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Respirator Fit Testing Requirements and Procedures
WHEN OSHA's revised Respiratory Protection Standard for General Industry, 29 CFR 1910.134, became effective on April 8, 1998, it provided employers with an all-inclusive reference source for fit testing guidelines. Before its revision, the standard made reference to testing a respirator's "face-piece-to-face seal" but provided no additional guidance on how to perform the test. The standard now specifies what needs fit testing, the kinds of fit tests allowed, the procedures for conducting them, and how frequently fit tests must be performed.
What's Covered
29 CFR 1910.134(f) states, "Before an employee may be required to use any respirator with a negative or positive pressure tight-fitting facepiece, the employee must be fit tested with the same make, model, style, and size of respirator that will be used." This statement is noteworthy because it mandates that tight-fitting positive pressure facepieces such as those used in PAPRs and airline respirators be fit tested. The statement also does not exclude disposable particulate respirators from fit testing.
Two methods are acceptable for fit testing a tight-fitting positive pressure mask:
1. The mask can be converted into a negative pressure respirator and equipped with filters appropriate to the fit test protocol being followed, or
2. An identical negative pressure respirator can be used as a surrogate for fit testing as long as it has the same sealing surfaces as the positive pressure respirator.
Fit Testing Procedures
Within the standard, employers are provided the option of conducting either a quantitative or qualitative fit test. The individual performing the fit test procedure requires no special certification. However, the individual must be able to prepare the test solutions, calibrate the equipment and perform the tests properly, recognize invalid tests, and ensure test equipment is in proper working order.
The ability to calculate fit factors (FFs) is also a requirement for the individual administering a quantitative fit test (QNFT). A FF is "a quantitative estimate of the fit of a particular respirator to a specific individual, and typically estimates the ratio of the concentration of a substance in ambient air to its concentration inside the respirator when worn."
As defined in the standard, a QNFT means "an assessment of the adequacy of respirator fit by numerically measuring the amount of leakage into the respirator." A QNFT is necessary for respirators that must achieve a FF of greater than 100. This means that in order to fit test a full face air purifying respirator (APR) to obtain its maximum APF of 50 (as defined in OSHA's proposed APF rule released on June 6, 2003), a QNFT must be used.
The reason there's a difference between FFs and APFs is that APFs generally incorporate a safety factor of 10. This safety factor is necessary because APFs in the workplace tend to be lower than the FFs achieved during fit testing. In order to fit test a full face APR to an APF of 50, a FF of 500 (APF of 50 times the safety factor of 10) would need to be achieved.
A QNFT uses an instrument to take a sample from within the wearer's breathing zone while the respirator is being worn. In addition to the instrument, a challenge agent and a probed respirator (or probed adapter for a standard respirator) are necessary to perform a QNFT. A QNFT is more precise than a qualitative fit test; it's also less commonly performed because of the complexity of the procedure and the prohibitive cost of the analyzation instrument. The protocol for a QNFT is detailed in Appendix A, subpart C to 29 CFR 1910.134.
The standard defines a qualitative fit test (QLFT) as "a pass/fail fit test to assess the adequacy of respirator fit that relies on the individual's response to the test agent." A QLFT, according to 29 CFR 1910.134(f)(6), "may only be used to fit test negative pressure air-purifying respirators that must achieve a fit factor of 100 or less." In other words, a QLFT can be used only to verify an APF of up to 10 (FF of 100 ? 10 percent safety factor = APF of 10).
The exception to this statement is called out under 29 CFR 1910.134(f)(8), where OSHA allows both QNFTs and QFLTs to be used to fit test tight-fitting atmosphere-supplying and tight-fitting powered air-purifying respirators. Tight-fitting positive pressure respirators do have APFs greater than 10.
To qualitatively fit test a positive pressure respirator, the respirator must be fit tested in the negative pressure mode. According to 29 CFR 1910.134(f)(8)(i), "Qualitative fit testing of these respirators shall be accomplished by temporarily converting the respirator user's actual facepiece into a negative pressure respirator with appropriate filters, or by using an identical negative pressure air-purifying respirator facepiece with the same sealing surfaces as a surrogate for the atmosphere-supplying or powered air-purifying respirator facepiece."
In broad terms, the downside to a QLFT is that it relies upon the subjective response of the individual being tested, so that reproducibility and accuracy may vary. The upside is that a QLFT is simpler to perform than a QNFT; the necessary testing equipment is also more accessible and economical.
Within appendix A of the standard, the following four acceptable QLFT protocols are defined: Isoamyl Acetate (more commonly known as banana oil), Saccharin Solution Aerosol, Bitrex Solution Aerosol, and Irritant Smoke (Stannic Chloride).
The test method performed will dictate the type of air-purifying element that's used on the facepiece. The isoamyl acetate QLFT requires respirators equipped with organic vapor cartridges. Both the saccharin and bitrex QLFT require respirators equipped with particulate filters (either a 95, 99, or 100 series filter is acceptable). To perform the irritant smoke test, the respirator needs to be equipped with either a P100 series particulate filter or HEPA filter.
It's important to note that when performing the irritant smoke test, no form of enclosure or hood for the test subject is to be used. The other QLFTs all require the use of an enclosure. Complete instructions for all QLFTs are detailed within appendix A to 29 CFR 1910.134.
Frequency
29 CFR 1910.134(f)(2) states, "The employer shall ensure that an employee using a tight-fitting facepiece respirator is fit tested prior to initial use of the respirator, whenever a different respirator facepiece (size, style, model or make) is used, and at least annually thereafter." In addition, fit testing must be repeated "whenever the employee reports, or the employer, PLHCP (physician or other licensed healthcare professional), supervisor, or program administrator makes visual observations of changes in the employee's physical condition that could affect respirator fit. Such conditions include, but are not limited to, facial scarring, dental changes, cosmetic surgery, or an obvious change in body weight."
Also, an employee who has passed a fit test but later finds the fit of the respirator unacceptable must be given a reasonable opportunity to select a new facepiece and be retested.
Recordkeeping
The employer is responsible for recording the results of fit testing. As stated under 29 CFR 1910.134(m)(2), the following information must be recorded: The name of the employee; the type of test performed (QLFT or QNFT); specific respirator tested; date of the test; and the results of the test. This information must be retained until the next fit test is administered.
Fit Checking
Fit testing should not be confused with a respirator fit check. A fit check, or "user seal check" as it is referred to in appendix B-1 to 29 CFR 1910.134, should be performed each time a tight-fitting respirator is donned to ensure there's an adequate seal. The appendix provides guidelines for performing positive- and negative-pressure fit checks but states, "User seal checks are not substitutes for QLFTs or QNFTs."
This article originally appeared in the May 2004 issue of Occupational Health & Safety.