PPE decontamination (Table)

Method

How To

Advantages

Disadvantages

PPE Used with Method

Heat[1][2][3]

(1)Heat at 70℃ for 30 min in an oven/blanket warmer/ heating pad without contact with metal
(2)Heat at 56℃ for 90 min without contact with metal

(1) Readily available equipment
(2) Effective decontamination and filtration efficacy is maintained for multiple heating cycles; after 24h of heat treatment, efficacy of N95 drops from 98.5% to 79.0%.
(3) Evidence of effectiveness up to 20 cycles

(1)Risk of melting any metal parts; melting will destroy the mask.
(2)Touching metal can cause charge decay within the filtration material for N95 respirators
(3) Never bring contaminated equipment home. Do not use your home oven.

N95 and surgical masks

Disinfecting wipes

(1) Thoroughly wipe the object
(2) Allow adequate contact time - depends on type

Quick and readily available

(1) Overuse can deplete supply of wipes
(2) Not all wipe types are effective against SARS-CoV-2
(3) Alcohol will compromise filtering efficiency of mask

Face Shield, goggles

Soap and warm water[4]

(1)Use detergent and warm water
(2)Rinse well
(3)If available immerse for 10 min in a germicidal detergent
(4)Air dry

Quick and readily available

(1) Efficacy on face shields is unclear
(2) Can destroy filtration efficacy in masks

Face Shield

Microwave generated steam[5][6]

Microwave for 5 minutes OR microwave on max power for 2 minutes with 50 mL of water

Convenient and has been shown to completely inactivate viruses

(1)Although suggested by the CDC, not approved by the FDA
(2)Might be uneven heat distribution
(3)Not recommended if any metal parts
(4)Reports of masks starting fires
(5)Use dedicated equipment (do not bring home or use in microwave also used for food)

N95 and surgical masks, disposable gowns

Ethylene Oxide[7]

ETO sterilization requires a machine for gas sterilization.

Simple to operate and monitor

(1)Carcinogenic
(2)Flammable; requires special storage
(3)Long cycle/aeration time
(4)Effective decontamination but unclear if filtration efficacy is retained

Generally not a recommended method

Not recommended by 3M

Chlorine disinfectant[8]

Wash with 5%-6% liquid sodium hypochlorite or solid calcium hypochlorite (alternatives: chlorine dioxide, sodium dichloroisocyanurate, or chloramine-T)

Quick and readily available

(1)Eye, throat, skin irritation; harmful if inhaled
(2)Efficacy decreases as pH increases
(3)Corrosive to metals when used in high concentrations; will decrease efficacy of masks that use metal

Face Shield

Steam[2]

120℃ steam for 3 minutes

Quick

(1) Requires access to controlled steam
(2) Steam treatment causes filtration efficiency to drop to ~85% after 5 cycles, and ~80% after 10 cycles[1]

N95 respirators and surgical masks

Autoclaving[5]

Place in autoclave at 300 kPa and 134-138℃ for 5 minutes

Fast, very effective for destroying viruses, and nontoxic

(1)High heat potentially degrades polyester and related synthetic material
(2)May compromise the efficacy of your PPE
(3)May not have immediate access to an autoclave machine and this

N95 and surgical masks, disposable gowns

Vaporized Hydrogen Peroxide (VHP)[7][9][10]

(1)In ventilated room, uniformly distribute 35% hydrogen peroxide solution
(2)Attain 480+ ppm VHP
(3)Maintain for 25 minute duration of gassing
(4)20 minute gassing dwell period
(5)Introduce fresh air through ventilation, sensors confirm HPV < 1.0 ppm, validate through biological indicators

(1)Safe for the environment
(2)Good for heat and moisture- sensitive objects
(3)Fast cycle time (55 min)
(4)Now an FDA approved technique
(5)Can complete at least 50 cycles and maintain filtration efficacy and fit on N95 masks

(1)Exposure at >1ppm can be harmful; eye, throat, skin irritation
(2)Not used for cellulose materials (cotton)
(3)Not readily available for every facility and often has to be done at a 3rd party facility

N95 and surgical masks, disposable gowns, face shields

Ultraviolet Germicidal Irradiation (UGVI)[11][12]

UV (254 nm, 8W, 30 min) for 10 cycles[1]

(1)Effective in destroying human respiratory viruses
(2) Listed method does not reduce filtration efficiency

(1) May not have access to a UV machine
(2) Mishandling the machine can be dangerous
(3) UV strength has to be controlled to not lessen filtration efficiency

N95 and surgical masks, disposable gowns

Time[13][14]

(1) Leave contaminated materials in a ventilated space (paper bag, tupperware with holes)
(2) Wait at least 72 hours before re-use - some recommend waiting 7 days or longer.

Materials are readily available

(1) Actual efficacy and time until “safe” to reuse materials is unclear - no explicit safe time and no guidelines.
(2) One lab-based study found viable viral particles on surgical masks after 7 days (< 0.1% original amount).

N95 and surgical masks, disposable gowns

Note: This table is informational only and has been compiled from the sources noted below. They are not formal recommendations endorsed by any governing body, UC San Diego, or the authors. There are no industry guidelines for PPE decontamination, and 3M guidelines currently do not recommend resterilization or reuse of N95 masks.[15] Decontamination of PPE should be done at your own discretion.

Author Information

Authors: Felicia Hung MPH Candidate Yale, Kevin Casey MPH Candidate Yale, Shiv Patel BS Human Biology Candidate UCSD, Danielle Urman MS1 UCSD
Completed on: 4/2/20Last updated on: 4/18/20

Reviewed by: Sara Baird MD

Reviewed on: 4/8/20

This summary was written as part of the CoRESPOND Earth 2.0 COVID-19 Rapid Response at UC San Diego. For more information about the project, please visit http://earth2-covid.ucsd.edu

References

  1. Price A, Chu L. Addressing COVID-19 Face Mask Shortages. Palo Alto, CA: Stanford University; 2020:9. https://stanfordmedicine.app.box.com/v/covid19-PPE-1-1. Accessed May 2, 2020.
  2. Tsai P. Information and FAQs on the Performance, Protection, and Sterilization of Face Mask Materials. University of Tennessee Research Foundation. https://utrf.tennessee.edu/information-faqs-charged-filtration-material-performance-after-various-sterilization-techniques/. Published March 31, 2020. Accessed April 2, 2020.
  3. Duan S-M, Zhao X-S, Wen R-F, et al. Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation. Biomed Environ Sci BES. 2003;16(3):246-255.
  4. Sirianni G, Borak J. How clean is "clean"? Regulations and standards for workplace clothing and personal protective equipment. J Occup Environ Med. 2010;52(2):190-6.  [PMID:20134338]
  5. Disinfection & Sterilization Guidelines | Guidelines Library | Infection Control | CDC. Disinfection and Sterilization. https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.html. Published May 24, 2019. Accessed May 2, 2020.
  6. Lore MB, Heimbuch BK, Brown TL, et al. Effectiveness of three decontamination treatments against influenza virus applied to filtering facepiece respirators. Ann Occup Hyg. 2012;56(1):92-101.  [PMID:21859950]
  7. Rutala WA, Weber DJ. Infection control: the role of disinfection and sterilization. J Hosp Infect. 1999;43 Suppl:S43-55. doi:10.1016/s0195-6701(99)90065-8
  8. Rutala WA. Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008. 2008:163.
  9. Schwartz A, Stiegel M, Greeson N, et al. Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic. Appl Biosaf. April 2020:153567602091993. doi:10.1177/1535676020919932
  10. Hale C. Battelle deploys decontamination system for reusing N95 masks. FierceBiotech. https://www.fiercebiotech.com/medtech/battelle-deploys-decontamination-system-for-reusing-n95-masks. Published March 30, 2020. Accessed April 1, 2020.
  11. Mills D, Harnish DA, Lawrence C, et al. Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators. Am J Infect Control. 2018;46(7):e49-e55.  [PMID:29678452]
  12. Lowe JJ, Paladino KD, Farke JD, et al. N95 Filtering Facepiece Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse. University Nebraska Medicine; 2020:19.
  13. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med. 2020;382(16):1564-1567.  [PMID:32182409]
  14. Chin AWH, Chu JTS, Perera MRA, et al. Stability of SARS-CoV-2 in different environmental conditions. Lancet Microbe. 2020;0(0). doi:10.1016/S2666-5247(20)30003-3
  15. Technical Bulletin: Disinfection-of-3M-Filtering-Facepiece-Respirators. March 2020. https://www.apsf.org/wp-content/uploads/news-updates/2020/Disinfection-of-3M-Filtering-Facepiece-Respirators.pdf.