We are tearing apart filters from furnace filters. Only the top two that filter out everything. You have to be cognizant of what side goes toward the person.
Also using Halyard H500. We use that for sterilizing instruments in the autoclave. Afterward, it keeps the tools safe and sterile. The H500, has two parts to the “fabric” and it does a really good job. It can be put back into the autoclave to be sterilized and reused. They are testing to see how many times, however. At least it is not a one-time thing, and what we use now can be reused after the instruments sterilized. I just ordered some to sew some masks. I am hoping to find someone who can print me off a few of these for the hospital ER.