OSHA memo clarifies fit-testing procedures
OSHA memo clarifies fit-testing procedures
Agency responds to 'numerous questions'
The U.S. Occupational Safety and Health Administration (OSHA) in Washington, DC, recently issued a four-page memorandum clarifying its current respirator fit-testing and fit-checking procedures. (See Editor's note on p. 65 for information on obtaining a copy of the memorandum.)
The new respirator certification guidelines established last year by the National Institute for Occupational Safety and Health (NIOSH) in Washington, DC,1 "directly affected our requirements for respiratory protection for exposure to tuberculosis and . . . generated numerous questions. . . . ," the memorandum states.
According to the memo, the three most commonly asked questions are:
* What does OSHA expect for a fit test?
* What is the difference between a fit test and fit check?
* What does OSHA expect for an acceptable fit test and fit check?
Two kinds of fit tests
While OSHA officials hammer out a proposed TB standard that no doubt will specify requirements for fit-testing the new N95 respirators, current agency regulations are set forth in the respirator standard (29 CFR 1910.134). While it does not delineate which fit-testing protocols to use, "OSHA would accept either a quantitative fit-test (QNFT) or qualitative fit-test (QLFT)," the document states.
A QNFT consists of wearing the respirator in a stable test atmosphere that contains a challenge agent, such as corn oil. Fit adequacy is determined by measuring and establishing a ratio of the challenge agent levels inside and outside the respirator. In a QLFT, an aerosol challenge agent is introduced into the area around the respirator wearer's face.
OSHA's fit-testing requirement calls for training to provide "an opportunity to handle the respirator, have it fitted properly, test its facepiece-to-face seal, wear it in normal air for a long familiarity period, and, finally, to wear it in a test atmosphere," according to the memorandum.
When the new N95 respirators are quantitatively fit-tested, OSHA requires a minimum "fit factor" of 100 to conclude that the mask fits the worker adequately to satisfy the current respiratory protection standard. The fit factor for a disposable or half-mask respirator is based upon the assigned protection factor of 10 (established by NIOSH and the American National Standards Institute [ANSI]) times the safety factor of 10 (ANSI Z88.2-1994).
For hospitals conducting QLFTs, adequate fit is determined by whether the worker can smell, taste, or detect the challenge agent. OSHA will accept tests using one of three challenge agents: irritant fume, saccharin, or Bitrex aerosol (denatonium benzoate). Testing protocols for the latter are described in a recent article.2
Fit check performed by wearer
In contrast to a fit test, a respirator fit check is "a quick determination of respirator fit by the wearer each time a respirator is donned to assure that a proper face-to-respirator seal has been achieved," the memo explains, admitting that a fit check on a disposable respirator is "difficult and often less reliable than fit-checks done on an elastomeric half-mask respirator."
Nevertheless, a recent article provides information on conducting fit checks with disposable respirators and supplies comparison data with the saccharin-aerosol protocol. The article concludes that when employees follow manufacturers' fit-check instructions, they are better able to detect and prevent a poorer quality fit.3
References
1. National Institute for Occupational Safety and Health. Respiratory protective devices; certification requirements. 60 Fed Reg (June 8, 1995):30,336-30,398.
2. Mullins HE, Danisch SG, Johnston AR. Development of a new qualitative test for fit testing respirators. Amer Indus Hygiene J 1995; 56:1,068-1,073.
3. Myers WA, Jaraiedi M, Hendricks L. Effectiveness of fit check methods on half-mask respirators. Applied Occup and Environ Hygiene J 1995; 10:934-942. *
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.