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.

Jun 15, 1983

ATTN: ARAs for Technical Support
Director, Field Operations
Director, Technical Support
SUBJECT: Acceptance of Closed-Circuit Self-Contained Breathing Apparatus

We have received numerous inquiries concerning OSHA's acceptance of two positive-pressure closed-circuit self-contained breathing apparatus (PPCCSCBA), the BioPak 60P and 30P (TC-13F-85 and 84). The major concerns have been whether these devices are permissible for use in atmospheres which are immediately dangerous to life or health (IDLH) or for use in the fire service.

You may recall that early in 1979, we accepted the BioPaks as a positive-pressure SCBA based on the performance tests conducted by NIOSH in spite of the fact that there are no certification criteria for the PPCCSCBA. Since then the Los Alamos National Laboratory (LANL) and the Lawrence Livermore National Laboratory (LLNL) have conducted comprehensive quantitative fit testing and fire testing of the BioPaks. The LANL results indicate that the BioPaks are positive-pressure SCBAs and when well fitted an individual can obtain a fit factor of 20,000 or higher which is equivalent to the open-circuit positive-pressure SCBA. The LLNL study also indicates that the BioPaks are truly positive-pressure SCBAs and shows that under severe (life and death) conditions of flash-over, the use of oxygen with the positive-pressure posed no significant additional hazard to the firefighter user.

Based on this information, we shall continue to accept the BioPak 60P and BioPak 30P as positive-pressure self-contained breathing apparatus and permit their use under conditions which are immediately dangerous to life or health. They are also in compliance with our standard on fire brigade, 29 CFR 1910.156; the BioPaks are acceptable for the fire brigade member to use in performing interior structural fire fighting.

I am attaching for your reference excerpts of the LANL and LLNL reports on the BioPaks as well as a Nuclear Regulatory Commission information notice on the use of closed-circuit SCBAs.

Additional information may be obtained from Mr. Ching-tsen Bien of my staff (FTS-523-7033).