A small filtering device carried by a miner underground, either on a belt or in a pocket, to provide the miner with immediate protection against carbon monoxide and smoke in case of a mine fire or explosion. The device is used for escape purposes only because it does not sustain life in atmospheres containing deficient oxygen. The length of time a self-rescuer can be used is governed mainly by the humidity in the mine air; e.g., in moist air it will last for a minimum period of 30 min, and in moderately dry atmospheres, for a period of 1 h or more.