Document rx1re9OBJ2Z02OgyoG8gy8RwV

0 / It la fact, th* KuLarr. and the medical and radiological feature* <1 th* case* * of fibrosis, together with the results of comparison of the dust wonts, all wo* tribati is r- degree to the view that with comparatively low concentration of dust is th* neighbourhood of 0 process, th* resulting cues of fibrosis amongst tie workers ia that procn** ere laager' ia developing tad remain laager in a milder augt. It foliow, therefore, that in such eases the nti of oecinulation of dost ia th* lung baa aot greatly exceeded the rate of elimination, usd a further point of great practical importance ooscrgci. &amdy, that ia order to prercat the full devdopment of the disease amongst asbestos worker* within tha apao* of aa average working lifeline, it ia necessary to reduce the oonoentrauoa of dn in the air of the workroom to a figure below that pertaining to *pinning at the tisae orer which these caaes were exposed. Not only dot* group 3 show the lowjst incidence of fibrous, but it form the largest individual group ia these sections of the industry--shout oaa third. RAaiios Dustituu of Various Atbtiioi Procustt.--'While Mat reference here to the varying amount of dost erolred by the different processes is accessary, the causation of theta differences sad methods of suppression of dust are diacuxied ia Fart II of this Report. Different asbestos processes do cause the evolution of different amounts of dust into the air of the workroom, and, under present conditions, the difference between the least dusty and the most dusty processes U very proacanoed. In some processes the production of asbestos dust is insignificant; ia a second group doit is continuously erolred but ia relatively low concentration, as ia pinning; ia a third group the rrolotioo of dust is eoatiauoua and in high con eeatratioa, as ia dry cloth wearing; and in a fourth group much dust is dissirpated in bursts of abort duration, as ia emptying the fibre from settling chambers by hand into hags. Some additional data were obtained by means of a limited number' of determinations of the dost content of the air at the breathing level of opera tives engaged in various processes, with tha aid of tbs Owens' Jet Apparatus. The figures ia Table 5 which were calculated from soma 90 determinations, give a rough idea of the general dustiness of the processes concerned, and also of the effect of localised exhaust ventilation and damping in reducing the concentration of dust ia soroF of them. The couati in other processes art expressed proportionately to the spinning, plaiting and braiding group, taken as unity. It will be eeen from this Table that the dustiest processes are opening (with old ftshioned tenser*), sieving (with no local exhaust ventilation), and shovelling or otherwise handling tsbesto* fibre,* with a comparative ficure of 2.34. The heaviest counts of all were foaad ia this group, in sack filling by fund in, a nettling chamber. The comparative vfiffure here was 0.84, bat the record wax denio, with much clumping togetherrof tha dost particles, with the result that the total dost aoaat arrived at was undoubtedly too low. Hext ia order is dry doth wearing without the application of localised exhaust ventilation, with a figure of 1.93. This is undoubtedly a dusty process, . and although local exhaust ventilation reduces the count at the breathing level oT the weaver, much duct still escape* into the workreom. Wearing doth wet. not merely dsxnp, reduces the dust count to a remarkable degree. Column Taxli 2.--JUlasios Dustituss of Mrfour Prottssss and Efftcts of Loealissd ExLauit VeniilaJttn a%d Danp Msfiodt i suppressing Dust. >ri4,*c. fUiliag. WiUdwl Usui tiit Wr*l ftkiwl w*CtU I1M8, m i*i t FaCt-*l U*< | cuu O-r ffVkoaial tl Ol ww* i Wbffrceaswalafi I| *. wttl* J <41 * Ol j'tj 1*4 * lai rDurbr. U*t rehowai fMUk ktu m Wl m UiUm LUkii*. Btj. *IUmi kut fIMbU mid* liiett m wniUr U. Ol D*< viU 001 0p49t|( *4 Wb%4lc UmI ftftUU on HI H\ i<u HI 14 tHi ^u*s- - * *" )