US Dept of Labor

Occupational Safety & Health AdministrationWe Can Help

Standard Interpretations - Table of Contents
• Standard Number: 1910.134; 1910.134(f)(7); 1910.134(f)(8)

December 27, 2011

James S. Johnson, PhD
JSJ and Associates
7867 Cypress Creek Court
Pleasanton, CA 94588

Dear Dr. Johnson:

Thank you for your July 6, 2011, letter to the Occupational Safety and Health Administration's (OSHA) Directorate of Enforcement Programs.  You requested an interpretation of the fit-testing requirements in the Respiratory Protection Standard, 29 CFR 1910.134.  Your paraphrased question and our response are below.  This response constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to other scenarios and questions.

Scenario:  There is some confusion about the fit-testing requirements that apply to NIOSH-certified respirators for chemical, biological, radiological, and nuclear (CBRN) protection.  Many respirator manufacturers include requirements in their user instructions for users to achieve a fit factor up to 2500 using a quantitative fit test (QNFT), if the respirator is to be used for a CBRN application.  The types of CBRN respirators currently available are self-contained breathing apparatus (SCBAs), powered air-purifying respirators (PAPRs), and air-purifying respirators (APRs) with canisters.  All respirators that require fit testing are equipped with a full facepiece.  The Respiratory Protection Standard's requirements for fit testing, as summarized in Table 1 of OSHA Directive CPL 02-00-120, Inspection Procedures for the Respiratory Protection Standard, permits either qualitative or quantitative fit-testing methods to be used for some full facepiece respirators.

Question:  Which protocol does OSHA require for fit-testing CBRN respirators?

Response: Workers wearing full facepiece air-purifying respirators must achieve a fit factor of at least 500 when using an OSHA-accepted quantitative fit test protocol.  OSHA's Respiratory Protection Standard, 29 CFR 1910.134, does not treat CBRN full facepiece respirators differently from other full facepiece respirators.  The standard designates an assigned protection factor (APF) of 50 for full facepiece air-purifying respirators.  The standard requires all workers who are 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.  While a manufacturer's recommendation for a pass level of 2000 or 2500 would provide an added safety factor when fit-testing their respirators, obtaining such a fit factor does not increase the assigned protection factor for that respirator, nor does it allow the use of the respirator in a more toxic atmosphere.  When enforcing this standard, OSHA would still require that these tight-fitting full facepiece respirators achieve the minimum pass level of 500 when using QNFT as provided in paragraph 1910.134(f)(7). OSHA also would allow a manufacturer's higher pass level to be used.

For fit-testing tight-fitting atmosphere-supplying respirators and tight-fitting PAPRs, paragraph (f)(8) allows employers to use either quantitative or qualitative fit testing (QLFT) methods with the respirator in a negative pressure mode.  As previously mentioned, if the QNFT protocol is used, OSHA requires the minimum pass level of 500 for QNFTs provided for in paragraph 1910.134(f)(7) for these tight-fitting full facepiece respirators, but also would allow a manufacturer's higher pass level to be used.

OSHA allows the use of QLFT for testing tight-fitting atmosphere-supplying respirators and tight-fitting PAPRs with the respirator tested in the negative pressure mode. These respirators will be used in a positive pressure or pressure demand mode in the workplace, and QLFT will determine whether the worker can get a reasonably good fit with the facepiece.  This testing procedure ensures the mask is capable of maintaining a positive pressure inside the facepiece during work activities and any leakage would be from inside the mask to the outside.

As you are located in California, you should be aware that the California Department of Industrial Relations, Division of Occupational Safety and Health (Cal/OSHA), operates an OSHA-approved State Plan that is responsible for the adoption and enforcement of standards throughout the State.  State Plans are required to set workplace safety and health standards that are at least as effective as the comparable Federal standards. Information on the Cal/OSHA program is available at Please contact Cal/OSHA directly for further information and to discuss your specific compliance situation:

Ellen Widess
Division of Occupational Safety and Health
1515 Clay Street Suite 1901
Oakland, CA 94612
PH: (510) 286-7000
FAX: (510) 286-7037

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  If you have any further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.


Thomas Galassi, Director
Directorate of Enforcement Programs

cc:  Region IX, Cal/OSHA, DCSP

Standard Interpretations - Table of Contents

Thank You for Visiting Our Website

You are exiting the Department of Labor's Web server.

The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.