“I’m wondering how effective a #4 Melitta coffee filter would be.”
Holes are too large, but apparently HEPA filters are good enough.
CV is .12 microns or so, holes in coffee filters tend to be a lot bigger. On the other hand, those CVs don’t usually fly around on their own, they live on droplets which makes the whole package bigger.
I was getting ready to throw out an uncomfortable bra last night. Suddenly I thought I could make 2 masks from it. Now I just need to find a way to keep them on. Right now,I would never use one in public but it things got too bad I might reconsider.