Fit testing ensures that respirators and other tight-fitting PPE properly seal to the wearer's face, providing the expected level of protection. Fit testing is essential before an employee is required to use a tight-fitting respirator and at least annually thereafter. Additional fit tests are required whenever a different respirator facepiece (size, style, model, or make) is used, or if there are changes in the employee's physical condition that could affect respirator fit, such as facial scarring, dental changes, cosmetic surgery, or an obvious change in body weight. [2]

There are two main types of fit testing:

Qualitative Fit Testing (QLFT):

QLFT is a pass/fail test that relies on the wearer's ability to detect a challenge agent, such as:

Isoamyl Acetate: The test subject should be able to smell the odor of isoamyl acetate (banana oil) at low concentrations. If the test subject is unable to correctly identify the jar containing the odor test solution, the isoamyl acetate qualitative fit test should not be performed. [7]

Saccharin: The saccharin taste threshold screening, performed without wearing a respirator, is intended to determine whether the individual being tested can detect the taste of saccharin. [7]

Irritant Smoke: During the test, the operator directs a stream of irritant smoke toward the face seal area of the test subject. The exercises are performed while the respirator seal is continually challenged by the smoke. If the person being fit tested reports detecting the irritant smoke at any time, the test is failed. [3]

Quantitative Fit Testing (QNFT):

QNFT uses instruments to measure the amount of leakage into the respirator. Acceptable QNFT procedures include:

Generated Aerosol: This method uses a non-hazardous aerosol, such as corn oil, to measure the fit of the respirator in a test chamber. [5]

Ambient Aerosol: This method uses ambient aerosol as the test agent and a condensation nuclei counter to quantify the respirator fit. [5]

Controlled Negative Pressure (CNP): This method uses controlled negative pressure and instrumentation to measure the volumetric leak rate of a facepiece to quantify the respirator fit. [5]

General requirements for all fit testing procedures include:

The test subject must be allowed to pick the most acceptable respirator from a sufficient number of models and sizes. [1]

Prior to selection, the test subject must be shown how to put on a respirator, how it should be positioned on the face, how to set strap tension, and how to determine an acceptable fit. [1]

The test subject should be informed that they are being asked to select the respirator that provides the most acceptable fit. [1]

The test subject should hold each chosen facepiece up to the face and eliminate those that obviously do not give an acceptable fit. [1]

The more acceptable facepieces are noted in case the one selected proves unacceptable; the most comfortable mask is donned and worn at least five minutes to assess comfort. [1]

The following criteria shall be used to help determine the adequacy of the respirator fit: chin properly placed; adequate strap tension, not overly tightened; fit across nose bridge; respirator of proper size to span distance from nose to chin; tendency of respirator to slip; self-observation in mirror to evaluate fit and respirator position. [1]

The test subject shall conduct a user seal check, either the negative and positive pressure seal checks or those recommended by the respirator manufacturer. [1]

The test must not be conducted if there is any hair growth between the skin and the facepiece sealing surface, such as stubble beard growth, beard, mustache, or sideburns which cross the respirator sealing surface. [1]

If a test subject exhibits difficulty in breathing during the tests, they should be referred to a physician or other licensed health care professional. [1]

If the employee finds the fit of the respirator unacceptable, the test subject shall be given the opportunity to select a different respirator and to be retested. [1]

Prior to the commencement of the fit test, the test subject shall be given a description of the fit test and the test subject's responsibilities during the test procedure. The respirator to be tested shall be worn for at least 5 minutes before the start of the fit test. [1]

The fit test shall be performed while the test subject is wearing any applicable safety equipment that may be worn during actual respirator use which could interfere with respirator fit. [1]

During the fit test, the subject will perform a series of exercises to simulate workplace movements, such as normal breathing, bending over, head shaking, and talking. [6]

A user seal check must be performed every time the respirator is put on to ensure an adequate seal. This can be done through positive and negative pressure checks or by following the respirator manufacturer's recommended procedures. [4]

Note: User seal checks are not substitutes for qualitative or quantitative fit tests. [4]