Abstract: A lightweight portable, self-contained, closed-type breathing apparatus comprises an oxygen pressure cylinder having connected thereto manually actuated oxygen flow control means. Included is a carbon dioxide scrubber having connected thereto breathing means including check valves and a breathing tube. A flexible breathing bag is provided, as are means for mounting the oxygen cylinder, the flow control means, the scrubber and check valves in fixed mutual relationship, with the oxygen cylinder and scrubber disposed within the breathing bag. The flow control means is constructed upon actuation, to meter flow of oxygen from the cylinder into the breathing bag. The check valves cause a user's exhaled breath to pass through the scrubber before entering the breathing bag, while causing a user to inhale directly from the breathing bag, bypassing the scrubber. An external canister protects the bag from accidental damage.