N95, N99, N100: What's the Difference Between Each Mask?
Dec 20, 2019·The key element that makes them masks rather than respirators is that they don’t have an air-tight seal against the face. In order for a mask to be certified by NIOSH and given a letter/number rating, it has to have an airtight seal. After all, if you’re trying to filter out a dangerous chemical, particulate, or smoke, if the mask isn’t ...