How effective are the aerosol filtration efficiencies for fitted face mask alternatives used during the coronavirus disease 2019 pandemic?
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.
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.
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.
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.
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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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
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 (firstname.lastname@example.org).
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.
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