Face mask primer

Simply capping the valve, as Lobo stated previously, results in the inhalation filter losing effectiveness over time much more quickly. A P100 respirator with a surgical mask placed over the exhaust, folded in a way to minimize leaks or sealed with gaffing tape, or printing an exhaust is much more effective all around. A surgical mask should be placed in a way that at least half of the surface area is still available.

Well said!

Fred R. Martin, M.D.