A small form of breathing apparatus for protection against carbon monoxide, worn on a miner's belt. It consists of a canister with a mouthpiece directly attached to it. The wearer breathes through the mouth, the nose being closed by a clip. The canister contains a layer of fused calcium chloride to absorb the water vapor in the air which destroys the efficiency of the other chemical called hopcalite. The self-rescuer affords protection for 30 min, so that miners surviving an explosion may walk out through a mine atmosphere that contains sufficient oxygen but also a fatal percentage of carbon monoxide.