A lightweight, low-profile compressed oxygen rescue breathing apparatus (rba) for mine rescue missions was developed by the Survivair Division, Inc., under contract to the Bureau of Mines. Cofunding this contract were the U.S. Fire Administration, U.S. Air Force, and U.S. Coast Guard. The apparatus is a positive pressure, closed circuit system with 2-h mission capability. The apparatus weighs 24 lb when fully charged. Weight and size reduction were realized by using lithium hydroxide (lioh) for carbon dioxide (co2) management, a composite glass-fiber-wrapped aluminum cylinder for oxygen storage, and lightweight plastic materials for backpack and breathing bag construction. Constant positive pressure within the breathing circuit is maintained by a pilot-operated pressure demand regulator and spring-biased breathing bags.