A respirator is only as good as its seal. Properly fitted respirators have a tight seal around the face so that air can only move through the filter, which protects the user from hazardous particulates. To ensure this, the Occupational Safety and Health Administration (OSHA) requires regular fit testing (via 29 CFR 1910.134) on any respirator that forms a tight protective seal on the user’s face. This can include filtering facepiece respirators, self-contained breathing apparatuses (SCBAs), supplied air respirators (SARs), powered-air purifying respirators (PAPRs), and others.

When is Fit Testing Required?

Testing a respirator’s fit and seal is done both at regular intervals and after changes in equipment or user.

• Annual tests should be done to ensure that the user’s respirator still fits.
• New testing should be done when a user has had significant changes in weight or has had facial or dental alterations.
• New testing should be done with any new respirator, as sizes are not standardized across brands and models.

How are Fit Tests Performed?

There are two types of fit testing: qualitative and quantitative.

Qualitative Fit Test (QLFT)

This type of testing has two specific uses:

• Negative-pressure air-purifying respirators, but only when used where the hazard level is ten times less than OSHA’s permissible exposure limit (PEL)
• Tight-fitting facepieces when used with powered, atmosphere-supplying respirators (including SARs, SCBAs, and combination SARs/SCBAs)

Using a pass/fail metric, this test relies on the user sensing the presence of an OSHA-approved test agent, each with a distinct quality:

• Isoamyl acetate (banana smell): for testing respirators with organic vapor cartridges
• Saccharin (sweet taste): for respirators with any class of particulate filter
• Bitrex ®: also for respirators with any class of particulate filter
• Irritant smoke (causes involuntary coughing): for respirators with level 100 particulate filters

A QLFT involves 7 exercises, all performed for 1 minute:

1. Normal breathing
2. Deep breathing
3. Turning head from side to side
4. Moving head up and down
5. Talking
6. Bending over; this may be replaced with jogging in place if the unit doesn’t allow for bending
7. Normal breathing again

 Quantitative Fit Test (QNFT)

This type of testing can be used for any tight-fitting respirator, as it involves measuring faceseal leakage with an instrument that grades the “fit factor.” Half-mask respirators require a minimum fit factor of 100, while a full facepiece negative-pressure respirator must reach a fit factor of 500.

There are three testing formats.

• Generated aerosol: uses a non-hazardous aerosol in a test chamber
• Condensation nuclei counter (CNC): uses an ambient aerosol with no test chamber needed
• Controlled negative pressure (CNP): this test temporarily cuts off air to create a vacuum.

To test the seal, the same exercises as a QLFT are used in addition to one more, where the user smiles or frowns for 15 seconds.

Seal Checks

OSHA recommends that any time a user puts on a respirator, they conduct a quick seal check. There are two types whose use depends on the respirator type.

• Positive pressure user seal check: the user exhales while blocking the respirator’s air paths to see if slight pressure builds up without leakage.
• Negative pressure user seal check: the user inhales while blocking the respirator’s air paths, which should cause the facepiece to collapse slightly when successful.

According to the National Institute for Occupational Safety and Health (NIOSH), over 3 million employees in 1.3 workplaces are required to wear respiratory protection. This protection prevents workers from inhaling hazardous particulates and contaminants in industries as distinct as construction and healthcare. OSHA-mandated fit tests ensure that this critical equipment works as intended to keep workers safe, preventing both acute and long-term health issues.