Document KRZ2KMbGg8J26qa553ZOJK8xx

r'\ oc. fe) 0. s Cn f References to Recent Literature - 7 obtain exact-reproduction of density and contrast, and all are describe! in this paper in some detail, 29 BASIC FACTORS It) INDUSTRIAL RESPIRATORY PROTECTION. L. Toleky. Liitteil. VolksgesunJheitsant. Nos, 1-3, pp. 3-7, 20-4, 27-34 (1938). (Austrian). The author thinks of industrial respiratory protection .as including more than si-ply oxhnust systems and respirators. Often the most effective neons of pro tection is provide! by abandoning the use of dengorous substances or by changing the process and methods to eliminate n hazardous gas or dust. In preventive work a prompt recognition of the danger is imperative, DuBt preventive measures aro described, such as enclosure of dusty processes, wot methods, etc., together with their cffectD and limitations. 30 RESPIRATOR FOR USE IN DUST-LADEN ATMOSPHERES. THE MARK IV DUST RESPIRATOR. S.A. Sad!, K.L. Green, G. Ds.vlos, U.S. Nicholson, A.S.G. Hill and H.H. Watson. Chen, & Ind. 52, 781-91 (August 20, 1958). (British). Tho requirements for a dust respirator ore stated and the dovelopnont of a new respirator is given in detail, Thu filter material of the latter is mado of 20 por cunt by weight of chrysotilo asbestos fibors and 80 por cent merino wool and they are held in place much tho same as in several American models. ..Most of the tostc for filtration efficiency wore made with carbonaceous Bmoko of 0.18 micron size, although some tests wore made with a fine flint dust. Tho authors feel that its efficiency exceeds that required by tho U.S, Bureau of Mines, whose methods of testing ere somewhat different. 31 GRANITE WORKERS' NASAL RESISTANCE IN BREATHING. E.C.J. Urban. J. Ind. Hyg. & Toxicol. 20, 635-40 (December 1938), The filtering or protective action of tho ncse is considered important enough by some to justify solaction of workers on tho basi9 of nasal condition and by others as not of sufficient magnitude to act ne an efficient filter. The author describes a series cf tests on 139 Vermont granite workers, selected at random, in which the nascl resistance was measured with a special type of apparatus that pulled verying amounts of air outnerd through the noee. The results showed that naer.l resistances do vary for different individuals but that the variation is slight, ana would be apparent only ovor a period of years. At best, it is only one of the factors in silicosis and because of the possible tuhorculous infec tion, other factors ae personal habita, physical condition, and infection con tacts, are more important. 32 DUSTi ITS HAZARD, CONTROL, AND COLLECTION WITH ESPECIAL REFERENCE TO SURFACE PLANTS. G.E. Lynch. Min. & Metall. A9, 516-20 (Decomber 19SB). The author summarizes the dust hazard from the plant engineers' standpoint and discusses in some detail certain principles of dust control. Dangerous dusts arthose almost invisible particles below 10 oicronB in size, as particles above that sizo rarely reach tho lungs; it is tho particlos below 10 microns which do net settle out of the atmosphere rapidly according to the laws of free settling. After particles cf these small sizes ore dispersed into the air it is almost im possible to collect or control them, so it is obvious that control muBt be appli' at the source of the dispersion. A discussion is then given of the principal methods of control and collection which ore available to engineora in their pro blems. The costs are describod as being comparatively low and there is a possibl salvage value in collected dusts, in addition to the other benefits.