NASA NTRS1985
Since the 1920s, the only respiratory protection which coal miners had available during exposure to toxic or irrespirable environments was a filter self-rescuer that catalytically converted carbon monoxide (CO) to carbon dioxide (CO2). The deficiencies of this self-rescuer, which have been described elsewhere (37) led to the support by the Bureau of Mines of the development of a new generation of self-rescuers which utilized potassium superoxide (KO2) as the air-revitalization chemical. Since KO2 reacts with exhaled breath and releases oxygen (O2) while it absorbs CO2, the new self-rescuers were closed-circuit devices which isolated the miner from contact with toxic or irrespirable atmospheres. A device with a one-h duration developed by Lockheed under contract with the Bureau of Mines (18) utilized 1.5 Ib of KO2, weighed 4.54 Ib and measured 6.5 by 3.6 by 7.7 in. Since the earlier, filter self-rescuer weighed about 2.5 lb and was worn continuously by the miner, the one-h, KO2-based device represented a substantial addition to the equipment that the miner was accustomed to carrying and, therefore, was considered to be too large and too heavy.