I make masks from cheesecloth, to wear when I go someplace that requires masking. They don’t filter very much of anything, but I have no reason to believe that I have the Commie Cooties, thus no reason to believe that I’m endangering anyone. As for precautions, I avoid crowds and wash my hands fairly often, and take some D3 when I happen to remember.
You may be one of the FReepers that I’ve heard have the cheesecloth mask. If I hadn’t already had my crocheted one, I would’ve used your suggestion. If this one falls apart for whatever reason, then I will try the cheesecloth type.