Occupational Safety and Health Administration (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.

Quantitative Fit Test (QNFT)

A quantitative fit test (QNT) 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

Read more about OSHA fit testing protocols.