March 18, 2015

Dr. Roy T. McKay
University of Cincinnati
Kettering Laboratory, ML #56
University of Cincinnati
Cincinnati, Ohio 45267-0056

Dear Dr. McKay:

Thank you for your letter to the Occupational Safety and Health Administration (OSHA), Directorate of Enforcement Programs. Your letter requested clarification on OSHA's approved qualitative fit testing (QLFT) protocols under Appendix A of the Respiratory Protection standard, 29 CFR 1910.134, using Saccharin or Bitrex™. This letter constitutes OSHA's interpretation only of the requirements herein, and may not be applicable to any questions not delineated within your original correspondence. We apologize for the delay in responding to your letter. Your paraphrased questions and our responses are below.

Question 1: If a person wearing the respirator during an OSHA-accepted QLFT fit test using Saccharin or Bitrex™ requests that the test be stopped and subsequently removes the hooded enclosure, is it permissible to continue at the point where the testing stopped?

Response: No, the fit test protocols are not written in performance-oriented language. Any significant variation from the required protocols would invalidate the reliability testing that was performed initially to gain OSHA acceptance and would add uncertainty to the validity of the fit test results. The test exercises are given in a sequence. In particular, steps 7 through 9 are meant to generate an even concentration within the test enclosure, and the total time of the exercises correspond to the concentration in the enclosure.

Question 2: If the answer to Question 1 above is no, is it necessary to repeat sensitivity threshold screening in a manner similar to when a subject detects the test agent during fit testing to ensure taste sensitivity has not changed?

Response: If the test is interrupted and restarted, the entire procedure needs to be performed, from the taste threshold screening to the fit test. As mentioned above, the protocols are not performance-oriented.

Question 3: Are there times when multiple subjects can be simultaneously fit tested by a single fit test operator while using the DeVilbiss Model 40 Inhalation Medication Nebulizer or equivalent, while maintaining the sequence of administered challenged aerosol required in Part I.A.14 of Appendix A to 1910.134 without interruption?

Response: The capabilities of the fit test operator and the equipment determine whether or not multiple subjects can be tested simultaneously. If the operator uses the DeVilbiss Model 40 Inhalation Medication Nebulizer or equivalent, the pump used must produce an aerosol in predetermined intervals, as detailed in Appendix A of the standard, to properly conduct the test. OSHA expects the operator to be knowledgeable of the basic principles for performing a general Bitrex™ or Saccharin QLFT test.

If the operator cannot follow OSHA-accepted fit test protocols in sequence, without interruption, while testing multiple subjects, then the fit test is not in compliance. The topic of testing multiple subjects simultaneously was previously addressed in a March 8, 2001 letter to Mr. Larry Janssen (see enclosed).

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

Enclosure