[Code of Federal Regulations] [Title 42, Volume 1] [Revised as of October 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 42CFR84.80] [Page 521] TITLE 42--PUBLIC HEALTH CHAPTER I--PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES PART 84_APPROVAL OF RESPIRATORY PROTECTIVE DEVICES--Table of Contents Subpart H_Self-Contained Breathing Apparatus Sec. 84.80 Interchangeability of oxygen and air prohibited. Approvals shall not be issued by the Institute for any apparatus, combination of respirator assemblies, or any apparatus or respirator component which is designed or constructed to permit the interchangeable use of oxygen and air.