Respirator fit test

Faces differ in size and shape, and a respirator that fits one person may leak for another. Leakage around the edge lets unfiltered air in, which can make a high-rated respirator behave like a much lower-rated one. A fit test identifies the make, model and size that give a reliable seal for that wearer.

There are two main approaches. Qualitative tests rely on the wearer's response, such as tasting or smelling a test agent that leaks in if the seal is poor. Quantitative tests use an instrument to measure how much test aerosol leaks into the facepiece. The rule describes which methods are accepted for which respirator types. Medical evaluation comes first, so that the wearer is cleared to wear the device.

Fit testing is repeated at intervals and when the wearer's face changes, for example after significant weight change, dental work or facial scarring. Facial hair that lies between the sealing surface and the skin is not compatible with a tight-fitting respirator. Loose-fitting hoods or helmets do not rely on a facial seal and may suit people who cannot be fit tested.

A passed fit test applies only to the model tested. Switching brands or sizes needs a new test. The wearer should also perform a user seal check each time the respirator is put on. Fit testing supports the effectiveness of an Assigned protection factor (APF) and is a key part of a Respirator program.