Clogging of nebulizers used during qualitative respirator fit testing (QLFT) are a common occurrence.  This video provides explains how to check nebulizers for clogging prior to the start and end of fit testing.  Failure to recognize inadequate aerosol output can allow a poorly fitting respirators to pass the fit test.  Simple techniques that can be used to resolve a clogged nebulizer are provided.  The ability to recognize a partially obstructed (clogged) nebulizer improves the overall quality of the fit test, which benefit the respirator wearer as well as the employer.