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Coronavirus (COVID-19)

Filtration Efficiency of Hospital Face Mask Alternatives Available for Use During the COVID-19 Pandemic

Educational Objective
To understand how effective the aerosol filtration fitted face mask alternatives are in combating COVID-19

1 Credit CME

JAMA Internal Medicine

Published Online: August 11, 2020

Original Investigation

Article Information and Disclosures

Emily E. Sickbert-Bennett, PhD, MS¹;

James M. Samet, PhD, MPH²;

Phillip W. Clapp, PhD³;

Hao Chen, PhD⁴;

Jon Berntsen, PhD⁵;

Kirby L. Zeman, PhD³;

Haiyan Tong, MD, PhD²;

David J. Weber, MD, MPH¹;

William D. Bennett, PhD³

Author Affiliations

¹Infection Prevention Department, UNC Health Care, Chapel Hill, North Carolina
²Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, North Carolina
³Center for Environmental Medicine, Asthma and Lung Biology, School of Medicine, University of North Carolina at Chapel Hill
⁴Oak Ridge Institute for Science Education, Oak Ridge, Tennessee
⁵TRC, Raleigh, North Carolina

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Key Points

Question How effective are the aerosol filtration efficiencies for fitted face mask alternatives used during the coronavirus disease 2019 pandemic?

Findings In this quality-improvement study of 29 fitted face mask alternatives, expired N95 respirators with intact elastic bands and masks that had been subjected to ethylene oxide and hydrogen peroxide sterilization had unchanged fitted filtration efficiencies (FFEs) of more than 95%, while the performance of N95 respirators in the wrong size resulted in decreased FFEs between 90% and 95%. As a group, surgical and procedure masks had lower FFEs relative to N95 respirators, with masks secured with elastic ear loops showing the lowest performance.

Meaning When new N95 respirators are unavailable, N95 respirators past their expiration date; sterilized, used N95 respirators; and other less common respirators can be acceptable alternatives.

Abstract

Importance Procuring respiratory protection for clinicians and other health care workers has become a major challenge of the coronavirus disease 2019 (COVID-19) pandemic and has resulted in nonstandard practices such as the use of expired respirators and various decontamination processes to prolong the useful life of respirators in health care settings. In addition, imported, non–National Institute for Occupational Safety and Health (NIOSH)-approved respirators have been donated or acquired by hospitals as a potential replacement for limited NIOSH-approved N95 respirators.

Objective To assess fitted filtration efficiencies (FFEs) for face mask alternatives used during the COVID-19 pandemic.

Design, Setting, and Participants For this quality-improvement study conducted between April and June 2020, we used the Occupational Safety and Health Administration’s Quantitative Fit Testing Protocol for Filtering Facepiece Respirators in a laboratory atmosphere supplemented with sodium chloride particles to assess the FFEs of a variety of respirators worn by a male volunteer and female volunteer.

Main Outcomes and Measures The FFEs of respirators commonly worn by clinicians and other health care workers and available respirator alternatives during the COVID-19 pandemic.

Results Of the 29 different fitted face mask alternatives tested on 1 man and 1 woman, expired N95 respirators with intact elastic straps and respirators subjected to ethylene oxide and hydrogen peroxide sterilization had unchanged FFE (>95%). The performance of N95 respirators in the wrong size had slightly decreased performance (90%-95% FFE). All of the respirators not listed as approved in this evaluation (n = 6) failed to achieve 95% FFE. Neither of the 2 imported respirators authorized for use by the Centers for Disease Control and Prevention that were not NIOSH-approved tested in this study achieved 95% FFE, and the more effective of the 2 functioned at approximately 80% FFE. Surgical and procedural face masks had filtering performance that was lower relative to that of N95 respirators (98.5% overall FFE), with procedural face masks secured with elastic ear loops showing the lowest efficiency (38.1% overall FFE).

Conclusions and Relevance This quality-improvement study evaluating 29 face mask alternatives for use by clinicians interacting with patients during the COVID-19 pandemic found that expired N95 respirators and sterilized, used N95 respirators can be used when new N95 respirators are not available. Other alternatives may provide less effective filtration.

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Article Information

Accepted for Publication: July 7, 2020.

Corresponding Author: Emily E. Sickbert-Bennett, PhD, MS, Infection Prevention Department, UNC Health Care, 101 Manning Dr, 1063 West Wing, Infection Prevention CB 7600, Chapel Hill, NC 27516 (emily.vavalle@unchealth.unc.edu).

Published Online: August 11, 2020. doi:10.1001/jamainternmed.2020.4221

Author Contributions: Dr Sickbert-Bennett had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Drs Sickbert-Bennett, Samet, and Clapp served as co-first authors and contributed equally to the work.

Study concept and design: Sickbert-Bennett, Samet, Clapp, Chen, Weber, Bennett.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Sickbert-Bennett, Samet, Clapp, Weber, Bennett.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Clapp.

Administrative, technical, or material support: Sickbert-Bennett, Samet, Zeman, Tong, Weber.

Study supervision: Sickbert-Bennett, Samet, Weber, Bennett.

Conflict of Interest Disclosures: Dr Sickbert-Bennett reports receiving consultation fees from PDI and Johnson & Johnson. No other disclosures are reported.

Funding/Support: This study was supported by a cooperative agreement between the University of North Carolina at Chapel Hill and the US Environmental Protection Agency (CR 83578501).

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The research described in this article has been reviewed by the Center for Public Health and Environmental Assessment, and the US Environmental Protection Agency and approved for publication. The contents of this article should not be construed to represent US Environmental Protection Agency policy nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

Additional Contributions: We would like to acknowledge David Diaz-Sanchez, PhD, of the US Environmental Protection Agency, and Philip Bromberg. PhD, of the University of North Carolina at Chapel Hill, for their invaluable assistance in the collection of study data and the review of the article. They were not compensated for their contributions.

References

Strategies for optimizing the supply of N95 respirators. Centers for Disease Control and Prevention. April 2, 2020. Updated June 28, 2020. Accessed July 24, 2020. https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirators-strategy/index.html

Additional ambient aerosol CNC quantitative fit testing protocols: respiratory protection standard. Occupational Safety and Health Administration. September 26, 2019. Accessed July 30, 2020. https://www.osha.gov/laws-regs/federalregister/2019-09-26

NIOSH-approved N95 particulate filtering facepiece respirators. Centers for Disease Control and Prevention. Updated June 15, 2020. Accessed July 24, 2020. https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/N95list1sect3.html

Appendix A: authorized imported, non-NIOSH approved respirators manufactured in China. US Food and Drug Administration. Updated June 24, 2020. Accessed July 24, 2020. https://www.fda.gov/media/136663/download

Decontamination and reuse of filtering facepiece respirators. Centers for Disease Control and Prevention. April 29, 2020. Updated April 30, 2020. Accessed July 24, 2020. https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

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Hinds WC., Filter efficiency. In: Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles. 2nd ed. Wiley;1999:196-199.

Rengasamy S , Eimer BC , Shaffer RE . Comparison of nanoparticle filtration performance of NIOSH-approved and CE-marked particulate filtering facepiece respirators. Ann Occup Hyg. 2009;53(2):117-128. doi:10.1093/annhyg/men086 PubMed Google Scholar Crossref

Wong SCY , Kwong RT , Wu TC , et al. Risk of nosocomial transmission of coronavirus disease 2019: an experience in a general ward setting in Hong Kong. J Hosp Infect. 2020;105(2):119-127. doi:10.1016/j.jhin.2020.03.036 PubMed Google Scholar Crossref

Offeddu V , Yung CF , Low MSF , Tam CC . Effectiveness of masks and respirators against respiratory infections in healthcare workers: a systematic review and meta-analysis. Clin Infect Dis. 2017;65(11):1934-1942. doi:10.1093/cid/cix681 PubMed Google Scholar Crossref

Lynch JB , Davitkov P , Anderson DJ , et al Infectious Diseases Society of America guidelines on infection prevention in patients with suspected or known COVID-19. Infectious Diseases Society of America. April 27, 2020. Updated April 30, 2020. Accessed July 24, 2020. https://www.idsociety.org/practice-guideline/covid-19-guideline-infection-prevention/

AMA CME Accreditation Information

Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.