Should full-face masks be fit tested with the nose cup removed or left in place?
One of the most important things to be concerned with when doing quantitative fit testing is that the mask sample is representative of the air the person is breathing. This usually means sampling from the “breathing zone” near the nose and mouth (a few fit test adapters sample exhaled air instead.) Many full-face masks are probed through the faceplate glass and do not sample breathing zone air when a nose cup is in place. When using such a mask, the nose cup should be removed so there is no barrier between the breathing zone and the sample point. Fit testing with the nose cup in place is OK if the sample is taken from inside the nose cup. Generally speaking, it’s best to fit test with the mask configured the same way it is actually used. The bottom line is that as long as the air is being sampled is representative of the air being breathed, do whatever makes you feel comfortable with regard to the nose cup. The nose cup does not contribute to the fit.
