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Filtration Efficiency, Effectiveness, and Availability of N95 Face Masks for COVID-19 Prevention

Educational Objective
To understand the filtration efficiency, effectiveness, and availability of N95 face masks for COVID-19 prevention
1 Credit CME

In March 2020, the soaring number of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections resulted in an unprecedented shortage of personal protective equipment (PPE) for clinicians and essential health care workers.1 The shortage was most profound among N95 masks. N95 respirators, named for their ability to filter 95% or more of tiny 0.3-μm particles, are the mainstay of protection against airborne pathogens.2 Airborne transmission results from contact with infectious particles contained within small (<5 μm) droplet nuclei (ie, aerosols) that can linger in the air for hours and be dispersed over great distances.2 In contrast, SARS-CoV-2 is primarily spread by large (>5-10 μm) respiratory droplets that can be expelled up to 6 feet horizontally and drop to the ground within seconds, against which surgical masks generally offer adequate protection.2,3 Nonetheless, the Centers for Disease Control and Prevention recommends that health care workers use N95 masks when caring for patients with confirmed or suspected coronavirus disease 2019 (COVID-19) out of concern for airborne transmission, particularly during exposure to procedures that produce high concentrations of aerosols (eg, intubation, extubation, noninvasive ventilation).2 To mitigate the shortage of N95 respirators, many health care facilities are pursuing nonstandard approaches to maintaining an adequate supply, including mask decontamination and reprocessing for reuse, which extend the wearable life of the mask beyond the expiration date, and procuring KN95 masks (N95 masks that are regulated in China).

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Article Information

Corresponding Author: Caitlin M. Dugdale, MD, 100 Cambridge St, Suite 1600, Boston, MA 02114 (cdugdale@mgh.harvard.edu).

Published Online: August 11, 2020. doi:10.1001/jamainternmed.2020.4218

Conflict of Interest Disclosures: Dr Dugdale reports receiving travel reimbursement from the Infectious Diseases Society of America and personal fees from the Joint United Nations Programme on HIV/AIDS. No other disclosures were reported.

References
1.
Jacobs  A , Richtel  M , Baker  M . ‘At war with no ammo’: doctors say shortage of protective gear is dire. The New York Times. March 19, 2020. Accessed August 6, 2020. https://www.nytimes.com/2020/03/19/health/coronavirus-masks-shortage.html
2.
Centers for Disease Control and Prevention. Coronavirus (COVID-19). Accessed June 25, 2020. https://www.cdc.gov/coronavirus/2019-ncov/index.html
3.
Infectious Diseases Society of America. Infectious Diseases Society of America guidelines on infection prevention in patients with suspected or known COVID-19. April 27, 2020. Accessed June 21, 2020. https://www.idsociety.org/practice-guideline/covid-19-guideline-infection-prevention/
4.
Sickbert-Bennett  EE , Samet  JM , Clapp  PW ,  et al.  Filtration efficiency of hospital face mask alternatives available for use during the COVID-19 pandemic.   JAMA Intern Med. Published online August 11, 2020. doi:10.1001/jamainternmed.2020.4221Google Scholar
5.
Morawska  L , Milton  DK .  It is time to address airborne transmission of COVID-19.   Clin Infect Dis. 2020;ciaa939. doi:10.1093/cid/ciaa939PubMedGoogle Scholar
6.
Radonovich  LJ  Jr , Simberkoff  MS , Bessesen  MT ,  et al; ResPECT investigators.  N95 respirators vs medical masks for preventing influenza among health care personnel: a randomized clinical trial.   JAMA. 2019;322(9):824-833. doi:10.1001/jama.2019.11645PubMedGoogle ScholarCrossref
7.
Nicas  J . It’s bedlam in the mask market, as profiteers out-hustle good Samaritans. The New York Times. April 3, 2020. Updated May 7, 2020. Accessed June 20, 2020. https://www.nytimes.com/2020/04/03/technology/coronavirus-masks-shortage.html
8.
Jeremias  A , Nguyen  J , Levine  J ,  et al.  Prevalence of SARS-CoV-2 infection among health care workers in a tertiary community hospital.   JAMA Intern Med. Published online August 11, 2020. doi:10.1001/jamainternmed.2020.4214Google Scholar
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