Unprecedented demand for N95 respirators during the coronavirus disease 2019 (COVID-19) pandemic has led to a global shortage of these masks. We validated a rapidly applicable, low-cost decontamination protocol in compliance with regulatory standards to enable the safe reuse of N95 respirators.

METHODS

We inoculated 4 common models of N95 respirators with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and evaluated viral inactivation after disinfection for 60 minutes at 70°C and 0% relative humidity. Similarly, we evaluated thermal disinfection at 0% to 70% relative humidity for masks inoculated with Escherichia coli. We assessed masks subjected to multiple cycles of thermal disinfection for structural integrity using scanning electron microscopy and for protective functions using standards of the United States National Institute for Occupational Safety and Health for particle filtration efficiency, breathing resistance and respirator fit.

RESULTS

A single heat treatment rendered SARS-CoV-2 undetectable in all mask samples. Compared with untreated inoculated control masks, E. coli cultures at 24 hours were virtually undetectable from masks treated at 70°C and 50% relative humidity (optical density at 600 nm wavelength, 0.02 ± 0.02 v. 2.77 ± 0.09, p < 0.001), but contamination persisted for masks treated at lower relative humidity. After 10 disinfection cycles, masks maintained fibre diameters similar to untreated masks and continued to meet standards for fit, filtration efficiency and breathing resistance.

INTERPRETATION

Thermal disinfection successfully decontaminated N95 respirators without impairing structural integrity or function. This process could be used in hospitals and long-term care facilities with commonly available equipment to mitigate the depletion of N95 masks.