Fit testing for the use of respirators
A respirator cannot protect the user from contaminants and hazardous substances if it does not fit his or her face properly. In order for the respirator to work correctly, there must be an adequate match between a respirator wearer’s face and the respirator. Because of that, respirator manufacturers normally offer facepieces in a variety of makes, sizes, styles and models.
As there are several types of respirators an employee might use during his activities, some of those types have to form a tight seal between the face or neck to function adequately. Those are called tight-fitting respirators. In that case, anything that interferes with the seal can cause a leak of contaminants into the breathing zone, thus compromising the worker’s safety and health. Therefore, identifying the make, type, style and size of respirator best suited for a certain employee is crucial before its use. This process is called fit test, and it is required by the Occupational Safety and Health Administration to all industries that use respirators.
According to OSHA, a “fit test” tests the seal between a respirator and a worker’s face. And for this purpose, there are two types of fit tests: qualitative fit testing and quantitative fit testing.
Qualitative fit testing is a method that relies on the sense of smell and taste, or the reaction to an irritant substance to detect a leakage into the breathing area of the respirator. There are four substances that can be used to qualitatively fit test a worker: isoamyl acetate (banana smell), bitrex (bitter taste in mouth), saccharin (sweet taste in mouth), and irritant smoke (causes coughing). Qualitative fit testing is usually performed for respirators that just cover the mouth and nose, also called half-mask respirators. On the other hand, quantitative fit testing measures the actual amount of a leaked substance with the use of a special machine that is connected to the facepiece by a probe and a hose. The accepted methods by OSHA to perform a quantitative fit test are: generated aerosol, ambient aerosol, and controlled negative pressure. In contrast to qualitative fit tests, quantitative fit tests can be used for any type of tight-fitting respirator. Both type of tests’ protocols are described in OSHA’s Appendix A to 1910.134.
Considerations before and after a fit test
Before wearing a respirator or being fit tested, the employer must medically evaluate all workers through a respirator clearance test in order to confirm that the employee has no health impediments for the proper use of a respirator. Prior to the actual fit test, the employee must be shown how to put on the respirator, position it on the face, set strap tension, and determine an acceptable fit. Once there is an acceptable fit, the employee needs to perform a seal check in order to confirm if the respirator is properly seated to the face or needs to be readjusted. In addition, if a worker needs to use prescribed glasses or any other protective equipment, such items must me worn during the fit test to check they do not interfere with the respirator’s fit.
Workers must be retested at least annually in order to be sure the respirator still fits correctly, since some changes in a person’s physical condition like weight change, facial surgeries, significant scarring in the area of the seal, or major dental work, might affect the seal between the user’s face and the respirator.
Last but not least, remember that not everyone can get a good fit with one specific respirator, so in case the respirator fails the test, you have to try other make, style, model or size until it fits you properly.