I do a fair bit of cutting, grinding and polishing of stuff like bone, horn, antler, shell; so i’ve always kept a stash (as well as real respirator with replaceable canisters); Much the same logic. The box isn’t sealed, so the dozen in my stash isn’t likely acceptable. I do have several nurse and EMT friends, and they know that I will fix them up (individually) if they ask. Luckily; our local area addressed the issue pretty early; so they haven’t gotten swamped.
Ron Charlotte
Gainesville, FL