Required fit factor for full-face CBRN respirators

October 26, 2011

Mr. Johnathan Morton

TSI Incorporated

[Recipient address omitted]

Dear Mr. Morton:

Thank you for your letter to the Occupational Safety and Health Administration (OSHA) concerning fit testing of Chemical, Biological, Radiological, and Nuclear (CBRN) respirators. This letter constitutes OSHA's interpretation only of the requirements discussed, and may not be applicable to any question not delineated in your original correspondence.

In your letter you mention that some respirator manufacturers have included a requirement in their user instructions that, if their respirator is to be used for a CBRN application, a fit factor of at least 2000 is required before it is assigned to any individual. The respirator you provided as an example is a negative pressure tight-fitting full facepiece respirator.

Question: What is the legally mandated fit factor for negative pressure full facepiece respirators when using the ambient aerosol condensation nuclei counter (CNC) quantitative fit testing (QNFT) protocol?

Answer: OSHA's Respiratory Protection Standard, 29 CFR 1910.134, designates an assigned protection factor (APF) of 50 for full facepiece air-purifying respirators. The standard requires all workers required to wear them to be fit tested using an OSHA-accepted QNFT protocol and receive a fit factor of 500 or greater to pass. This level was mandated as the result of rulemaking. While a manufacturer's recommendations for a pass level of 2000 would provide an added safety factor when fit testing their respirators, obtaining a fit factor of 2000 would not permit an increase in the assigned protection factor for that respirator, nor allow it to be used in a more toxic atmosphere. In OSHA's enforcement of its standard, OSHA would still require the minimum pass level of 500 for QNFTs provided for in paragraph 1910.134(f)(7) for all tight-fitting full facepiece respirators, but would also allow the higher pass level to be used.

As a manufacturer of respirator fit testing devices that are sold throughout the United States, TSI Incorporated should be aware that 27 states and territories, including Minnesota, administer their own OSHA-approved occupational safety and health program, or state plan. Though most of these states have adopted standards identical to federal OSHA's, some state plans may have adopted a different respiratory protection standard. See OSHA's Web site at http://www.osha.gov/dcsp/osp/index.html for a list of the state plan states and territories and links to contact and other information and to their Web sites.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov. If you have any further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.

Sincerely,

Thomas Galassi, Director

Directorate of Enforcement Programs