1. Without a mask, I coughed while probing the space around my face with one of my hands, at a distance of maybe 9-12 inches away.
I could easily feel significant airflow from the cough in a cone in front of mouth. Nothing to the sides (for purposes of this discussion, "side" means significantly off-axis from from the line down the middle of the cone, so includes above and below the face, not just left and right).
2. Same test, with mask. I either did not detect any airflow or just detected a bare hint of some at the same test distance as unmasked. (I'd need an assistant to tell which, since I can't think of a good way to do a blind test alone).
There was definitely some airflow out the sides with the mask, as I could see by the coughs fogging my glasses, but it only seemed to be very close to my head.
3. I Repeated the above, but replacing "cough" with "blow as hard as I can". Same results.
How does one escape concluding from this that if I'm infectious wearing a mask will reduce the volume over which my releases of air containing virus laden droplets spread? Or that this means my chances of passing it on to someone I'm only spending a little time with (clerks helping with a purchase, people standing in the same line for something, etc) will be reduced?
It means that they're moving in a more diffuse fashion, so they may not spread quite as fast. But once in the air, they can still drift around.
That said, viruses are larger than air molecules, and the droplets that carry them are considerably larger than that. They're larger than the pores in N95 masks, in fact. So yes, there's good reason to expect that masks provide protection.
On the gripping hand, this study isn't really about any of that. It's about mask mandates, which has to factor in whether people comply, what materials they're using, how much noncompliance matters, etc.
So yes, you can take "Wearing a mask helps" for granted, even if you need to think a little deeper than "I can't feel the air". Each individual act on that. But more importantly, "Requiring people to wear a mask helps", which is an important action for legislatures, not just individuals.
I think that was one of the fears in the first place, and one reason why the CDC didn't initially recommend masks for the general population. However, experience has shown that many Americans will "tend to behave in more dangerous ways" during the pandemic even without a mask, so that fear was unfounded.
The anti-mask arguments I've seen amount to the argument that masks don't work perfectly. Of course they don't. They reduce transmission, and that's the point. It's a numbers game where the goal is to keep the virus's R factor under 1.0.
The phrase, "Studies show ..." seems to me to be a more significant human invention, to motivate immediate behavior, than the actual technical studies themselves.
Just slap "Studies show" on the front of any believable collection of words which could be reasonably determined to be "common sense", and watch the behaviors trend.
TL;DR: Not enough independent media is reporting all the facts. Simply having reputable people link to and explain the mask particulate logarithmic analysis would go a long way: https://advances.sciencemag.org/content/6/36/eabd3083
