The photos I see indicate that some are using hillbilly masks. Nothing, even an N95 mask, is foolproof. But even a homemade mask home-sewn from old T-shirts is better than no mask. I've read that a cotton T-shirt is 69% as effective as an N95 in filtering out particulate material. The amusing thing is that cotton blend is better than 100% cotton:
CDC does advise health care workers working with SARS patients to wear a special mask called an N-95 respirator. But even these masks offer limited protection from coronaviruses. The name of the mask says it all. The “95” means the mask, if properly fitted—and that “fit factor” presents a big if—can filter out particles down to 0.3 microns 95 percent of the time. (A human hair is roughly 100 microns in diameter.) Human coronaviruses measure between 0.1 and 0.2 microns, which is one to two times below the cutoff.
Why aren’t bra cups on your list?