Use a Mask Without Valves

vitals.lifehacker.com

This is an important point, and for some reason I haven't seen it discussed very widely: masks with valves protect you, but they don't fully protect anyone else.

And additionally, N95 and similar masks are "wasted" in a non-professional use:

https://news.ycombinator.com/item?id=23957506

Reply on news.ycombinator.com