Fit Testing

There are four steps involved in the fit testing process: choosing the respirator, fit checking, taste threshold (sensitivity) screening, and the fit test. A company should provide various sizes from different brands to have available for selection for their employees. People have a variety of face and head sizes so there must be different types available for them to select which one is most comfortable. Before an employee can decide which one is most comfortable the company must first show them how to properly put the respirator on, including the position of the face piece on the chin and around the bridge of the nose. Once the employee has chosen a proper respirator they should next be taught how to perform positive and negative fit checks.

A fit check makes sure that the respirator properly fits the employees face and that no air is getting into the mask. There are two types of tests, positive pressure and negative pressure. This fit test should be completed every time the respirator is worn. A positive pressure test is when the user breathes out, which exerts a positive pressure on the respirator. On the other hand, a negative pressure check is when the user breathes air in, which exerts a negative pressure on the respirator. To perform these tests the user will properly put the respirator on and then they must cover the surface of the respirator completely. The entire respirator acts as a filter and this is why the entire thing must be covered. The easiest way to do this is to cover the respirator with a sheet of plastic.

To complete the positive pressure test the user should breathe out gently and feel around the respirator to see if air is escaping from the face piece. If the user does not feel air escaping around the face piece, they have passed the positive fit check. However, if they feel air escaping around the face piece, the respirator should be repositioned and perform the fit check until a positive result is achieved.

To complete a negative pressure fit check the user should inhale, thus creating a vacuum which causes the respirator to be drawn in slightly toward the face. If this does not occur then the test has failed and the respirator should be removed and examined for any holes or a problem with the seal. If neither is found then the respirator should be repositioned and the test should be re-performed until it results in a positive result.

The next step in fit testing is the taste threshold screen test. A dilute solution is used to determine if the wearer can detect the substance while wearing the respirator. Two substances that could be used are: saccharine (sweet taste), or bitrex (bitter taste.)

The fit test is finally performed after completing the above procedures. The subject should wear the respirator for at least five minutes before the fit test. The test subject should perform the following exercises for at least 30 seconds each, while the tester continues to squeeze the correct amount every thirty seconds: · Normal breathing · Deep breathing · Turning head from side to side, inhaling at both sides · Nodding head up and down, inhaling in both up and down positions · Bending forward to touch toes, inhaling when head is down · Talking (Ask the subject to read a paragraph aloud, such as The Rainbow Passage, or ask them to tell you a story, etc.) · End by resuming normal breathing.

This is the rainbow passage:

When the sunlight strikes raindrops in the air, they act like a prism and form a rainbow. The rainbow is a division of white light into many beautiful colors. These take the shape of a long arch, with its path high above, and its two ends apparently beyond the horizon. There is, according to legend, a boiling pot of gold at one end. People look, but no one ever finds it. When a man looks for something beyond his reach, his friends say he is looking for the pot of gold at the end of the rainbow.

http://www.aphl.org/aphlprograms/infectious/tuberculosis/TB-Core-Curriculum/Documents/FitTestProcedure.pdf