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 4, 1994

MEMORANDUM FOR:     REGIONAL ADMINISTRATORS

THROUGH:            LEO CAREY 
                   Director 
                   Office of Field Programs

FROM:               STEVE MALLINGER 
                   Deputy Director 
                   Directorate of Technical Support

SUBJECT:            NIOSH Respirator User Notice

We have just received a Respirator User Notice from NIOSH concerning the malfunctioning of self-contained breathing apparatus (SCBA) equipped with a mask mounted regulator (MMR).

These breathers are made by the Mine Safety Appliance (MSA) Company with the following certification numbers: TC-13F-256, TC-13F-257, TC-13F-258, and TC-13F-302. The affected regulators have a quick disconnect mechanism to attach it to the facepiece of the SCBA. NIOSH received several reports which indicated that the MMR had separated from the SCBA facepiece when the device was used under subfreezing temperatures in the presence of water spray. Once the regulator is separated from the SCBA facepiece, the wearer is left unprotected. Since the SCBAs are used under immediately dangerous to life or health (IDLH) environments, the separation of the MMR from the facepiece can be life threatening.

The regulator separation can occur under the following conditions:

1. Lack of lubrication of the facepiece adapter O-ring.

2. Dirt and debris accumulated in the quick disconnect mechanism.

3. Ice formation in the quick disconnect mechanism during cold weather operation.

NIOSH is working with MSA to correct the MMR separation problem. In the meantime, NIOSH does not recommend the use of MSA SCBA with MMR in an environment where the temperature is below 0 degrees C in the presence of water spray.

The Agency is not affected by the NIOSH User Notice since all of our SCBA are equipped with a belt-mounted regulator. I am attaching a copy of the NIOSH Respirator User Notice for your information. NIOSH has requested us to make this notice available to a wider audience. Please inform your CSHOs that they should communicate this problem with employers who may have the affected MSA SCBAs during their inspections.

Please contact Ching-tsen Bien of my staff at 202-219-7065 if you need additional information.