Sure.. if you can made delicious rich coffee out of that filter, then it is pretty useless for viral filtering, because well, it's letting through too much.

That being said, one of the purposes of a mask is to stop yourself from spewing droplets in the air as you speak, cough, sneeze, etc.. So any old thing would do, a scarf, a bandit-bandana.. oh yea! We should be in the Banditos look, we can all wear mouth bandanas with clever patterns, the skeletons and artistic stuff, you know? Woot, we're all pseudo-cowboys now!