NIOSH/OSHA. Up to 25 mg/m3: (APF = 10) Any supplied-air respirator. (APF = 50) Any self-contained breathing apparatus with a full facepiece. Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other ...