[tomp]

No idea. I’m not an expert.

My physics intuition says that air filter is almost equally effective whereever it is (your mouth or another person’s mouth). It depends on the details though - how big the virus is? How far does it travel? How much of it comes out “dry” vs in water droplets? How big are these water droplets? What’s the distance it can travel in a droplet vs “dry”? And so on and so on. My prior says that eyes aren’t a big transmission factor (as the virus has particular affinity towards lung cell receptors) and that the only way that mask efficiency is radically different depending on who’s wearing it is, if the virus is mostly exhaled in water droplets and most of them evaporate in the next 1-2 meters (so when you inhale through a mask, it doesn’t filter the tiny virus particles, whereas exhaling into a mask does filter the less tiny water droplets).

But the bigger point is, it doesn’t matter. Masks can help, and that should be enough to make a decision, like a general rule or recommendation to wear masks (or face coverings).