respirators that rely on a mask-to-face seal need to be annually checked with either
qualitative or quantitative methods to determine whether the mask provides an acceptable
fit to a wearer. The qualitative fit test procedures rely on a subjective sensation
(taste, irritation, smell) of the respirator wearer to a particular test agent while the
quantitative use measuring instruments to measure faceseal leakage. The relative workplace
exposure level determines what constitutes an acceptable fit and which fit test procedure
is required. For negative pressure air purifying respirators, users may rely on either a
qualitative or a quantitative fit test procedure for exposure levels less than 10 times
the occupational exposure limit. Exposure levels greater than 10 times the occupational
exposure limit must utilize a quantitative fit test procedure for these respirators. Fit
testing of tight-fitting atmosphere-supplying respirators and tight-fitting powered
air-purifying respirators shall be accomplished by performing quantitative or qualitative
fit testing in the negative pressure mode.
Appendix A. Fit Testing Procedures (Mandatory).