➡️ I'm seeing a lot of "N95s work and other masks do not"

➡️ Filtration is relative, not absolute

➡️ Summary and infographic ⬇️
maskevidence.org/mask-types

⬇️%s are filtration percentages for submicron (less than 1 micron) particles - aerosol data - the relevant size because

90% N95s without fit testing
70% Level 1 medical with cotton overmask
50% Level 1 medical or well-fitting 2-layer cotton

What does it mean?

➡️ Wear the best mask available

If you have access to N95s or FFP3s with overhead elastic, wear them

Otherwise use what you have: any mask is better than no mask

A certified medical mask with a good-fitting cloth mask over the top to improve the edge seal is a great low-cost combo

Mask braces are a bit uncomfortable but is you are in a high-risk situation (eg health care worker not supplied with routine N95s) they greatly improve the filtration of medical masks


@cmclase I think in terms of "inhalation dose" which part of the picture, the rest being how receptive a given vector is -- temperature of nasal passages, for example, and humidity, and so on. I lower dose with the open window and the Corsi box, and in public with the N95.

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