I have to just

at these really dirty looking masks that folks have on their face.
The facts are they struggle to breath-so the mask slips of the nose, or sits on their chin.
It's filthy from touching it so many times.
Full of germs as their own food particles, breath, just coats the inner surfaces of the mask.
Then it restricts the free flow of air which then increases the intake of carbon dioxide.
I fully understand that some folks have medical issues and they wear a mask as precaution.
Best precaution is stay away from others. (That's a hard one to do if living in a zoo)
I wore non toxic dust masks at varied jobs for many years. Some high dust jobs!
Winter temps stepping or working outdoors at work at times (real cold temps a mask doesn't hurt like cold air can , believe it or not)
The cold though sure showed leaks towards safety glasses.
And paint dust , fiberglass dust , foundry dust will tell if a mask isn't sealed well.
And guess what? Nontoxic particle masks are called nontoxic for a reason. They filter out bigger chaff. Not toxic or micro particulates.
Respirators I wore too. Spaying paint. Pumping /transferring acids. Ect..
Safety glasses with respirator and face shield and Tyvek suit and rubber boots heavy rubber gloves.
And still got acid burned on skin more than once.
Soaked with sweat on hot summer work details around the giant ovens and washer systems ect. All that gear had to be carefully removed and decontaminated.
Are canister filters a source of infection if virus is caught on/in them ?
If so the ideal time to change them out and contain/isolate the used ones would be immediately after use and exposure? Which would rely on knowing when an exposure occurred. Or else , constant filter changing.
I wear a mask at the hospital when required. (None last time.) Not my policy. And the folks that see me there wear them everyday.
I have obviously worn a lot of masks a lot of years for varied reasons.
Used to be seeing one in public meant low immunity individuals.
I had nothing to say about that. And same today if someone is wearing a mask.
Ever see folks still pull a nasty hankie out of thier pocket and blow thier nose?
I'd just as soon not share surfaces or personal space or a washing machine with them.
Nope. not all are ill.