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 https://www.osha.gov.

March 8, 2001

Mr. Larry Janssen, CIH
Technical Service Specialist
3M Occupational Health & Environmental Safety Division
3M Center Building 260-3B-09
St. Paul, Minnesota 55144-1000

Dear Mr. Janssen:

Thank you for your letters of August 2 and December 14, 2000 regarding a multi-station modification 3M has developed to the Bitrex™ aerosol qualitative fit test (QLFT) published in Appendix A of the Occupational Safety and Health Administration's (OSHA) respiratory protection standard, 29 CFR 1910.134. Your request involves the substitution of a computer controlled electric pump for the nebulizer squeeze bulb required by the Bitrex™ QLFT protocol for generating the test aerosol concentration, along with the use of a multi-station manifold to allow for five subjects with the same taste sensitivity level to be tested simultaneously. The same DeVilbiss Model 40 nebulizer body used with the squeeze bulb is used with the electric pump. The sensitivity and test aerosol concentrations, exercises, and other elements of the fit test protocol are not changed.

In our April 3, 2000 letter to 3M we stated that using an electric pump in place of the squeeze bulb was a modification to the Bitrex™ QLFT protocol contained in Appendix A. However, based on the information you provided in your original December 9, 1999 letter, OSHA agreed with you that this modification by itself did not constitute the development of a new fit test method. Our April 3 letter also stated that OSHA will consider the electric pump and squeeze bulb Bitrex™ methods to be equivalent.

A major change from your original request to use the electric pump nebulizer is your subsequent request for inclusion of a new multi-station fit-tester that could be used to fit-test up to five people at the same time. The multi-station modification you proposed did introduce new concerns. However, the changes to the solenoid valves, pressure sensor, and software used with this multi-station fit test instrument should insure the system will alert the operator or shut down the fit test if the pressure goes out of the correct operating range. Based on the demonstration 3M performed for OSHA staff, OSHA believes that proper training and written instructions for individuals operating the electric pump nebulizer are also necessary to ensure proper fit testing.

While OSHA will consider the multi-station electric pump nebulizer and the squeeze bulb Bitrex™ methods to be equivalent, the Agency will expect the operator to be knowledgeable in the conduct of the QLFT. More specifically, the operator should know the basic principles for performing a general Bitrex™ fit test (e.g., instructing the subject to breathe through the mouth with the tongue slightly forward during the screening portion of the test), along with the knowledge necessary to successfully operate the 3M multi-station fit test apparatus and software. Therefore, the fit test operator will need to be proficient in the use of the 3M fit testing software and knowledgeable in any necessary additional written instructions when performing the QLFT.

Thank you for your interest in occupational safety and health. Please be aware that OSHA's enforcement guidance is subject to periodic review and clarification, amplification or correction. Such guidance could also be affected by subsequent rulemaking. In the future, should you wish to verify that the guidance provided herein remains current, you should consult OSHA's website at
http://www.osha.gov. If you have any further questions concerning this matter, please feel free to contact the [Office of Health Enforcement] at (202) 693-2190.


Richard E. Fairfax, Director
[Directorate of Enforcement Programs]

[Corrected 6/2/2005]