The proper fit of a face-fitting respirator mask is an OSHA requirement. If the mask does not fit properly, efficiency will be lost and a dangerous condition could result, depending on the circumstances of use. A respirator cannot provide proper protection without a tight seal between the facepiece and the face of the wearer.
A facepiece is designed to form a complete seal with the face, whether it is operating in a positive or a negative pressure mode. Manufacturers provide masks in various sizes, allowing a proper fit for most individuals.
Fit testing is the procedure that is performed prior to being assigned a face-fitting respirator, and annually thereafter. Fit testing must be performed anytime a different respirator facepiece is used, such as size, style, model, or make. An additional fit test must also be conducted whenever a user reports, or a physician or other licensed health care professional, known as PLHCP, makes visual observations of changes in the individual’s physical condition, such as facial scarring, dental changes, cosmetic surgery, or obvious changes in body weight, which could affect respirator fit. Testing is conducted to ensure that the respirator forms a proper seal to the individual’s face. There are two types of fit tests: qualitative and quantitative.
A qualitative fit test is conducted with a test agent such as a harmless, odorous chemical or an irritant smoke. During this test, the individual is exposed to the test agent, usually in a special tent, while wearing a specific respirator. If the individual smells the odor, or if the nose and throat become irritated, the respiratory mask has failed the test. Another mask size is then worn and tested again until no odor or irritation is detected and a satisfactory respiratory mask has been determined.
A quantitative fit test is a more sophisticated test conducted when high fit factors are necessary due to conditions of highly toxic or dangerous atmospheres. During a quantitative fit test, the air inside the facepiece is sampled with an electronic instrument to measure the difference between the air outside and the air inside the facepiece. This test determines the amount of leakage into the respirator compared to a formula for fit factors and whether a satisfactory fit is achieved.
To achieve a proper face-to-mask piece seal every time a respirator is worn, a user seal check must be performed before entering a hazardous atmosphere. This check is conducted by the wearer in two different ways. The first is called the negative pressure check. To perform this check, the mask is put on and adjusted to feel comfortable on the face. Then, the individual’s palms are placed over the inhalation inlets or squeeze the breathing tube of an air supplied respirator, to prevent any passage of air. The person inhales until the mask collapses slightly from the suction and holds for a few seconds. A seal is achieved if the mask holds the negative pressure.
The other user seal check is called the positive pressure check. To perform this check, the mask is put on and adjusted to feel comfortable on the face. The exhalation valve is closed with the palm of the hand. Then, the individual exhales into the mask until positive pressure causes the facepiece to bulge slightly and holds for a few seconds. A seal is achieved if no leaks can be detected and the facepiece holds the positive pressure.
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