I mean, if you're infected and cough its a physical barrier of sorts... it will reduce the amount of droplets in the air and def reduce sputum expelling.

If you're not infected it'll help stop you touching your mouth and nose at the very least.

These are not air filtration protections as such but they're def better than "no protection" and in their own way will help reduce the curve...

No doubt one of the many newly minted epidemiologists across the Internet ;-)

Plenty of people in the West are of the opinion that anything less than an N95 is useless. I know because I've argued with them and see comments everywhere to that effect. It doesn't help that the CDC and other Western health institutions have spoken against mask use.