Step 3. Is the respirator intended for entry into unknown or IDLH atmospheres (e.g., an emergency situation)?
a. If yes, one of two types of respirators are required: a pressure-demand SCBA with a full facepiece or a pressure-demand SAR with a full facepiece in combination with an auxiliary pressure-demand SCBA. Auxiliary SCBA must be of sufficient duration to permit escape to safety if the air supply is interrupted. b. If no, proceed to Step 4. Step 4. Is the exposure concentration of the contaminants, as determined by acceptable industrial hygiene methods, less than the NIOSH REL or other applicable exposure limit? a. If yes, a respirator is not required for routine work. For escape respirators, determine the potential for generation of a hazardous condition caused by an accident, spill or equipment failure. See Section IV. Page 17, for a discussion and selection of escape respirators. Proceed to Step 6.* b. If no, proceed to Step 5. * If respirators are required by the employer to be worn (even if below the occupational exposure limit), OSHA requires that the employer establish and implemen
