Face masks are most effective at reducing the spread of SARS-CoV-2 when the infected persons wear them.

I've made this comment elsewhere, but I do recommend wearing eye protection.

Also, the N95 and KN95 designators doesn't specify if there's a vent valve or not. Just get the ones without one. Any mask will still catch spit from coughs. If you're in a space that gets saturated, the room has ventilation issues and masks are unlikely to do much anyway. CO2 monitors can indirectly measure the saturated level. It's unhealthly to be in spaces like that, covid or not.