Capitol Hill Blue Forums Science and Technology Health, Medicine & the healing Sciences Coronavirus: The Plague of The 21st Century?

That is actually not true. It is what was said when the pandemic was starting, and in my opinion it was a calculated lie, to avoid a run to masks, so that healthcare workers would have them. Masks that are not N95 still deliver some significant protection. Procedure masks (a.k.a. surgical masks when they are sterile, or simply the hospital-grade facemasks, those usually yellow or blue with ear loops), if they are properly fit, that is, worn tight and with the nose clip well-positioned, confer above 90% of protection to the healthy individual wearing them. It still doesn't compare to the N95 which with a proper seal, exceeds 99% of protection. But it's not like the facemask is useless for the healthy person like officials initially insisted. Cloth homemade masks, though, offer a lot less protection than procedure masks. They depend on the material (high thread count bed sheets being the best one). The ones with pouches for a filter help more if you insert a HEPA vacuum cleaner filter, but still, the protection drops significantly from the one provided by a procedure mask, especially for small particles like the SARS-CoV-2 (better for large particles like the influenza virus). Apparently shop towels are second best after vacuum cleaner filters, but again, better for large particles. Scarves deliver almost no protection whatsoever (unlike Trump said), like 2%. This information comes from a study of some 20 different masks and materials all the way up to hospital-grade procedure masks and N95 masks, with small and large particles, which I linked to in another site (sorry, currently I don't have the link on me).

Anyway, the take home lesson is, if you don't have an N95 mask (with a proper seal), at least try to get hospital-grade procedure masks and wear them tightly. If you can't get them, then make homemade masks with high thread count bed sheets, double-layered with a pocket, and insert a HEPA vacuum filter. That's the best you can do.

Me, I do have both N95s and procedure masks, so I'm not wearing homemade masks, but that's the best advice I can give, based on that study. That was an industry study using a device to blow particles of different size onto the various masks. I also saw a real scientific study blowing actual viruses into simulated faces (mannequins) and comparing procedure masks poorly fit, procedure masks tightly fit, N95 masks poorly fit without a seal, and N95 masks tightly fit with a seal. While, again, obviously the N95 with a seal beat all other options, a procedure mask tightly fit still beat an N95 poorly fit. So, no, they are absolutely not useless like health officials wanted the population to believe, at first.