Respirator fit and fit testing

Fit testing is required for employees wearing tight-fighting respirators, such as disposable or reusable respirators. This procedure helps ensure the user has selected the correct size respirator and that a seal against the face can be made in order to provide the expected protection.

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Qualitative and Quantitative Fit Test

Learn more about the difference between qualitative and quantitative fit testing protocols.
The importance of respirator fit

Find information to help users perform their everyday seal check test.
Fit testing resources

More information to help support you and your respirator fit test program.

Illustration of lab worker giving qualitative and quantiative respirator fit testing

Qualitative and quantitative fit testing

OSHA requires qualitative or quantitative fit testing before a user wears a mandatory respirator on the job, and must be assessed at least annually. In addition, fit tests should be performed:

whenever a different size, style, model or make of respirator is used, and
when any facial changes occur that could affect fit, such as significant weight fluctuation or dental work.

Qualitative Fit Test (QLFT)
A qualitative fit test (QLFT) may only be used to fit-test:

Negative-pressure, air-purifying respirators, as long as they’ll only be used in atmospheres where the hazard is at less than 10 times the permissible exposure limit (PEL).

Tight-fitting facepieces used with powered and atmosphere-supplying respirators.

QLFT is pass/fail and relies on the user’s senses using one of four OSHA-accepted test agents:

Isoamyl acetate (banana smell); only for testing respirators with organic vapor cartridges.

Saccharin (sweet taste); can test respirators with a particulate filter of any class.

Bitrex® (bitter taste); can also test respirators with particulate filters of any class.

Irritant smoke (involuntary cough reflex); only for testing respirators with level 100 particulate filters.

Each QLFT method uses seven exercises performed for 1 minute each:

Normal breathing.

Deep breathing.

Turning head side to side.

Moving head up and down.

Talking.

Bending over (or jogging in place if fit test unit doesn’t permit bending at the waist).

Normal breathing again.

Read more about OSHA fit testing protocols.

View our online catalog for qualitative testing products.
Quantitative Fit Test (QNFT)
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 OSHA-accepted QNFT test protocols:

Generated aerosol uses a non-hazardous aerosol such as corn oil generated in a test chamber.

Condensation nuclei counter (CNC) uses ambient aerosol and doesn’t require a test chamber.

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, 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 for a full facepiece negative-pressure respirator.

Learn more about Quantitative Fit Testing of Respirators (PDF, 346 KB)

View our online catalog for quantitative testing products.

3M Respirator Fit Testing Procedure Equipment

View all fit testing products

View our online catalog of products to help you run a successful fit testing program.

Qualitative testing products

Find apparatus hoods, nebulizer and other products for qualitative testing.

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Fit testing kits

Find testing kits with apparatus hoods, nebulizer and solution options.

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Quantitative testing products

Find disposable and reusable respirators for use with fit testing as well as test adaptors.

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Probed fit testing respirators

Find probed respirators for use with fit testing.

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Digitize the fit test process with the 3M™ Wear it Right app

Make the task of qualitative fit testing less tedious with the tap of a button. Test both reusable and disposable respirator wearers and perform up to five fit tests at one time.

Now available for download on all smart phones and tablets from the following stores:

Follows OSHA fit testing protocols

Preloaded with OSHA qualitative fit test protocols and meets OSHA Standard 29 CFR 1910.134, Appendix A.
Go paperless with easy recordkeeping

Import wearer details & export fit test records, eliminating the need to track manually.
Convenience just a download away

Qualitatively tests both reusable and disposable respirator wearers with Bitrex® or Saccharin.
Two modes, One app

The app has two modes – one for fit testers who need less step-by-step guidance and one for those who prefer more detailed guidance.

illustration of two workers wearing respirators will the seal highlighted in blue

Does respirator fit matter?

If a worker's respirator doesn't seal properly, there's no certainty it is providing the expected protection.

WATCH: IMPORTANCE OF RESPIRATOR FIT

A good fit means the respirator will seal your skin. A respirator can only work when air passes through the filter. Air will take the path of least resistance, so if the seal isn't there, the air will go around rather than through the respirator - and therefore the lessen the protection.

Compatibility with other PPE

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.

To catch these problems before they happen on the job, OSHA requires any PPE that could interfere with the respirator's seal to be worn during the fit test.
User seal check: An essential everyday test

A user seal check ensures the tight-fitting respirator is being worn right each time the user puts on the respirator. Employees are required to do so by OSHA regulations unless the use is voluntary

Users can either perform a positive-pressure or negative-pressure seal check as described in the product User Instructions.

OSHA user seal check procedure

Types of Respirator User Seal Checks

Positive-pressure seal check

Positive-pressure seal 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 sin't leaking around the edges of the respirator.

Negative-pressure seal check

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.

Fit Testing Frequently Asked Questions

Fit tests must be performed before employer-mandated use of a tight-fitting respirator, per OSHA
In addition, OSHA stipulates that fit testing of employees must occur at least annually; whenever a different size, style, model or make of respirator is used; and when any physical change occurs that could affect fit (such as, for example, significant weight fluctuation, dental work, or other facial changes).
Disposable respirators need to be fit-tested.
Also known as filtering facepieces, these tight-fitting respirators must be fit-tested before mandatory use at a job site.
Voluntarily used respirators don’t require fit testing.
If the employer provides respirators for voluntary use but they aren’t required, they don’t need to be fit-tested – but 3M still recommends it.
OSHA doesn’t require certification to perform fit tests.
However, the OSHA standard does specify that fit test administrators should know how to conduct a test, recognize invalid results, and properly clean and maintain equipment. Read more about OSHA fit testing protocols.
There are two kinds of fit tests.
A qualitative fit test (QLFT) may only be used to fit-test certain negative-pressure, air-purifying respirators and positive-pressure, atmosphere-supplying respirators. It relies on the user’s ability to detect a particular taste, smell or irritant. 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.”
A respirator’s assigned protection factor (APF) is only valid if the respirator fits correctly.
The workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program as specified by 29 CFR 1910.134. Without fit testing, there’s no way of knowing if the respirator is actually able to provide its advertised level of protection for a specific worker.
A good fit means the respirator will seal to your skin.
A respirator can only work when air passes through the filter. Air will take the path of least resistance, so if the seal to the face isn’t secure, the air will go around rather than through the respirator. Therefore, it is essential to ensure a proper fit when wearing tight-fitting respirators.
Any PPE that could interfere with the respirator’s seal must be worn during the fit test.
Respiratory protection is often worn simultaneously with other personal protective equipment (PPE). 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, and could interfere with the respirator’s seal. Fit testing should ensure that equipment is compatible and doesn’t reduce the effectiveness of the respirator due to a compromised face seal.
Tight-fitting respirators cannot properly work with facial hair.
Beards, mustaches, or even stubble interfere with the seal of a tight-fitting respirator. That’s why OSHA requires that employees be clean-shaven the day of the fit test and prohibits any facial hair in areas where the respirator comes into contact with the face.
A respirator that shifts during movement may not retain its seal.
That’s why fit testing involves several exercises, such as head turning and speaking. This determines the respirator’s ability to retain its seal when the worker is in motion.