Microwave-Generated Steam Decontamination of N95 Respirators Utilizing Universally Accessible Materials

Zulauf, Katelyn E.; Green, Alex B; Nguyen, Alex; Jagdish, Tanush; Reif, Dvir; Seeley, R.; Dale, Alana

doi:10.1101/2020.04.22.20076117

Cited by 13 publications

(16 citation statements)

References 18 publications

(26 reference statements)

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“…In the 18 MS2 results 22,23,44,56,64,66,72 , UVGI for 1-10 minutes did not achieve >3 log reduction, nor did 70°C dry heat for 15-30 minutes. Steam for 10 seconds -15 minutes did achieve >3 log reduction.…”

Section: Mask Disinfectionmentioning

confidence: 80%

A systematic review of mask disinfection and reuse for SARS-CoV-2 (through July 10, 2020)

Rothe

Rohm

Mitchell

et al. 2020

Preprint

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We conducted a systematic review of hygiene intervention effectiveness against SARS-CoV-2, including developing inclusion criteria, conducting the search, selecting articles for inclusion, and summarizing included articles. We reviewed 104,735 articles, and 109 articles meeting inclusion criteria were identified, with 33 additional articles identified from reference chaining. Herein, we describe results from 58 mask disinfection and reuse studies, where the majority of data were collected using N95 masks. Please note, no disinfection method consistently removed >3 log of virus irrespective of concentration, contact time, temperature, and humidity. However, results show it is possible to achieve >3 log reduction of SARS-CoV-2 using appropriate concentrations and contact times of chemical (ethanol, hydrogen peroxide, peracetic acid), radiation (PX-UV, UVGI), and thermal (autoclaving, heat) disinfection on N95 masks. N95 mask reuse and failure data indicate that hydrogen peroxide, heat, and UV-GI are promising for mask reuse, peracetic acid and PX-UV need more data, and autoclaving and ethanol lead to mask durability failures. Data on other mask types is limited. We thus recommend focusing guidelines and further research on the use of heat, hydrogen peroxide, and UVGI for N95 mask disinfection/reuse. All of these disinfection options could be investigated for use in LMIC and humanitarian contexts.TOC ArtSynopsisIn resource-limited contexts, N95s are reused. We recommend using heat, hydrogen peroxide, or UVGI to disinfect and reuse N95 masks.

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Section: Mask Disinfectionmentioning

confidence: 80%

A systematic review of mask disinfection and reuse for SARS-CoV-2 (through July 10, 2020)

Rothe

Rohm

Mitchell

et al. 2020

Preprint

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“…Throughout the pandemic, a number of academic institutions have collaborated with industry partners to find effective methods to decontaminate medical grade PPE with varying degrees of success [4,5]. Here, we have used a commercial ozone disinfection cabinet to test the effect of two different ozone treatments on the survival of the MS2 bacteriophage.…”

Section: Introductionmentioning

confidence: 99%

“…Here, we have used a commercial ozone disinfection cabinet to test the effect of two different ozone treatments on the survival of the MS2 bacteriophage. A non-enveloped, single-stranded RNA virus, the MS2 bacteriophage has been proposed as a conservative surrogate for the SARS-CoV-2 virus, as nonenveloped viruses are more resistant to decontamination than enveloped, lipid viruses [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of an Ozone Disinfecting and Sanitizing Cabinet to Decontaminate a Surrogate Virus for SARS-CoV-2 on N-95 Masks

Beaudry

Mej

et al. 2020

Preprint

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Medical demands during the COVID-19 pandemic have triggered a grave shortage of medical-grade personal protective equipment (PPE), especially, N95 respirators. N95 respirators are critical for the personal protection of medical providers and others when being exposed to individuals with infections caused by the SARS-CoV-2 coronavirus. To address the shortage of N95 respirators, innovative methods are needed to decontaminate coronaviruses from N95 respirators, allowing them to be safely reused by healthcare workers. For this research, we use a commercial ozone disinfecting cabinet to examine the efficacy of ozone-based disinfection of a conservative surrogate virus for SARS-CoV-2, the MS2 bacteriophage. Treatment of mask materials with enhanced ozone treatment resulted in 2.38-log 10 (>99%) reduction of phage from household dust masks and a range of 1.43-log 10 (96.2%) to 4-log 10 (99.99%) reductions of phage from common N95 mask materials.

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“…In [43] a microwave-oven steam treatment for 3 minutes attained similar results. In [44] a gauze-type surgical mask retained good filtering efficiency of about 0.78, at its most-penetrating particle size, after decontamination using a 3 minute dry heat (rice-cooker) at roughly 155 C.…”

Section: Some Practical Mask Considerationsmentioning

confidence: 56%

Critical levels of mask efficiency and of mask adoption that theoretically extinguish respiratory virus epidemics

Kot

2020

Preprint

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Using a respiratory virus epidemiological model we derive equations for the critical levels of mask efficiency (fraction blocked) and mask adoption (fraction of population wearing masks) that lower the effective reproduction number to unity. The model extends a basic epidemiological model and assumes that a specified fraction of a population dons masks at a given initial number of infections. The model includes a contribution from the ocular (nasolacrimal duct) route, and does not include contributions from contact (fomite) routes. The model accommodates dose-response (probability of infection) functions that are linear or non-linear. Our motivation to study near-population-wide mask wearing arises from the concept that, between two mask wearers, the concentration of particles at inhalation should be the square of the mask penetration fraction. This combination, or team, of masks can provide a strong dose-lowering squaring effect, which enables the use of lower-efficiency, lowercost, lower pressure-drop (easier breathing) masks.For an epidemic with basic reproduction number R 0 =2.5 and with a linear dose-response, the critical mask efficiency is calculated to be 0.5 for a mask adoption level of 0.8 of the population. Importantly, this efficiency is well below that of a N95 mask, and well above that of some fabric masks. Numerical solutions of the model at near-critical levels of mask efficiency and mask adoption demonstrate avoidance of epidemics. To be conservative we use mask efficiencies measured with the mostpenetrating viral-particle sizes. The critical mask adoption level for surgical masks with an efficiency of 0.58 is computed to be 0.73. With surgical masks (or equally efficient substitutes) and 80% and 90% adoption levels, respiratory epidemics with R 0 of about 3 and 4, respectively, would be theoretically extinguished.

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Microwave-Generated Steam Decontamination of N95 Respirators Utilizing Universally Accessible Materials

Cited by 13 publications

References 18 publications

A systematic review of mask disinfection and reuse for SARS-CoV-2 (through July 10, 2020)

A systematic review of mask disinfection and reuse for SARS-CoV-2 (through July 10, 2020)

Effectiveness of an Ozone Disinfecting and Sanitizing Cabinet to Decontaminate a Surrogate Virus for SARS-CoV-2 on N-95 Masks

Critical levels of mask efficiency and of mask adoption that theoretically extinguish respiratory virus epidemics

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