Table 1.
Decontaminating N95/FFP2 masks for reuse: results of the systematic review 2011–June 2020
| Title | Authors | Intervention | Microorganisms tested | Quantification method | Outcome: log reduction compared to control | Data on physical integrity/fit/filtration/residue | Sterilization/probable disinfection (minimum 3-log reduction for disinfection, 6-log for sterilization) | Method recommended (see text for the definition of this column) | Comments |
|---|---|---|---|---|---|---|---|---|---|
| Liquids | |||||||||
| Cleaning of filtering facepiece respirators contaminated with mucin and Staphylococcus aureus [2] | Heimbuch et al | Benzalkonium chloride (Wipes) | Mucin or Staphylococcus aureus | CFU assay | 3–5 | Fail | Disinfection | No | |
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods [3] | Lin et al | Ethanol 50–95% | Bacillus subtilis spores | CFU assay | N/A, but culture results were positive | N/A | Failed | No | |
| Effect of various decontamination procedures on disposable N95 mask integrity and SARS-CoV-2 infectivity [4] | Smith et al | Ethanol 70% | SARS-CoV-2 | RT-PCR | likely > 3 log | Fail | Disinfection | No | The initial contamination was at 3 log as it was coming from human sample |
| Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus [5] | Fischer et al | Ethanol 70% for 10 min | SARS-CoV-2 (HCoV-19 nCoV-WA1-2020 (MN985325.1)) | TCID50 | 4 | Fail | Disinfection | No | |
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods [3] | Lin et al | Hypochlorite in a 0.54% solution | Bacillus subtilis spores | CFU assay | N/A, but culture results were negative | N/A | Disinfection | N/A | No colonies but no info on log reduction |
| Cleaning of filtering facepiece respirators contaminated with mucin and Staphylococcus aureus [2] | Heimbuch et al | Hypochlorite (Wipes) in a 0.9% solution | S. aureus | CFU assay | 4–5 except for nose pads | Fail | Disinfection and failure | No | All masks had good disinfection except for on the nose pads (less than 2 log reduction) |
| Cleaning of filtering facepiece respirators contaminated with mucin and Staphylococcus aureus [2] | Heimbuch et al | Nonantimicrobial detergent wipes | Mucin or Staphylococcus aureus | CFU assay | 1 | Fail | Failure | No | |
| Heat | |||||||||
| Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus [5] | Fischer et al | Dry heat at 70 °C for 10–60 min | SARS-CoV-2 (HcoV-19 nCoV-WA1-2020 (MN985325.1) | TCID50 | > 1to > 3 depending on time | Pass (max 3 rounds) | Disinfection and failure | Yes | Ability to disinfect was time dependent |
| Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators [6] | Cadnum et al | Dry heat at 70 °C for 30 min | Staphylococcus aureus (MRSA) and bacteriophages MS2 and Phi6 | CFU assay, Plaque assay | Bacteriophages < 1, MRSA > 4 | N/A | Disinfection and failure | No | Failure for bacteriophages |
| It’s not the heat, it’s the humidity: Effectiveness of a rice cooker-steamer for decontamination of cloth and surgical face masks and N95 respirators [7] | Li et al | Dry heat at 100 °C for 15 min | MS2 ad MRSA | Plaque assay | < 3 log10 reduction | Pass (visual) | Failure | No | |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | Dry heat at 82 °C for 30 min | Staphylococcus aureus and Geobacillus stearothermophilus | Plaque assay | S. aureus: < 1.0 log10, G. stearotherophilus: < 0.3 log10 | Pass | Failure | No | |
| Decontamination of face masks and filtering facepiece respirators via ultraviolet germicidal irradiation, hydrogen peroxide vaporization, and use of dry heat inactivates an infectious SARS-CoV-2 surrogate virus [9] | Ludwig-Begall et al | Dry heat at 102 °C for 60 min | Porcine respiratory coronavirus (PRCV) | TCID50 | ≥ 4 | N/A | Disinfection | N/A | |
| Decontamination of Surgical Face Masks and N95 Respirators by Dry Heat Pasteurization for One Hour at 70°C [10] | Xiang et al | Dry heat at 60 °C and 70 °C 60 min | E. coli, S. aureus, P. aeruginosa, K. pneumonia, A.baumannii, C. pseudodiphtheria, and C.albicans, Inf A virus (H1N1) | TCID 50 | N/A, but culture results were negative | Pass | Disinfection | Yes | |
| Dry Heat as a Decontamination Method for N95 Face Respirator Reuse [11] | Oh et al | Dry heat at 120 °C for 50 min |
Tulane virus, rotavirus, adenovirus, transmissible gastroenteritis virus |
Plaque assay | Tulane > 5.2, rotavirus > 6.6, adenovirus > 4.0, gastroenteritis > 4.7 | Pass | Sterilization and disinfection | Yes | All disinfection except for rotavirus which reached sterilization |
| Thermal Disinfection Inactivates SARS-CoV-2 in N95 Respirators while Maintaining Their Protective Function [12] | Daeschler et al | Dry heat at 70 °C for 60 min | SARS-CoV-2 and E. coli | TCID 50 | mixed: > 4 for SARS CoV-2, < 1 for E.coli | Pass | Disinfection and failure | Depends | Failure for E.Coli. Recommendation dependent on microorganism present |
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination method [3] | Lin et al | Dry Heat (electric rice cooker) 149–164 °C | Bacillus subtilis spores | CFU assay | N/A, culture results were mixed | N/A | Failure | N/A | Possibly disinfection after 24 h, but not immediately |
| Efficacy of moist heat decontamination against various pathogens for the reuse of N95 respirators in the COVID-19 emergency [13] | Oral et al | Moist heat at 60 °C at 80% humidity for 30 min | Bovine viral diarrhea virus (BVDV), Porcine Parvovirus (PPV) and Influenza A Virus, S. aureus, P. Aeruginosa and A. Baumanii | cell culture | S. aureus: 5.32 P.aeruginosa:5.7 A. Baumannii:5.92 InfA:4.35 modestly BVDV:1.62 PPV:0 | N/A | Disinfection and failure | N/A | Failure for BVDV and PPV |
| A pandemic influenza preparedness study: Use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets [14] | Heimbuch et al | Moist heat at 65 °C at 85% humidity for 30 min | H1N1 | TCID50 | > 4 | Pass | Disinfection | Yes | There was only a visual examination for fit and integrity |
| Biological Aerosol Test Method and Personal Protective Equipment (PPE) Decon [15] | Hinrichs et al | Moist heat at 62 °C at 85% humidity for 20 min | influenza virus A (H5N1) | RT-PCR and TCID50 | ≥ 4 | N/A | Disinfection | N/A | |
| Effect of moist heat decontamination on methicillin-sensitive S. aureus for the reuse of N95 respirators in the COVID-19 emergency [16] | Gil et al | Moist heat at 60 °C at 80% humidity for 30 min | S. aureus (methicillin sensitive) | CFU assay | 5.31 | N/A | Disinfection | N/A | |
| Thermal Disinfection Inactivates SARS-CoV-2 in N95 Respirators while Maintaining Their Protective Function [12] | Daeschler et al | Moist heat at 70 °C at 50% humidity for 60 min | SARS-CoV-2 and E. coli | TCID 50 | mixed: > 4 for SARS CoV-2, < 3 for E.coli | Pass | Disinfection and failure | Depends | Failure for E.Coli because initial contamination was too low, but was probably disinfection. Recommendation dependent on microorganism present |
| Effectiveness of three decontamination treatments against influenza virus applied to filtering facepiece respirators [17] | Lore et al | Moist heat at 65 °C for 20 min | H5N1 | TCID50 | ≥ 4.62 and ≥ 4.65 | Pass | Disinfection | Yes | |
| It’s not the heat, it’s the humidity: Effectiveness of a rice cooker-steamer for decontamination of cloth and surgical face masks and N95 respirators [7] | Li et al | Moist heat for 12–15 min | MS2 ad MRSA | Plaque assay | > 5 log10 reduction | Pass | Disinfection | Yes | There was only a visual examination for fit and integrity |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | Moist heat at 80 °C at 60% humidity for 30 min | MS2, phi6, influenza A virus S aureus, G. stearotherophilus | Plaque assay | MS2: > 6.8, Phi6: > 6.6, influenza virus: > 3.4, and MHV > 1.4, S disinfection > 2.9, G. stearotherophilus < 0.3 | Pass | Sterilization, disinfection and failure | No | MS2: Sterilization, Phi6: Sterilization, Influenza virus: Disinfection, MHV: failed, S aureus: failed, G. stearotherophilus: failed |
| A pandemic influenza preparedness study: Use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets [14] | Heimbuch et al | Moist heat (microwave-generated) for 2 min | H1N1 | TCID50 | > 4 | Pass | Disinfection | Yes | There was only a visual examination for fit and integrity |
| Biological Aerosol Test Method and Personal Protective Equipment (PPE) Decon [15] | Hinrichs et al | Moist heat (microwave-generated) for 2 min | influenza virus AH5N1 | RT-PCR and TCID50 | ≥ 4 | N/A | Disinfection | N/A | |
| Effectiveness of three decontamination treatments against influenza virus applied to filtering facepiece respirators [17] | Lore et al | Moist heat (microwave-generated) for 2 min | H5N1 | TCID50 | ≥ 4.81 and ≥ 4.79 | Pass | Disinfection | Yes | |
| Evaluation of microwave steam bags for the decontamination of filtering facepiece respirators [18] | Fisher et al | Moist heat (microwave-generated) for 1.5 min | MS2 bacteriophage | CFU assay | 3.10 – 4.64 | Mixed | Disinfection | Mixed | Can be only recommended in some cases, depending on model of the mask and how much water is absorbed. Some failure for physical integrity/fit/filtration |
| Microwave-Generated Steam Decontamination of N95 Respirators Utilizing Universally Accessible Materials [19] | Zulauf et al | Moist heat (microwave-generated) for 3 min for 1, 5, or 20 cycles | Escherichia coli MS2 bacteriophage | Plaque assay | 5–6 | Pass | Sterilization and disinfection | Yes | Average 6-log10 PFU and a minimum 5-log10 PFU reduction after a single three-minute microwave treatment |
| Steam treatment for rapid decontamination of N95 respirators and medical face masks [20] | Li et al | Steam (autoclave, short cycle) at 100 °C for 10–30 s | S. aureus (MRSA), G. stearothermophilus spores, bacteriophage MS2 | CFU assay | MS2 and MRSA > 3, G. stearothermophilus spores: fail | Pass | Disinfection and failure | No | Failure for G. stearothermophilus spores. Authors also tested a 2 s cycle, but the test failed |
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods [3] | Lin et al | Steam (autoclave) at 121 °C for 15 min | Bacillus subtilis spores | CFU assay | N/A, but culture results were negative | N/A | Disinfection | N/A | No colonies but no info on log reduction |
| N95 mask decontamination using standard hospital sterilization technologies [21] | Kumar et al | Steam (autoclave) at 121 °C for 40 min | Vesicular stomatitis virus, Indiana serotype (VSV) or SARSCoV-2 (contaminated group) | TCID50 | VSV: > 6, SARSCoV-2: 5.2–6.3 | Pass | Disinfection and Sterilization | Yes | Some FFRs may have had too low a level of contamination to ensure a 6-log reduction |
| Gases | |||||||||
| N95 mask decontamination using standard hospital sterilization technologies [21] | Kumar et al | Ethylene oxide (EtO) for 60 min | Vesicular stomatitis virus, Indiana serotype (VSV) | TCID50 | VSV: > 6 | Pass | Sterilization | No | |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | Ethylene oxide (EtO) 55 °C for 60 min at 45% RH | MS2 | Plaque assay | > 5.8 | Pass | Disinfection | No | |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | Hydrogen peroxide (gaseous HPGP) in a 59% solution for 24 min | MS2, phi6, influenza A virus | Plaque assay | Phi6: > 7.9, influenza virus > 3.8, MS2: 5.6 | Pass | Sterilization and disinfection | No | Sterilization for Phi6, disinfection for influenza virus and MS2 |
| Effect of various decontamination procedures on disposable N95 mask integrity and SARS-CoV-2 infectivity [4] | Smith et al | Hydrogen peroxide (gaseous HPV) in a 30% solution (500 ppm) at humidity between 38–99.5% for 20 min | SARS-CoV-2 | RT-PCR | 2 masks: ~ five log10 reduction < 3 log | Pass | Disinfection | No | The initial contamination was at 3 log as it was coming from human sample |
| Aerosolized Hydrogen Peroxide Decontamination of N95 Respirators, with Fit-Testing and Virologic Confirmation of Suitability for Re-Use During the COVID-19 Pandemic [22] | Derr et al | Hydrogen Peroxide (Gaseous-aHP) in a 7% solution for 12 min | SARS-CoV-2, Herpes simplex virus 1, Coxsackie virus B3, Pseudomonas phi6 bacteriophage | Plaque assay | N/A, but culture results were negative | Pass | Sterilization | Yes | |
| Vapor H2O2 sterilization as a decontamination method for the reuse of N95 respirators in the COVID-19 emergency [23] | Oral et al | Hydrogen Peroxide (Gaseous-HPV) 410 ppm for 180 min | SARS-CoV-2 | Plaque assay | > 2.6 | Pass | Disinfection | Yes | The initial contamination was too low to be able to detect sterilization |
| N95 mask decontamination using standard hospital sterilization technologies [21] | Kumar et al | Hydrogen peroxide (gaseous-HPV) in a 35% solution (750 ppm) for 60 min | Vesicular stomatitis virus, Indiana serotype (VSV) or SARSCoV-2 (contaminated group) | TCID50 | VSV: > 6, SARSCoV-2: 5.2–6.3 | Pass | Sterilization and disinfection | Yes | Some FFRs may have had too low a level of contamination to ensure a 6-log reduction |
| Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus [5] | Fischer et al | Hydrogen peroxide (gaseous-HPV) (1000 ppm) for 10 min | SARS-CoV-2 (HCoV-19 nCoV-WA1-2020 (MN985325.1)) | TCID50 | > 4 | Pass | Disinfection | Yes | |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | Hydrogen peroxide (gaseous-HPV) 446–659 ppm | MS2, phi6, influenza A virus, murine hepatitis virus, E. coli, S. aureus, G. stearothermophilus, A. niger | Plaque assay | > 2 | Pass | Failure | No | |
| Decontamination of face masks and filtering facepiece respirators via ultraviolet germicidal irradiation, hydrogen peroxide vaporization, and use of dry heat inactivates an infectious SARS-CoV-2 surrogate virus [9] | Ludwig-Begall et al | Hydrogen peroxide (gaseous-HPV) in a 59% solution (750 ppm) for 28 min | Porcine respiratory 38 coronavirus (PRCV) | TCID50 | ≥ 5 | N/A | Disinfection | N/A | |
| Hydrogen Peroxide Vapor sterilization of N95 respirators for reuse [24] | Kenney et al | Hydrogen peroxide (gaseous-HPV) 30–40-min gassing phase at 16 g/min | Phages phi-6, T7 and T1 | Plaque assay, TCID50 | N/A, but complete eradication of phages from masks | Pass | Sterilization | Yes | Limit of detection was 5PFU, lower than infectious dose, and authors used the term "sterilization" |
| Disinfection of N95 respirators by ionized hydrogen peroxide during pandemic coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 [25] | Cheng et al | Hydrogen Peroxide (Gaseous-iHP) in a 7.8% solution | Influenza A virus subtype H1N1 | TCID 50 | N/A, but culture results were negative | N/A | Disinfection | N/A | No growth, but no specific log reduction mentioned, paper uses term "disinfection" |
| N95 mask decontamination using standard hospital sterilization technologies [21] | Kumar et al | Hydrogen peroxide (gaseous-LT-HPGP) in a 59% solution for 47 min | Vesicular stomatitis virus, Indiana serotype (VSV) | TCID50 | VSV: > 6 | Pass | Sterilization | No | LT-HPGT-treated masks failed testing beyond the first cycle |
| Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators [6] | Cadnum et al | Hydrogen Peroxide (Gaseous) and Peracetic acid for 1–3 cycles of 21 min, and a single cycle of 31 min | S. aureus (MRSA) and bacteriophages MS2 and Phi6 | CFU assay, Plaque assay | 1 cycle: > 2.1, 2 cycles: > 3.6, 3 cycles > 6 log10 | N/A | Sterilization, disinfection, failure | N/A | Outcome was dependent on the number of cycles (3 cycles resulted in sterilization) |
| Scalable In-hospital Decontamination of N95 Filtering Facepiece Respirator with a Peracetic Acid Room Disinfection System [26] | John et al | Hydrogen Peroxide (Gaseous) and Peracetic acid in a 18% solution at at 20 °C for 12–19 min | MS2 bacteriophage and G. stearothermophilus spores | CFU assay | 6/6/4 | Pass | Sterilization and disinfection | Yes | Shorter cycle led to disinfection. Can't be used with masks containing cellulose |
| Enveloped Virus Inactivation on Personal Protective Equipment by Exposure to Ozone [27] | Blanchard et al | Ozone at 20 ppm and 70% humidity for 40 min |
Influenza virus A A/WSN/33, RSV A2 |
Plaque assay | 4 | Mixed | Disinfection | Mixed | Although the facepiece was unaffected for fit/filtration, the elastic band failed |
| Fast and easy disinfection of coronavirus-contaminated face masks using ozone gas produced by a dielectric barrier discharge plasma generator [28] | Lee et al | Ozone at 120 ppm for 1 and 5 min | HCoV-229E | TCID 50 | 3 | Pass | Disinfection | Yes | The initial contamination was too low to be able to detect sterilization |
| Disinfection of N95 Respirators with Ozone [29] | Manning et al | Ozone at 450 ppm and 75–90% humidity for 120 min | Pseudomonas aeruginosa | CFU assay | > 7–> 9, (one sample failed disinfection-1.38 log reduction) | Mixed | Sterilization and failure | Mixed | There was a single failure, but one needs to verify why one mask failed the test. Although the facepiece was unaffected for fit/filtration, the elastic band failed |
| N95 mask decontamination using standard hospital sterilization technologies [21] | Kumar et al | Peracetic acid dry fogging system (PAF) at 80–90% humidity for 60 min | Vesicular stomatitis virus, Indiana serotype (VSV) or SARSCoV-2 (contaminated group) | TCID50 | VSV: > 6, SARSCoV-2: 5.2–6.3 | Pass | Disinfection and sterilization | Yes | Some FFRs may have had too low a level of contamination to ensure a 6 log reduction |
| Ultra violet light | |||||||||
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods [3] | Lin et al | UVA at 365 nm and 1.87–37.44 J/cm2 for 1–20 min | Bacillus subtilis spores | CFU assay | N/A, but culture results were positive | N/A | Failed | No | |
| A Scalable Method for Ultraviolet C Disinfection of Surgical Facemasks Type IIR and Filtering Facepiece Particle Respirators 1 and 2 [30] | Lede et al | UVGI at 253.7 nm and 6 lamps, each 0.6 J/cm2 for 40 min | S. aureus | CFU assay | 7 | Pass | Sterilization | Yes | |
| Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators [31] | Mills et al | UVGI at 254 nm and 1.1 J/cm2 and 48% humidity for 40 min | Influenza virus (H1N1) | TCID 50 | ≥ 3 log on 12 of 15 FFR models and straps from 7 of 15 FFR models | N/A | Disinfection and failure | N/A | |
| A method to determine the available UV-C dose for the decontamination of filtering facepiece respirators [32] | Fisher and Shaffer | UVGI at 254 nm and 0.15–1.5 J/cm2 for 1–10 min | MS2 coliphage | Plaque assay | minimum IFM dose of 1000 J m^-2: log reduction > = 3 | Mixed | disinfection | No |
Model dependent outcomes. Model-specific exposure times to achieve this IFM dose Ranged from 2 to 266 min. Mostly failure for physical integrity/fit/filtration |
| The Effect of Ultraviolet C Radiation Against SARS-CoV-2 Inoculated N95 Respirators [33] | Ozog et al | UVGI at 254 nm and 1.5 J/cm2 for 60–70 s/side | SARS-CoV-2 | TCID 50 | N/A, culture results were mixed | N/A | Disinfection and failure | N/A | Disinfection but not for all models of masks (5 models of N95 tested) |
| Effects of relative humidity and spraying medium on UV decontamination of filters loaded with viral aerosols [34] | Woo et al | UVGI at 254 nm and 1.8 and 3.6 J/cm2 and 30,60, and 90% humidity for 30 and 60 min | MS2 | Plaque assay | mixed, highest inactivation efficiency: 5.8 log | N/A | Disinfection and failure | N/A | Disinfection, but not for all masks and conditions |
| Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods [3] | Lin et al | UVGI at 254 nm and 1.13–22.68 J/cm2 for 1–20 min | Bacillus subtilis spores | CFU assay | N/A, culture results were mixed | N/A | Failure | N/A | Possible disinfection after 24 h, but not immediately |
| Effectiveness of three decontamination treatments against influenza virus applied to filtering facepiece respirators [17] | Lore et al | UVGI at 254 nm and 18 kJ/m2 for 15 min | H5N1 | TCID50 | ≥ 4.54 and ≥ 4.65 | Pass | Disinfection | Yes | |
| A pandemic influenza preparedness study: Use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets [14] | Heimbuch et al | UVGI at 254 nm and 18 kJ/m2 for 15 min CHECK SAME AS LORE) | H1N1 | TCID50 | > 4 | Pass | Disinfection | Yes | There was only a visual examination for fit and integrity |
| Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus [5] | Fischer et al | UVGI at 260-285 nm and 0.33 J/cm2, 0.99 J/cm2, and 1.98 J/cm2 for 10, 30, and 60 min | SARS-CoV-2 (HCoV-19 nCoV-WA1-2020 (MN985325.1)) | TCID50 | between 1 and 3, depending on the time | Pass | Disinfection and failure | Yes | Time-dependent: failure for masks below 60 min, probable disinfection at 60 min |
| Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators [6] | Cadnum et al | UVGI for 1 and 30 min | S. aureus (MRSA) and bacteriophages MS2 and Phi6 | CFU assay, Plaque assay | 0–4 | N/A | Disinfection and failure | No | Outcome depended on model of mask and pathogen, only 1 of 9 masks qualified as disinfected |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | UVGI at 200-315 nm for 5 min | MS2, phi6, influenza A virus, murine hepatitis virus, E. coli, S. aureus, G. stearothermophilus, A. niger | Plaque assay | MS2: 0.7 – 1.3, Phi6: 0.2 – 1.8, influenza: 1.4 – 1.7, MHV > 1.4, S. aureus < 1.0, G. stearotherophilus < 0.3 log10 | Pass | Failure | No | |
| Effect of various decontamination procedures on disposable N95 mask integrity and SARS-CoV-2 infectivity [4] | Smith et al | UVGI at 254 nm and 0.63 J/cm2 for 33 min | SARS-CoV-2 | RT-PCR | < 3 log | Fail | Neither | No | The initial contamination was at 3 log as it was coming from human sample |
| Decontamination of face masks and filtering facepiece respirators via ultraviolet germicidal irradiation, hydrogen peroxide vaporisation, and use of dry heat inactivates an infectious SARS-CoV-2 surrogate virus [9] | Ludwig-Begall et al | UVGI at 254 nm and 5.2 J/cm [2] for 4 min | Porcine respiratory 38 coronavirus (PRCV) | TCID50 | ≥ 4 | N/A | Disinfection | N/A | |
| Disinfection effect of pulsed xenon ultraviolet irradiation on SARS-CoV-2 and implications for environmental risk of COVID-19 transmission [35] | Simmons et al | UVGI for 5 min | SARS CoV-2 | Plaque assay | > 4.79 | N/A | Disinfection | N/A | |
| Biological Aerosol Test Method and Personal Protective Equipment (PPE) Decon [15] | Hinrichs et al | UVGI at 254 nm and 18 kJ/m2 for 15 min | influenza virus AH5N1 | RT-PCR and TCID50 | ≥ 4 log10 TCID50 | N/A | Disinfection | N/A | |
| Reusability of filtering facepiece respirators after germicidal UV irradiation [36] | Vernez et al | UVGI + dry heat (Dry Heat at 70 °C for 15 min and then UVGI at 254 nm and 60 mJ/cm2 for 4 min) | vB_HSa_2002 and P66 phages | Plaque assay | > 3 | Pass | Disinfection | Yes | |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | UVGI + dry heat (Dry heat at 82 °C and UVGI at 200–315 nm) | MS2, phi6, influenza A virus, murine hepatitis virus, Staphylococcus aureus | Plaque assay | The influenza virus: > 3.9, the mouse coronavirus: 1.1, Phi6 deposited in PBS < 1.5 when heated to 82C and at ~ 8% RH. S. aureus: 1.2 | Pass | Disinfection and failure | No | Influenza virus: Disinfection MHV: Failed MS2: Failed, Phi6: Failed S. aureus: failed |
| Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital [8] | Wigginton et al | UVGI + medium humidity heat (Heat at 80 °C, RH at 62–66% and UVGI at 200–315 nm for 15 min) | MS2, phi6, influenza A virus | Plaque assay | influenza virus: > 3.9, mouse coronavirus MHV > 1.1, MS2 > 6.8, Phi6 > 6.6 | Pass | Sterilization, disinfection, failure | No | MS2: Sterilization, Phi6: Sterilization, Influenza virus: Disinfection, MHV: failed |