Document 9J97m4zzgqoEZe94vRR8QYZR5

s&Bfer tT.rw'V'** *" Jt&ev;*; CHAPTER XI gjpLrators and Respiratory Protective Devices FRANK A. PATTY ^.''Historical Resume and Present Approval Procedure fator is defined as a device covering the mouth or nose, to prevent the ,,Jlfi6xious substances. The oldest record we have of the use of such |8ratvgiven in the first century a.d. by Pliny the Elder, who wrote of fiS^S: wearing bladders over their faces to avoid inhaling mercury- ``feas masks, oxygen-supplying apparatus, and hose masks (diving Jre.introduced into Europe during the nineteenth century but they did rfjjigineral industrial use until after World War I. Oxygen-breathing vajjntroduced into the United States about 1907. Its first general ii'-lj'|0 with its adoption for mine-rescue work? The canister gas mask 8^" into this country when the United States Bureau of Mines was ,, hlem of developing a military mask for the American soldiers in `"'rk later grew into the Research Division of the Chemical Warfare Jpfferviceable mask for war uses was developed,, and at the end of \ as continued by the Bureau with a view toward the development Gstiia'lSmask. "Sj " ^tp'0military masks of the acid-gas and organic-vapor type were "`fflffiafket by salvage dealers after the war, but were used by returning l$l|p^Qtion against all gases. This error was encouraged by some of the extravagant claims concerning .the masks.. .As a >i;esult.there _Iffijjjfipr'mainly nonfatal, around ammonia reffigerating plants and |fight|rs who were exposed to carbon monoxide. The alarm caused by ini^s^groduced an extensive educational campaign through. news* ?jteci^cal press, and personal instruction. Research ''gradually de- |ffi||i|ypp!!dr' vfffi'Ous gases, and the universal canister -that- protects Bmrdgn gases or combinations of gases. The next step was the develop11?a8k, which is simple and foolproof, and which.offers respira,-. _ J&y situation that can be reached by 150 ft. of hose. JfJlpce, however, personal respiratory protective apparatus tha^ 343 mH ww*