A respirator fit test is a method used to verify if a particular size and model of a respirator provides an adequate seal on an individual's face. An appropriately fitted respirator is crucial to prevent exposure to hazardous substances in the air, including dust, mists, fumes, gases, or vapors. Respirator fit tests are conducted to fulfill safety standards set by organizations such as the Occupational Safety and Health Administration (OSHA).
There are two types of respirator fit tests: qualitative and quantitative.
Qualitative Fit Test (QLFT): This is a pass/fail test that relies on the wearer's sensory response to detect leaks in the respirator's seal. During the test, the individual wears the respirator, and a testing agent (like a bitter or sweet aerosol, or irritant smoke) is introduced around the respirator. If the wearer can taste, smell, or react to the testing agent, it indicates a leak in the respirator's seal.
Quantitative Fit Test (QNFT): This test uses a machine to measure the actual amount of leakage into the respirator. It does not rely on subjective sensation or taste/smell, but rather provides a direct numerical value called a fit factor. These tests include generated aerosol, ambient aerosol, and Controlled Negative Pressure (CNP) fit tests.
Respirator fit testing should be conducted at the time of initial fitting and periodically thereafter, ideally on an annual basis. However, fit testing should also be done whenever a different size, style, or brand of respirator is used, or when the wearer's physical condition changes (e.g., significant weight loss or gain, major dental work).
It's essential to note that fit testing is different from user seal checks. The latter is a quick check performed by the wearer each time the respirator is put on to ensure an adequate seal has been achieved at that moment. In contrast, a fit test is a more thorough check performed less frequently, designed to ensure the respirator chosen is suitable for the wearer's facial characteristics and provides a reliable seal over time.
Respirator fit testing is an integral part of many workplace safety programs, as it helps to ensure workers are adequately protected from airborne hazards in their specific working environment.