typically called respirators.
This one was well past it's prime.
and don't buy the grey rubber version.
After a couple months,
the rubber will emit a sticky residue.
It washes off easily,
but there is a sweet smell that will remain.
Soon after cracks appear.
the 3M 7502.
The mask part is made of a silicon,
lasts forever and doesn't get sticky,
even when left out in the sun.
I went cheap and got these on eBay,
about half the normal price
with free shipping that took a couple weeks.