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.


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.
    • Moving head side to side.
    • Moving head up and down.
    • Bending over (or jogging in place if fit test unit doesn’t permit bending at the waist).
    • Talking.
    • 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

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    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.


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.

  • Illustration of guy wearing disposable respirator with safety eyewear
    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.

  • Illustration of a guy wearing disposable respirator with the seal highlighted in blue
    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 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.

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

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