Vapourized Hydrogen Peroxide Decontamination in a Hospital Setting Inactivates SARS-CoV-2 and HCoV-229E without Compromising Filtration Efficiency of Unexpired N95 Respirators

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.

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Scalable in-hospital decontamination of N95 filtering face-piece respirator with a peracetic acid room disinfection system

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.1257 ◽

2020 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Amrita R. John ◽

Shine Raju ◽

Jennifer L. Cadnum ◽

Kipum Lee ◽

Phillip McClellan ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Peracetic Acid ◽

Structural Integrity ◽

Filtration Efficiency ◽

Material Structure ◽

Cycle Duration ◽

Bacteriophage Ms2 ◽

Large Numbers ◽

High Level ◽

N95 Respirators

Abstract Background: Critical shortages of personal protective equipment, especially N95 respirators, during the coronavirus disease 2019 (COVID-19) pandemic continues to be a source of concern. Novel methods of N95 filtering face-piece respirator decontamination that can be scaled-up for in-hospital use can help address this concern and keep healthcare workers (HCWs) safe. Methods: A multidisciplinary pragmatic study was conducted to evaluate the use of an ultrasonic room high-level disinfection system (HLDS) that generates aerosolized peracetic acid (PAA) and hydrogen peroxide for decontamination of large numbers of N95 respirators. A cycle duration that consistently achieved disinfection of N95 respirators (defined as ≥6 log10 reductions in bacteriophage MS2 and Geobacillus stearothermophilus spores inoculated onto respirators) was identified. The treated masks were assessed for changes to their hydrophobicity, material structure, strap elasticity, and filtration efficiency. PAA and hydrogen peroxide off-gassing from treated masks were also assessed. Results: The PAA room HLDS was effective for disinfection of bacteriophage MS2 and G. stearothermophilus spores on respirators in a 2,447 cubic-foot (69.6 cubic-meter) room with an aerosol deployment time of 16 minutes and a dwell time of 32 minutes. The total cycle time was 1 hour and 16 minutes. After 5 treatment cycles, no adverse effects were detected on filtration efficiency, structural integrity, or strap elasticity. There was no detectable off-gassing of PAA and hydrogen peroxide from the treated masks at 20 and 60 minutes after the disinfection cycle, respectively. Conclusion: The PAA room disinfection system provides a rapidly scalable solution for in-hospital decontamination of large numbers of N95 respirators during the COVID-19 pandemic.

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Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital

10.1101/2020.04.28.20084038 ◽

2020 ◽

Cited By ~ 8

Author(s):

Krista R. Wigginton ◽

Peter J. Arts ◽

Herek Clack ◽

William J Fitzsimmons ◽

Mirko Gamba ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Relative Humidity ◽

Hepatitis Virus ◽

Biological Indicators ◽

Biological Indicator ◽

Filtration Efficiency ◽

Full Scale ◽

Moist Heat ◽

N95 Respirators ◽

The Impact

AbstractImportanceFiltering facepiece respirators, including N95 masks, are a critical component of infection prevention in hospitals. Due to unprecedented shortages in N95 respirators, many healthcare systems have explored reprocessing of N95 respirators. Data supporting these approaches are lacking in real hospital settings. In particular, published studies have not yet reported an evaluation of multiple viruses, bacteria, and fungi along with respirator filtration and fit in a single, full-scale study.ObjectiveWe initiated a full-scale study to evaluate different N95 FFR decontamination strategies and their impact on respirator integrity and inactivating multiple microorganisms, with experimental conditions informed by the needs and constraints of the hospital.MethodsWe explored several reprocessing methods using new 3M™ 1860 N95 respirators, including dry (<10% relative humidity) and moist (62-66% relative humidity) heat (80-82 °C) in the drying cycle of industrial instrument washers, ethylene oxide (EtO), pulsed xenon UV (UV-PX), hydrogen peroxide gas plasma (HPGP), and vaporous hydrogen peroxide (VHP). Respirator samples were treated and analyzed for biological indicator inactivation using four viruses (MS2, phi6, influenza A virus, murine hepatitis virus), three bacteria (Escherichia coli, Staphylococcus aureus, Geobacillus stearothermophilus), and the fungus Aspergillus niger. The impact of different application media was also evaluated. In parallel, decontaminated respirators were evaluated for filtration integrity and fit.ResultsVHP resulted in >2 log10 inactivation of all tested biological indicators. The combination of UV-PX + moist heat resulted in >2 log10 inactivation of all biological indicators except G. stearothermohphilus. Greater than 95% filtration efficiency was maintained following 2 (UV-PX + <10% relative humidity heat) or 10 (VHP) cycles of treatment, and proper fit was also preserved. UV-PX + dry heat was insufficient to inactivate all biological indicators. Although very effective at virus decontamination, HPGP resulted in decreased filtration efficiency after 3 cycles, and EtO treatment raised potential toxicity concerns. The observed inactivation of viruses with UV-PX, heat, and hydrogen peroxide treatments varied as a function of which culture media (PBS buffer or DMEM) they were deposited in.Conclusions and RelevanceHigh levels of biological indicator inactivation were achieved following treatment with either moist heat or VHP. These same treatments did not significantly impact mask filtration or fit. Hospitals have a variety of scalable options to safely reprocess N95 masks. Beyond value in the current Covid-19 pandemic, the broad group of microorganisms and conditions tested make these results relevant in potential future pandemic scenarios.

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Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa610 ◽

2020 ◽

Cited By ~ 1

Author(s):

Krista R Wigginton ◽

Peter J Arts ◽

Herek Clack ◽

William J Fitzsimmons ◽

Mirko Gamba ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Influenza A ◽

Hepatitis Virus ◽

Biological Indicator ◽

Filtration Efficiency ◽

University Hospital ◽

Murine Hepatitis Virus ◽

Gas Plasma ◽

Bacteria And Fungi ◽

N95 Respirators

Abstract 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 oC 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 four viruses (MS2, phi6, influenza A virus (IAV), murine hepatitis virus (MHV)), three 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. HPV was moderately effective at inactivating tested viruses, resulting in 1.5 to >4 log10 observable inactivation. S. aureus inactivation by HPV was limited. Filtration efficiency and proper fit were maintained following 5 cycles of heat with moderate RH, and HPV. Although 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. Conclusion Both moist heat and HPV are scalable N95 reprocessing options as they achieve high levels of biological indicator inactivation while maintaining respirator fit and integrity.

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Aerosolized Hydrogen Peroxide Decontamination of N95 Respirators, with Fit-Testing and Virologic Confirmation of Suitability for Re-Use During the COVID-19 Pandemic

10.1101/2020.04.17.20068577 ◽

2020 ◽

Cited By ~ 3

Author(s):

T. Hans Derr ◽

Melissa A. James ◽

Chad V. Kuny ◽

Devanshi Patel ◽

Prem P. Kandel ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Healthcare Providers ◽

Biological Indicators ◽

Filtration Efficiency ◽

Virus Inactivation ◽

Virus Species ◽

Viral Pathogen ◽

Low Concentration ◽

Fit Testing ◽

N95 Respirators

AbstractIn response to the current demand for N95 respirators by healthcare workers responding to the COVID-19 pandemic, we evaluated decontamination of N95 respirators using a low concentration aerosolized hydrogen peroxide (aHP) system. This system dispenses a consistent atomized spray of micron-sized, low concentration, hydrogen peroxide (H2O2) particles over a treatment cycle. Multiple N95 respirator models were subjected to ten or more cycles of respirator decontamination, and masks were periodically assessed for qualitative and quantitative fit testing to verify respirator integrity. In parallel, we assessed the ability of aHP treatment to inactivate multiple viruses absorbed onto masks, including phi6 bacteriophage, HSV-1, CVB3, and SARS-CoV-2. Given that SARS-CoV-2 is transmitted via expired respiratory droplets and aerosols, it is critical to address respirator safety for reuse. This study provided experimental validation of a suitable aHP treatment process that decontaminates the respirators while maintaining N95 function. After ten rounds of aHP treatment, respirators passed N95 filtration efficiency testing. Virus inactivation by aHP was comparable to the sterilization of commercial spore-based biological indicators. These data demonstrate that the aHP process is effective, on the basis of zero failure rate on fit-testing of respirators, effective decontamination of multiple virus species including SARS-CoV-2, successful sterilization of bacterial spores, and filtration efficiency maintained at or greater than 95%. Collectively, these studies support the use of specific aHP decontamination protocol that permits safe reuse of N95 respirators by healthcare providers.ImportanceThe ongoing COVID-19 pandemic has led to unprecedented pressure on healthcare and research facilities to provide adequate personal protective equipment. Given that the current pandemic is caused by a respiratory viral pathogen, the availability of highly protective respirator facepieces is critical to limit inhalation of this virus. While respirator facepieces were designed for single-use and disposal, the pandemic has increased overall demand for N95 respirators, and corresponding manufacturing and supply chain limitations have necessitated the safe reuse of respirators when necessary. The biosafety level 3 (BSL3) facility used in this study regularly utilizes aerosolized hydrogen peroxide (aHP) to decontaminate equipment and spaces. We repurposed this technology for N95 respirator decontamination during the COVID-19 pandemic. Results from virus inactivation, biological indicators, respirator fit testing, and filtration efficiency testing all indicated that the process was effective at rendering N95 respirator safe for reuse.

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The protective performance of reusable cloth face masks, disposable procedure masks, KN95 masks and N95 respirators: Filtration and total inward leakage

PLoS ONE ◽

10.1371/journal.pone.0258191 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0258191

Author(s):

Scott Duncan ◽

Paul Bodurtha ◽

Syed Naqvi

Keyword(s):

Geometric Mean ◽

Particle Diameter ◽

Standing Position ◽

Filtration Efficiency ◽

Protection Factor ◽

Respiratory Illnesses ◽

Particle Penetration ◽

Preventive Health Measure ◽

Materials Used ◽

N95 Respirators

Face coverings are a key component of preventive health measure strategies to mitigate the spread of respiratory illnesses. In this study five groups of masks were investigated that are of particular relevance to the SARS-CoV-2 pandemic: re-usable, fabric two-layer and multi-layer masks, disposable procedure/surgical masks, KN95 and N95 filtering facepiece respirators. Experimental work focussed on the particle penetration through mask materials as a function of particle diameter, and the total inward leakage protection performance of the mask system. Geometric mean fabric protection factors varied from 1.78 to 144.5 for the fabric two-layer and KN95 materials, corresponding to overall filtration efficiencies of 43.8% and 99.3% using a flow rate of 17 L/min, equivalent to a breathing expiration rate for a person in a sedentary or standing position conversing with another individual. Geometric mean total inward leakage protection factors for the 2-layer, multi-layer and procedure masks were <2.3, while 6.2 was achieved for the KN95 masks. The highest values were measured for the N95 group at 165.7. Mask performance is dominated by face seal leakage. Despite the additional filtering layers added to cloth masks, and the higher filtration efficiency of the materials used in disposable procedure and KN95 masks, the total inward leakage protection factor was only marginally improved. N95 FFRs were the only mask group investigated that provided not only high filtration efficiency but high total inward leakage protection, and remain the best option to protect individuals from exposure to aerosol in high risk settings. The Mask Quality Factor and total inward leakage performance are very useful to determine the best options for masking. However, it is highly recommended that testing is undertaken on prospective products, or guidance is sought from impartial authorities, to confirm they meet any implied standards.

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Assessing changes to N95 respirator filtration efficiency, qualitative and quantitative fit, and seal check with repeated vaporized hydrogen peroxide (VHP) decontamination

American Journal of Infection Control ◽

10.1016/j.ajic.2021.11.005 ◽

2022 ◽

Author(s):

Christina F. Yen ◽

Robert Seeley ◽

Patrick Gordon ◽

Lalitha Parameswaran ◽

Sharon B Wright ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Filtration Efficiency ◽

Qualitative And Quantitative

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Scalable In-hospital Decontamination of N95 Filtering Facepiece Respirator with a Peracetic Acid Room Disinfection System

10.1101/2020.04.24.20073973 ◽

2020 ◽

Cited By ~ 1

Author(s):

Amrita R. John ◽

Shine Raju ◽

Jennifer L. Cadnum ◽

Kipum Lee ◽

Phillip McClellan ◽

...

Keyword(s):

Peracetic Acid ◽

Structural Integrity ◽

Filtration Efficiency ◽

Material Structure ◽

Cycle Duration ◽

Bacteriophage Ms2 ◽

Large Numbers ◽

Care Workers ◽

High Level ◽

N95 Respirators

AbstractBackgroundCritical shortages of personal protective equipment (PPE) especially N95 respirators, during the SARS-CoV-2 pandemic continues to be a source of great concern among health care workers (HCWs). Novel methods of N95 filtering facepiece respirator (FFR) decontamination that can be scaled-up for in-hospital use can help address this concern and keep HCWs safe.MethodsA multidisciplinary pragmatic study was conducted to evaluate the use of an ultrasonic room high-level disinfection system (HLDS) that generates aerosolized peracetic acid (PAA) and hydrogen peroxide for decontamination of large numbers of N95 respirators. A cycle duration that consistently achieved disinfection of N95 respirators (defined as ≤ 6 log10 reductions in bacteriophage MS2 and Geobacillus stearothermophilus spores inoculated onto respirators) was identified. The treated masks were then assessed for changes to their hydrophobicity, material structure, strap elasticity, and filtration efficiency (FE). Assessment of PAA off-gassing from a treated mask was also performed.ResultsThe PAA room HLDS was effective for disinfection of N95 respirators in a 2447 cubic feet room with deploy and dwell times of 16 and 32 minutes respectively, and a total cycle time of 1 hour and 16 minutes. After 5 treatment cycles, no adverse effects were detected on filtration efficiency, structural integrity, or strap elasticity. There was no detectable off-gassing of PAA from the treated masks.ConclusionThe PAA room disinfection system provides a rapidly scalable solution for in-hospital decontamination of large numbers of N95 respirators to meet the needs of HCWs during the SARS-CoV-2 pandemic.

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Ethanol-Drying Regeneration of N95 Respirators

10.1101/2020.04.12.20059709 ◽

2020 ◽

Author(s):

Albert I. Nazeeri ◽

Isaac A. Hilburn ◽

Daw-An Wu ◽

Kabir A. Mohammed ◽

D. Yovan Badal ◽

...

Keyword(s):

Standardized Testing ◽

Rural Areas ◽

Degradation Mechanism ◽

Adsorbed Water ◽

Filtration Efficiency ◽

Drying Methods ◽

Routine Practice ◽

Filter Efficiency ◽

Filtering Efficiency ◽

N95 Respirators

AbstractA critical shortage of respirators, masks and other personal protective equipment (PPE) exists due to the COVID-19 pandemic. Of particular need are N95 respirators, which use meltblown microfibers of charged polypropylene. An intensive search is underway to find reliable methods to lengthen the useful life of these normally disposable units.Recent experiments on respirators cleaned with ethanol solutions found drastic post-treatment drops infiltration efficiency (>40%). This has been attributed to a mechanism whereby ethanol disrupts the charges in the microfibers, reducing their ability to trap particles. The CDC/NIOSH has issued guidance directing clinicians and researchers to pursue other methods of decontamination.In our experiments, we replicated the drop in efficiency after 70% ethanol treatment, but we found that the efficiency rose again after more effective drying, which we achieved with a vacuum chamber. After drying at pressures of < ∼6 mbar (0.6 kPa), the measured filtering efficiency rose to within 2% of the pre-washing value, and we found that this was sustained for 5 cleaning-drying cycles in three models of N95 masks. We stress that our tests are not meant to certify that the respirators are safe for use, which would require further, standardized, testing under NIOSH protocols. The tests presented here are used to understand basic mechanisms by which treatments can decrease or increase filtration efficiency.The main mechanism underlying the loss and recovery of filter efficiency seems to be the deposition and removal of water molecules adsorbed on the fiber surfaces, a hypothesis which is supported by several observations: (A) the filtering efficiency increases non-linearly with the weight loss during drying. (B) filtration efficiency shows an abrupt recovery as the vacuum pressure drops from 13 to 6 mbar, the range physically attributable to the removal of adsorbed water. (C) Optical microscopy of the microfiber layer reveals surface wetting of the fibers, which is most resistant to drying in dense regions of the fiber network. These observations indicate that losses in filter efficiency may be caused by the wicking of water into the dense fiber networks, reducing the available surface area for filtration.Such a degradation mechanism has two implications: (A) Ethanol and other aqueous decontamination methods may be more viable than previously assumed. Investigations of such methods should specify drying methods in their protocols. We employ vacuum chambers in this study, but other methods of removing adsorbed water could be equivalent. (B) This mechanism presents the possibility that mask filtration performance may be subject to degradation by other sources of moisture, and that the mask would continue to be compromised even if it appears dry. Further research is needed to determine the conditions under which such risks apply, and whether drying should be a routine practice for respirators undergoing extended use.This study introduces a number of methods which could be developed and validated for use in resource-limited settings. As the pandemic continues to spread in rural areas and developing nations, these would allow for local efforts to decontaminate, restore, and test medical masks.

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Analysis of SteraMist ionized hydrogen peroxide technology in the sterilization of N95 respirators and other PPE: a quality improvement study

10.1101/2020.04.19.20069997 ◽

2020 ◽

Cited By ~ 3

Author(s):

Avilash K. Cramer ◽

Deborah Plana ◽

Helen Yang ◽

Mary M. Carmack ◽

Enze Tian ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Personal Protective Equipment ◽

Occupational Safety ◽

Medical Center ◽

Academic Medical Center ◽

Biological Indicator ◽

Protective Equipment ◽

Pre Treatment ◽

Environment Chamber ◽

N95 Respirators

AbstractObjectiveThe COVID-19 pandemic has led to widespread shortages of personal protective equipment (PPE) for healthcare workers, including filtering facepiece respirators (FFRs) such as N95 masks. These masks are normally intended for single use, but their sterilization and subsequent reuse could substantially mitigate a world-wide shortage.DesignQuality assurance.SettingA sealed environment chamber installed in the animal facility of an academic medical center.InterventionsOne to five sterilization cycles using ionized hydrogen peroxide (iHP), generated by SteraMist® equipment (TOMI; Frederick, MD).Main outcome measuresPersonal protective equipment, including five N95 mask models from three manufacturers, were evaluated for efficacy of sterilization following iHP treatment (measured with bacterial spores in standard biological indicator assemblies). Additionally, N95 masks were assessed for their ability to efficiently filter particles down to 0.3µm and for their ability to form an airtight seal using a quantitative fit test. Filtration efficiency was measured using ambient particulate matter at a university lab and an aerosolized NaCl challenge at a National Institute for Occupational Safety and Health (NIOSH) pre-certification laboratory.ResultsThe data demonstrate that N95 masks sterilized using SteraMist iHP technology retain function up to five cycles, the maximum number tested to date. Some but not all PPE could also be sterilized using an iHP environmental chamber, but pre-treatment with a handheld iHP generator was required for semi-enclosed surfaces such as respirator hoses.ConclusionsA typical iHP environment chamber with a volume of ~80 m3 can treat ~7000 masks per day, as well as other items of PPE, making this an effective approach for a busy medical center.

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