The employer shall provide the following respirators for employee use in IDLH atmospheres:
A full facepiece pressure demand SCBA certified by NIOSH for a minimum service life of thirty minutes, or
A combination full facepiece pressure demand supplied-air respirator (SAR) with auxiliary self-contained air supply.
All oxygen-deficient atmospheres shall be considered IDLH. Exception: If the employer demonstrates that, under all foreseeable conditions, the oxygen concentration can be maintained within the ranges specified in Table II of this section (i.e., for the altitudes set out in the table), then any atmosphere-supplying respirator may be used.
Respirators provided only for escape from IDLH atmospheres shall be NIOSH-certified for escape from the atmosphere in which they will be used.