Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus

Fischer, Robert J.; Morris, Dylan H.; Doremalen, Neeltje van; Sarchette, Shanda; Matson, M. Jeremiah; Bushmaker, Trenton; Yinda, Claude Kwe; Seifert, Stephanie N.; Gamble, Amandine; Williamson, Brandi N.; Judson, Seth; Wit, Emmie de; Lloyd‐Smith, James O.; Munster, Vincent J.

doi:10.3201/eid2609.201524

Cited by 212 publications

(376 citation statements)

References 7 publications

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“…Six peer-reviewed studies and one non-peer-reviewed study have examined the viability of SARS-CoV-2 ( Table 3 ). Virus viability was assessed on a number of different materials, including glass [ 33 , 36 , 37 ], metal [ 27 , 36 , 37 , 38 , 39 , 40 ], plastic [ 27 , 37 , 38 , 40 ], paper [ 37 ], cardboard [ 27 ], rubber [ 38 , 40 ], wood, and cloth [ 37 ] ( Table 3 ). As observed for SARS-CoV-1, there was marked variation in the viability of SARS-CoV-2 across different types of materials ( Table 3 ).…”

Section: Virus Viabilitymentioning

confidence: 99%

“…Importantly, some studies have determined the viability of SARS-CoV-2 directly on PPE or PPE-derived materials, including FFRs [ 37 , 38 , 39 , 40 ] ( Table 3 ). Fischer et al [ 39 ] reported a ~4.0 log 10 reduction of SARS-CoV-2 on N95 FFR disks after 24 h but, according to Chin et al [ 37 ], it took 7 days to achieve ~4.8 log 10 and ~3.0 log 10 reductions in SARS-CoV-2 infectivity on the inner and outer layers of surgical masks, respectively ( Table 3 ). Notably, while yet to be peer reviewed, the study by Kasloff et al [ 40 ] assessed SARS-CoV-2 viability using a soil load of mucin, bovine serum albumin, and tryptone as the inoculum, said to represent typical infectious body fluids of infected patients.…”

Section: Virus Viabilitymentioning

confidence: 99%

“…Heilingloh et al [ 54 ] inactivated SARS-CoV-2 in a liquid medium (>6.7 log 10 reduction) with an applied UVC dose of 1048 mJ/cm 2 ( Table 4 ). Fischer et al [ 39 ], Smith et al [ 42 ], and the unpublished Ozog et al [ 56 ] studied inactivation on N95 respirators, and UVGI treatment was not entirely efficacious against SARS-CoV-2. In Ozog et al, not all samples tested achieved a ≥3.8 log 10 reduction with UVC at 1500 mJ/cm 2 , with treatment failure common on FFR straps [ 56 ] ( Table 4 ).…”

Section: Disinfectionmentioning

confidence: 99%

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

Derraik

Anderson

Connelly

et al. 2020

IJERPH

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

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Section: Virus Viabilitymentioning

confidence: 99%

Section: Virus Viabilitymentioning

confidence: 99%

Section: Disinfectionmentioning

confidence: 99%

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

Derraik

Anderson

Connelly

et al. 2020

IJERPH

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“…Different filter treatments as microwave-generated steam, warm moist heat and ultraviolet germicidal irradiation at 254 nm were able to determine a >4-log reduction of virus concentration in samples of facepiece respirators inoculated with H1N1 influenza virus. In 93% of cases, the virus was reduced to undetectable levels (13).…”

Section: Discussionmentioning

confidence: 99%

“…These contamination cycles caused light drops in filtration performance; however, the reduction of filtration performance revealed with this method is lower than that observed by a 70% ethanol sterilization cycle leading to alterations of filter structure. The decontamination process carried out with UV rays, on the other hand, did not result in any significant structural alterations of the filter (13).…”

Section: Introductionmentioning

confidence: 85%

Reusability of P3 facial filter in pandemic emergency: a 3D Analysis of a filter microstructure with X-Ray micro-tomography images after dry heat and UV sterilization procedures.

Borro¹,

Raponi²,

Fattore³

et al. 2020

Preprint

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Objective: We sought to evaluate the effects of heating and UltraViolet (UV) sterilization on level 3 protection microstructure (P3) used on disposable filtering facepieces.Intervention: P3 facial filter has been exposed to dry heat and UV sterilization procedures.Methods: P3 facial filter samples underwent standardized sterilisation processes based on dry heat and UV irradiation techniques. We analysed key parameters of internal microstructure, such as fibres thickness and porosity, before and after sterilization using 3D data obtained with a synchrotron radiation based X-ray computed microtomography (Micro-CT). The analyzed filter has two inner layers that we called "finer" and "coarser" layers. The "finer" layer consists of a dense fibers network while the "coarser" layer has a less compact fiber network. Results: Analysis on 3D images showed no statistically significant differences between P3 Filter of Controls and dry heat/UV sterilized samples. In particular, averages fibres thickness in the finer layer of Controls, 60° dry heated and UV irradiated samples group was almost identical for each group. Average fibres thickness for coarser layer of Controls, 60° dry heated and UV irradiated samples group was very similar measuring 19.33 µm (±0.47), 18.33 µm (±0.47) and 18.66 µm (±0.47), respectively. Of note, there was no substantial difference in fibres maximum thickness in the finer layers and coarser layers. For Controls group samples maximum thickness was on average of 11.43 µm (±1.24) in the finer layer and 59.33 µm (±6.79) in the coarser layer. Similarly, 60° dry heated group samples were thickened 12.2 µm (±0.21) in the finer layer and 57.33 µm (±1.24) in the coarser layer, while UV irradiated samples group the mean max thickness is 12.23 µm (±0.90) in the finer layer and 58.00 µm (±6.68) in the coarser layer.Theoretical porosity analysis resulted of 74% and 88%, for finer and coarser layer, respectively. Theoretical porosity of finer layers tend to decrease on dry heat and UV irradiated samples when compared with the respective controls samples.Conclusions: Dry heat and UV sterilization processes do not substantially alter morphometry of the internal microstructure of the P3 filter samples studied with Micro-CT. The current study suggests that safe P3 filter facepiece reusability is theoretically feasible and should be further investigated.

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Filtering Facepiece Respirator (N95 Respirator) Reprocessing

Schumm

Hadaya

Mody

et al. 2021

JAMA

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IMPORTANCE The COVID-19 pandemic has resulted in a persistent shortage of personal protective equipment; therefore, a need exists for hospitals to reprocess filtering facepiece respirators (FFRs), such as N95 respirators. OBJECTIVE To perform a systematic review to evaluate the evidence on effectiveness and feasibility of different processes used for decontaminating N95 respirators. EVIDENCE REVIEW A search of PubMed and EMBASE (through January 31, 2021) was completed for 5 types of respirator-decontaminating processes including UV irradiation, vaporized hydrogen peroxide, moist-heat incubation, microwave-generated steam, and ethylene oxide. Data were abstracted on process method, pathogen removal, mask filtration efficiency, facial fit, user safety, and processing capability. FINDINGS Forty-two studies were included that examined 65 total types of masks. All were laboratory studies (no clinical trials), and 2 evaluated respirator performance and fit with actual clinical use of N95 respirators. Twenty-seven evaluated UV germicidal irradiation, 19 vaporized hydrogen peroxide, 9 moist-heat incubation, 10 microwave-generated steam, and 7 ethylene oxide. Forty-three types of N95 respirators were treated with UV irradiation. Doses of 1 to 2 J/cm 2 effectively sterilized most pathogens on N95 respirators (>10 3 reduction in influenza virus [4 studies], MS2 bacteriophage [3 studies], Bacillus spores [2 studies], Escherichia virus MS2 [1 study], vesicular stomatitis virus [1 study], and Middle East respiratory syndrome virus/SARS-CoV-1 [1 study]) without degrading respirator components. Doses higher than 1.5 to 2 J/cm 2 may be needed based on 2 studies demonstrating greater than 10 3 reduction in SARS-CoV-2. Vaporized hydrogen peroxide eradicated the pathogen in all 7 efficacy studies (>10 4 reduction in SARS-CoV-2 [3 studies] and >10 6 reduction of Bacillus and Geobacillus stearothermophilus spores [4 studies]). Pressurized chamber systems with higher concentrations of hydrogen peroxide caused FFR damage (6 studies), while open-room systems did not degrade respirator components. Moist heat effectively reduced SARS-CoV-2 (2 studies), influenza virus by greater than 10 4 (2 studies), vesicular stomatitis virus (1 study), and Escherichia coli (1 study) and preserved filtration efficiency and facial fit for 11 N95 respirators using preheated containers/chambers at 60°C to 85°C (5 studies); however, diminished filtration performance was seen for the Caron incubator. Microwave-generated steam (1100-W to 1800-W devices; 40 seconds to 3 minutes) effectively reduced pathogens by greater than 10 3 (influenza virus [2 studies], MS2 bacteriophage [3 studies], and Staphylococcus aureus [1 study]) and maintained filtration performance in 10 N95 respirators; however, damage was noted in least 1 respirator type in 4 studies. In 6 studies, ethylene oxide preserved respirator components in 16 N95 respirator types but left residual carcinogenic by-product (1 study). CONCLUSIONS AND RELEVANCE Ultraviolet germicidal irradiation, vaporized h...

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Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus

Cited by 212 publications

References 7 publications

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

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

Reusability of P3 facial filter in pandemic emergency: a 3D Analysis of a filter microstructure with X-Ray micro-tomography images after dry heat and UV sterilization procedures.

Filtering Facepiece Respirator (N95 Respirator) Reprocessing

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