Fit Testing

A respirator that does not fit correctly cannot properly protect its wearer. Each employee who wears a tight-fitting respirator must undergo one of two types of fit tests to make sure there is no inward leakage of air. These tests must be done with the same make, model, style, and size of respirator as the worker will be wearing.

Respirators should also be comfortable for the wearer. There should be room for eye protection if need be, and room to talk. Masks should not slip, and should fit properly on the chin and across the bridge of the nose. Before each fit test, employers must arrange for the worker to undergo a medical examination to be sure that he or she is physically able to use a respirator.

For each fit test, the wearer must attempt normal breathing, deep breathing, moving the head side to side and up and down, reciting a passage or poem, smiling or frowning, bending over, and then breathing normally again. Each of these exercises must be done for one minute, except for smiling or frowning, which is only required to be done for fifteen seconds.

There are two types of fit tests: qualitative, which is based on user response; and quantitative, which is based on numerical measurements.

Qualitative fit tests expose the person wearing a respirator to a test agent, such as a sweet or bitter solution or mild irritant. If the wearer is unable to detect the test agent, the test is considered successful. Otherwise, the employer will need to select another respirator for the worker.

Quantitative fit tests measure the amount of a test agent both inside and outside the respirator. The result of the test is determined by taking the average ratio of the two measurements. For example, if the amount of test agent outside the respirator is 1,000 parts per million, and the amount inside during all exercises is 10 parts per million, then the average ratio is 1,000 over 10, or 100. The resulting number is that respirator's "fit factor." Quarter and half masks must have a minimum fit factor of 100. Full facepiece respirators must have a fit factor of at least 500.

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