3M Center for Respiratory Protection
Tight-fitting respirators must seal to the wearer’s face in order to provide expected protection. This includes disposable respirators (also called “filtering facepieces”). Therefore, fit testing is required in many countries before a user wears a mandatory respirator on the job. In addition, fit tests should be performed:
Current fit testing regulations don’t require fit test administrators (fit testers) to be certified, but they must be competent to conduct a test, coach wearers to fit respirators correctly, recognize invalid tests, and properly clean and maintain equipment. However, some countries have voluntary fit tester competency assessment schemes, for example the BSiF Fit2Fit scheme which operates in the UK.
Read more about fit testing regulations
There are two kinds of tests: qualitative and quantitative.
There are two kinds of tests: qualitative and quantitative.
A qualitative fit test (QLFT) may only be used to fit-test:
Filtering facepieces and half-masks (with particulate or combination filters) only. Qualitative methods may be suitable for full face masks according to some fit test regulations and only in certain circumstances. QLFT is pass/fail and relies on the user’s senses to taste an approved test agents, the predominant agents being:
o Saccharin (sweet taste); can test respirators with a particulate filter of any class.
o Bitrex® (bitter taste); can also test respirators with particulate filters of any class.
Each QLFT method uses seven exercises performed for 1 minute each:
o Normal breathing.
o Deep breathing.
o Moving head side to side.
o Moving head up and down.
o Bending over at the waist.
o Reading / talking aloud.
o Normal breathing again.
A quantitative fit test (QNFT) can be used to fit-test any tight-fitting respirator. It involves using an instrument to measure leakage around the face seal and produces a numerical result called a “fit factor.” There are three commonly-accepted QNFT test protocols:
o Generated aerosol uses a non-hazardous aerosol such as common salt (NaCl) generated in a test chamber.
o Condensation nuclei counter (CNC) uses ambient aerosol and doesn’t require a test chamber.
o Controlled negative pressure (CNP) uses a test that creates a vacuum by temporarily cutting off air. (There is also a fourth method, which is an abbreviated version of this one.)
QNFTs use the same seven exercises as QLFTs (in the US plus an additional “grimace” test where the subject smiles or frowns for 15 seconds).
A fit factor of at least 100 is required for half-mask respirators and a minimum fit factor of 500 (US) or 2,000 (UK) for a full facepiece negative-pressure respirator.
Respirator fit is important because it involves several major issues:
Safety glasses, hearing protection, face shields, hard hats and coveralls can all vie with a respirator for real estate on a person’s face, head or body. For instance, if a half face respirator doesn’t fit well (especially if it’s too large), it can overlap with glasses. The more that happens, the more fogging can potentially occur on glasses, and the more likely it is that they’ll interfere with the respirator’s seal.
See the product User Instructions for more details.
To catch these problems before they happen on the job, fit test regulations require any PPE that could interfere with the respirator’s seal to be worn during the fit test.
Employees wearing tight-fitting respiratory protection should perform a seal check each time they put on their respirator, and may be required to do so by national regulations unless the use of the respirator is voluntary. A fit test ensures that the respirator is able to fit and provide a secure seal, but a user seal check ensures that it’s being worn right each time.
Users can either perform a positive-pressure or negative-pressure seal check:
o A positive-pressure check means blocking the exhalation valve on a half or full facepiece respirator or covering the respirator surface on a filtering facepiece, usually by using your hands, and trying to breathe out. If slight pressure builds up, that means air isn’t leaking around the edges of the respirator.
o A negative-pressure check involves blocking the intake valves on a half or full facepiece respirator or covering the respirator surface on a filtering facepiece, typically using your hands and trying to breathe in. If no air enters, the seal is tight.
See the product User Instructions for more details.
Fit testing is not only required by many national regulators; it’s vital to respiratory safety. This list provides some of the whys and hows of fit testing.
Fitting Posters - Reusable Respirators
Running a Fit Test Programme
The Fit Testing Record is the employer documentation that fit testing has been completed and passed for employees. This record must be kept with the respiratory protection program documentation until the next required fit testing.