A scalable method of applying heat and humidity for decontamination of N95 respirators during the COVID-19 crisis

Anderegg, Loïc; Meisenhelder, Cole; Ngooi, Chiu Oan; Liao, Lei; Wang, Xiao; Chu, Steven; Cui, Yi; Doyle, John M.

doi:10.1371/journal.pone.0234851

Cited by 58 publications

(81 citation statements)

References 15 publications

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“…The possibility that disposable N95 masks could be sterilized and reused was raised 15 years ago as a strategy to address shortages arising from medical emergencies 3 – 5 , but following an FDA-funded study by the Battelle Memorial Institute 6 , relatively little subsequent research has been performed on the topic 7 – 9 . Recently, in response to acute N95 mask shortages, multiple strategies for mask sterilization have been proposed and studied, including exposure to ultraviolet (UV) germicidal irradiation, vaporized hydrogen peroxide, moist heat, ethylene oxide, and gamma irradiation 7 – 13 . In this study, we evaluate a recently developed technology, ionized hydrogen peroxide (iHP), as a method for sterilizing N95 masks and other PPE.…”

Section: Introductionmentioning

confidence: 99%

Analysis of SteraMist ionized hydrogen peroxide technology in the sterilization of N95 respirators and other PPE

Cramer

Plana

Yang

et al. 2021

Sci Rep

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The COVID-19 pandemic has led to widespread shortages of personal protective equipment (PPE) for healthcare workers, including of N95 masks (filtering facepiece respirators; FFRs). These masks are intended for single use but their sterilization and subsequent reuse has the potential to substantially mitigate shortages. Here we investigate PPE sterilization using ionized hydrogen peroxide (iHP), generated by SteraMist equipment (TOMI; Frederick, MD), in a sealed environment chamber. The efficacy of sterilization by iHP was assessed using bacterial spores in biological indicator assemblies. After one or more iHP treatments, five models of N95 masks from three manufacturers were assessed for retention of function based on their ability to form an airtight seal (measured using a quantitative fit test) and filter aerosolized particles. Filtration testing was performed at a university lab and at a National Institute for Occupational Safety and Health (NIOSH) pre-certification laboratory. The data demonstrate that N95 masks sterilized using SteraMist iHP technology retain filtration efficiency up to ten cycles, the maximum number tested to date. A typical iHP environment chamber with a volume of ~ 80 m3 can treat ~ 7000 masks and other items (e.g. other PPE, iPADs), making this an effective approach for a busy medical center.

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Section: Introductionmentioning

confidence: 99%

Analysis of SteraMist ionized hydrogen peroxide technology in the sterilization of N95 respirators and other PPE

Cramer

Plana

Yang

et al. 2021

Sci Rep

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“…Nine studies 24,26,27,33,37,42,48,49,62 evaluated the effect of moist heat between 60 and 100°C. The method did not alter mask t, odor or comfort.…”

Section: Moist Heat / Pasteurizationmentioning

confidence: 99%

Decontamination methods for respiratory protection mask model N95: a rapid review

Probst

Guerrero

Cardoso

et al. 2020

Preprint

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Background: N95 respiratory protection masks are used by healthcare professionals to prevent contamination with 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 review was carried out in September 2020 using a simplification of the formal systematic review process, which simplified the stages of a complete systematic review, including the exclusion of an assessment of study methodology.Results: A total of 563 articles were retrieved of which 48 laboratory-based studies were selected. Fifteen decontamination methods were included in the studies. Hydrogen peroxide was evaluated by 19 laboratory studies, ultraviolet germicidal irradiation by 21, ethylene oxide by 4, dry heat by 11, moist heat by 9, ethanol by 5, isopropanol solution by 2, microwave oven by 11, sodium hypochlorite by 10, autoclave by 7, electric rice cooker by 3, cleaning wipes by 1, bar soap and water 1, multi-Purpose High-Level Disinfection Cabinet by 1 and chlorine dioxide by 1. Five methods appear promising: hydrogen peroxide vapor, ultraviolet irradiation, dry heat, wet heat/pasteurization, and microwave ovens.Conclusions: Positive results should be considered with caution as they represent a small number of studies, reflect ideal laboratory conditions, and may have limited applicability in realistic situations and for health systems.

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“…2006). Since that time, research has been conducted on a variety of decontamination methods, including physical and chemical options, to extend the supply until additional supplies become available (Viscusi et al 2009;Bergman et al 2010;Fisher et al 2011;Heimbuch et al 2011;Viscusi et al 2011;Lore et al 2012;Heimbuch et al 2014;Lin et al 2018;Mills et al 2018;Anderegg et al 2020;Cadnum et al 2020;Fischer et al 2020;Grinshpun et al 2020;Jatta et al 2020;Li et al 2020;Ma et al 2020;Pauley et al 2020;Schnell et al 2020;Widmer and Richner 2020;Xiang et al 2020;Zulauf et al 2020). Moist heat is one of the methods that was shown to reduce the amount of infectious MS2 phage (Fisher et al 2011;Li et al 2020;Zulauf et al 2020), methicillin-resistant Staphylococcus aureus (MRSA) (Li et al 2020), influenza virus (Heimbuch et al 2011;Lore et al 2012) and avian infectious bronchitis virus (Ma et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, other research on the stability of SARS-CoV-2 on surfaces and in aerosols has shown that the virus loses viability quicker at higher temperatures and relative humidity conditions (Aboubakr et al 2020;Biryukov et al 2020;Schuit et al 2020), suggesting that this approach will be effective for decontamination of FFRs contaminated with SARS-CoV-2. It has also been shown that moist heat often does not degrade FFR performance for collection efficiency and inhalation resistance (Bergman et al 2010;Fisher et al 2011;Viscusi et al 2011;Lore et al 2012;Anderegg et al 2020;Zulauf et al, 2020), though some moist heat conditions have impacted FFR fit or the adhesion of the foam nose pad on certain FFR models (Bergman et al 2010;Viscusi et al 2011;Lore et al 2012). Consistent with these studies, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for moist heat as described in the Steris Steam Decon Cycle in AMSCO Medium Steam Sterilizers (Hinton 2020), and 3M issued a technical bulletin stating that moist heat was an acceptable method for select FFR models (Anon.…”

Section: Introductionmentioning

confidence: 99%

“…Such an approach may be necessary for FFR users who are not in the healthcare profession, as they are less likely to have access to more sophisticated equipment, are not covered by the EUA (Hinton 2020), and are expected to be a lower priority to receive replacement FFRs during a critical shortage. Researchers have used rice cookers, plastic containers, steam bags and convection ovens to generate moist heat, as just a few examples (Fisher et al 2011;Anderegg et al 2020;Li et al 2020;Ma et al 2020;Zulauf et al 2020). The present research was conducted to identify a method of applying moist heat to FFRs that would not exceed the 75°C maximum temperature recommended by 3M and is affordable and accessible to users who are not covered by the EUAs currently in place.…”

Section: Introductionmentioning

confidence: 99%

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

Choi

Richardson

Sunderman

et al. 2020

Lett Appl Microbiol

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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.

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A scalable method of applying heat and humidity for decontamination of N95 respirators during the COVID-19 crisis

Cited by 58 publications

References 15 publications

Analysis of SteraMist ionized hydrogen peroxide technology in the sterilization of N95 respirators and other PPE

Analysis of SteraMist ionized hydrogen peroxide technology in the sterilization of N95 respirators and other PPE

Decontamination methods for respiratory protection mask model N95: a rapid review

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

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