skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Durability of Disposable N95 Mask Material When Exposed to Improvised Ozone Gas Disinfection

Abstract

The principle finding of this report is that both commercial and a novel material used for N95 mask filters can endure many cycles of disinfection by ozone gas (20 ppm for 30 minutes) without detectable degradation or loss of filtration efficiency.  N95 masks and surgical masks (hereafter referred to as masks) typically use a filtration material fabricated from meltblown polypropylene.  To achieve maximum filtration efficiency while maintaining a reasonable pressure drop, these nonwoven fabrics are also electrostatically charged (corona discharge is the most common method used), to maximize attraction and capture of aerosols and solid particulates.  Under normal circumstances, the reuse of masks is generally discouraged, but in times of crisis has become a necessity, making disinfection after each use a necessity.  To be acceptable, any disinfection procedure must cause minimal degradation to the performance of the filter material.  Possible performance degradation mechanisms include mechanical damage, loss of electrostatic charge, or both.  One of the most practical and direct ways to measure combined mechanical and electrostatic integrity, and the subsequent ability to reuse mask filter material, is by the direct measurement of filtration efficiency. In this paper, we report that small numbers of disinfection cycles at reasonable virucidal doses ofmore » ozone do not significantly degrade the filtration efficiency of meltblown polypropylene filter material. By comparison, laundering quickly results in a significant loss of filtration efficiency and requires subsequent recharging to restore the electrostatic charge and filtration efficiency. A common assumption among biomedical scientists that ozone is far too destructive for this application.  However, these direct measurements show that mask materials, specifically the filtration material, can withstand dozens of ozone disinfection cycles without any measurable degradation of filtration efficiency, nor any visible discoloration or loss of fiber integrity.  The data are clear: when subjected to a virucidal dose of ozone for a much longer duration than is required for viral inactivation, there was no degradation of N95 filtration efficiency.  The specific dosages of ozone needed for ~99% viral inactivation are thought to be at least 10 ppm for up to 30 minutes based upon an extensive literature review, but to standardize our testing, we consider a dose of 20 ppm for 30 minutes to be a reasonable and conservatively high ozone disinfection cycle. Finally, the material tested in this study withstood dosages of up to 200 ppm for 90 minutes, or alternatively 20 ppm for up to 36 hours, without detectable degradation, and further testing suggests that up to 30 or more disinfection cycles (at 20 ppm for 30 minutes) would result in less than a 5% loss of filtration efficiency. This report does not address the effect of ozone cycling on other mask components, such as elastics.« less

Authors:
 [1];  [2];  [3];  [1];  [1]
  1. Univ. of North Carolina, Chapel Hill, NC (United States)
  2. North Carolina State Univ., Raleigh, NC (United States)
  3. Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1617319
Report Number(s):
SAND-2020-4308J
Journal ID: ISSN 2690-2656; 685510
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
The Journal of Science and Medicine
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2690-2656
Country of Publication:
United States
Language:
English
Subject:
virus; virucidal; viricidal; COVID-19; PPE; N95; surgical mask; reuse; decontamination

Citation Formats

Dennis, Robert, Pourdeyhimi, Behnam, Cashion, Avery, Emanuel, Steve, and Hubbard, Devin. Durability of Disposable N95 Mask Material When Exposed to Improvised Ozone Gas Disinfection. United States: N. p., 2020. Web. https://doi.org/10.37714/JOSAM.V2I1.37.
Dennis, Robert, Pourdeyhimi, Behnam, Cashion, Avery, Emanuel, Steve, & Hubbard, Devin. Durability of Disposable N95 Mask Material When Exposed to Improvised Ozone Gas Disinfection. United States. https://doi.org/10.37714/JOSAM.V2I1.37
Dennis, Robert, Pourdeyhimi, Behnam, Cashion, Avery, Emanuel, Steve, and Hubbard, Devin. Fri . "Durability of Disposable N95 Mask Material When Exposed to Improvised Ozone Gas Disinfection". United States. https://doi.org/10.37714/JOSAM.V2I1.37. https://www.osti.gov/servlets/purl/1617319.
@article{osti_1617319,
title = {Durability of Disposable N95 Mask Material When Exposed to Improvised Ozone Gas Disinfection},
author = {Dennis, Robert and Pourdeyhimi, Behnam and Cashion, Avery and Emanuel, Steve and Hubbard, Devin},
abstractNote = {The principle finding of this report is that both commercial and a novel material used for N95 mask filters can endure many cycles of disinfection by ozone gas (20 ppm for 30 minutes) without detectable degradation or loss of filtration efficiency.  N95 masks and surgical masks (hereafter referred to as masks) typically use a filtration material fabricated from meltblown polypropylene.  To achieve maximum filtration efficiency while maintaining a reasonable pressure drop, these nonwoven fabrics are also electrostatically charged (corona discharge is the most common method used), to maximize attraction and capture of aerosols and solid particulates.  Under normal circumstances, the reuse of masks is generally discouraged, but in times of crisis has become a necessity, making disinfection after each use a necessity.  To be acceptable, any disinfection procedure must cause minimal degradation to the performance of the filter material.  Possible performance degradation mechanisms include mechanical damage, loss of electrostatic charge, or both.  One of the most practical and direct ways to measure combined mechanical and electrostatic integrity, and the subsequent ability to reuse mask filter material, is by the direct measurement of filtration efficiency. In this paper, we report that small numbers of disinfection cycles at reasonable virucidal doses of ozone do not significantly degrade the filtration efficiency of meltblown polypropylene filter material. By comparison, laundering quickly results in a significant loss of filtration efficiency and requires subsequent recharging to restore the electrostatic charge and filtration efficiency. A common assumption among biomedical scientists that ozone is far too destructive for this application.  However, these direct measurements show that mask materials, specifically the filtration material, can withstand dozens of ozone disinfection cycles without any measurable degradation of filtration efficiency, nor any visible discoloration or loss of fiber integrity.  The data are clear: when subjected to a virucidal dose of ozone for a much longer duration than is required for viral inactivation, there was no degradation of N95 filtration efficiency.  The specific dosages of ozone needed for ~99% viral inactivation are thought to be at least 10 ppm for up to 30 minutes based upon an extensive literature review, but to standardize our testing, we consider a dose of 20 ppm for 30 minutes to be a reasonable and conservatively high ozone disinfection cycle. Finally, the material tested in this study withstood dosages of up to 200 ppm for 90 minutes, or alternatively 20 ppm for up to 36 hours, without detectable degradation, and further testing suggests that up to 30 or more disinfection cycles (at 20 ppm for 30 minutes) would result in less than a 5% loss of filtration efficiency. This report does not address the effect of ozone cycling on other mask components, such as elastics.},
doi = {10.37714/JOSAM.V2I1.37},
journal = {The Journal of Science and Medicine},
number = 1,
volume = 2,
place = {United States},
year = {2020},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:

Works referenced in this record:

Evaluating resistance of polymeric materials for outdoor applications to corona and ozone
journal, April 2010

  • Ma, Bin; Andersson, Johan; Gubanski, Stanislaw
  • IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 17, Issue 2
  • DOI: 10.1109/TDEI.2010.5448112

Ozone for Inactivation of Aerosolized Bacteriophages
journal, August 2006


Measurement of the inactivation kinetics of poliovirus by ozone in a fast-flow mixer.
journal, January 1979


On the ozone protection of polymers having non-conjugated unsaturation
journal, May 2001


Ozone Gas: Scientific Justification and Practical Guidelines for Improvised Disinfection using Consumer-Grade Ozone Generators and Plastic Storage Boxes.
journal, March 2020

  • Dennis, Robert; Cashion, Avery; Emanuel, Steven
  • The Journal of Science and Medicine, Vol. 2, Issue 1
  • DOI: 10.37714/josam.v2i1.35

Electrostatic Respirator Filter Media: Filter Efficiency and Most Penetrating Particle Size Effects
journal, January 2000

  • Martin, Stephen B.; Moyer, Ernest S.
  • Applied Occupational and Environmental Hygiene, Vol. 15, Issue 8
  • DOI: 10.1080/10473220050075617

Mechanism of enteroviral inactivation by ozone.
journal, January 1981


Development of a Practical Method for Using Ozone Gas as a Virus Decontaminating Agent
journal, May 2009

  • Hudson, James B.; Sharma, Manju; Vimalanathan, Selvarani
  • Ozone: Science & Engineering, Vol. 31, Issue 3
  • DOI: 10.1080/01919510902747969

Surface Germicidal Effects of Ozone for Microorganisms
journal, July 2003


Latex condom deterioration accelerated by environmental factors: I. Ozone
journal, March 1989


Kinetics of Inactivation of Waterborne Enteric Viruses by Ozone
journal, January 2018

  • Wolf, Camille; von Gunten, Urs; Kohn, Tamar
  • Environmental Science & Technology, Vol. 52, Issue 4
  • DOI: 10.1021/acs.est.7b05111

Comparative response of mixed cultures of bacteria and virus to ozonation
journal, January 1983


Inactivation Kinetics of Viruses and Bacteria in Water by Use of Ozone
journal, December 1974