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Rapid Expert Consultation on the Effectiveness of Fabric Masks for the COVID-19 Pandemic (April 8, 2020)
Pages 40-46

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From page 40...
... Fineberg, M.D., Ph.D. Chair Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats This rapid expert consultation responds to your request concerning the effectiveness of homemade fabric masks worn by the general public to protect others, as distinct from protecting 1 Copyright National Academy of Sciences.
From page 41...
... In line with these observations and logic, current dichotomous infection control precautions should be updated to include measures to contain both modes of aerosolised transmission. This may require airborne precautions to be used when at risk of any aerosolized infection, as airborne precautions are considered as a step-up from droplet precautions." Gralton et al.
From page 42...
... A mask made from a four-layer woven handkerchief fabric, of a sort that might be found in many homes, had 0.7% filtration efficiency for 0.3 micron size particles and a Delta-P of 0.1". Much higher filtration efficiency was observed with filters created specifically for the research from a five-layer woven brushed fabric (35.3% of the particles were trapped)
From page 43...
... The median viral loads after coughs without a mask, with a surgical mask, and with a cotton mask were similar: 2.56 log copies/mL, 2.42 log copies/mL, and 1.85 log copies/mL, respectively. All swabs from the outer mask surfaces of the masks were positive for SARS-CoV-2, whereas swabs from three out of the four symptomatic patients from the inner mask surfaces were negative.
From page 44...
... 5 Copyright National Academy of Sciences. All rights reserved.
From page 45...
... 6 Copyright National Academy of Sciences. All rights reserved.
From page 46...
... Member Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats APPENDIX Authors and Reviewers of This Rapid Expert Consultation This rapid expert consultation was prepared by staff of the National Academies of Sciences, Engineering, and Medicine, and members of the National Academies' Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats: Richard Besser, Robert Wood Johnson Foundation, and Baruch Fischhoff, Carnegie Mellon University. The following subject matter experts also provided input: Sundaresan Jayaraman, Georgia Tech, and Michael Osterholm, University of Minnesota.


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