"So, I have a construction N95-type mask: its vent/valve/whatever is dead center right on the front. If we're talking about droplets/aerosols mostly, it seems d

"So, I have a construction N95-type mask: its vent/valve/whatever is dead center right on the front. If we're talking about droplets/aerosols mostly, it seems directionality would be a pretty big factor ..." This is correct, but look closely - there is a flap valve inside the little valve housing that hinges at the top, and the direction of the exhaust is downward.