2 ms·

I'm honestly curious as to what mechanism could exist on a mask that could filter air in one direction only (and also why someone would build a surgical mask to

I'm honestly curious as to what mechanism could exist on a mask that could filter air in one direction only (and also why someone would build a surgical mask to do that) - surely you want protection in both directions?

dragonwriter 6y ago
> I'm honestly curious as to what mechanism could exist on a mask that could filter air in one direction only You could have a mask that formed a tighter seal with internal underpressure, but moves slightly away from the face allowing exhalation to escape with overpressure. Obviously, you wouldn't want that in a surgical mask, but it pretty easy to do. There are more complex variants you could do where the difference in operation is driven by the direction of pressure differential.