What are we talking respirators anyway, N95 masks, or those plastic respirator things? Like this: https://www.grainger.com/product/3M-...spirator-5T569
I'm not sure many of the latter were ever designed for medical usage, some are, but I suspect many were designed for labor of the sort that generates lots of dust etc.. So their effectiveness, who knows. Some say much of covid is droplet transmission (the whole droplet v aerosols thing) so then ANY of it AND faceshields as well would probably work for droplets.
It's just with a respirator you are going to look like: I'm ready for World War I, bring on the mustard gas! It's a scary look … But if that what it takes to get people to cover their face … who knew.