Cotton masks have recently been found to be the LEAST effective of all masks. As thebix stated, the FDA maintains a list of approved and "authentic" KN95 masks. The "K" designates made in China. One of the companies on the list is Powecom.
Why use KN95 masks? Because they're essentially the same as N95 masks (95% or greater filtration of particles larger than 0.3 microns in diameter) but much cheaper. They have a snugger fit on the face than the blue surgical masks. However, the source of KN95 masks needs to be verified because some copies don't contain the materials they claim to have.
See, for example, the KN95 masks produced in China by Powecom for Bona Fide masks in Mount Vernon, NY. Bona Fide is an offshoot of a company called Ball Chain Mfg. (A ball chain is the chain used to turn on lights etc.) The company was formed in response to the shortage of masks for hospital workers in New York in 2020. The important thing here is that Bona Fide gets its masks directly from the Chinese manufacturer so the source can be authenticated. You can read their statement on the authenticity of the masks at
https://bonafidemasks.com/content/Au...0Statement.pdf. Powecom and the supplier Bona Fide were also listed by the New York times in an review of authentic versus unauthentic masks.
You can buy Powecom masks directly from Bona Fide at
https://bonafidemasks.com/Powecom-kn...IyMTMiOjEwOTh9. They cost $8.30 for 10 masks. This is a trustworthy company. I purchased from them and received the masks in a couple of days. If you call them, you get a live person. I found these masks very hot but apparently they're now made differently to increase breathability.
How do you know the Powecom masks you get are authentic? There is a coated sticker on the package. You scrape off the coating to reveal a serial number and you check the serial number online at Powecom. See Powecom at
http://powecom.com/about.html