We have the N95s and they can be sterilized by heating to 160F for 30 minutes, so we rotate them. Each one is sterilized after each use out shopping, etc. I have two little brown paper bags, one marked "dirty." After use the mask goes in there to bring into the house and heat. I may switch to steam instead. The CDC still takes a noncommittal position on sterilization. Instead, they suggest five for every healthcare worker, rotating them, under the presumption that the virus can only last 72 hours on a mask...