Fitted Filtration Efficiency of Double Masking During the COVID-19 Pandemic | Otolaryngology | JAMA Internal Medicine | JAMA Network
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    1 Comment for this article
    Size of filtration particles
    Jean-Marc Guichet, MD, PhD, Doct Sci | London (Princess Grace Hospital) and Milan (Columbus Clinic Centre)
    The most important thing for filtration efficiency is the size of the particles. Many researchers have studied particle sizes out of the range of the  SARS-CoV-2 virus  (0.1 micron).

    A study should consider a range of test particles from 0.05 to 0.2 microns, but not larger, to validate the real engineering filtration for the SARS-CoV-2 virus.The particle size of cigarette smoke is similar to SARS-CoV-2, and basic tests (simple respiration) show the weaknesses of masks.

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    Research Letter
    April 16, 2021

    Fitted Filtration Efficiency of Double Masking During the COVID-19 Pandemic

    Author Affiliations
    • 1Infection Prevention Department, UNC Medical Center, Chapel Hill, North Carolina
    • 2Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, North Carolina
    • 3Oak Ridge Institute for Science Education, Oak Ridge, Tennessee
    • 4Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill
    JAMA Intern Med. Published online April 16, 2021. doi:10.1001/jamainternmed.2021.2033

    Although global vaccination efforts against SARS-CoV-2 are underway, the public is urged to continue using face masks as a primary intervention to control transmission.1 Recently, US public health officials have also encouraged doubling masks as a strategy to counter elevated transmission associated with infectious SARS-CoV-2 variants.2 US Centers for Disease Control and Prevention investigators reported that doubling masks increased effectiveness, but their assessment was limited in type and combinations of masks tested, as well as by the use of head forms rather than humans. To address these limitations, this study compared the fitted filtration efficiency (FFE)3,4 of commonly available masks worn singly, doubled, or in combinations.