Qualitative Fit Testing

Qualitative fit testing of a respirator subjects the wearer to a test agent to see if the wearer can detect the agent. For negative pressure APRs, qualitative fit testing can only be conducted if the respirator requires a fit factor of 100 or less. For SARs and PAPRs, the facepiece must be temporarily converted to negative-pressure mode, regardless of the mode it will be used in. Qualitative fit tests can be conducted using one of four test agents: isoamyl acetate (which cannot be used for particulate respirators), saccharin solution aerosol, Bitrex solution aerosol, and irritant smoke. The protocol for each follows a similar format. For the purposes of this course, we will use the Bitrex protocol as an example.

First, a taste threshold screening is conducted without a respirator to make sure the test subject can detect the bitter taste of Bitrex. The subject wears an enclosure about 12 inches in diameter and 14 inches tall on his or her head. The enclosure should have a small hole at the front to accommodate a spray nozzle. The test administrator makes a solution of Bitrex, salt, and water; places the solution in a nebulizer; and then uses a nebulizer to spray the solution into the hole in the enclosure. The subject breathes through the mouth with his or her tongue slightly extended, and then reports when he or she tastes or smells the Bitrex. If the subject cannot detect the Bitrex after 30 sprays, a different test agent that the subject can detect must be used. If the subject does detect the Bitrex, the fit test can continue.

Once it is determined that the test subject can detect the test agent without a respirator, the fit test may proceed. The subject should not eat, smoke, chew gum, or drink anything but plain water for 15 minutes before the test. To begin the test, the subject puts on the respirator to be tested, and again enters the enclosure. The test administrator makes a much stronger Bitrex solution and places it in a different nebulizer. The subject again breathes through his or her slightly open mouth with the tongue extended. The administrator sprays the nebulizer into the hole the same number of times as it took for the subject to detect the Bitrex during the threshold screening.

After the initial sprays, the subject must perform the test exercises (normal breathing, deep breathing, moving the head side to side, and so forth, for one minute each). Every 30 seconds, the tester must replenish the concentration in the enclosure by using half the original number of sprays. If the exercises are completed and the subject does not detect the Bitrex, the respirator has passed the fit test. If the subject does detect the Bitrex, the entire fit test procedure must be repeated with another respirator until one is found that fits the test subject properly.

To learn more about Respiratory Protection visit our Cal/OSHA Respiratory Protection Online Training web page.