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.

November 4, 2013

Mr. Paul G. Harrington, Assistant Manager
Technical and Regulatory Support
U.S. Department of Energy
Office of River Protection
P.O. Box 450, MSIN H6-60
Richland, Washington 99352

Dear Mr. Harrington:

Thank you for your May 7, 2013, letter to the Occupational Safety and Health Administration's (OSHA) Directorate of Enforcement Programs. Your letter requested clarification of OSHA's assigned protection factor (APF) policy for pressure-demand, full-facepiece, supplied-air respirators (SAR) in conjunction with an auxiliary escape bottle. Your paraphrased question and our response are presented below.

Background: Your letter describes the Federal Register, Volume 71, No. 164, dated August 24, 2006, as stating that the combination pressure-demand, full-face piece SAR with auxiliary SCBA respirator is equivalent to an SCBA, and, therefore, the APF for an SCBA applies. However, you also mention that OSHA publication 3352-02 2009, Respiratory Protection: Assigned Protection Factors for the Revised Respiratory Protection Standard, contains a picture of a SAR with an egress SCBA ensemble that lists the APF as limited to 1,000, unless it is "used in escape mode." If it is used in an escape mode, then according to OSHA publication 3352, it is assigned an APF of 10,000.

Question: Why are pressure-demand, full-facepiece SARs used in non-escape mode listed with an APF of 1,000 in the Respiratory Protection Standard, 29 CFR 1910.134, Table 1?

Response: The Federal Register, Volume 71, No. 164, dated August 24, 2006, and OSHA Publication 3352-2009 are both stating the correct protection factor in different ways. The Respiratory Protection Standard, 29 CFR 1910.134, and the Federal Register, Volume 71, No. 164, dated August 24, 2006, state:

"When using a combination respirator (e.g., airline respirators with an air-purifying filter), employers must ensure that the assigned protection factor is appropriate to the mode of operation in which the respirator is being used." [Emphasis added].

The combination pressure-demand, full-facepiece SAR with auxiliary self-contained breathing apparatus (SCBA) does not obtain supplied air from the compressor or stationary tank to the air hose at the same time as the auxiliary SCBA is supplying air from the bottle. When the respirator combination is being used in non-escape mode, the auxiliary bottle is not operating, and, in this mode, the APF is the same as a full-facepiece SAR (1,000). When the respirator combination is in escape mode, the air-line hose assembly has either failed or was disconnected so that the wearer may escape or change locations in an environment that is considered immediately dangerous to life or health (IDLH). Once the auxiliary escape bottle is being used solely without the air-line, the APF is converted to 10,000 for a full-facepiece SCBA. Therefore, the information provided in the Federal Register and the OSHA publications are both correct.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at http://www.osha.gov. If you have further questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.

Sincerely,

Thomas Galassi, Director
Director of Enforcement Programs