The Definition of Fit Testing

Definition of Fit Testing

Fit testing is a test that checks whether a specific make, model, style and size of tight-fitting respirator seals properly to an individual worker's face. A respirator only protects as well as its seal. If contaminated air leaks in around the edges, the filter or cartridge rating means little.

A mask that seals well on one face may leak badly on another. Fit testing identifies which respirator works for each wearer before they rely on it in a hazardous atmosphere. In the US, it is a mandatory part of any respiratory protection program where tight-fitting respirators are required, under OSHA 29 CFR 1910.134(f). Construction follows the same rule through 29 CFR 1926.103.

OSHA Fit Testing Requirements

When fit testing is required

Under 1910.134(f), employees who use a tight-fitting facepiece respirator must pass a qualitative or quantitative fit test:

• Before they first use the respirator in the workplace.
• Whenever a different respirator facepiece (size, style, model or make) is used.
• At least annually after that.
• When the employee, a supervisor, the program administrator or a physician reports changes in physical condition that could affect fit, such as facial scarring, dental changes, cosmetic surgery or an obvious change in body weight.

If a worker finds the fit unacceptable after passing, they must be given a chance to choose a different respirator and be retested.

Medical evaluation comes first

Paragraph 1910.134(e) requires a medical evaluation to determine whether the employee can safely use a respirator before they are fit tested or required to wear one. Some heart and lung conditions make respirator use unsafe.

Facial hair

Under 1910.134(g)(1)(i), tight-fitting respirators must not be worn by employees with facial hair that comes between the sealing surface of the facepiece and the face, or that interferes with valve function. Someone who cannot or will not be clean-shaven where the mask seals needs a loose-fitting option, such as a powered air-purifying respirator with a hood.

Who must be fit tested

The rule applies to tight-fitting respirators, including filtering facepieces such as N95s, elastomeric half masks, full facepieces and tight-fitting supplied-air or SCBA facepieces. Loose-fitting hoods and helmets do not require fit testing. Voluntary use of a filtering facepiece, where no respirator is required, is handled under Appendix D rather than the fit testing rule.

Qualitative vs. Quantitative Fit Testing

The approved procedures for both are set out in Appendix A to 1910.134.

Qualitative fit testing (QLFT)

QLFT is a pass/fail test that relies on the wearer's sense of taste, smell or reaction to an irritant. With the respirator on and a hood over the head, a test agent is introduced. If the person detects it, the seal is leaking. The four OSHA-accepted QLFT protocols use:

• Isoamyl acetate, which smells like bananas, for respirators with organic vapor cartridges.
• Saccharin, a sweet-tasting aerosol, for particulate filters.
• Bitrex (denatonium benzoate), a very bitter aerosol, for particulate filters.
• Irritant smoke (stannic chloride), which causes an involuntary cough.

Before the test, a sensitivity check confirms the person can detect the agent at all. QLFT may only be used for negative pressure air-purifying respirators that must achieve a fit factor of 100 or less, which in practice means half masks and filtering facepieces.

Quantitative fit testing (QNFT)

QNFT uses an instrument to measure leakage numerically and produce a fit factor. OSHA's accepted methods include:

• Ambient aerosol condensation nuclei counter (CNC). Often called a condensation particle counter (CPC), the device compares particle concentrations outside and inside the mask.
• Controlled negative pressure (CNP). The device briefly draws air out of the sealed facepiece and measures how much leaks in. A shorter variant, CNP REDON, is also accepted.
• Generated aerosol. A test aerosol is released in a chamber and measured inside and outside the mask.

To pass, a half facepiece must reach a fit factor of at least 100 and a full facepiece at least 500.

The test exercises

Both methods run the wearer through a set of exercises, such as normal and deep breathing, turning the head side to side, moving it up and down, talking and bending over.

Fit Testing Mistakes to Avoid

Treating a user seal check as a fit test

A user seal check, covering the mask and breathing in or out to feel for leaks, is something the wearer does every time they put the respirator on. Its procedures are in Appendix B-1. But it is not a fit test. It cannot confirm that a particular model and size fits a person's face.

Testing in one model, issuing another

A fit test applies to the exact make, model, style and size tested. Link the purchasing list to fit test records.

Letting annual retests slip

Fit test dates should sit alongside other expiring requirements in the training matrix, with reminders before they lapse.

Ignoring other PPE

Safety glasses, hearing protection and hard hat straps can break a respirator seal. Workers should be fit tested wearing the same personal protective equipment they will wear on the job.

Example of Fit Testing

A cabinet manufacturer issued N95 filtering facepieces to workers in its sanding area to control wood dust. Annual fit tests used the saccharin protocol. During one round, three workers failed on the medium size. Two passed on a small size from the same maker. The third, who had lost significant weight since the previous year, failed on every N95 the company stocked.

The company moved him to an elastomeric half mask with P100 filters, which he passed, and updated his medical evaluation as the program required. The review also found that several new hires had been issued a different N95 model after a supplier shortage and had never been tested in it. Purchasing was told that respirator models could not be changed without the program administrator's approval, and those workers were retested before returning to the sanding line.

Frequently Asked Questions: Fit Testing

How long does a respirator fit test take?

Most individual fit tests take about 15 to 30 minutes, including the sensitivity check for qualitative methods, donning and adjusting the respirator, and running through the test exercises. A failed test and a retry in a different size or model adds time.

Who is qualified to perform fit testing?

OSHA does not require a specific license or certification. The person conducting the test must be able to prepare the test agents correctly, calibrate and operate equipment, recognize invalid tests, and follow the Appendix A protocols exactly. Many employers train in-house staff; others use occupational health clinics or consultants.

Does an N95 need fit testing?

Yes, when the N95 is required by the employer or by an OSHA standard. A filtering facepiece is a tight-fitting respirator, so all the fit testing, medical evaluation and training requirements apply. If an employee chooses to wear an N95 voluntarily where no respirator is required, the employer only needs to provide the Appendix D information and confirm the respirator itself does not create a hazard.

Can someone with a beard wear a respirator?

Not a tight-fitting one, if the beard falls where the mask seals. OSHA prohibits it under 1910.134(g)(1)(i). Options include a loose-fitting powered air-purifying respirator with a hood or helmet, or shaving the sealing area. Where facial hair is kept for religious or medical reasons, employers should discuss the loose-fitting option and accommodation obligations rather than assign a respirator that cannot seal.

What records must be kept for fit testing?

Under 1910.134(m), employers must keep a record of qualitative and quantitative fit tests, including the employee's name, the test type, the pass or fail result and the test date. The record must also include the make, model, style and size of respirator tested, and for QNFT, the fit factor and strip chart or other recorded results. Keep it until the next fit test.