Abstract: Portable emergency breathing apparatus is disclosed which is comprised of a compressed breathing gas container having a housing mounted on the open end thereof which supports a pressure gauge, a pressure reducing valve assembly, and burst valve, fill valve and needle valve components. The pressure reducing valve controls the flow of breathing gas from the container to a breathing hose attached to the housing and leading to a face mask or hood worn by the user. The housing has a flat axially outer end relative to the container and a radially outer periphery which is within the cylindrical plane of the side wall of the container, and the housing is structured for mounting on the container so as to optimize compactness of the apparatus and protection of the pressure gauge and the pressure reducing, burst, fill and needle valves from damage during storage and use.