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-. "Cr-- (?'< fi- -*' 4 , v** - - r 1 > V.- ' HOME OFFICE t* REPORT -B-*^7 -* j .< r *. . sr^A* Crew* Cifyifki f.iirrvtj *^ ^y'/** * ON ' ", * -PART .L Occurrence*ef Pulmoairj Fibrotlt ud other * *.. ........... **'- .* ;Fulm6jby Affection* is Aiberto Worken '* `>'y_S j ' " n> ffc---, T . --i \ . - '* .^^epe^fhek, -mjd, ,, HM. *ekW I.t. < f>cl-<on AND v ' / -C W. PRICE b. .* i!\- * * * . *\ r-**:- ' ,* *.* . * * / --. . . -v..* *. i I : V.l. .* . T' .* / ' ` `<4 ' n <4*s *i -. . .'* * X`\r .-- :* r%>Tw?V.%V.\. v# * [] K* Jv'*** ?>: V* ;L'.' * '%.# i PRINTED AND PUBLISHED ' LONDON: BY HIS MAJESTY'S STATIONERY OFFICE.,v *:*<.'-' 5L' r .. V To brpvduud dined/ (na H.M. STATIONERY OFFICE it the following iddrauai ' .* . Adutnl Home, JCingiw-i/, London, W.Cl; lad, Gwoeje Street, Ediabvrjb; --. fc. v- , (rI., i V . (.%. * ;1 i** \ . l . . . ; * * * __ * York Stmt, Minehatcr; t, SC Andrew'* Cracait, Cardiff; 't*' ,*' * IJ. Donegal! Square Wat, Bdfut; ` ` .- or through ui/'BoalcKfleT. 4r'- . r \ K-rod r* 1930 ^ Price If. yt K(' il * - V H / . Z: . : i\ )M) * * ur^w .* IT * * 4 ,`v . 4 *;.#, U .i Ti4-. . ,.o***'*-'**.*,4 '* *, : cn . 0004 *.'.Vi SCF-ALLF-00155 1 ?7U 'll m a a v .r. CONTENTS. r*t i # I Ivmsvnie# % 9* Um*i l*ifr ra* mi I oc Tit* Kiivfi *1 4ibtiui I ti ii m liTVTiunit Tk hpaUltto *1 rl 8tfrt*0* il ^ifbtn III Tk Ch*ir*l EmiwmHi* imj RUinUr^i *(iwu4 tlMWIIMH |l III ljlf* 4 Hiann ft Imuv Nimtftuy F*k**i l Sibfi<N tt'**ti tin A*6*** b*0*c . TM IlK^in l( Pul*r) Flltfmu (to A441IM Mf|*ktn lfn\4 ll A| *4 l4Mlk * ItopUtIMM EHwt ! W*rt ii Oiflmirt llilim* Dwim #f T*rii> \*kt*i Pro*tw . CaMMP*liM *1 l>w *i*4 U**`* *f I I* P!* ftiMktmmt If Ik fi1ir**i P4II* dMl OtlfllNM if |M A*t*f<Mltol ( II** A|h#M*l Prl*/**<* (Mb S*Ulf ,, Tl**rl>**<* , t Fimti imiiniK ni Phiut Prvotmn* n mi Amuim Hat**** t Pu*(utit U***iro * Tm Uvnoot Pm. 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' 11 1' Thit Report was bid Wore Parliament on the 24th March, 1930, but has not been published as a Command Paper. \\ t it f ti&*-h' - V-\ PC Q 4 / 4 Th* Right Hoc J, JR Cum*, M.P.. Hit Majesty** Secretary of State for the Borne Department. Hour timer, 17(1 Hard, 1930 Sr*. - _ I tubait herewith Report by Or. K. R. A. Meriwether arid hr. C. W. Price aa tlieir i&qairiex into tha health ooudition* of the ethertee industry. Or. Mere* ether'* investigation* oa th* medical aid* are of mat (cieatihc value. They establish the facta that the inhalation of athntn* aiut overs,period of yean result* is the development of aserioustypeof Ebrotit of the loop, that the derelapment of the disease varies in direct proportion to the length of the xpo*ure to do*:, and that u*oeptibili(y to the ditcooe is not effeciea either by *ge or tea. . Th* remedy for these condition* u to b< found, a* in the cue of ao many industrial diseases, in the suppression of dutt. The eoeond part of the Repoit indicate* that lhia point haa only recently been appreciated. In the non.textile section of the ind entry, so serious difficulties arise as regard* the application of exhaust ventilation. Tor the textile section, it it evident that a good deal f experimental work will hare to be carried out before completely tucoeuful ventilating appliances or* evolved effectively to remove all the dust. I have the hooour to be. Sir, Your obedieat Servant, GERALD BELLHOUSE. f. H.hf. Chief Inspector of Factories. )\ r / 0 s Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry. / PARTI. THE OCCURRENCE OF PULMONARY F1HKOSIS AND OTHER PULMONARY AFFECTIONS IN ASBESTOS WORKERS. 1.--iKTMOUCnOK. This Report is baaed upou lie data obtained in an exUuaivt investigation daring tie yun 1923 ud 1929. Tie inquiry was initiated by. tie Factory Departratal of lie Home Office following lie discovery in February, 1923, uf a case of sea-tubercular fibrosis of tie lunge ia as asbestos worker, of aufUcieut severity to seoeuiute treatment ia hospital (Seiler's Cate*). " ~ I'rior to tile, this Department bad knowledge of only two doatbs of xslrttos worker*, about whom (bare was expert opinion tint tie inhalation of *sbeto duet bad at least contributed to. If sol caused, the fatal outcome. The first of these, sow referred to aa tbs 4` Montagu* Murray Case,'* occurred in 1900, but all that is known concerning it ia contained ia tie evidence riven by Dr. Montague Murray ia 1900, before tie Departmental Committee os Cotupeusstioa for Industrial Diseases'. Ia this case post mortem examination confirmed liic clinical diagnosis of extensive noo-tubereular pulmooary fibrosis. Tit seamd (Cocke's Case*) occurred in 1921. Here, although Cooke1 and Stuart McDonald* were of tbs opinion that the luug* showed a progressive dust fibrosis together with a chroam CUbercaioui infection, the etiological relationship between the inhalation of asbestos dust, and fibrosis of the lungs would have been strengthened by tint abvence of a tuberculous iafoctioa. _ ' An. early surrey of the industry in 1910-11 by lha Department did not dis close any evidence of the existence of a serious health betard in the industry, but some experiments on animals conducted ia 1912 by Professor J. XI. Beattie of Sheffield university for the Department showed that Che inlialatiou of asbestos dust will cause a mild degree of fibrosis. , When, therefore, investigitioa of Seiler's Case shewed that other industrial and infective causes of fibrosis could be definitely excluded, the necessity of deciding whether the supervention of Uu* disease in an'asbestos worker was an exceptional occurrence, or evidence of i grave health risk in the industry, was spporent and the investigation referred to was undertaken. 2 --Erracra or 1*jutuht Dust Umk tux Lohcs. a The most important local effects which may follow the inhalation of dust include pulmonary and bronchial catarrh, asthma, bronchitis, fibrosis of the bugs, and secondary changes, such aa emphysema, local or diffuse. These chaagm in the longs, which may be looked upon as a measure of the efforts of the living tissues to repel or incarcerate the irritant particles of dust, necessarily cnue_interference with the general efficiency of the lungs The impairment of functional capacity may be slight or acvere, and temporary or permanent, de- peadisg on the variety of dust, and on other factors, such as concentration of dust and length of exposure. a Moreover, individuals whose lungs have keen effected as the result of the inhalation of some dusts, (how on iucreaxed susceptibility to die supervention of respiratory infections, such as tubcrculosii or pneumonia. Fibrosis of the lung* is recogaiscd to be the most important lesion caused by the inhalation of dust, end the proneness of workers with s dust fibrous to be effected with pulmonary tuberculosis has beck shown to be the main cause of the increased mortality rate from the latter disease ia certain dusty oceursa. tiaos ^ . . >. t t*..` % e * * This triad--exposure to dual, fiJbroaif of tbe lungs, and high mortality rate from pulmonary tuberculosis--was found to be eomroou Co a number of urge asd important industries, and in all of .them the dust iocrimiRated was ft* exyiialltae all tea (SiO,). These features were sot observed, bowevtr, is ether . Industries in which, white there wss erposure to siliceous dust, the silicawss Tound to exist is the combined fora u a silicate and sot in (ha free condition. Thus. shortly, Irta ailica came to ba regarded a* the pre-eminent cause of industrial fibroeis of the lanp and as a sotahie factor in the production of the mortality rata from pulmonary tubcrculosi* in Certain industries. Whilst the pulmonary fibrosis produced by free silica (Silicosis) baa been, and "ii being, minutely investigated, the potentialities, as fibroxis producers, of dost other than free silica, have not been fully explored, although it appears certain that some other inorganic dusts can, and some cannot, produce fibrosis coder the cooditiaos met with in industry. That a aerious, oven fatal, degree of hbrosis^ can be produced br tome of tb*** ether dusts has sot been generally appreciated, although lUdliata in a thoughtful paper* has drawn attention to this point, in reporting a fatal case of pulmonary fibrosis caused by dust of suo orthodase basalt containing no free ailica. t: TXi Mature af Atbttioi.--The fibrous minerals eoutuereially known as asbestos fall into the latter g-roup, the silica being combined with metallic bases, mainly mArseuum or iron and, to a les exteut calcium, sodium or aluminium. Tbe term u a collective name applied to a variety of silicate mutuals which differ from each other' io chemical composition and physical properties but resemble ooa another in their finely fibrous nature and flexibility, their tuIuc depends on the facility with which thoy can be split up into long and flexible fibres for spinning and wearing, oo their resistance to heat aad adds, aad on their insulating properties with respect to heat and alecuidty. Varieties af asbestos pocsexs these, characteristics .in differing degree. ' Practically speaking, oil that goes under the name asbestos in commerce is either fibrous serpentine, or a fibrous mineral of the hornblende group, of which the most important are crocidolile, amoiite and trcrooUte. Serpentine asbestos or chrysolite is essentially a hydrated silicate af magnesium, containing little iron and practically no calcium. The hornblende varieties contain leu mag nesium and anally more calcium, aluminium and iron--erocidoliu and amosite being mainly silicates of iron. * * 3.--Scars cr^rai ImnuncaTioM. * - Asbestos is very largely used in industry, being an, important const!fueat of tosny different products. The diversity of industries concerned cade it essential that aoiaa restriction of the field of investigatiou should be decided open. . ' The manofactoring processes affected fall wore or leas sharply into two groups (1) those in which there it exposure to pure asbestos or asbestos mixed with a very small percentage of cotton or other vegetable fibre, aad (2) those in which there is exposure to a mixture of dusts, of which ssbestos is but one. The former group comprises, in the msiu, the textile branch of the industry, s branch manufacturing insulating materials from practically pure asbestos, and some preliminary processes in other branches. Tbe latter group includes a number of processes in which the proportion of asbestos tu the dust evolved ranges from a negligible quantity upwards Since it is impossible to evaluate the effect on the lungs of miked dusts, of which asbestos dust is only one component, until the action of asbestos dust itself was determined, the examination of workers for the .purpose of thic enquiry was restricted to workers employed io processes included in group (1), in other word*, to workers as nearly as possible exposed to the influence af pure asbestos dust Furthermore, the effects of previous exposure to othec irritant dusu tuch as that of free wlics, had to be excluded. ' Q s 7 Tl* Pcjrnloii** at Rili.--The (nu number of workers -who ay be ' exposed to the inhale tioa of asbestos dust to say extent is unknown, and, owing * to the great verity of processes euneeraed, then are insuperable difficulties is nicertainiog this figure. Kor, ia feet, would enlightenment os thie point be of say particular value. It ie otherwise, however, with respect to the figure representing the somber ooostaatly exposed is the course of their daily work In the iafiueaoa of pare or altsoel pare ashes(oe duet. Soate iaformation oo thie point ie very desirable to cheek the adequacy of the sample of worker! examined, end to envisage the problem confronting the industry. . While only a rough approximation's possible, it ie believed that about 2,200 U the present number of persona is tab country exposed is their daily work to the inhalation of asbestos duet, either pure nr admixed with a email proportion of cottaa. It should oat be overlooked that thie figure does sot include the considerable number of workers exposed to the infiueuoe of mixed durte of which asbestoe ie but one, and eosunouly not more than 20 per cent, of the mixture. Of these 2,200, the sample examined numbered 30 (excluding 11 for reasons referred to later) or 10.0 per cent, Stltciim #/ Werkrrt far h'xojuiaattre.--The selection of workers for examination was not Isft entirely to chanae, since it was early evident that the proportion of those employed 10 years and upwards In the industry was very sms 11; therefore, In each factory those longest employed were preferred, since the importance of including e sufficient sample of this group is evident. Regard was also paid to the other end of the scale so es to obtain information as to the length of exposure to dust necessary before effects are manifested, and also to the particular process on which the worker was engaged. By balancing the component groups of the sample is this way as the enquiry proceedoJ. it wax fell that the maximum t/*.TV>tion would be obtained. . fjo the shortest time. m ~. It follows, therefore, that in respect of length-of exposure Intacta* dust, the component groups of ths sample do not_ bear the same relationship`rv-'Illth. other as the corresponding groups of the industry under review. Th* sub joined Tables will make this dear. Tsble 1 shows the distribution according to length of employment (sot necessarily in one factory}' of 775 workers, the total number engaged os those processes is several factories. Table 2 shows the sample of 3G3 workers distributed in the ctau way. Tests 1. Tantx 1 Yurt utpU/ti. KuW. fr-4 la-u ... is-ie ... ie tad -!> _ ... ,, .. e* too 01 u ir Tult " TU *1 TUl 1*3 ts-s H 1*1 II IS* Y<ri : v , Mrurte 1 K"u'* I ,4-t ,, M~ 1S-U _ n-ii ,, ft sad r _. -- ... ... ft 141 14 tl tl ruit _. 14! sTT.ul t-s 11-s Sl-S 1-T * 100 The enormous preponderance numerically of workers employed under five years is striking, as also is the very low percentage of workers 'employed 10 yuan or longer. Comparison of the two tables shows that the effect of the method of selec tion of workers for examinatioo is that the number examined in each, successive five yean employment group ii a progressively greater proportion of the total number which could hare been examined io each particular group. i f, >. r' ` fC / I V.v .V I ty`'ln. 0 - .* o 6' n w n w w il I] l i * - With a solitary exception,all those examined wtfi at work on ths day ol examine tina. 4 Tkt Clintedl jTxa<inariVa Slondardt cdvpttd.--The nature and purpose of the inquiry were explained to each worker whom il u proposed fj*}!*6. individually, end bis or her co-operation obtained, hack indmduaTs previous industrial history, subsequent to leaving school, u sated an detail. This wu essential ia order to exclude, especially, the effect of prerioua work ia nor of the numerous processes iuvolviog exposure to free silica "J4*.1. *d, to a leu extant, the effect of other duxu. Similarly, the in dividual* medical history u scrutinised from childhood onwarda, to determine the physical Urtl_ oo entry into the industry nod any subsequent changes. Particular attention wu paid to accounts of pulmonary ailments, dome of which, like asthma and bronchiti, are ootmnuu enough amongst the general population, yet are alio nonspecific eigtu of irritation caused by the inhalation * -of duat, whilst othen, like influenza and pneumonia, are occasionally fallowed by a degree of pulmonary fibrosu. War service, If any, wu gone Into, especially ae to whether there waa any hiitory of the worker having been a pj cuualty *l Mf fi*- The family and pcraoual history in raped of pulmonary tuberculoeu was enquired into, and alao aa to any close association with known caae* of thia diieaae in friends or relative!. In approaching the pertinent (abject f tymptome, great care waa taken to avoid leading questions, especially ia liciting information u to the existence of any undue ahortncca of brtaU). . The sexual details of the pbyitca! exanunnliou do not call for continent. Inasmuch aa they followed the usual line* of a detailed examination of the cheat, with ohaervatiene of the gviucrul hc.iltli and of the oonditioii of the upper air passage*. vr - Heferenae must be made, however, to the aUndard of normnlity adopted ia - assessing the atale of'the lungs. The appraisement of any departure from the 'normal' tuuaaurily presuppose* the exutonuc of such a standard. Every clinician has attany^**u ^ r^~>1' jjf experience, his own clear conception of -Urtr -horinvT~iefi,| but it i* not often that he muss' C*iuii'mls~i!22t'i2:ii ~ state in spt-thy words, in fact it vccuin scarcely possible to do so, and this for cVeraj* Jensons; the heart and lungs function efficiently within wide limits of applied strain, and, although vestiges of past disease may be present and apparent os examination, they will be unimportant if they will never tax the organism beyond these limits, are uoo-progressive and do not predispose to other disease. Agt itself has recognisable effects, but for this reason atone, the chest cannot be oocsidered abnormal.. ^ There ia obvious disparity between the standard of physical fitness required for an air pilot and thsl required for Ufe insurance at ordinary rates; in dividuals reaching either atandard can be els seed a* '* normal," yet many attain ing the Utter atandard have never approached the former. * Thus, within limits, various gradations of normality may be distinguished, and correspoodug standards constituted without inaccuracy, the precise status ef any standard being determined by the purpose for which it it established, for too purpose of this enquiry the standard adopted has been that oyinoed in any large group of parson* liriug under similar environmental conditions, apart from work in dusty oocupatious, ns those of the group being considered. This is neither a high standard nor a very low etaudard, hut the average stan dard of normality displayed amongst the iuductrial population of this country. Rudiograf-lit heoKiwtiiou / tit 4imgt.--Ia addition a careful radio graphic ex* nutation of the chest was made iu mauy (133) case*, the necessity for which in investigations into the e/Iects of dust upon the luugs has been emphasised repeatedly by various authorities. It was not, of course, feasible to obtain technically sufficient radiograms of all the workers examined, denied as they were from factories scattered over the country, some in districts remote from a radiological centre The mode of eclcction was dictated by the needs ef the tituatic*.. with the abject of elucidating material points germane to the Investigation, e g., the elucidation of complicating affections, in measuring the i \\ i i bC?, - \J 0 axttnt ud progress of th* lesions end hoaxing the point at which tht earliest . radiographic gu* appear, and finally u a chock upon the human factor presented by the examiner himself. 1--Eutn-Ti or ni IfcqoiXY. To anticipate, examination of the data, collected in thu investigation leads v> th eondcsian that the inhalation of aabestoo dust over a period of Jean results in the development of t eeriout type of fihroeii of the lungs. 4 Atbtttoti*~-tli Ptlnanary Fibretit of A AtHot Wttkrrt.--It is helpful to risuslise fihrosU of the lung* as it oecun in asbestos workers as the slow growth of fibrous tissue (scar tissue) between the air cells of the long wherertr the in haled dost comes to rest. While new fibrous tissue it being laid down like s spider's web, that deposited eariief gradually tracts' This ncrpui tissue i not only useless as s snbstiuita for the air tells, but with miHtr.yyl J"l'*ltUTT1 of the caueaxire dust, by iu lavasioa of oew territory and consolidation of that alres-d/ hccapied. is gradually, ana literally, straiigles the essential tissues of the langr-------" ---------------------- . . 1 ' In common with other essential organs of the bod/ the lungs hare a large reaenro of tissue for ate fa emergencse* and to permit of diminution of functional capacity due to advancing age or disease. For this reason, and because throne of the longs it essentially a local disease, it is only when the fibroeis progresses to the extent of obliterating this resenrt, that undue short ness of breath on any extra effort draw* the worker's attention to the fact that his health is not what it should he. The other symptoms of the disease inch as ooagh are equally unassuming, and tfre readily ascribed to some oammen and tririat cause. From this poiut tht progress of ths disease is mors rapid, since it ii now encroaching on the remaining sound tissue of the lungs, already only jus: suihcieni to maintain him in his ordinary daily activities. Ultimately, if no ante respiratory infection has precipitated a fatal termination'-* i CAfre it reidteH* when the lungs can do lilLli more than maintain life, and the shortness of breath "' la its main elioica! features, therefore, the, disease resembles aUioosii, as might be expected It differs from silicons, however, in the mode of distri bution of the fibrous tissue in the lungs, in its more rapid development, is its radiological features, and, there is some reason for believing, in a lessened susceptibility to the supervention of pulmonary tuberculosis, the liability to which disease is so definitely an added bawd In silicosis. Tit A tbmot Boditt.--7a the lungs of those exposal to asbestos dust, angular particles derived from asbestos,1 and spicules of asbestos" an found on microscopical examination, end also numbers -of peculiar bodies described by Cooke and Hill' and Sinart VfcBonald*. They are yellowish brown in colour, of elongated, bead-like form, often with bulbous ends. Cooke* and Roodbaose Gloyse* independently demounrated a mineral core in these bodies, evidently derived from the asbestos fibre Stewart and Haddow" hare 1* demonstrated their presence in the sputum of asbestos workers. These bodies bare sot been found to occur in any other human affection. They have been found in the sputum within a comparatively abort time after exposure to asbestos dust, and in the ahoesce of clinical or radiological evidence of pulmonary fibrosis, their presence cannot be taken at present as indicating aaytiung more than previous inhalation of asbestos dust. ' Tkt /rurider-ci of Pulnonary Fibretit in Atbttiot Worker* --The extent of tht risk to health associated with exposure to asbestos dust under present indus trial conditions may now bo considered in detail. * Of the 374 workers of bath sexes examined, 105 were found to hare a diffuse fibrosis of the lungs attributable to the inhalation of dust. Ten of these, and one other in which there were earlier signs of ths atme condition, hove been excluded from further consideration, inasmuch that it was felt that previous work in other dusty occupations, such oj ^uarrykig. and coal mining, mar have been the prime or a contributory factor in the development of the pulrtioairy lenioas found f 4 r * k>V?* * lU ' Thin, 85 of 543 worker*. or 2fl.2 per cent. ehowtd * definite teiwii 4ue to ubcaincdost. An additional 21 wens found with pNCUisiveaigna ttuftiie***, bat these jlt given bo weight is lie general conclusions, which bn dertTM solely from ixx--.iz*.llaa of tie 95 cua oi definite Sbroiii. Of lie 133 radiographed, 82 presented rsdiogrnphical signs of B diffuse fibro*i, and is b further 25 there were auggestire radiological chocgee sol definitely diffuse fibrosis. Ia 10 of tie former group end 3 of the letter the changes were pouibly referable to prior work in oilier dusty occupations or to other cause, end tie/ ere therefore excluded, leaving S3 cases of fibrosis end 22 with signs ruggeuiec of ear!/ change* ia tie long* du* to a.ebriUw,--sufficient' radiological confirmation. % YiTisi infereneea tiovild bo drown from time figure* t--Certainly not that Si.U per cent, or roughly 1 in 4 of those at present exposed ta asbestos dual ia their daily work hare fihrwu of the longs. A* mealioucd previously tie sample examined ia loaded with a greater proportion of -workers employed 3 yean and over *!* obuins in these section* of tie industry at the present due (Table* 1 and 2 abort), and aa shown in Table 3 below <he incidence of fibrosis increases with tie length of employment. Therefore in order to obtain nn approxima tion of tie general incidenoe rate of fibroeia in these section* of -the industry a correction most bo applied on tits account. Applying tie rates shown in Tchl* 3 to lie fignret in Table 1, it appean that tie general incidence rate of fibrosis of tie lungs amongst those employed in these section* of the industry is rather less than 1 in 8, or, excluding those employed under 5 yurs, rather leas than t in 3 '. Further correction* would have been naertsary if tie sample had included an undue proportion of worker* from tie morn dusty processes, but this was found not to be tie case. 'Also no correction is required on ocoount of differin'? age distribution since, as will be aocn later, tie incidence of fibrosia is unaffected thereby. Sex has no effect. These general incidence rates are convenient merely as affording a rough indication of tie inherent risk associated with exposure to asbestos dual at the present time. They hare no permanent value either aa an index of tie general risk of Sinaia in the industry from year to year, or as a measure of the risk in any particular factory or group of employees. This must be-so since'not only wiU the distribution of workers in the industry according to process and length of employment very from yep to year in accordance with trade develop ments, but the increasing application of methods for the suppression of dust will bar* s cumulative effect in reducing the fibrosis incidence rata in futum year* * Effttit cf A ft and Lnyth af Employment.--Table 3 show* the distribution of the workers examined according to leogth of employment, and Table 4 their distnbutios according to age, together with the indaeoce rates of fibrosis in each case. * *- " TaUt 3.--ItaAcxu / Fibratit rdalivt ta Lanytk af Empityixint. Tun CapUftS. KtaUr Tmiwt M ... ... M . .,, l*-u _ ... U-lt.............. to *a4 *. . T.ul. ... II 141 14 SI ' ,*s Ciw f hknui Av.r.gt .(< U }Mn, Crvup Ict4i*ju pf WIU 0( Ct.up Im am ( FitrMia ; Of uu f Fikra.u. * i ! -- lit i-i i ae-s tr ail a.-. ts aa- *l-S IT 1 44' j*a 44 4 <Z'Z IH tl t* \ -* aoi 4(*4 B P ft 0 ft ft ft ft ft 1j 'll 4 11 ?itu 4.--Insidmct / fUrutii rJatjwt ta Aft. Cuss ii Fikruia Aitnp tufib */ safUrwsel . " hi ** y aii Orwr KattUr ruaiifi Gnf Of Cr.S 1-- JtoaUi. ImMiiii rr * wt mt F**ik**r*aw. . Of Uau tl tiknus. UrulS 90-41 ^ M4 4M *. .u IMI ... u. eo ut .. u ISO 100 St ts IS _M IS * * . I*f SO 10-0 *) ' tl*l SI <1-0 n*i 4*t 11 It'S 0-1 1S-S es-s IS-0 ll-S Tiuii _ Ul ft H-t l*. 11.1 These table* indicate the outstanding importance af length of employment (and hence length of exposure to dust), and the negligible effect* of age, on the production of fibrosis. Thai age groups SO/39 and 50/09 (Table 4) have Incidence rate* of 30 pr seat, and 37.9 per out. respectively, aol a vide difference, since the groups include workers u> various proorwe exposed to different eoucaitration* of duet. Moreover, the average length of employment in these two groups, excluding the cue of fibrosis, ii almost identical, hut considerably test than the average length for all the cases of fibrous (13.5 yean). _ It appearx_aI*o from the same Table that no apeelal susceptibility to the development of fibrosis ii ehowa by young persons, anIras it is considered that the figure of 8.7 years, the average length of employment of the cua of fibroait la age group 20/29, hoi been thorieaea by increased susceptibility of agea nader 20. Ju, however, tlx average age of this groap at cases of fibrosis i* 2U.T yean, and alto bentuse the establishment of fibrosis docs sot necessitate immediate retirement from work, this ie largely discounted. _ . a Column 4 of_Table 4 also shows a general irregularity which, in itself, painte strongly to the negligible effects of age in the production of fibrosis. _ Turning to the effects of length of employment a very different picture la seen. Table 3 shows that after 5 yean* exposure, the incidence rate mounts rapidly, and after'10 years increases almost in geometrical progression. _ Efltci' of Weri is differrut Proccittt.--There are Insuperable difficulties in ascertaining trustworthy figures of the precise incidence of fibrosis amongst workers in particular asbestos processes. This is the mult of the common practices in the industry of bousing mapy processes in one room, and of workers i transferring from one process to another. These two (actors, the influence of A dust from neighbouring processes, and* prior work io other asbestos processes, ' operate to obscure the effects due to work in any one process. By distributing the-worken, however, according to the process la which each has been longest employed and grouping similar processes together, it is possible to draw certain broad conclusions as to the relative effect of work in different processes. In this wsy groups were obtained as follows:-- ` ` (1) Crushing, opening, disintegrating and mixing. (2) Carding. (3) Spinning, twisting, doubling, plaiting, ate. (4) Insulating mattress making . (5) Weaving and associated processes. -* (S) Miscellaneous processes and remaining unclassified workers The outstanding point brought out in this way is the relatively very low incidence rate of fibrosis in group 3 (termed " spinners *' for convenience) as compared with each of tbs other groups There is some indication also that imoogjt * epinneri ** the disease takes longer to develop. Study of the radio grams, also, reveals further indications confirmatory of this. Moreover, estima tions or the dust content of the air in the neighbourhood of these processes and in that of othera in the various groups show that the evolution of dust in group 3 is also relatively low (Table 5). r 3 i U l t. \lw\ [J N?- H tel 0 / It la fact, th* history, and tha medical and radiological feature* <1 th* cues * of fibrosis, together with the result* of comparison of the dust counts, all eon* ' tribal* is r- degree to tbs view tbit with comparatively low eonoeatrattoo of dust is the neighbourhood of 0 proceu, th* resulting cues of fibrosis amongst tie worker* ia that process axe laager' ia developing tad remain laager ia a milder augt. It foliow, dunfore, that in each cues dus nti of eccinulatioa of dost ia th* lung li11 aot greatly exceeded the rate cf elimination, aad a further point of great practical importance amerges. oamdjr, dut ia order to prercat the full devdopment of the diaeaaa uaoagu asbestos worker* within the epao* of aa average working lifeline, it ie necessary to reduce the concentre- uon of dmi ia dte air of the workroom to a figure below that pertaining to *pinning at the tuae orer which these cuo 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 oae third. RdaSiw^ Duttituu of Various Atbnloi Rrocuitt.--'While some reference here to the varying amount of dost erolred bp the different processes is neccaaarj, the causation of these differences tad methods of Suppression of dust are dis cussed ia Fart II of this Report. Different asbestos processes do cause the evolution of different amounts of dust into the air of the workrooms, and, under present conditioos, the difference between the least dusty and the most dusty processes ! very proacanoed. Za some processes the production of asbestos dust is insignificant; ia a second group dut is continuous!/ erolred but ia relative!/ low concentration, aa ia spinning; ia a third group the evolution of dust is eontiauou and in high eon- eentration, as ia dr/ cloth wearing; and in a fourth group much dut is dissi- rpated is bums of abort duration, as in emptying the fibre from settling chambers by hand into bags. Some additional data were obtained by means of a limited number' of determinations of the dut content of the air at the breathing level of opera tives engaged in various processes, with the aid of tbs Owens' Jet Apparatus. The figures ia Table 5 which wen calculated from soma 90 determinations. _ give a rough idea of the general dustiness of the processes ooaoeraed, and also * of the effect of localised exhaust ventilation and damping in reducing the concentration of dust ia acme' of them. The counts in other processes art expressed proportionately to the spinning, plaiting and braiding group, taken as unity. , ' It will be seen from this Table that the dustiest processes are opening (with aid ftshioned teasers), sieving (with oo local exhaust ventilation), and shovelling or otherwise handling asbestos fibre,* with a comparative fieure of 2.34. The heaviest counts of all were foaad in this group, in seek filling by hand ia, a nettling dasher. The comparative Jigure here was 0.84, bat the record was denio, with mach clumping togetherrof the dost particles, with the result that the total dost aoant arrived at was undoubtedly too low. _ Next 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, . end although local exhaust ventilation reduces the count at the breathing level oT the weaver, much duct still escapes into the workroom. Wearing doth wet. not merely dstmp, reduces the dust count to a remarkable degree. Column Tsatc 2.--Ritalin Dustimss of ooriour Prottssss and Zffsets of Loealissi RzLauji Veniilalitn *d Danp Msfiodt in tvpprtuitf Dust. fltiliag. WiUdwl Usui tiit Wr*l ftluoil 9(tU I1M8, m i*i t Fat-* U*< | cuu O-r Uoi l ffbaaat Ol wUwil* ,lI %*. J <41 * Ol )** 1*4 H4 lai Drr. rub P9Ubmt4| fMUl k4U m Wla m Uium lUkii*. 0p49t|( *4 ntj. kut fIMbU mbil< wniUr U. Wb4%44ml,c iU rth*M4l Uoal ffftUl* m Ol nw HI H\ i<u HI 14 tHi *--1 - ** *" ) 7 for bud narrow) wearing, wel, not accurate liaci the figur* has been ^ raised by dust from a neighbouring di7 cloth boa. hfaUress ButVia; without any precautions, (uch u axhauat ventilation, or damping fioor*, table* and *010111, follow* out with * figure of 1.S3 (See footnote Table S). Application.of exhaust, ventilation, and damping reduce* the figure considerably, but it but be that the figure* la column* i end 10 are too low, tiaoe oousu for aome subsidiary proemes, ittch u buttoning, aewlag, and cutting oat, an aot available. } It will be obeerred that carding, although essentially a very duity proeexi, produced a eoeparatire figure of only 1.17. Title ia duein part to partial andoeutt of Uu working parte of the carding machine, hot it taoctly the remit of the applicatioa of local exhaust Tenlilation. Moreover, the figure doe* sot take into account tha aztremely duaty oporatiou of (tripping. fieldtire to the comparative Dumber* for tha other different prootua, the figure of 1 for epinning, plaiting and braiding i* probably rather too high, owing to contamination ay doit from neighbouring and nor* duty processes. Sample* of a*be*toa vary much in chemical couetitutiou and physical pro- Cirtiea, and of the throe main varietiee, ehryaotUe, eroddoUle, and amodte, the iter two, in the opinion of experienced worker*, oaaally tire rite to more due than chryaotile in the textile manufacturing proorosu*. no evidence ni found to indicate that any oaa of tha throe varicue* ia more, or leas', potent than tha other* in producing fibre*!*, other factor*, such a* ooocsutratiou of dual, being equal. A peculiarity of (ho aabetto* fibre ii that it first fragment* longi tudinally, and apparently thia process can go on indefinitely, aince there it so ultimata fibre comparable to a vegetable fibre ouch a* cotton. Cenctntraiicn #/ Ihut cad Lrufti / cycnr Jfactuary ta Predvi* fiirttu.--Yrosz the data ao far examined it oeern* clear that bhroeu of the lung* ia a definite oouupational riak among*', atbeato* worken a* a claaa. Furthermore, it appear* that the riak fall* meet hearfly on throe longest em ployed and on throe engtged ia tha more duaty processes. Soma farther consideration of these two important facto**, length of em ployment and concentration of dust, ia desirable. Obviously, to some extent, they axe interdependent, aince, a griming that a (pacific quantity of aiheeto* dual moat be faVslwt to produce a generalised fibrosis, the fibrosis will result from exposore for a period of time varying with the concentration of dust is the air breathed. ^.Simsoa" report* the cate of tut aihrotro mill worker iu South Africa, txproea for 12 month* to a very duaty atmosphere, who died from a rapid tuberculosis; section* of tha tune* showed, apart from tha changes due to tuber culosis, a moderately marked fibrosis.1 Burton Wood and Page" report the earn of an^tabeams apinner, employed 13 months, who died from a generalised tuberculosis, 6 month* after oeaaing work. In tbit cate a little fibrous tissue wu generally to be men surrounding tha ubeun* fibres found in the lung tiude, but there was no gross fibroma. It seems probable, therefore, although further research is very suucasary, that not oaly u a certain minimal quantity of tha dust required for the production of a featrallied fibrosis, but that inhala tion of the dust in high concentration results tn the production of a more marked degree of fibrosis in a shatter time, than when the oonocnlration is low, ' Investigation of this important matter--concentration of dust and length of expo*ura necessary to produce fibrosis--from the clinical side is beset with difficulties, one of the most confusing being that the "existence of a clinically Koognuahle diffuse fibrosis is quite compatible with contioued work in the industry, and, therefore, the eases of fibroau discovered in such an investigation at this are in various stages of the disease, with the result that the point at which they first became recognisable clinically eaonot be ascertained. Despite this, same confirmatiou of the hypothesis that the length of ex posure to asbestos dust uwesaary to produce norosis varies inversely with the rouccntration of the dust io U air, within certaiu low and high limit*, mav be ebuinod. .* B P t 0 ', 14 / Tabl*. I ahowa tit average age and length of employment of tit cases of fibroeii ia tit group* of prcxxuci previously dealt with (p. 11). Titu C. 1/ Cam* ( TilrwU. S|<. Avri|i L*tftA f ZBpUfa*tt L Orwtiis ifUHS <u!iu*ttli>a ai<it| i. Cu4it . -- .. m. - a. tsUatsa iwMctac, s*utti*e, pU<ii*a i*. 4. Kuvtmi moXiM* ... .. __ -- a Wm*i*( ttU u*oi**4 pmax* ... e. IIU-lli 11, ,i |mm h! tmliiif *liiSe nrtm. . -- o *,, * T**l* ,, _. ,,. -- *ii I** SI'S 81*1 ** *11 >9*9 !> 11*1 ts- IH 111 IJi Tit mash laager average period of employment of tie cuter of fibrosis ' la group 3 u compared with the other group* will be noted, lien is also . .least exposure to sett iu group'3. Ilaotms, therefore, that in this group a {. looser period elspeed before tie fibrosis developed, or that it progroutd Ins * .rapidly. This is tie more apparent if tie incidence rates of fibrosis amoagts workers employed is tie processes ia group 3 are compared with tie corresponding rates for workers employed iu the more dost/ processes comprised ia groups 1, 3, i, 5. takes together. These rates an set out ia Table 7. Tabu T.-- Gtmpariien ie/wren tie Inadtiux Sates / yitrutu anaupt Wrrltr* fm.y/oytd im Group 3 (iu* du*t/ procuiti) and At laadtaa Mate* sjninjtl Wrritrt mpittytd u Group* 7, 3, dt 4, taitu leyetker (m,tr* . dusty proruut). --~ * 0-4 m i "i -s or XofM s= <3 i wo s Tw taruTu. a* Ja-M. im. 4 1 *5 It 4 1 = 4& X s= c # i t X * _J "n ec <3 A *> a* u.11 It 4 t <3 s S 4 mr 1 X 4 1 i= <3 4 +1m - Grvup 1 --. _ Cnop* 1, , , S <ua tfih*x as 4T fir UlL -- 44 IV MIL 1 * 04 far MIL f "T II -- u at a*t * tt III t* r*t MIL 4 JI-4 1 r UL 4 ift a *i IS it 44*4 Orw, t biuite, IvUtiicSmUlic *UI(ihC W. Cnmfm tttlB CnUias iu, wtus mIIim h!<( iU ram* ait fi It will be sees that, after 5 years' employment, the rates are coast*lastly . ouch higher cmnagst those employed ia tie more dusty processes, and, whereas * (he rate is high from about 3 years onwards ia the more dusty processes, it is sot util about tie 15th year of employment is reached ia the leas dusty processes lhat the rate for the Utter becomes high, and approximates to that reached after about 5 years' employment in tie more dusty processes. Exposure to different concentrations of dust, together with the effect of (lie recognition of tbs cases of fibrosis ia different stage* of the disease, also afford, an explanation of the widely differing lengths of employment of in* - dividual case* of fibrosis, which ranged from 5 years to over 30? While no definite case of fibreels clearly due to asbcitos dust was found amongst workers with less than 5 years exposure, the possibility of such eases occurring with H fr t,t , (V A _* P-' ^ t' ' l' A I A ): exposure to high coaoealrationi of dust cannot be ruled out. Three cases were found will 3, 3J and 4| ^ein work in asbestos, respccliisi/, hut iu ***'B there *u previous exposure la ether dusts (tee p. 10). Suptxvr. for Uu view le provided by (1) Professor Beeuiu'e cxperuueoti previously mentioned, which aeao&tlreted that the lung* of guinea-pigs ex posed fur 43 end VS hours to asbestos duel allowed "definite cellular pro liferation, though not very extensive, and ihie ie certainly a preliminary stage in the production ef fibrosis (3) Simeon`t otee mentioned above, and hu report in the tame paper on the lunge ef a guinea-pig exposed by Jiavrogwdato to asbestos duet for 100 hour* during a period of St days. On the death of the animal (from suae* other than aabatosis) tome 32 month* later, aectiaai of the lunge ahawed a alight generalised fibrotis. In commenting on the amount of fibrosis found, ha elate* that " a comparison between the human cue* and the experimental showed the fihroeie was more rapid and extensive in the human cases then in the experimental animal,** aud again * the amount of fihroeie in two of the human cuee area quite rapid, and if due to the pretence of asbestos dual, the initial rate of production u rapid when compared with present day sou-infective ailicoei* on the Sand (3) data from Ihie investi gation, in which 21 of the 3C3 workers showed elgtu suggestive of oouimeaeiog hbro*ie (p. 10}. Of these 12 had been employed for less than 1 year*, and 6, for between 4 and 5 jean. . To rum op, therefore, It appears probable that concentration of duel and length of exposure ae factors in the production of fibrosis are interdependent within certain limits. While it warms neceasejy for the production of generalised . fibrosis of the lunge that a definite minimal quantity of dust must be inhaled, the lower the oouumtration of dust in the air breathed, the longer the lapse of tixue before the fibrosis it fully developed, and within a certain limit, the higher the concentration ef dust, the toouer the fihroeie homines fully developed and the more intense the inrolmoment of the lung tissue. If this hypothesis is comet, and the evidence points Lu at, the practical inferences are of rtrj great importance, aince it follow* that the application . of measures resulting in the reduction of the concentration of dust in the air in the neighbourhood of dusty asbestos processes will cause, firstly a great in crease in the length of time before workers develop a disabling fibrosis, and secondly, the almost total disappearance of the disease, as the measures for the suppression of dust ar* perfected. piiablmrui produced by lit Jtbutei Fibretit.--Begirding the amount of disablement produced by the development of pulmonary fibrosis in tsbeitos workers,--for a number of years thi* u surprisingly alight, even more so then is generally the esse in sihoosu. This is partly due to the character of the disease, and partly to the nature of 4the work, which in tho majority of these proaesaei does not involve much physical exertion. The affected person may, end often does, continue at work with occasional inlcrmiasioaa, latterly, due to exacerbations of bronchitis, until the coadition is advanced, although he suffers increasing^ incouvenieneei from shortneai of breath, on exertion Some times a terminal broncho-pneumonia, or other acute infection, commence* while still at work, and there is no long period of invalidism. ' , There is so doubt but that fibre*is of the type produced by asbestos an of itself lead to complete disablement and to a fatal termination, and this in the absence of a muperadded tuberculous infection. Particulars have been collected up to the end of 1020 of 10 cates in which an advanoed degree of the aihqUa fibrosis without tuberculosis was the primary cause of death. In 0, the muse of death was verified by post mortem examination and is the 10th, repeated clinical, radiological and sputum ex aminations confirmed the diagoosis la an 11th case, post mortem examination showed that a lobar pneumonia had auperveued upon lunge already the scat of a .moderate degree of tie asbalm fibrosis With one exception, all these deaths occurred in the years 1927-20 The length of exposure Us asbestos dust in,these cases varied between 9 and 24 years tu s, '-sjn-y&n j - lt ->r fa K # . 1< It ix sot simaUd that few fatalities, in which the cause of death has beta verified 07 strict enquiry, ere any criterion of the true effect of the disease ou the mortality relee f aabatos worker* Other* art known in here occurred in which the cxiatenoe of the asbestos fibroaii hu bees determined io life, but bo poet mortem examination hu bees pouible. Praartu Dvraiion 0/ iLt Ditvut.--The rate af progress and duration of the disease varies within wide Uaila With continued expoxuro to high } concentrations of duel, the fibroeie may be folly developed iu from 7 to t reart, J and may cullm death after about 19 year* exposure, exospliooally in a snorter / , period. On the other hand, with cxpoeurt to Jess concentrations of duel, the I ' period of maturation of the fibrot it but be extended to'15, SO or 25 yean. Thera era definite iodicetiaai, derived iroa the indualrinl historic* and ex* amiaation of worker*, that a diminution in the concentration of duet ia the air breathed, either by charset of employment front a high]/ duaty prooeaa to oca Leu duaty, or the effect oftuethod* taken for tho suppression of dual, recall! ia a prolongation of thia period of maturation of the fibroeii, except ia the* late stages of the disease. While thie u eo, the exietence of a clinically to* cognisable degree of the asbc*toe filsroeie in any individual i an additional advene factor ia the prospect* of recovery from any acute infection of the long*, atich ai pneumonia or brancho-pueumoaia. Auocistio* of (he Atbtttet fibretit will Pw/mewary felttwlMU.^-Ar previoualy mentioned (p. 5}. ailiaueU, the fibroeia of the lung* due to tho inhalation of free silica dual, baa an unhappv aa^Ocutioa with palnsoaary tuhercnlom, in that there ia a much increased Liability to the supervention of the Utter disease amongst silicotic*. It ia of imparlance, therefore, both from the point of view of the individual worker, and an iu bearing upon lb*, scope of the preventive mejuure required, to enquire whether there ia a similar liability attached to the ashesto* fibroeia. * * It wUl be remembered that in this investigation Use examination of worker* wax restricted to those at work at the.tuue of the examination, and, therefore, a number_cf advanced cases of fibrosis, and a number of case* of pulmonary tuberculosis--with or without an asbestos fibrosis in addition--who bad either given op work *or who were oil work temporarily, will hare been missed. Moreover, the supervention of a tuberculous infection on a lung already ' the subject of fibroeii produces an increase io symptoms, previously unnoticed or disregarded, and induces the worker to seek medical advioe. Be is then appropriately advised to give up hie duaty employment, migrates from the is* dustry, and may or may not accept sanatorium treatment. Thus there tends to be a drift of such cases from the fibroeia producing industry. In fact, during the course of the investigation, information was obtained of a number of persons, previoualy employed in asbestos, who were either at home or in eanatoria. suffering from chest complaints. ' Precise information ex to the incidence of pulmonary tuberculosis amongst asbestos workers cannot be obtained therefore, in the absence of periodical uedieaJ examinations in the industry, without prolonged enquiry involving the tearch of the records of local sanatoria, traciug workers known to have oeaxed work in asbestos, and examination of death certificates, and of the sickness record1 of firms, where these are kept. Nevertheless, with these reservations, the data obtained iu hii investigation did not disclose any outstanding susceptibility to pulmonary tuberculosis, cither amongst asbestos worker* as a class, or amongst the case* of fibrosis.. Seminary,--The outcome of this"investigation is to establish the existence of a definite occupational risk in the asbestos industry. This takes the form of a distinct type of fibrosis of the lungs, resembling silicosis in its main clinical aspects, but differing from that ditease in the mode of diilributiou of the fibrous tissue in the fungi, in its radiological features, iu the enhanced rate of development under average conditions in this oouotry, and as far as the evidence goes, in a lower susceptibility to the supervention of pulmouary tuberculosis * The asbestos fibrosis results from the iulialatiou of asbestos dual, the proximate causes being concentration of dust -in the air breathed and length TSe ua*lic&( RutulAfial *bu11--J U ISu luwill S, |jLjlJl.fifcl aUvVvt. 0 0- j IT f exposure to iu Thai the incidence rate i* highest u the eat: duily pro . ocua tad amongst thou karat employed. Ap and " have bo apparent twfliiiin^. oa the production of the disease. * t.--Txcrxuu Smutxwt rut PaxaufT BtcocxmoK of tsx Assures Fuxoiii. . It U of lateral lo consider why it it that this duett* has only recently attracted notice and become a problem is the industry, although asbestos wee .known to, and worked by the ancients. idxaj facton contribute to thie poeitiont aome dependent on the suture of the duasxe, acme oa the pbeoamenal expansion of the industry, other* aa the advance of medical aciencc. While axbeslot hex been known and epaimodieally worked for hnndrtdx of jrurs, it ii only in thx next 40 yean or eo that it hex been commercially exploited to any extent. Hoi only that, bat it ii leu than 30 yean ainoe the pet expin- aioa of the induxtry commenced. Even after a number of yean of aieady erpan el on, the industry te dill comparatively email, and the worker* employed in th* 'aexentiallr duty processes relatively lew. - ' The insidious aneet end unobtruelr* signs and symptoms of the dixriM la itx earlier eoune, its eorart advance by imperceptible stages, ite pointe of Tcaetshtance Utterly to fihwid taberculosU, with which iafeslisa it ii awrftirnc exeodetad, end the migration of thcae affected from the industry, her# all com bined to delay ite recognition ax an entity, and to obtain the causal agent. Knowledge of the effectx of (pacific dusts upon the long* hex been needy -extended in thx put 20 year*, bat ronUrch hu been mainly concerned with the more important and widespread rule associated with the dusts containing free -silica, and enquiry into the effectx of other duts had to wait open those invest!- -getion*. . J.--ParvxirnTx ]diAKJaxx. The necKtary prerantire meaxurex include, first, those directed specifically towardx the mippreoioa and control of the dust evolved in manufacturing pro- -cecees, which are examined in Pert II of, thix directed towards those employed in the industry. f--mnyuf** _ These letter include the control of the ditrtee by periodical medical examina tion of the workers, by which those unfitted by health reasons' an prevented from -entering the industry, and eases of fibrosis and pulmonary tabcrculaeii an detected at the carlmxl possible moment. The ulumate and only reliable test -of the effectiveness of the preventive measure* adopted in the industry will be ioond in the statistics derived from the records of periodical examina tion of the workers. . __ > They 1m include the education of the individual, ax in other dangerous trades, to a aane appreciation of the riak, and to hi* personal raponaibiliiy in the prevention and sapprexxion of duel. - -j The protection afforded by respirator* is only partial, and there is a roal*^ danger that the use of them mey gtye a sense of felt* security. Asbestos dost floating in the air coniaini a majority of particle* of the order 2a. and under, many being only 0.3a Cn.Vrv xoch). in cue. In practice, the discomfort of constant wear, and difficulty in speech, etc., render workers very unwilling to use this form of protection for any length of time. Since, however, a high class respirator will trap a proportion of the large par ticle* which con enter the lung, they cannot be aud to be valueless, hut can only be recommended ax a second line of defenoe, and not in substitution for Other preventive measures specifically directed to the control of dust as star ax possible to its point of origin. Under very exceptional circunutanoca there may p< scope for the use of the efficient type of breathing apparatus, comprising a mask or helmet with a long tube, enabling the wearer to breathe pure air from t distance. 7.--Tn* OuTtoox. Frau consideration of thenature of the processes in the aabmto* industry, end other relevant nutters, it U felt that the outlook for preventive measures is good. That is to say that in the space of a decade, or therubouu, the effect of 11 11 11 11 11 II fiercetic application of prmTcntive ntuorei should b apparent in t grtalxtdue- tioti u ihi incidence of fibrosis. i--*-' * . As immediate temporary rise Is the, incidence lute u probable, do*.to tit _ accusnultud damage, partly a legacy of tit wu yurt, but with tit pasting of ` the peak, a itaaAy foil should en*ue. V*'.* *5 , Much genetem uuuUsoe hoi hoes received from many source* during lit course of this iatesc.igs.tiaa; these ore gratefully acknowledged elsewhere. Specis! thank* are due, however, to Dr. E. n\ Twining of Msnrnfcsseleas'd Dr. N. Ttturesll of Leeds for their indiipenaable expert assistance is the elucidation "of the radiological fasturea, to Dr. W. E.a Cooke, Professor M. J. Slewert'-and Dr. Roodhouse Gloyse, whose researches is the same held are well known; isd to Dr. I. M. D. Grieve for information from as onpubluhed study of a group of asbestos worker* *' * r * & < c &K ' SxnuHCtt. " 'S'-'i Seiler, H. E., Brit. Med.Jnl.. 1S2S, II. 982. - \ . *-" 7't Departmental Comm?tree on Compensation for Industrial Disease*. . -o (a) Minutes of Evidence, Appendices and Index, 1007. Cd.'SiSQ, . " p. 127. ' (I) Beport. 1807. Cd. 3495, p. H. - 3. Cocke, W. E., Brit. Mod. Jnl., 1924.11, 147. ................... 4. Coolca, W. E.. Brit. Med. Jnl. 1927. II, 1024. ........... * 1- i. McDonald, Stuart, Ibid. p. 1025. * ' a. Bari horn, C., Studies in Industrial Hygiene, No. 13, Report of th* Director- General of Public Eeilth, Nsw Sooth 'Wale*, 1927. * ' !-**' t--:i 7. Cooke, W. E., and Hill, C, F., Jnl. Bnyil Micros. Soc. >1927, 232.-* * 5. Cooke, W E.. Brit. Med. Jnl., 1923, II. S78. .s. Gloyne, S. Boodhouse, " Tubercle ", 1929, X, 404. ' 10 Stewart. M- J., and Haddcrw, A. C,, Jnl. Path, scad Bad., 1929, mil, . ,. . 172 . . . .. - "t aui 11 Simeon, F. W., Brit: Med. Jal.. 1923 I. 833. * -12. Wood. W. Barton, and Page, D. S.. Tubercle ", 1930, X I*,'!-,~ `sV.-sw\s~i * * i | * part h. . w V.- Psoctests Grtrotc But to Dust axn MrraoPs rot rrs StrrrixssioK?' -st : * 1.--InrsoaocnoK. s Os ** * tZi ^ The asbestos industry has developed greatly in recent years and continues, to expand rapidly, mainly because of the demand* of the motor, -electrical, engineering and building industries, nn3 of the increasing attention now paid Co the insulation of steam plant to promote fuel economy. ... \ Asbestos products may, for convenience, he divided into urea main froups:-- . TutUtt. a (a) Yarn and cloth. . .- - .. Nea-TtstU**. ;.; . (I) Millboard, paper, aabeatos-cement sheets, tiles, and other build ing material*, sheet material of rubber or bituminous mixtures.coatsin- mg asbestos. ,: (c) Insulation material* and articles. . ~ .. , id) Brake and clutch lining*. e) Packing and jointing*. , ' . ...... (/) Asbestos-covered electric conductors--electrodes, cable* aad wiring, coil* for electric machinery. . (?) Miscellaneous, including moulded electrical and other goods.ietc. Soto* factories make both textile and nan-teslile good*.-'So-called n "ibented " asbestos, i.e., opened or broken-up material in s' fine- flock-hi* l T B p. ) n o> n n n si n) il is si )f F 0 _ w. condition, u manipulated, wm?TmA with other materiola, io lire* quantities in . the factor!** included in froup (a), (1), end (r), and ta & muon cmaller extent > ia toactf the other factories and workshop*. - (a} `Ashesto* yarn is wares into eloth'far insulation Battreai covering*, ia* culeUng wrapping*, filtering materiel, Ire curtains, fir*-ematiering blanket* and firo-rwisung clothing. xiarrowtr woven material ia produced lot beltisjg for conveyors, brake lining* aad inmlating tape. Some iihcitw cloth la rubber-proofed for use in tne manufacture of ateam packing* cad jointing!. Beside* ita main uae for wearing, sabeaU* yarn ia braided and plaited for aid u packing, end aim for inruUuag material. Spools of pars are tupplieJ to factories in which electric cable or electrode* era made, and polithed thread for th* completion of incandescent mantle*, (4) Aabcat/w millboard and paper are manufactured from pulp containing . abort nir* asbestos, by c wet method, Ilka ordinary millboard cad paper. AaWtoa-rrfvnt ahoeti, tils*, gutter*, pipe*, etc., for building cad similar pur* poao* ere mad* from wat mixture* at Portland cement cad chart fibre caheato*. A. synthetic ooaposition aheet ia made from c rubber miring, far uae ca jointing. Bitnminoua miring* containing cabe*to* era made for switchboard panelling, cad other mixing! for Scoring*. - _ (c) Indialion material! include fiberized caheato*; * magnesia," to-called containing about 15 par cent, of fiberized caheato* and 85 per cent, of magnesia, end other finely dimed mixture* oompoied partly of fiberitrd asbestos, uaod ca insulating nr amt* or pleaten; fiberixad cbe*to* itiffeaed into thick aheeta, like met*_, for lining balkhead* of ships; jahapod aectioaa and aloha, moulded from fiherieed aabcota* or mixtures containing it, or built up of corrugated cahertoa paper ao as to encloae air cello; mattresses, made of csbesto* doth and filled with nbcriied csbestos, magnesia, or ether filling. (<f) Brakccnd dutch li'aingi era chiefly prepared from impregnated end heat-treated caheato* doth, but also from mauldea caheato* material. {*} Plaited cad braided cabea'to* yarn, proofed cabesto* doth* end oorn* poaiuan aheet are uaed in making packing* ud jointing*. (/) Electrode* for welding wore era plaited with caheato* yarn or covered with c paste containing axixato*. Some electric cable ud wiring required to a with*land heat cr* plaited with cabeatoa yam; field ooila for'electric'machinery " may b* wrapped with asbestos tape. . _ _ . (y) hCiicellaneou* muufectared crude* or product*, composed wholly or partially of caheato*, include, ia addition to moulded electrical ud other good*, aihcnlo* putty ud powder, rubber boae plaited with cabesto* yam, end many other*. : ' ' Apart from manufacture, certain work ia carried on in premise* subject to the factory ud Workshop* Ada, ca well ea in other premise*, which involves use or manipulation of asbestos or product* aoniaining it. The insulating of - boilers, pipes, angina, and part* of ship* is the mott important. Much of this work is done on board ship by contractor* wbo employ a considerable outdoor stall. ' 2.--Pwcisu. Th* farLories ud workshops included in (a) to (y) number at least ICO, of which 18 are textile factories. This total is based on lieu supplied by the District Inspectors. It does not include the Urge number of work* where there ii incidental sue of asbestos packing end jointing, asbe*to*-covered electric cable, or other finished goods, required for completing other manufacture*. There is only one works is which the employees concerned with cabesto* xoood 500, There ore many email premises in which but a few employees, ia same cases only on* or two, an employed. A small M asbestos " deportment ii found in a number of important factories. Textile department* on usually well _ housed in modern buildings. A few of the, older textile factories Lav* been improved recently by iht addition of modem buildinp. In ona case c badly housed small concern is in process of removal to newly constructed premises. Tbe asbestos-eement sheet fcetoric* are modern premises of large Soar area, lofty end spacious, in the main, single storey buildings. The cable and electrode fictcrie* are also modern cad generally suitable \) -t f > ,' /;W: ho'-.A r > -.VV'm * (k 'Xs-' >:* V- te^tf 'Lry~i . 1 ' So& small works, man puticuisrly tbo*c engaged is making 'boiler ecm- pocitians, in urus-liilVctory. A few in nen open-sided lbelli. Such premises art difficult to keep dun. ._ . Shoe works are coogested with plant and stocks of suterial. This may ruult fros inadequate aooouuaodatloa or a temporary falling-off in ike demand, bat Use effect on cleanliness is bad. The dost srolred in manufacturing pro* etiMi is eon difficult to control if tbs premises are unsuitable, particularly if crowded with plant or material. Cleaning is not easily accomplished and the dust is more concentrated. '* Ken/ils/ura.--The amistresseats provided for rantileting asbestos works vary as in other iadttstriea. Dust removal systems, where nsed, affect & measure ~ of genera! res Illation. A number of workrooms in tactile 'factories are rutilated by plenum systems, the air supply being warmed in winter. Onerhead extracting propeller fans are but little used now and would bo unsuitable. In one mattress making room axtraction fans connected to largo orerlsoad hoods an used. _ Extraction by downward displacement, the air being drawn through openings in the floor, or near floor level, has not been met with, but has been considered for some wearing rooms. This system, if designed of * capacity 'sufficient to effect a high standard of general ventilation, would tend to reduce the dust in the general atmosphere at breathing level, sad, with other safeguards, be a possible slteraatire to localised exhaust rentilation. It could not bo success ful without efficient heating, owing to the rapid change of air entailed. Separation of Preceiver.--In many works several pruxxses are carried on in - the tame room. Ia the absence of effective means of preventing escape of dust ' into the air, many workers tre subjected to a risk from which they would other wise be immune, or to a greater risk than that arising from their own work. In a few textile factories crushing and opening plants art placed dote to spinning and carding machines. Spinning (rimes era installed dose to looms and wet and dry wearing an carried on dose together. In nan-textile premises there is more effective separation of dusty work and processes from non-dusty. _ 3.--DtscxirnoK or Pxogusu axn Faxvunrvx Miami. : t A complete account of manufacturing methods is not attempted. Attention u mainly directed to the dust-producing processes, a description of which, is broad outline, has been deemed neocssary to make dear the circamatinees under which exposure to dust arises,' and the character and object of the remedial measures already in use or here reoemmeaded. Somewhat important change* are. on foot which, it ia ouhdently hoped, will greatly reduce exposure to dust in certain hitherto dusty processes. On the other hand, certain developments, e.g., speeding up of textile machinery, and the increased use of asbestos in various industries, may intensify the dust problem, if adequate measures to deal with the dust are not taken. _ " Tjwritxs." (a) Tun and Cloth. - The manufacture of sabesloe yarn and doth proceeds ou the whole like that of other textiles, but there art tome important differences. Tiber!sod and other asbestos material ia -free!y handled in various operations, ia gathering " waste," and in cleaning. Exposure, in soma degree, to asbestos dust, u cpmmon throughout all the factories, but steps hava been taken, extending over many yean, to deal with dust produced at various points, though the necessary degree of efficiency has, generally ipealdug, not been reached. Exhaust ventila tion plant* used in th< best-equipped asbestos factories for removing dust sppcsr to be as efficient as those used m other textile industries, and to hava been applied over a wider field At regards other safeguards against dust, e.g., substitution of mechanical methods for handwork for feeding the machines in preliminary operations, efficient enclosure of machines, and vacuum methods of cleaning, HtUe development has bocn made. Opening.--Asbestos, suitable for yarn, has usually to be crushed, and in all esses " opened " (" fiberited ") before it is'ready for carding These prepara tory processes re effected bv machinery, hut entail much handwork Sepsraiing (to remove iron) and grading or sieving follow crushing, but precede opening 1,* jr i> K ffr ir t " IVe 00 st ifeUrisJ foe yarn it not usually trailed in disintegrators, but ia mast factories , these msrhiiws an asd for ibtriring watt* asbestos 7mo, ate. Crushing * flattens out sod breala op the mineral without damaging the fibres. It is ocwm- pLiahed cither is a Urge edge runner, or in a small pan mill of tits mortar mixing trpe. The material is emptied upon tie floor close to (be machine, *ha annuals 01 several sacks sometime* being tpread os the floor to obtain a rough " mixing." The crashed auAmal is either takeu from the machine hr hand, or discharged through a boson delivery elide, usually filled into locks or skips and. if necessary, weighed 00 a portable weighing machine. A few edge runners discharge upon abort inclined lattices and the material fells automatically into the sack or skip. . ' ' Edge runners give rise to dut of considerable esiouot^where short fibre is crushed; same are enclosed and have exhaust applied. This is always neces sary. Pan mflls are net enclosed and also gits rise to dost, though last ia amount. Handwork, e.g., sack emptying sad filling, mixing, shovelling and feeding machine pans or lattice fseds, gives rise to iluu, sometimes of considerable sunaoat,' sad Is dons without rhnts Application of exhaust draught would be facilitated, if feeding were dons from a higher level so that Kicks might be emptied under enclosed conditions, i.e. ia a emptying apparatus. Automatic debvery and rrverubl* bagging lattices eliminate dust produced io hud filling of aacks, but require to bs efficiently enclosed with draught applied. An open travelling baud posting round on slectro-magnet is used for separating loose iron, the asbestos being delivered to sc elevator. Enclosed apparatus should be adopted. Enclosed rotary sieves (rotaries) or loug'oscillating frame sieves an used for roughly- grading crashed material. Emories should bo mechanically fed and the asbestos collected under enclosed eoadiiioas (not always done) and exhaust applied to the machine enclosures, otherwise unnecessary dust is created. Some oscillat ing sieves art very open, the material being allowed to foil on the floor, and being filled into soda by hand. Very dusty conditions are then inevitable. Efficient . anrincarq with exhaust draught applied and, to avoid hand filling, automatic delivery and begging lattices, also enclosed sad exhausted, as used in some coses, ars generally practicable. Crigbtoa openers, enclosed eentrifnnl machines, are rued for opening crushed asbestos, preparatory to carding. Cartful mixing or blending of crushed material is cfWtiyl by spreading it evenly ia layers on the floor over a considerable area--cotton may be added at this stage if required--and when feeding, taking a vertical cut through the moss. Admixture with a email proportion of cotton may also be achieved or blowing if into the feed opening. The opened material u delivered upon a lattice and collected either ia a large container or iu sacks, automatic barging lattices being used'in tame eases. Ir-lian?fat feeding under enclosed concations, with exhaust draught applied to feeding lattices or-other oaarcyert, should be adopted. Hand feeding gives rise to dust, from *-v empty-" ing, shovelling and particularly mixing on the floor. Mixing is a mat hindrance to elimination of hand work; it is asserted that poor yarn results tf it is not done and that machine miring has been tried and gave less satisfactory results. If retained, it should be none it a higher level than the opener, under a large exhausted canopy and the mixture led at a series of chutes. Delivery lattices aboold be well oarlnsed and exhaust applied,as now done in some cases; otherwise dost ia evolved. a Opened material not repaired at once, may be stored in open bins in the workroom, involving emptying and filling aacks or skips, which necessarily cause dust. This storage in bulk ehould be avoided; alternative arrangements might be adopted which avoid dust. . Some material, e.g., long fibre waste from later processes, is opened st ehdosed lattice-fed teasers or willeys, not infrequently of primitive design, worn out, and emitting much dust, notwithstanding that a fan is an integral part of the machine. These old machines should not be for opening. Dust may b< emitted at feed points of modern machines, particularly when the feed.is irregular. Exhaust is necessary at the fad lattia for thi$ reason aud also because feeding itself causa dust. The material is either discharged upon a lattice for immediate collection, or blown fata a chamber. The standards suggested for Crighlon machines ehould be adopted. - 0 I;- V. tp? & / . it EjapperUilioa foedaare Urg'd/ used with opening aachifiex; tht hopper lipi are about 3 fact I inches above floor Urel. Much dust U produced inahovel- fending u il ii difficult to avoid oauterisg at the lip. An euelooed Uldce, fed at or jiut below floor level,with localised .exitus: applied to tbe enclosure i< more satisfactory. _ . . Single disintegrators, or two or three machine* in Mriee are uied for break ing np textile or other aibeetoe vuU, store rarely for opening crashed asbestos Present arrangements for preliminary hand aortingof waste are unsatisfactory; it should be amnapliehed at a covered bench, suitably exhausted. Whereas in some coses, th* indraught si the disintegrator feed opening! caused by the rapid rotation efth* tour ii not sufficient to remove dust, and because, at any rate, as soon as it it itapped, eaespe of dust stay mult from reversed air currents, rchaost should be tpplied here tlso. Disintegrated material is blown into chsabert, a blower fan being in tome rma mnnerled In A. A,\\irrrj nt th* inutim to m-iLr f Hwmpr >reng)it. Air pressure in th* chamber is relieved in different ways, the tides soay be covered with sacking, allowing much dust to escape, a *' relief balloon ** connected, or exhaust applied. Chamber* connected with disintegrating and teasing.machine* vary is sine, earns are little mere than a Urge box, other* are more roomy. Some, bat not all, are separated from the workroom. They are catered for emptying, the material being tiled into socks or skips by hand after the machine is stopped or the flow of material diverted to another chamber. Work in chambers is very dusty and its clioiastion is most desirable. (Sea page 24.) Carding,---Ccnxlderail* developments have taken place in recent years, -pne or two important new cardroonx* have been started. Many new machines, including tome of foreign construction, hats been installed. The machines, of large overall dimensions, arc ol the toller and clearer type. Modera cards are of high class construction and fitted with two dnffer cylinders supported on a carriage, which can be racked into or out of position, for fine yarns, a brasher and a hniahtr, constituting a set, is used, nmnetted by lattioes, lap flirtr from th* former being automatically fad to the finisher card. In cases where ihi sliver is collected in cans, a Derby doubler is used for prepar ing laps for finisher cards. ,' Stogie machines and breaker cards art equipped with hopper lattioe feeds oupplied from skips or sacks, handfuls being dropped in, and shaken apart sj fed, or the sack emptied into the hopper. The asbestos falls intermittently upon a creeper food which conveys il to the " lidur-in ** feed rollers, between which point and the doffer the material is under enclosed conditions. > The material is combed from the open doffera of finisher cards, as a web or ** sheet ", the sheets from the two doffera usually being combined at a con denser, and the resulting sliver yam wound into spools. Occasionally, combed web is collected without being ooadensed, the condenser carriage being with drawn. In other carding, th* sliver may be obtained as a Up. . Admixture with ootton is usually accomplished by carding the two materials together, a cotton Up being mounted above the creeper feed, and the cotton fed through the feed rollers with the asbestos. The evolution of dust at cards is inevitable and a fine dust cloud may be observed in most ccrdrooms. Suppression of dust cannot be realised unless machines are maintained dean and u satisfactory repair, and there is effective enclosure of various parte. Above all, localised exhaust must be applied at well-defined points of dust emission, and improved stripping arrangements pro vided. Wide spadog of machines is also desirable. The upper parts of modern machines are usually provided with well made wooden covers and the lower parts are enclosed below in metal. The frames are well enclosed at the sides A hinged metal cover, fitted in some cases, pre vents escape of dust produced by movements of the feed lattice. A curtaio of fabric is leas satisfactory. In older types, particularly, the wooden covers mav oot fit satisfactorily, the cylinders may not be truly aligned with the frame and other dcfecu may account for aide escape, of dust, not controllable by exhaust. Such defects should be remedied. Creeper /eeds, doffers and condensers and connecting lattices between breaker and finisher cards are sot enclosed. Dust is evolved at doffer combi and at creeper feeds 1 r- ! ' l S A t*v- \<r ts K I- te, pM n n n n i); \v Ir 111 11 11 11 il 11 14 0 33 I^ljW uJuwt ventilation u irst applied to carding machine. w*)' fun ago. Method! and appsxstui have rinoe beaa gradually improved tad duct IodCY. xh*mt u applied At (a) lie prewer At uc creeper fa; (4) Xa roller At licker^is: (e) top oi cylinder; (5) taco doffer, Air guide* or boodi bewg fitted at these "potote with connecting branch ducU. Mud couplings, used on branch pi pa, facilitate tasy diimanthnc. Bruch pipe sites and duct velocities are liberal. The improvement realised by applying powering exhaust at each of the poiau mentioned, at all of which avolutioa of dust ia important. shows that thii practice ahould be followed generally and gives point to tbe view expressed by evne oocspitre thot carding can be carried on practically dutufrte. Apart from the abore ease, exhaust ia applied ia nearly all caeca to the cylinder!; in a moderate proportion to the creeper feed; in a few,.to one doffer--the top, and ia one or two only, to the bottom doffer. But, apart from dual-emitting poinu not provided for, the mult* stay be inadequate. Cording machines are occasionally installed and put into use without exhaust, this ahould never be done. Efficient results are net possible unless the exhaust draught ia applied as rJotelr as poeaible to (he dust-prodneiag points. Transverse air guides, with branch dnets connected at each end, are apparently mote efficient than pyramidal hooda of tbs usual type. Duets of adequate diameter and high duct velocities are essential. _ . The uiaal air guide for the cylinder, provided to effect removal of dust ' both during carding, and. stripping and grinding (though proved inadeqeate far stripping) is placed a little above an opening in the crown of the cover. Two branch duetx. aa shore, and in addition a larpsr central branch duct (for nse during stripping) are wonacted to it. The shallow space below the baric of tho atr guide it closed up during carding by a wooden binged piece--thrown back for atripping--and the dost produced at the cylinder ia prevented from escaping by inflow of air from the room, at the front. The dust-laden air is withdrawn at the ride duets. In stripping inflow of atr carrying Mac of the tripping dust takes place from below the lifted 'cylinder cover; the central brand) duct, kept dosed hr a blast gala during carding, ia then folly opened to provide a greater air volume. In one factory, a circular doffer rieaning brush runs continuously above the doffer tomb. A pyramidal exhaust hood ia provided, hut much dust escapes; unicsi fully efficient eshau.it is devised an alternative to this cleaning, if really necessary, ahould be found. The collection of combed web, previously referred to, ii dona without exhaust and dust is produced. Collection might be effected by cxbaost draught as applied for removing aide waste at condenser^. _ * Notwithstanding the we of ooven for card lattice feeds dusty conditions are produced and exhaust draught should be anplied at this paint also. SirijrpUg Grinding.--Card " stripping or cleaning ia done when tic machine is opened out for grinding, which followi cleaning and taka place at each machine about once a week, but shorter andlonctr intervale also obtain. In one important factory the two processes are combined in one operation. Roller and clearer cards mast be opened out, i.e.. the lattice feed and breast, and con denser and doffer carriages arc drawn hack, the cylinder ooven arc raised, and the various email rollers.^ whi$h art cleaned and ground at a special machine, removed. The cylinder is first cleaned, with the doffer carriage drawn back'; the carriage u then replaced sad the doffen, run at a grtatlv increased speed,' cleaned in torn. Cleaning take* about ten minutes and ia usually done in working hours, but in one ease, at least, after. The men press their M atrichia " or flat hand brushes shoot 12 inches long covered with card clothing, against the wire- oovered surfaces. Much of the debris ia heavy and fails to the floor. Dust is evolved in a dense rioud, same being removed at the cylinder exhaust hood. In- one oase floor openings, beneath the machine, arc connected to (he exhaust. Present exhaust arrangement* are altogether inadequate, particularly so as regards the bottom doffer. Much dust is therefore carried into the general atmoeohere of the room 'The eleanen wear respirators or *' helmets.*' In a^ few cases, more effective measures are taken, e.g., the opened-eui machine ii almost^enlirely enclosed with high ranvai-covered screens, In the 00 * u` t ' V 1 ' work* where cieaaag lakes place after workitic boons, an auxiliary axhaust . ayslexn, with a band for1 Use bottom daffer, is brougut into use. * Grinding which take* several boon, if sa auloostie process effected by ' abrasive aorcrod rollers drirtn by the machine. The sail amount of duu produced it dueSj af a metallic character'. * In tbe factory when grinding and cleaning are combined, the dofer exhaust ' arrangement! art first re-cocnected _ Much leu dust it cvolvcdaod appears to be dealt with mere effectively. This firm consider that band strickliag Before grinding should no: be allowea. Their methods may, bo*ever, sot be generally applicable. A little (trickling may be necessary after grading to remort email pieoee of ddbfis- Tbe trade reaoraiM that present eonditioax are not satisfactory and expert* menu are being made with the object af dereloping improved appliances In one case revolving brush is being tried, with'independent exhaust draught applied /by flexible ooaneetraas'f it i aaid to give promise of success. Tbe brush it narrower than tbe band strickle and less dust is evolved at o particular moment. . In another case, a vacuum fitting is under consideration. Previous use of vacuum stripping was given up because of rapid erosion of the metal pipe bends and other pans, unless elective dust suppression is realised for stripping, all workers, other than strippers, should be excluded while it is in progress and for some time afterwards, and the room well ventilated. The machine fur cleaning and grinding the smaller rollers, which gives rise to much dust, should be fitted with efficient exhaust arrangements--a straight forward matter---end as completely enclosed ss practicable to collect tbe heavier .dfbris, precautions which are not always taken. The machine is either installed in the carding room, or in a room adjoining. Independent machines should be provided to deal with rollers of different lengths, otherwise inconvenient adjust " menu, liable to be neglected, have to be made. Cord Sid* Watt* Treat*f.--The irregular *' selvedge '* of carded fibre, separated at the two (idea of the finishing card, being unsuitable for sliver yarn, ie removed by eaction draught to a *' side-end " machine, which prepares it for further use. The material is blown upon perforated cylinders; the air escaping at the side and the material being discharged on the floor. The process produces dust, particularly when tbe feeding is irregular, the air then having a tree path between tbe cylinders. Tho material should be delivered under suction ana not under pressure, a " pressure ** machine being unsuitable. ' Spinning and Doubling.--iYarn, is spun at flyer or ring frames which may carry up to BO spiudles, 40 on each side. Much piecing is required owing to the comparative weakness of the fibre. A fine metal thread is spun with asbestos, for Drake linings and certain other purpose*. Mule spinning u not practised in this country. A Urge amount of doubling is carried on. Spiuning, more particularly ring epiuning, gives rise to dust, eouiinuouslyprodueed by the " ballooning ,r out of the fibre owing to the rapid rotatiou of the spindles, which may ran at speeds of 1.700 revolutions per minute, and intermittently, when the yarn breaks. Doubling ic less dusty than spinning. While the amount bears no comparison with that produced in carding, and is less than that from dry weaving, the workers are continuously exposed to sonic dust, more in eome factories than in others, doubtless due to differences in working methods or materials. Exhaust draught for its removal has not been applied hitherto, but experiments in one factory* bare been so far successful that tbe firm are prepared to equip all spinning and doubling frames with exhaust ventilation pUnt, embodying ft) exhaust ducts parallel with the frames, above the tin rollers, with shaped hoods at intervals, each to deal with a small croup of spindles, and (ii) for more effective-concentration of the draught, panelling for the ends and lower parts of the frames beneath the spindles, capable of being easily removed when necessary. Such safeguards may require somewhat wide application unless special gtaeral ventilation is provided. JKoryriny.--Warp beams arc prepared in the usual way from creeling frames, a small evolution of dust occurring at the frames and beaming machines; localised exhaust ventilation could hardly be applied effectively. A partitianed- off spaee. mechanically ventilated crosswise, with extraction t low level would effect improvement .... . )^ . o0 / is tVijudiny .--Ifsay winding machines art used, varying from makeshift types of primitive coaitructioa, el which the practice way obtain of boldiogthe yarn ^ in the hand, to modern universal wlnden for winding " cheeses." Ihist may * * be evolved to some extent, particularly in connection with the above practice, which could be eliminated. Application of exhaust draught will then probably not be necessary, except in particular cases'. Piaitinj exd Braiding.--Plaiting and braiding, also carried on in engioe packing end electric cable factories, and done at machine* of normal design, cause some evolution of dust, except where the yera is impregnated with " gTcaae." 'While the amount of dust is sometimes less than in spinning, the difference is no: material. But there is perheps less exposure of the operstive under ordinary working condition! end precautionary measures other than localised ethins: ventilation may suffice. ' W*aving.--Loomi vary greatly in alxe and general arrangement. Ai many as 140 looms may be found in e tingle room, hut this it exceptional. The clear apace between machines may not exceed IB inehes. Some looms are independently driven by electric motors. Cotton warp or wtft it sometimes used. Tain doth, fur mattress eovers, fillers, clothing, etc., is woven from a tingle warp beam at a simple type of loom. Belting looms, for thick belting and brake lining material are complicated, several wsrp beams, arranged in tandem under the loom, or in some other convenient way. being required. These looms are narrow, but often very long. Tape looms arc also narrow, unless several tapes art woven together when errera! shuttles, in line, working in unison, ere used. Cloth is beamed at the front in the usual way, but belting may be led under the loom, end coQed high above it, at the back. Host wearing is " dry," but some weaving is done wet, cither Warp or weft, end occasionally both being welted. Wei weaving is accomplished more easily and a closer weave obtained, but rusting of heald fittings, and the tubse- 3uent drying entailed and the leas satisfactory appearance of the material are tsadvantages. Thoroughly dry fabric is requires for brake lioings and rubberproofed material, and wet woTen cloth may be strongly objected to on this account. Considerable evolution of fine dust occurs in dry wearing as a result of (a) the forward movement of the tiny in " beating up," this source being dose to the operative, (i) the repeated cootacts of the rising and`falling warp threads with their neighbours, this source being the most important from a quantitative standpoint. If) the disturbance of " dust " or " fluff " on machine parts, especially those sa motion. A fine dust cloud may be observed behind the Jbcalds abort the warp threads. Much less dust is produced in wet weaving. Same " dry " looms ere now fitted with localised exhaust usually applied to deal with dux: evolved by both {a} and (4). in some (a) only. (a) A fiat horizontal " hood " is fitted in front of the operative, just above tbe cloth, the opening faring towards the healdi; (4) either an upright pyramidal hood, placed transversely, or horizontal flat hoods, one on each side facing each othtr, art fitted dose behind the healds% Tbe second arrangement is tlie more effective for narrow looms, as the " scissors-like " action of the warp threads appears ta displace most of the dust to the sides The exhaust draught has effected some improvement, but all the dust is not removed, especially that produced by (!)._ It mar be impracticable to apply the draught to all dust-producing points behind the healdi. particularly at long looms, but greater tucoexs would have been achieved with more powerful draught and larger air displacements, ax is sow being recognised. ' The methods described for dealing with the dust created by (4) must be less saeaessful at doth looms of ordinary width A few such looms in one factory lave recently been equipped with large " bonnet " hoods.' fitted transversely, dote down over the machine, covering the slay, reed and healda. The hoodi are of hemispherical section, with extensions over the shuttle boxes An internal electric light fitting, and hinged sections, facilitate working A powerful draught, suitabl) applied, should prevent escape of dust, generated within. It another case, experiment it said to have shown that a transverse inclined hood firing the operatise, placed just below the warp near the front of the toon, cm bi more effective far reducing dust cooeentfation in the air breathed, than present arrangements, and the nev design is to be substituted ) ) 1 n 5 o0 / 16 Application of efficient dust removal arrangements to weaving is dearly difficult. The expedient of installing individual machines or ansfl (roups of msehines in suitably ventilated tsuu Icxjbii or cubicles, u suggested under ""Warping " does sot appear to her* been tried, but might U eoasidered if localited arrangements ore not sufficiently tflcclive Long sorrow sheds, for o siagle lix.e of looms, ventilated u suggested, might be o possible alternative. _ . CUtk Puking, Examining, Jflorurinp.--There operations iarolre running ' 'out the rolls of doth oad lead to produce a small amount of dust. If carefully doae, so that very little dust is crested, other precautions may be unnecessary. Noh-Tmtius. FiberLxcd asbestos is oat used in some of the oda-ttatile factories and exposure to axbcslot dust may be slight or even negligible. Dust is evolved in factories or departments where such material is prepared for subsequent use. Or for sale,, ana also Jin departments, where fiberized material or dry mixture* containing it are manipulate in preliminary manufacturing processes Again, finishing processes, involving abrading or cutting at bigb speed, may be a source* of dust, but such dust may contain only a small percentage of asnestot. The application of exhaust draught, where suggested in the following description of processes, is in most cases o straightforward problem, comparable with many others met with in non-textile factories, e.g., wood working sod grinding, where machinery similar to that described is used. . Fibtrixing or O-pminn.--Fiberixing is almost exclusively confined to works in groups (h) and (e). hsudi of the work is done under less supervision than io textile factories and unsatisfactory machinery is more ooamon. Primitive teasers {** devils ") are used in several mattress-making works, and chamber work is also an unsatisfactory feature (sec p 22). In same asbestos-cement sheet factories, crushed material, from edge runners, falls into worm conveyors below, which transfer it automatically to disintegrators. In on* large works, the process is being entirely enclosed; the material from the edge xuandn, which are kttioe-fed, will be discharged upon a conveyor and raised by an elevator to large overhead storage hoppers,'fitted with automatic bagging lattices. localised exhaust draught will be applied at feeding and delivery points, where dust might escape. . Chambers have been eliminated in some large works, with beneficial results. -The material, after being disintegrated.or opened, is fan-handled, aud blown to a hopper Cued with bottom rotary delivery valves, the air being re-circulated. The material is bagged at lattices. Direct supply to a manufacturing point is another improvement sow being tried. Such pneumatic conveyance should be practicable in many eases. Localised exhaust at feeding and discharge points of these systems is neoessaVy. Vacuum methods for filling sacks may also be' practicable. . If chambers arc retained, the necessity for entering them might be avoided, by providing chambers of small front to back dimensions fitted with low doors, at which sack filling would be done, localised exhaust ventilation being applied over the doors. (b) Millboard, Paper, Sheets and Tiles. . ' The wet mixtures for millboard, paper, and asbestos-cement products are prepared in a beater, as used in paper mills. Dry fiber!zed asbestos is emptied into the beater trough, the sacks being shaken to some extent. Evolution of dust occurs before the materia! becomes mixed with the circulating water. Occa sionally a sack is emptied before the water U turned on. Several sacks are required for a charge and the process'll repeated a number of times daily. Precautions are not takea at present but the dust might be avoided by (<r) mechanical feeding under enclosed conditions, as appears to be done in some foreign works, (4) applying exhaust draught, (c) feeding in small quantities and tn such a way that tbe material is wetted at once. - Finishing processes an sibestos-eemeit sheets include sawing to size, corru gating, pressing and drilling, carried on in some factories with the material so mout as to prevent dust, and this practice should be adopted generally. ii 4 S3 stud band uvi can be enclosed below -the table* aud inverted hoods Sued, the exhui draught Ueiue applied sj for woodworking machine*. Efficient arrangeusdots should b ixadily practicable for all tawing work here. ,,.-"A/neii<r.--Vfattrtuei art manufactured by practically ail firm* who produce iaaaUlioa requisites, though only occaiionally by tone. Mattresses for large contract* are made is tba contractor*' premitet, their outdoor <te5 taking necessary measurements and prtpariug rough plan*. A mattress haj sometimes to be made oa aite. Mattress making involves, broadly ipeaking, the sequence of processes associated with the making of domestic mallriuse*. The work is almost entirely hand work. Length* of asbestos doth Ior covert are cut out on a wide beucu and terra op. by treadle or power driven machine*, to an extent depending on the method of filling Large mattresses may be tevrn along one tide only or both aide* may be teamed tad filing done from both cad*. Betore filliug, cover* are turned inside out. Supplies of filliug material, which usually, but may sot, contain fiberited asbesto*. are brought, in tacks or skips, from chamber*, or taken from open bins, in the room, kept supplied from the chnnibent, or from sacks, of material supplied by outside firms. Filling is done by baud, aouop or shovel, and quantities may be wejghed. The end filling of long doubte-senmed mattresses, referred to above, necessitates the workmen mounting on the beuch to empty the material from skips into the openings. After filling, the mattress is levtHM r'r beaten, to make the filling lie evenly withio, the hand or a Mat wooden beater being used. Finishing processes include finnt tewing, stubbing or buttoning, fixing on books, etc. -. . Some dust is produced at the cutting out bench, in opening out the roll of cloth, and at the tewing machine, but far more in taking material from bint or sacks, in weighing, filliug and levelling. Beating of the cloth produces asbestos dust, the amount of which is largely increased if the filling contains asbestos. The work is largely done without regard to the necessity fur suppressing dost. All benches are entirely open. Localised exhaust draught is not applied. . _ Oat firm hare Improved conditions considerably by the following pre cautions :-- _ " ~(s) Keeping floors and benches damp and spraying coven before filling. Ease connections and spray fillings are provided. (6) Sub-division of department into several independent workrooms, (r) Exclusion during filling of all worker* not so employed, the excluded workers proceeding to another scctiau. (<f) Mechanical ventilation of each room by cross ventilation, embody ing plenum supply (wanned when necessary) st one side and low level extraction at the opposite side, the air being changed between 10 and 20 times per hour. (#) Enforcement of use, by fillers, of respirators. - _ These precautions do not include application of localised exhaust ventilation, without which mattress filling and beating must involve some risk of inhalation of dust. For small mattresses, a wide double-sided canopied bench with exhaust draught applied at gratings along the centre line might be used, the filling material being supplied within the canopy. Such a bench may not perhaps he practicable for the making of large mattresses but tlie possibility should be explored. Otherwise at watt the precautions rtferrtd to above should be adopted. (d) Sraka and Clutch linings. Before beiog impregnated, the ihy asbestos cloth, known as "grey,1" may be calendered at squaring rolls and in all cases the coils are eased out to separate them p little, so ensuring thorough treatment by the liquid. A little dual is prbduccd in these operations but insufficient to render special precautionary measures uecrvtury. Other preparatory work* on " grey *' arises in the matin** of special linings. Leugths of cloth arc lightly hammered to ring sluoe. in templates, then cut with chisel or shears and the radial edges sewn together at a wire-stitching machine, as used in book-binding Dul occurs in hammering and stitching A canopied bench fitted with localised exhaust arrangements might be provided and the machine placed uoder exhaust diaught. i1 ' V k1 f1 X r.3 t; ' tk1 k* i* t 5* Dry impregnated material it shaped and finished mainly -by power-driven / machines. g. knives, circular end guillotine, cutting presses, hydraulic aquoexiog * presses tad hand u*i Cutting tad awing expose ends of wire tnJ leave rougn idga; trimming tad, etnoothing, done on grinding wheels and linishere, are necessary to obtain exact site and finish. Ail the operations, except equeetiag. produce waste, tad dust is created ia some The dust Is bury tad sticky tad less likely to fly about tbao dry asbestos dust. Tbe amount u cousideruble at awing and grinding machines and localised exhaust draught, to remove it, has been applied--in some cases with much success--and ie always necessary. Inverted hoods arc fitted at band saws, just below the tables, tbe dust being drawn through the small openings in the table guides. A powerful draught is aoeatial. Grinding and finishing wheels include, id addition to ordiuary siugle-dsxc machines, two-disc and verticil spindle segmental grinders, used far flat Uuings. The hoods by which the draught u applied to all lbc*<s types are similar to those applied to the same machines when used for mete! grinding. Tlic position is similar as regards linishert, a hood being fitted in line with and at tae back of the baad. A baffle ptite to prevent dust being carried past tbe baud by the high linear speed of the band is a necessary addition. Special linings and anti-friction bushes are moulded from disintegrated impregnated waste. Some dust i created in tins filling of mould* and efficient localised exhaust draught any be necessary. The articles are shaped and finished as just described. Bushes art turned and bored in lather, with production of waste aad dust, bat cxhaaxt draught is not at preseut applied though possibly accessary. . ' (] Packing tad Jointings. Engine packing is cither (a} '* cloth ** packing built up from cloth, usually rubber proofed an both tides, handling of wbi?li docs not cause dust, end (1} *** rope " picking made from yarn, at bratdiug and plaiting machinery, as used ia textile factories, -(a) Negligible amounts of dust tuay arise at the spreading machine, from the uaproofed doth, aud,-ia building up, from materia! proofed oo one side only. (fi) ** Chooses " of yaru arc first rewound on bobbins . (or the braiding aad plaiting machines. Simple winding mcchatiUnix art sued. Some little dust is produced; special preventive measures will usually not be neoesary. . Hat packing, known os *' grummet," is made, on a small scale, front asbestos yarn, threaded on a needle and wound ia and nut by lianj, as balls uf wool are wound. This apparently inxigniGcani process causes sufficient dust to cover ia a short time the hair and dothing of the workers and should be doue at a canopied beach provided with localised exhaust arrangements.(I) (I) Asbestos-covered Electric Conductors. Elteirodu.--Electrodes are eitlier wrapped with yaru, die usual xoeihod or passed through paste containing asbestos bore, yam being wrapped upon this coaling. The former method is usually achieved by a small high sliced stranding machine fitted with a flier carrying (he spools or bobbins of yara, the wire travelling axially through the flier. Treatment with consolidating liquid, ttrlightening and cutting to length follow, all done sit the stranding machine. Alternatively, tingle electrodes may be wrapped by a simple windiog mechanism, hand-operated or power-driven. Faste-covcred electrodes are also made singly at small extruding machines, a flier for feeding the yarn being fitted behind the extruder. After drying, a short length of the covering ut unu end is ground away, leaving the hare metal accessary for braking electrical contact in the holder, when in use. Small abrasive wheels, almost entirely enclosed, are used. Sutall amounts of dust arc projected front fliers, tiiuugli insufficient prob ably to require the adoption of special precautions. Much dust is produced in grinding ends and efficient exhaust ventilation is essential; present apparatus, where provided, is capable of iroproveinetil. The process would be unnecessary if bared ends were left in manufacture, and experiments directed to this desirable er.d are being made and give promise of success V* 1 ,' K< lV ` I 0 * so Preparatory proocMei iu -paste snaking include (i) dry griudiug ef fiberizcd . asbestos by small vertical d>. grinding wUevL. fed si the ventre inns t hopper above tad discharged inn the periphery into a bos below, aud (ii) bud mixing of (be ground materials at a bench, Involving emptying out of dry niatcrial icio pane. Dm: u produced, the amount being considerable iu griudiug Little precaution U taken. The processes might be accomplished under obumt entirety enclosed coudfliaus, eiTiciest exhaust draught being applied at poscu where dry material is exposed, i,{., ia feeding. Rewinding of yam it sometime* necessary and primitive arrangcn.eaU may bo used, the practice ttferrej to ou page 34 being followed, and sj'i considerable amount of dust ia produced, the practise should be given up. Cablt an.d WiringAabectos-covcred cable and wiring constitute a email percentage of the output of the cable factories. The yarn u braided and plaited on the conductors at machines, sot reserved for ** axbcstoe " products, aimilar to those previously described. Rewinding of " cheeses,*' as received from ashestns textile factories, is done at universal winding mndiiuex. The amount of dust evolved ia small, and special precautionary measures are apparently sot required. Field-caU Wrapfiuf.--Field tails for electrical machinery are wound with ' asbestos tape by hand at ordinary work beaches. The process does not giro rise to appreciable quantities of dust. (g) MUeelUneous. ifottided Goods.--Sane cluctricsj insulating fillings are moulded from varniah'imprcgnated fiberized asbestos, prepared after thorough drying ia a mixer and ground iu as edge ruuuer. Alternatively, impregnated scrap, grauud in a rumble;, way be used. The preparatory processes an dry or practically dry material are intonmttent, and surolve sack emptying, shovelling, weigniog, - filling and emptying shallow trays. They are' carried ou iu an open scanner without special precautions except that as regards grinding, hanging curtains may be used at the edge runner, and the scrap nimbler ia enclosed. Dust is evolved iu she processes mentioned and localised exhaust ventilation should be applied to eject iu resuoral, with,-in addition, effective enclosure of some hand work, e.g., emptying of trays Unto machines could be done inside a cabinet Erovided with internal arrangements for securing the uayt and an external assdle for turning them over. Localised exhaust may be necessary for final trimming if done at abrading wheels. ' Moulded articles made in othertradc* may cuuuiu but a small proportion of asbestos, although a lure quantity may he used In ouc case the asbestos is sieved after drying, both operations being done in enclosed machines, and, in addition, dry mixing, dsue iu rotary machines, and paste mixing, on open nils, as in rubber works, are also required. Processes carried an with some risk of exposure to dust include emptying of sacks iota bins, filling ef treys for drying, feeding at the sieve elevator hoppers, the dry mixer, ana the rolls Localised exhaust u applied at (a) the elevator hopper, (1>) the storage chamber above an intermediate nagging jioiui, (e) the dry mixer, and (</) the rolls More efficient arrangements appear to be desirable for (a) and (c); the feeding of the elevator night be dooe under enclosed condition*'if a cabinet as mentioned above were provided into which the trays could he inserted. Localised exhaust is necessary at storage bins. Huai trimming of rough edges is done unde.* efficient exhaust draught. Other processes of comparatively minor importance, e.g . asbestos putty mixing, in which there is handing and feeding of dry material in preparatory processes, will call for precautions as previously described for similar work 4.--S.cks. Iu a few eases sacks of sailcloth or other close!v oven material are used inside the factories Such sacks are much to be preferred to those made of the ordinary material, which is " leaky " and gives rise to dust in handling S.--Cumnim: or Wokxs. Maciiinkiiv aku Sacks. Some factories arc kept in a more cleanly stale ilian others, hut higher standards and improved methods are desirable'generally Weekly deasitg by dry methods is general in textile factories, hut is more effectively done ir, same f.  SI * as atLerv fdesuiog may alto Ik done during the week. Tbs .Jk whack pslher* is a wt reader* cleaning * very dusty operation. Young . nb avy be sen oa carding machine! bntshiop dust into the air from the mb, at, in oaariderahle amount, tur ether worker*. _ Some firsts have wit,iif mi Mt froqoeol regular cleaning! and wore aatiifactory methods hy faying1 brfare twoeping. VaoBB cleaning method! hare not beeu adopted and eueli methods seem 4e ngorded aj impracticable, but this cun hardly tie accepted. Portable _ ohkub acta ore constantly uied with great advsutage iu other claatot of worka, ' at, electric cable factories, by adult dtaner* who keep the machine!, plant, snoict pipe*, etc., thoroughly clean. _ If neon methods arc not adopted, well organised daily cleaning, b\ adults, >[ diarp methodi for floor cleaning, should he the rule iu textile factories heater (apply with suitable hose and spray connections should be provided. D&ris produced in asbestos-cement sheet works under moist conditiont may kmoae dry and cause general dusty conditions. Cleaning should be so frequently Jmana to pervens this. _ The deuiag coder machines ieh a looms and cnnl* entail* collecting * *Ai nf caamderable value, done at present by hand. Vacuum collection should tyjamiTili" r is principle, it is already used for removing tide waste at finishing bus. The sound principle of collecting card waste, through floor openings, lor hen adopted in one new factory, and might be followed in others, with sw--itic atQerting arrangements. Aide cleaning is done in a few Urge works in enrkwed inm-hines. involving mm risk of exposure to dust in filling and emptying, notwithstanding the pmririoo of localised exhaust rentilatiou. A type of " exhausted " machine sdfcl does uoc involve such work is to be preferred. * * SuKuaar aho TltmuutMostiums. Asbestos factories and workshops cover a great variety of processes The priasim differ widely in structural features nod are congested in many cases nhsaae&iacrj or material. Processes arc largely carried on in close association. ' Dust is produced at many kinds of taadiioet, iu hand procn* work, and in dlsmlr iarirfratal operations, particularly in emptying settling chambers, and iu flieadUng of "fiberixed " asbestos. . Ja urtilr factories, pure ashesto* dust is continuously produced, iu differing nsmaats, at all the principal machines. Card stripping, a very dusty operation, is asBoHy. effected by hand strickles. Baud mixing of different grades and varieties, incidental to opening procrvscs. is also dusty mMaatng machines, to making insulating mattresses (a dusty baud process), and m madeattl hand work. Dust, though rarely pure asbestos, is produced iu Boiibiac operations, e.g., sawing, grinding mid other abrading of asbestos products. . jp* appropriate methods for suppreisiou of dust may ooly be fully deter* otaed wheu the harmful effects of comparatively low concentrations of asbestos oat en: duly appreciated. Very dusty processes will not fall to be recognised, but m processes such os spinning and weaving, in which in other textile trades speeisl methods for dust control arc not required, due precautions are also aecosacy. The asbestos manufacturers are clearly confronted with the necessity of attaining conditions in their industry which will ensure much less dust in the asbestos ** 61,1 *** tl0*erale^ *u "1*"/ comparable trades not using The principal methods for the rutttml of dust arc- fa) application of exhaust drnuslu at dust-producing points, fi) substitution of enclosed mechanic-1 methods for hand eouvewms, and for dusty hand work generally: U) effective enclosure of dust-producing machines and plant, (V) substitution of wet methods for dr) ' 8 F4- & 0 3! , Each of these fiat in particular sphere of utility, and the particular indica tion* for their adoption are put forward inter alia in the rcoomendalioas be'.ov ' JtECOKilEKDATIOIfS. (1) Application of Efficient Localised Exhaust VeatUatloa at dust-producing ' points. This measure, of the greatest iiaporiauu: where manufacturing aod incideuUl processes occasion escape of dun not coatrolled by cuelosurc or other measures, ii necessary for:-- () Dutl-prtdveiuf mack!net, tj -- (!) Crushing, distutegratiug. teasing and other opening _ machines; sieving machines; fibre grinding machiues, dry mixing ' machines; rolls fed with dry mixings. (ii) Carding machines (to suppress dust from cylinder and dorters, caused by stripping and grinding, in addition to that pro duced by cardiug); card side waste exhaust machines: looms for dry weaving; stripping and grinding machiues; other textile . machiues, if the dust evolved renders this preventive measure necessary. . (ill) Sawing, grinding, trimming, polishing and other abrading machines, used on dry asbestos products. () Feeding and delivery lattices, or other conveyors, at machines or other plant; feed hoppers at elevators; baggiug lattices; feeding of dry* material at wet mixing machines. , (e) Chambers, containers, " cycloue ** hoppers, or other enclosed space iuto which fiberized .asbestos or mixtures containing it are delivered, or past. (d) HVorfc benches, c.g. for mattress making, waste sorting. (<) Various hand operations, c.g., sack emptying and filling, weigh ing, mixing. This is the principal measure hitherto adopted, and is probably that most generally applicable. It has been applied to some only of the above machines, and appliances, but not la hand work. The methods of applying the exhaust draught, and other associated factors, are beeomiug more effective, but there are few fully satisfactory plants. Special difficulties remain to be overcome in some Cases, c.g., looms, mixing, mattress making.' Ifuot surmounted, an alternative, via., general ventilation of a high standard applied so as to draw the dust-laden air away from the worker, should be provided. (2) Substitution of enclosed mechanical methods lor hand conveyance, and for dusty hand work* gtnerally. This measure-- (<s) avoids depositing material in chambers,, intermediate filling and emptyiog of sacks or skips, hand feeding of machines, and other incidental hand work; (6) permits of final filling and weighing, under the lean dusty con ditions, of materials for dispatch; * (e) renders exhaust draught more effective, or, in some cisea, unnecessary It is already employed to some extent, and its further application, wherever possible, is greatly to be desired. (3) Effective enclosure of dust-producing machines aod plan1., (a) To prevent escape of d(u*. not controlled by exhaust draught, or (ti) to render Us application more cfitciei.l Kg ft. \a. h(, - y- t. ! Q n n n <2 I & li t l. i 1.1 1) n * ** m (1} Substitution ol wet nethods for dry. To reduce the dust given oC in certain proctiies aud work, e.g., f/i) a'coneiderable amount of wearing; (i) mattress making, by wetting tlie coven before filling, and by frequent welting of fioon and benches; ' (e) final .cawiog, and other machine processes, in a*i*u>-ccmciii aheet end tile factories, before the prepared material hoi had lime to dry; (rf) works' cleaning, by damping floors and benches, before brushing or sweeping. Tbia measure Blight be adopted to n greater extent tbau at present. (5) Elimination of certain dust-producing appliances. Certain appliance* are used in a few works, sometimes with a measure of precaution, but which emit much dust, difficult or impossible to control by efficient enclosure or exhaust draught. They should not be retained unless effectively modified. () exposed doffer brush at carding machines; () card aide waste exhaust'machines, delivering under pressure, (<) certain willeyi and teasers, particularly old machines. (6) Abandonment of Settling Chambers In Manufacturing Processes, to the utmost extent. (7) Effectual separation of processes to prevent unnecessary exposure to dust. New factories should be laid out to us_lo avoid exposing" workers to risk from processes upon which they arc not engaged. lu particular, there should be effectual separation of-- (a) opening, cardiug and weaviug, from cadi oilier, and from any oilier process; * (b) spinning, doubling, plaiting aud similar processes, from work not causing dust; . (c) mattress making, from all other work; (<i) chambers, containing fiberited asbestos in bulk, and dus: settliug chambers aud apparatus, from any workroom. Tlie separation of mattress making should be adopted Ju existing works, and other separation referred to. as far as practicable. ' (8) 'Wide spacing ol dust-producing machines in new factories and, as far as practicable, in existing works. This measure would bring about permanent reduction of dust concentration in the air of the workroom as a whole, and provide improved cleaning facilities (9) tTsa of tacks of close texture material for internal work. (10) Efficient cleaning system with wide use oi vacuum methods. (See alto ({)) (11) Storage el asbestos and other goods to be outside workrooms. (12) Exclusion ol young persons Iron specially dusty work. A'ote.--Fariu.ul.tr preventive itw.tsurcj. of a mcJtcal nature are ruferted to iu Fart I, where also the limited r.tluc ol rcspirntoia as n safeguard in this iudiutrt is briefly discussed ' 1} %ii i) II II m}grw- 11 l 11 < )! . 4 U Kotk oh Exhaust Viktiuitiun in AsutsTu* Wonax. * Some exhaust plact* are carefully designed od reasonably efficient, but ' tome are ill-dtiiguea and inefficient; outer*, again, du tool effect removal of dust lo a sufficient exteut. The draught may not be applied as closely u possible to the dutt-produciug points, or may be too weak. The emission of a visible dus: cloud at a point where exhaust is applied is a dear indication of inadequacy. Extensive alterations of existing planU may produce serluus loss of efficient'. Exhaust provision for new maeliiuerr and processes should, therefore, general!' speaking, be made iudependenily. while advantages result from dealing will, many dust-preduciug points, by a single exhaust plant, a number of self-contained plants, with independent fans and settling apparatus, Is often more effective. Exhaust ventilation applied uu a large scale entails continuous removal of a considerable volume of air /runs the room. The supply of fresh air must be ample of the efficiency of the exhaust ventilation mar be minced. Iu winter, the workers arc liable to bring about this result by closing windows and doors. Plenum ventilation capable of supplying (lie volume extracted, the incoming air being warmed, may therefore toe desirable, where extensive exhaust plants ' ora installed. Efficiency of an exhaust ventilation plaut may be greatly reduced by in efficient dust-settling methods Each fun ahoutd discharge into as independent settler. Settlers adopted in utheito, works include cyeloflci, large chambers connected with cyclones, large chambers enclosed with sadking or OUier filtering material, aud bag filters. Cyclones and chambers are usually well separated from workroom* Bag filters are stow beiug commonly adopted, for email instal lations. Tboc filters and ** balloons " ure sometimes placed inside workrooms a bad practice. They are best placed in freely ventilated roomsr effectively separated from workrooms Filtering fabrics fur settling dust gradually becuiue dogged; and ax this effect increases the exltaust plaut become* more aud more ineflicieat, the volume ' qI air snored by the fan being reduced. Such settlers must therefore be kept dean. The usual practice is to boot the filtering material. Arrangemeuts for shaking bags from outside,'or automatic shaking apparatus are not provided. Asbestos dun docs not appear to be to difficult to detach frotn suitable filtering . material as aome dusts, but imu-it dun is produced iu beating Efficient shaking arrangement*, avoiding this exposure, should be provided if this method of settling is retained. Some firms strongly_ support the view that it should he given up because of the difficulty of maintaining the exhaust plant at the highest efficiency. The matter merits careful consideration, in particular,* the efficiency of (lie exhaust plant should be kept under constant observation by a responsible person. * Cyclones ahoutd be of adequate dimensions. The combination of chamber and cyclone is used extensively, the fan discharging'the qir into the chamber, to which the cyclone inlet is connected. The efficiency of this arrangement should remain practically constant. E. Jl. A. MEREWETHER. , CHAS. IV. PRICE Uth March, 1930. ft 9mm f i. i