Further evidence for the efficacy of face masks from the American Institute of Physics journal "Physics of Fluids".
1) The volume of the cough-cloud without a mask is about 7 and 23 times larger than in the presence of a surgical mask and an N95 mask, respectively.
2) Don't use masks with exhalation ports.
There's a fair bit of mathematics in the methodology of this paper (differential equations and a little bit of calculus), but it's safe to skip over and and just read the text.
Just to have it handy in one place, I've added several of other sources of evidence (a paper from Nature, a paper from JAMA, and the Vanderbilt paper) that provide further evidence to suggest the efficacy of masks in attenuating viral contagion via droplet spread.