1) Masks get saturated by large "respiratory droplets" containing viral molecules. Air turbulence against trapped droplets may create aerosols that eventually diffuse around edges. Continued...
COVID Masks: Mechanistic View: Part 2: Fine Aerosol Emissions:
Masks may increase fine aerosol emissions from: 1) nebulization of large droplets into fine aerosols, or 2) friability of certain mask materials creating "aerosolized fomites."
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Here are the studies:
1) Masks get saturated by large "respiratory droplets" containing viral molecules. Air turbulence against trapped droplets may create aerosols that eventually diffuse around edges. Continued...
Study: Ha'eri 1980
Title: The efficacy of standard surgical face masks: an investigation using "tracer particles"
Albumin tracer particles put inside a surgical mask were dispersed into the room by breathing.
https://t.co/Ll5CfBPVj6
Study: Liu 2020
Title: Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals.
SARS-2-COV sub-micrometer aerosols not tightly bound to surfaces, get airborne when PPE is taken off.
https://t.co/GK9SeOwgcj
https://t.co/qlzLK1N1Aw
Do our masks stop large droplets or do they nebulize them into Aerosols? From my emulsion days, best way to get a monodispersed emulsion is to force H20 through a pore sized membrane that has a different phase (oil or air) on the other side of it. https://t.co/Y9UCmWZ7uT pic.twitter.com/bGZBxI6lUT
— Kevin McKernan \U0001f642 (@Kevin_McKernan) October 24, 2020
2) "Aerosolized fomites" from the mask material itself (e.g. cotton or fabric) are shed during breathing. These tiny organic particles - fomites - are contaminated by even smaller viral molecules.
Friability of mask materials: Cotton or fabric may emit fine particles < 1 um, possibly spreading viral contamination. This study found breathing through DIY masks of cotton or fabric increased forward emission of fine aerosols.
https://t.co/nks9rCb6Ox
Cotton or cloth releases tiny organic material - aerosolized fomites - that can potentially serve as a conduit for viral molecules.
Limitations:
Only measured 2 minutes of emissions
Only measured forward emissions; not emissions around edges; may underestimate total emissions vs no mask
Could not tell if medical-grade masks also increased aerosols when fully contaminated with droplets
Title: Influenza A virus is transmissible via aerosolized fomites
Found that non-respiratory "aerosolized fomites" (organic debris) contaminated with a virus can infect other animals. May play large role in viral transmission.
https://t.co/p3lRxeqOiA
So masks might capture some viral debris, but emissions might be in a more easily transported aerosol.
It's analogous to someone mistakenly power sanding lead paint to remove it. The total amount is reduced, but remaining portion is in a more hazardous form.