I've been yelling about this on Twitter all day, and I feel honor-bound to spread the message as far as possible. Masks work! Yes, even simple homemade masks. Aerosolized droplets of saliva that would otherwise fly out of your mouth will instead land on the inside of the mask. That's true even if all you do is wrap a T-shirt around your head. There is ample evidence, but I beg you to use common sense. Think it through. Can you reach the porous membranes of your nose and mouth while wearing a mask; is it easy to touch those spots? Will a layer of material across your facial orifices — almost any material, in fact — be likely to impede the expulsion and inhalation of viral matter? I have faith that you can figure it out.