How to Perform a Respirator Fit Test

According to OSHA 29 CFR 1910.134(f), employees must be fit-tested before using any respirator with a tight-fitting facepiece. Respirators with poorly fitting face shields may expose the wearer to higher levels of contaminants.

Employees must be tested with the same make, model, style and size respirator that they will use on the job site.

Fit testing must be conducted annually, or in accordance with local regulations. Employees should have a new fit test following changes in personal appearance, such as facial hair growth or dental surgery, which could affect how the facepiece fits.

Respirator fit tests include these steps:

1. Employees must have training and medical clearance to use a respirator.

2. Employees must make a seal check to confirm that the respirator fits.

3. During quantitative fit tests, a device measures whether air escapes the respirator.

4. Before qualitative fit tests, a taste threshold screening shows whether employees can taste the flavored solution used during the test.

5. During qualitative fit tests, employees wear the respirator and signal whether they can detect the test solution.
   
   
   
   
   

Take the following steps to prepare for fit-testing a respirator.

• Make sure that any employee who uses a respirator has completed a medical questionnaire and received medical clearance. You can find the Respirator Medical Evaluation Questionnaire on the OSHA website.
• The employee must also have completed respiratory protection training within the past year.
• The employee must choose the type and size of respirator they will use. The workplace must provide a variety of sizes.
• The employee must be taught how to properly put on the respirator and place the straps correctly. This includes positioning the facepiece on the chin and the bridge of the nose.

The employee must seal-check the respirator to make sure it fits snugly and comfortably through the following steps:

• Begin the seal test by covering the entire respirator, ideally with a piece of plastic, such as plastic film.
• During a positive pressure seal check, the wearer should breathe out gently and feel if air is escaping around the face. If so, the respirator should be repositioned and re-checked until the wearer feels no air escaping.
• During a negative pressure seal check, the wearer should gently inhale, drawing the respirator slightly toward the face. If the respirator is not drawn forward, remove the respirator and check for defects such as holes or a warped sealing edge. If none is found, reposition the respirator and try again. When the respirator draws toward the face, the respirator has passed the negative pressure seal check.

Determine whether you’ll need a qualitative fit test (QLFT) or a quantitative fit test (QNFT). Qualitative fit testing (QLFT) relies on the respirator wearer’s senses to determine if the seal the respirator makes with the wearer’s face has a gap or leak. QLFTs may only be used to fit test:

• Negative pressure, air purifying respirators only used in atmospheres where the hazard is less than 10 times the permissible exposure limit
• Tight-fitting facepieces used with powered and atmosphere-supplying respirators

QNFTs use an instrument to check the face seal for leakage, rather than the user’s senses, and can test all other positive and negative pressure respirators.

Pro Tip: If an employee wears eyeglasses or will wear safety glasses with the respirator, make sure they also wear them during any checks or tests.

The first part of qualitative fit testing is giving the subject a taste threshold screening, also called a sensitivity test. This tests the subject’s ability to taste the flavored test solution.

The most common solutions used in the OSHA-accepted and ANSI-accepted qualitative fit tests are either a sweet-tasting saccharin aerosol or a bitter-tasting aerosol called Bitrex.

• Before the taste threshold screening, make sure the subject has not eaten, chewed gum or drunk anything but water for the last 15 minutes.
• Place the test hood over the subject’s head, leaving about six inches between their face and the hood window. (They will not wear the respirator for the taste threshold screening.)
• Tell the subject to breathe with mouth open and tongue extended.
• Place the nebulizer through the hole in the window and give 10 sprays of either the bitter or the sweet solution. The taste threshold screening uses a diluted version of the test solution.
• Have the subject notify you when they taste the test solution. If they can’t detect it, do 10 sprays and test again. Do an additional 10 sprays as needed but stop testing after 30 sprays. Use the same type of solution for these sprays.
• If the subject fails to taste the solution, wait 15 minutes and repeat with the alternate solution. For example, if they failed to taste the sweet, try again with the bitter.
• If subject tastes the solution, move onto the fit test.

Follow these instructions for qualitative fit testing a respirator.

The test subject should put on the respirator mask and wear it for 5 minutes before the fit test.

Place the hood over the subject’s head as described above. Have the subject breathe with mouth open while wearing the respirator.

Rapidly inject the same number of spritzes recorded during the sensitivity test (ex. 10, 20 or 30).

Compress and inflate the nebulizer bulb, then inject one-half the original number of squeezes (5, 10 or 15).

Have the subject perform seven fit test exercises for at least 30 seconds each:

• Normal breathing
• Deep breathing
• Turning head side to side
• Nodding head up and down
• Bending forward to touch toes
• Talking, such as reading a passage aloud
• Finish by resuming normal breathing

The respirator fails if the subject tastes the solution at any point. If the respirator fails, stop the test, wait 15 minutes and repeat the seal-check and test process with a different respirator.

The test is successful if the subject does not taste the solution at any point during the fit test.

Pro Tip: If the subject has difficulty breathing during the test, stop the test immediately.

Quantitative fit testing (QNFT) involves numerically measuring the amount of leakage into the respirator. Many QNFTs have similar steps to the QLFT but involve using an instrument to check the face seal for leakage, rather than the user’s senses.

Respirator fit test devices are designed to work on respirators with compatible, built-in probes. When making a QNFT on a standard respirator, use an adapter probe to measure the contaminants inside the facepiece.

There are three OSHA-accepted QNFT test protocols.

• The generated aerosol method uses a non-hazardous aerosol, such as corn oil, dispensed in a booth or test chamber.
• The condensation nuclei counter method uses laser technology to measure ambient aerosol concentrations inside and outside the respirator.
• The controlled negative pressure method uses a test that temporarily cuts off the breathing air to the facepiece to create a vacuum and measures the leak rate, or air flow, needed to maintain the vacuum on the mask.

QNFTs require equipment that costs more than QLFTs and can be complicated to operate. QNFTs also are more precise than QLFTs, are easier to document and do not rely on workers’ subjective responses.

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