https://advances.sciencemag.org/content/early/2020/08/07/sciadv.abd3083">https://advances.sciencemag.org/content/e... Paper looking at respiratory droplets emitted from people talking w/various masks.
Takeaways:
1) Chances are, the mask you wear blocked most droplets in this study. Every type did except a bandana ( #12), knitted ( #3), or a fleece gaiter ( #11) (thread).
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2) Knitted ( #3) and a bandana ( #12) didn& #39;t block as much. A fleece gaiter ( #11) made more, smaller droplets than no mask! When people mention airborne transmission, it& #39;s caused by small droplets (not just floating virus), so this covering may be especially bad. /2

3) Multilayer masks w/polypropylene did particularly well. This is true of 2-layer polypropylene ( #4) or 3-layer cotton/polypropylene/cotton ( #5), surgical masks ( #1, the middle layer of these is typically a special polypropylene fiber), and N95 ( #14, same here). /3

4) Valves on N95s ( #2) let some droplets out, but less than expected - they were about as good as most cloth masks. Worth seeing if this holds up - some cities have banned them based on the reasonable assumption they don& #39;t protect anyone but the wearer. May not be true. /4

5) Surgical ( #1) and N95 ( #14) worked best. Based on how they work, reasonable to speculate these results could extend to other similar masks (nonmedical 3-layer disposables, especially w/melt blown inner layer, KN95, KF94). Many of these are now widely available). /5

6) Takeaway: most common mask types blocked droplets that can carry virus. Wearing a bandana, knitted, or fleece gaiter? Consider switching. Looking for an upgrade? Consider one w/polypropylene fabric or nonmedical 3-layer/KN95.
More here: https://www.npr.org/sections/goatsandsoda/2020/07/01/880621610/a-users-guide-to-masks-what-s-best-at-protecting-others-and-yourself
/6/end">https://www.npr.org/sections/...