[Costco] KN95 Disposable 5-layer Face Mask, 20-pack - $64 ...
Jul 19, 2020·Heating at 85*C, 30% humidity for 20 mins allows them to be re-used many multiple times. Donning/doffing the masks can also reduce efficiency over time. Presumably N95 masks have a better fit than surgical masks, too, so fiddling around with the mask will also disrupt the barrier over time.