Document Z8RQk3nOYknaQ1j8QkJGZZOOJ

Ho.\i; -.irnc 7. -zr? C 0 P V Tt REFORT ON EFFECTS OF ASBESTOS DUST ON THE LUNGS ami DUST SUPPRESSION IN THE ASBESTOS INDUSTRY PART IPART n. Occur.-cue; of Pulmonary Fibrosis and other Pulmonary Affections in Asbestos Workers Processes jiving rise to dust and methods tor its surioressioa _____ BY E. R. A. MEREWETHLR, M.1X* H.M. Mt.lK.il I.T.-aHt AND C. w. PRICE PLAINTIFF'S EXHIBIT MET-116 < R-c PRINTiH'i AM! rum.lSiTD y ? i lAr-isTV's stat: ONURY OFFICE. Tr- be n !. i I* 1 A N ivlY -V .'.:i -rssvi . Auas(r_! :Ii'...... R \Y. C.r. :;o. Sire *1, ; Vurl: A:. * - C It. P : ........^...i....... v . *r*.rciu : !- i-; .:i.. /_ y. _^ 03744 CONTENTS. PaCT I. 1. ISTeOllCCTlOX ........................................ -- -- ....................... t. ICmxTJ. or InnmxT Ui*n vms Ttir Erxci................................................................... Tito Xaturo of Asbcsiu* ................................ - -- ................................... 3. Score or the l.'n-uTicvrtON ................................................................... ............ The Population at ri^le ................................... '............................................. Selection oi Worker* ior Examination ................................................................... Tlx Ctiniral Examination and standard' adopted............................................. Hildio;rr.|>inc Examination of the Lun^i ... .,, ... .i *. msut.Ti or tur. Ixtivinr............................... - _ ... -. ._ Ajbcitotii--The Pulmonary Fibroins of Alberto* Worker* ....................... The Asbestos llvdies ... -..................... - -- ... .~ TI<o- Incidence of I'uJmnuary Fibrosis iu Asliestos Worker*........................ Effect* of Age and Ectigth of Kmtdoyutent _. ... Effort of Work in Different Frov* ... -- ... Relative Dustiucas of Tarioui Asbcstoi Processes..................................... Concentration n{ Dust and T.e:`ct!t oi rixjnHnre ticcc*rnry to prcd'icc FiU~ Disablement iirnbuccd i.y the .isl'C'to* Fibrosis ... Prottmii and Dnralu.n of t!.*. Disease................................................................... Association of the Asbestos Fibrosis with i'-.iiatenary Tuberculosis ... Sununarv ... -....................- -- -- -- -- _ -- 4. Faccous urttr.tiivi.vc nit PittstsT ffr-oormoN or nit Asusrros Viueojis. *. Pi:tvu.vrtvt Hetsvr.tx 7. Tat Ctnooic HKTtlttNCt*. 1. IxtuOiiiXTjny Pact !l. .................................................... t Ptoiists. ......................... ...................... - Ventilation ................................... ............. Separation of PrcrcKi .................................- X UtavaiMtox or Pitoo.-i-i am. Pi:eVcsti\i; ... Tlstiuis .............................................. (u) Yarn ami Cloth .. ................................... Openin; ................................................ (`.rrilinu ........................ Stripping .tmi Cl.a ........................... Card .'id. W.n' ?r- tsplliuiln; and !\i.!' \Y.*rp:i.a. .1 l'i...'.r ; "-i W...1V,.,. 3 Xov*iuVH:i.i *... ......................................................... FlU rjf.ticr; or Q.-y-m-.Z (b) MiIUio.it J. JVM" r. St-ccts sr.d Tiles ................................... (c) I ttsul.iL:t Materials end Arf;o!-* .. .............. -- -- Consolidated Shoe!* ................................. -- Sections and Slab-. ...................... -.................... .. Mattresses ..................................... ... (d) Brake and Clutch Linings ... .............. _ ... -- ~... -- () T.tcki:ig siid Jointing*............................................. . if) Asbestos-covered Electric Conductors .............. _ ... Electrodes ................................... ... ... _ Cable and 'Vi ring .............. .............................................. Field-Coil WraiHMiig ... ... .............. (j) Miscellaneous ........................................................ ... ... % Moulded Goods .............. ....................... .. _ 4. Saccs -- ... ... ft. CixsxiS'G of XTockj, MscitTxnu *xo Sacks.............. ft. Susnaev a.no ntY?sii:cxoAnoxs ...................... .. Xorc ox Esiuor Vesnunox :x Aka*vs Wooes.............. 2c 2G 2? 2? T* 2ft -- 2ft 2ft 2ft 20 30 30 30 30 - 30 - 30 - 31 34 This Kcrr; ;as p.ol K-:: ;-i. hd'nrc P:;r!i ,,d r.s on t!ic 2 Uh M;;:*ch, If'-O. hut 0372b The liiyl.L Ilo,.. J. R. Ci.vncs, M.P.. His Majesty's Sorrel ary of Stale for the Home Department. Home Office, 17tk March, IhGO. Sin, I submit herewith a Report by Hr. E. R. A. Merev.-cthcr and Mr C. 'V. Price on their inquiries into the health conditions o: thc'nshestos iutiustry. Dr. Mcrcwechcr's investigations ou the medical side are or' great scientific value. They establish the facts that the inhalation of ashcatos dust over a period of years results in the development of a serious type of fibrosis of die lungs, that the development of the disease varies in direct proportion to the length of the exposure to dust, and that susceptibility to the disease is not affected either by age or sex. The remedy for these conditions is to bo found, as iu the case of so many industrial diseases, in the suppression of diut. The second part of the Rcpo.-t indicates that this point has "only recently been appreciated. In tin* non-textile sect:or. of the industry, no rrious difficulties arise as regards rite application of exhaust ventilation. Tor the textile section, it is evident that a good den! of experimental tvorit trill have tn he carried <nit Ik*fere completclv successful ventilating appliances are evolved effectively to remove.all the dust.' I have die honour to lie. Sir, Your obedient Servant. GERARD RELLUOrSE. II.M. Chief Inspector of Factories. 0 3727 Report on Effects of Asbestos Dust on the Lumps and Dust Suppression in the Asbestos. Industry. PAirr i. the occirnnr.xa* or ruLMoXAHv fiuko-si* and otileu PULMONARY AFFECTIONS IX ASBESTOS WOUKFKS. 1.--iKTSOUCCTiOX. Tliis Ilcivu-t is bn^cd upon the data ol't.tiued iu .in extensive investigation during the vans I'rjf and l'J'-i 'l'Lic inquiry was initiated by the Factory Department of the liume Quite following tue discovery in February, 10iS. m a case oC li'iu-lubeicuiar fibrosis of the lungs in an asbestos worker, of suiUcien: severity to necessitate treatment ia hospital (Seiler's Ca?e'). Prior to tliis, this Department had knowledge of only two deaths of aslxtos worker*, about whom there was expert opinion chat the inhalation of asbestos dust had at least contributed to, it mu caused. the fatal outcome. The tirst of these, now referred to as the "Montague Murray Case,'' occurred ia 1000, bat all that is known concerning it is contained id the evidence given by Dr. Montague Murray iu 15 00, before the Departmental Gmtmiuee on L'umijcnsation for Industrial Diseases*. In this ease pn*t mortem examination couhnncd the clinical diagnosis of extensive r.cn-cui'or.uiar pulmonary fibrosis. The second ' (Cooke s Cu-e"; oeetirn.-u in Lbd-k Here, although G.>'ke and Smart MeDouahr vrrre of "he opinion that the lungs .'hewed a nrcgrcs'ive rinse dbrosis tegethor with a chronic inhere::", ns infection. the ctioiugie.il relationship between the inhalation of asbestos di;t and fibrosis of the lungs would have been strengthened by she. absence of a p.dc.-rc'.ilou.< infectior,. ~ An early survey of 11,- industry in 1010-11 by the Department did not dis close any evidence of the existence of a serious health iiazarrf in the industry, hut romi experiments on animals conducted^ it; 101g by Professor J. M. Beattie of Si;c-:'::-r'-.i 1`nivtrsuv for the Department showed. that the iuhaiatiou of asbestos dust will cause a mikl degree of f.l-ro-is. When, ihrwiiii.TO. iinesi:g;.:i..ii of Seiler's Case showed that other industrial and infective causes of i'ilmisi? eouid Lv definitely excluded, the necessity of deciding whether the supervention -u liti.- dise.i-i- iu an a.-lxstos worker was an cxrcptivsal occurrence. or evidence >( a grave health risk iu the ii.rlvi.-tiy. was apparent and ihe investigation referred to was undertaken. 2.--Effects of Ir.nrr.-.ttv Dv.-t I Tux the Euncs. The most important local e:\-.ts which may follow the iuhaiaiion of dust include pulmonary and bronchial c-atii:. a.-ikm;;, brvr.thitU. lihrosis of the lungs, and secondary change?, s'lc'i as emphysema. local or diffuse. 7!:e:C cluiRgc* in the luii-gs, witiclt may hv looked u:>'u a> a measure of the eu.irt* of the living tissues to repel or UHatxera :v me irrit.iut par.ivies of dust. iicvv's.iriiy cause interfercaec 'viti: :iu general edk-teu-.y of the lungs. The impairment of functional capacity may le .-light nr severe, anil tcruj-wurv >r permancM. de pending on the variety m d::.-:. a ini on other factor?, siit.li as couccuirution of dust and length cf o\re.. Moreover, individual' v.h,.-,* 'm:;; have lv,:: :i.Tevte-l as the result .if '.he inhalation -mue -b.:-\v a:: in-.vv::-."! ?ti.~.t-p;:::i; v !o the ?i:;v:m of j e.-tni'rv 'nle. 1* f.'." rm.m -i- v-r :::i..|iia Fibr.-:' i-l i l>v ! 1- iid.. -i I,.- :: ' ' v. cl I'1 in r..: - " . t lo-.s uugs is *e. : .., -1 : cr il ':: *-i. uiM--.ri.iii: ii-ei'" "*. 'if-- ,.i -ai;;i .i .Iu-. ' . ` i i.- ;;; 1.1" i t, .1 i *. , .1 0 3728 G This triad--exposon- re bu-l . f.'-rosis ,'1' the lungs. "s t u i high mortal i;v aare from pubic.-nm-v tul.ure.lu-i--was iuu:ul re he .orur;.;! re ,i rr.uurer ui l.ir1.".' and important inda-in.-. and in .ill of tlnm the tin-' iiu-tin: mated -.v.i# iiw crystalline silica These features wore not observed. however-, in other industries in which, while there was exposure to siliceous tin.-!, tlie silica was found t cxi.-t in the combined form as a silicate and not in the free coi:ditren. Tims, shortly, free silica came to he regarded as the pre-eminent cau.4 of industrial fihro-.is of the lungs aud as a noinldo fiuicr iu the production of the excess mortality rate from pulmonary tuhcreuk'sis iu certain industries. Whilst the pulmonary fibrosis produced 'ey f.-im silica (Silicosis) has been, and is being, minutely investigated, the potentialities', as fibrosis producer#, of dust ctlicr than free -iiira have ut l*ecn :uilv explored, although it appears certain thar some other inorganic direts can. and some cannot, produce hbrosis under the conditions met with in industry. That a serious, even fatal, degree of fibrosis can be produced by some of these other dusts has not been generally appreciated, although I3adtiani in a thoughtful paper' has drawn attention to this point, in reporting a fatal case of pulmonnrr fibrosis caused by dust of an orthoclase basalt containing no free silica. The Nature af Asbestos.--The fibrous minerals commercially known as asbestos fall into the latter group, the silica being combined with metallic bases, mainly magnesium or irc>u aud, to a less extent calcium, sodium or aluminium. The term is a collective name applied to a variety of silicate miucmls which differ from each otiier in chemical ^composition a ad physical properties but resemble one another in their aaeiy til ious nature and iiexibility. Their value denends on the facility with widen they can he split into !:ng anti ilexibio fibres ror spinning and wearing, on their resistance to heat and acids, aud ou their insulating properties with respect to heat and electricity. Varieties of asbestos possess these characteristics in dinering degree. Practically speaking, all that goes under the name al'estcs in commerce is either fibrous serpentine, or a 5brou# mineral of the- hornblende group, of which the most important are rrccicolitc, smosne and remoli::. Serpeurine asbestos or chry#o:i'ie is essentially a hydrated silicate of magnesium, containing iitrle iron and practically so -aicium. The hornblende .arietiss contain less mag nesium and usually more calcium, alnminittrn anti iron--crocidclite and utnc.-fte being mainly silicates of iron. 3.--Scars os ns Ixvsstui.v--o.w Asbestos is very largely used in industry, being an important constituent of many different products. lac diversity of iiwiu.-tries concerned made it essential that some restriction of the held of investigation should be decided upnu. The manufacturing prucc#~os adc-lcd fall more nr less shnrplv into two groups (1) these in v.bkh there is cx;*v.-urc to pure a.-re-sto# or asi-csios mixed with a very small peivonrage of cotton or otiu r ...< i:>;L. fibre, and 'ui th.'rc iu which tlierc is exposure to a mixture of dusts, of which jsIkis:os is but cue. The former group comprises, in lire main, the textile branch of the itidiistrv. a bra mi i mauuiuttaring iiisuLuiug mater;.-.1.- tre-ui practieaiiy pure asbestos, aud some preliminary pre-e.-i-os m uthcr branches Tlie latter group imbibes a . ' pro. in which tlie .report ion of n>l.o-re- it-, i!:e du.-i . v..ivvb range- ;: ; .i nr_.. . l ie qimmuv" ..owart:.- rini-c it ih> iu:p"--:i-k' evalu: the a;.,-. ; -i: :h.- :::::;er. .iu.-ts. w iuvii a-oe-tor bus; rev . vp an; ' : i.e :. :: ot ;:>:c-re- : :; was d\ ! .rmivd. was :v-1 ;!!. d io v. words. << v. r.i c\.reit o; e-i os a- pre;.. .< i; re.- :v re .. ! :,, gi ; i. .. b re: '- b::.-l i art . r; \ !;r'' vI ir -a, a I;.i; '1 i ; i re c: i - ,... r b 0372.fi 7 The ithi itt Hit':--Thv irrr -i number 01" worker* who mnv Sp exposed lo l!it i:ib.lU:ir.u ul a.-ber-t.". uu.-l In .my vMerii i> uiiInIk.u ii. nuu o:irto the great vanviv ui' pre, ; -?<'? omi .-rued, mere fire i :--n; >o i:: I j|.^ linVu. lii; ascertaining shi< I inure. NUr. in l.ict, wotiii! ciiiigliUmuc.it on tins [x.int he of any particular value. It is otherwise. luiwovcr. 'vitli rvspoet tn the figure representing the uumi-cr constantly cxpu-eJ in the course of tiieir daily work to tiio iuilueuce. of pure or almost pure asiie.-tus dust. Some information on tins point is very desirable to chock the adequacy of the simple of workers examined, and to envisage tlie " problem confronting the industry. ^ While only a rough approximation is possible, it is believed that about 2,200 is the present number of persons in this country on nosed in their dailv work to the inhalation of asbestos dust, cither pure nr admixed with a small proportion of cotton. I: should j'.ot 1c overlooked that this figure docs not include the considerable number of workers exposed to the influence of mixed dusts of which r.ak'stos is but one, and commonly not more than 20 per vent, of the mixture. Of these 2.200, the sample examined uumhered 302 (excluding II for reasons referred to later) or 10.5 per cent. Selection of Workers for Examination.--The selection of workers for examitratioa was not left entirely to chance, since it was early evideu: that the proportion of those employed 10 years and upwards in the industry was very small; therefore, in each factory those longest employed were preferred, since the importance oc including a suilscient sample of this group is evident, llogitrd was also paid to the other end of the scale so as to'obtain information as to the lengrh of exposure to dust necessary before effects are manifested, and also to the naviicuhtr process on which tiic worker was engaged. By balancing the component groups of the sample in this war as the enquiry proccedcu, it was felt that the maximum information would be obtained in the shortest time. -- It follows, therefore, that in respect of length of exposure to asbestos dust, the component groups of tire sample do not bear the same relationship to each ocher as the corresponding groups of the industry under review. The sub joined Tables will make this clear. Tabic 1 shows the distribution according to length o: employment met necessarily in one factory,! of 773 workers, the total number engaged ca those processes in several factories. Tabic 2 shows tlm sample ot o'.3 workers distributed in the same way. T-inui 1. Yean eapkiyed. 0-4 ................ 5-9 ................ 10-14 ................ t;-it> ................ 20 and over Total* Nutunsr. I'crrtntacc ot Total. 1 4S3 <2'3 200 23-S SI S- 3-1 --< J ICO Taulk 2 Year* employed. 1 Xuialxw. ; 0-4 .................. 5-9 ................. , ie-u ................. 15-19 ................. 20 and over Tola!* S9 141 < 23 21 3C3 Terror:*;:* vl Tq:*L 24*5 av* 23 2 5 ** l UU Tl;e enormous nrv|-':'.dcrai'.cc muverirn lie .-.f workers employed uniter ti rears is -trilling. :i- also is the very : -w porcviii.ige of worker? vmpkir.i " years or b uyer. Cvumari-.-n of the two dw.vs that < the meth-xi 1 j.-.t; (,, w'..- e\:i:..:tmU i ti. . r . iu ! ::i five vr:: rs vt- .. p:. t:. - " U.r ij-w*. ; :-.i "i ............. nimd.r v.: ah ..mb; u:;ie <- m e\.;t:.:i.c-i .me rt ; *. 03730 s 'Willi a solu.:r\ i-xa-;:..a a!! <-X ;t n i i 11a t n 111. c\.I'.uiu-.-d v. ..-re .;t won; pu ,;_.x -,( T/i'J CUmrul Ab tli:i iihitiOii Hit'/ '! --Tlie :i:it'a.: . a'i.! purpr.-c id' l!io iit'i'iirv were v-x) i! .111 :>,c i in c-aili worker wbor:'. it. was j-jm .-<j to examine, indivnlimllv. liis nr her co-operation *-W;uii:t*ti. p.,,;, m- (liviclnai s previous industrial history, siiiisetjiicl.l l*. l.-avir:-.; school. uas noted in detail. Tin's was C".'inial in nr.ivr to ex. hide. -:l*v. the cue-. I |<ri-. vious work in any of the uiiuicpms miM'-s-j invnivii.v t-xpauvr u> ir.v silica dust, nul, In a less extent, tin* diet of other diisls. Similuriv, iho m- dividual's medical history v..:.. scrutinised I'rnm chiMhe-nd onwards. to'deierniiiii: the physical level un entry into the industry at-*! any snhsonucnc tun litres. Particular attention was paid to accounts nl' pu!::iou:irv oilmeiits, some" ivf which. like nsihm.i anti bronchitis, are cnninmn cii-nt-eh" amou-.-s: the t;e;u-rai poptilnlinn, vet are also tiou-sptcinc signs of irritation caused hi- the- inhalation of dti.-t, whilst otiiers. like .i.tiuc.ua and piicuiaoui.-i. arc -j,.c:isioualIv followed by a degree of pulmonary fibrosis. War >ervieO. i;` any. was trace into.' eit:totally 25 to whether there was any history of the worker haying Steen a gu> easnaltv at any time. The family and personal hisinrv in u-sivvt of pulmonary tuber culosis was enquired into, end also as to any close assr< ia-J0n with known cases of this disease in friends or relatives. Iu approaching the pertinent subject of symptoms, great care was taken to avoid leading questions, esrwcinllv iu eliciting information as to the existence of any undue shortness of breath. The actual details of tbs physical examination do not call for comment, inasmuch as they followed the usual linos of a detailed examination of the chest, with .ihsei-rniions of the general health and of the condition of the upi>er air passages. IlciorriKe mus.r be made, hnwr-vor. to the standard of normality adopted in assessing the stare of the lung*. The appm-onum; of any departure fr-tn the nonual nec-esajrily pre-supp-oscs the existence of such a standard. Every clinician has attained, as the result of ex j ;criencel'his- own clear conception of the normal ckc.it. but if is act often that he Suds it necessary to aetitte :h.s state iu so many words, in fact it seems scarcely possible to do "so. and this fur several reasons; the hear: ar.d iur.gs ttu-- timi odid.-titiy within wide limits of applied strain, and. nitkaupii vestiges of p-f disease may Us present ami apparent on examination. tin.-v will be unimportant if they wiil never tax the organism beyond those limits, arc ni<ii-pr*-grc-sstre-uni do no: predispose to other disease. Age itself lias ria/'cuisr.hio eitcr.s. hut fur this reason clone, the chest canaci he considered abaomai. There it obvious disparity between the standard of physical f;tiu-s* required for an air pilot and tint: required tor life iii.<nm:utr at ortiiacry rates: in dividuals reaching either standard can be classed as " ti** rrn.nl." yet many ,utam ing the latter standard have never i-.ppruaciu-d the former. Thus, within limits, various gradation* of normality may be distinguished, and eurrcspo.-idng standard* ceostiiitted with.*;:: nr.nv, the iirce.se status of any standard being determined by the p-.:r;'-'**e f*r v.hh,.i it is established. For the purpose of this enquiry the stau.iard has bvC'.i that evinced in anv large group m livttm I-.-r >ii::i!.r onvtr-iuin-ov.ial tun-iiti.Mis. annrt from work in music o < ..nations, as these or t!n- nrotip being i-in.'idci-v.*!. This is neither a high standard irr a very !ov. stand:::-*!, but the cven*.ge stan dard of normality displayed amongst the indu.-tt-ini pop-ciceio:: of -.his country. iv I'..i //.'."<.*.* of t!r- /.;:.**'. in -itio:: ,i lare'::: :b: - graphic e'tamtualiou <>; :iv- vbc.-t \v:s ivade maiiv --. t!ie uv.i-.sii-. for winch in invest iu.it u-as it.: * o: np :i tt.c i.nc; na: . u cmpiiasiscd rcpvatoii'' t*v v.-. .i t -. ~. h v.,i. fa it. >* . 'Ui'-- to (.l.taii! tc a!1v si;:: '-1. '." r::*!l*mr:-:- - *? :b! tb.- w..:!.ar. i ::* *-f *!. -;w. ;ir (|j(\ ulti' ` lit i ' ' = 11 * ;<:.* * * * - -: i ;! oi' i ni " i 11;.i!1 . i A ` !!*:* t * * > b..: -u' ' "* i::vc* 1 ir'i f i >* *' `....... : f - ; 1 037 3 9 extent and prom-* of the ic-ueti' .md 1 im r;:iTM the point nr v.-!iir!i the earliest radiographic appear. nod liii.illy a> a check up-m ti:c human fuclor plt-culed !<v ihe examiner kimr'dl'. 4. -- Rksh-ts or Ti:n Ixqiu:y. To anticipate, ('MMuinniimi of the data mltrcied in this investigation lends t.n tlic conelm-inti that the itihal.i'.trui of a.dv-to* dust over a period of years results in tin- development r.f a serious typo of filuosis of the lung*. A s-h^fta!hr Pi'ltmi.Kiru Fibro.<i.< of Asbestn* ir'o;7.-/'i'>\--Tt is helpful to visualise fii>ro*i-. of the lung; a? it occurs in ."'.liost.is workers its tlic slow growth of fibrous tissue (s-.-nr tn**iKd tv! ween the air cells of the lung wherever the in haled dust comes to rc-t. While new lihnms tissue is iving laid down like a spider's uvb. that deposited earlier gradually contracts. This fibrous tissue is not only usolrs* a* a -nhstitnte for the air ceils, i.-nt with coutinned inhalation of the causative dust. I>v its invasion of new territnrv and consolidation of that already occupied, it gradually, and literally, strangles the essential tissues of the lungs. In common with other essential organs of the body the lungs have a large reserve of tissue for use in emergencies and to permit of a diminution of functional ospaciiv due to advancing age or disease. For this reason, and because fibrosis of the lungs is essentially a local disease, it is only when the fibrosis progresses to the extent of obliterating this reserve, that undue short ness of breath on any extra etTort draws the worker's attention to the fact that his health is not what it should be. The other symptoms of the disease such as cough are equally unassuming, and are readily ascribed to some common and trivial cause. From this point the progress of the disease is more rapid, sines it is now encroaching on the remaining sound tissue of the lungs, already only past stiiTicicn! to maintain hint in hi.- ordinary daily activities. Ultimately,"if no acute respiratr-rv infection has precipitated a fatai termination, a stage is reached when th; lungs can do little more than maintain life, nud the shortness of breath becomes extreme. In its main clinical fcatnres. therefore, the disease resembles silicosis, as might he expected. It differs from silica-ts. however, in the mode of distri bution at the fibrous tissue in '.lie lungs, in its more rapid development, in its radiological -cattirt*. and. there is some reason for believing, -in a lessened susecptihilitv to the supervention of pulmonary 'nbtreulosis. the liability to which disease is so def.ni-.eiy an added hazard in silicosis.. The As'-'lot fiv'ii.s-- In the !;:ng< of those exposed fo asbestos dust, angular particle* derived *re*n .ishc#*os.' aod spicule* of asbestos" are found on microk-opica' irare.iijntk'U. and also nund-ers of ;vrerlinr bodies rioscrilvd bv Cooke and TTjir ,rr:.i Stuart TdcPon.-duk They are yellowish brown in colour, of elongated. K-uddikti form. ; iron with hull-ons cuds Cooke* and Hood house Glovnc* independently demonstrated a mineral core in these Itodies, evidcnUv derived from the asbestos fibre, ytewavt and Uaddnw have also demonstrated their presence in the spntum of .i.il^-t'v* workers. These bodies hare not Leon found to occur in anv '-ii-.er human effectin''.. They have been found in the spntum within a comr.av.-.tivric -ivrt time after exposure to asl>csfos dust, and in the alisem.? of clinical or radiological evidence of pulmonary fibrosis, their presence canur.t be taken at ore-pit as indicating anything more than previous inhalation of asbestos dust. The I n, ;.1.-.:rr ,,r P >w-rc f"7)/viA v ns the risk: tn health associated witji to adie.*ns trial condiicns Tn.'.v r.r.w !<? i--tv'ered ir. detail. The extent of antler present indus Of tin- - ".'tria-T - h - \e* ex.i.'mc-I. I'* found ro have a miiii-e fibrosis of iiivg* .it: :o me i*!1 ,.f Ten of ihc-v and one otiu-r in -vhi. '-rher of ! i .- --ten- . I'diri'e:. have i-.-'it excluded ft-- -I '-ir:!-. :n.'v.- - :: felt :h:it prm. ions work in r.t! v O" ".T ' - -".I:.. ~ I. e : . I inlivir,:. lit:v ' \ c been tiu ;*i :' o- .t me- i- : he ei- -. ' i' ; emor of me pul- : v lesion.* inure! i.U's A _______________________ 037 3-3- aBBHMBWBIHWBgBiMUUllWJJMEWeMMWaPaitfltMM 10 Tims, 'J*> of Jud workers, or 2C.2 per rent. showed a definite fihr..i, to asbestos dusl. An addini'mil 21 \wie ictiiid v. ith piviursivc signs o! tin.-, d:.-e:n.i:, but these arc viiveii no v.c'c'la iri the gvnei.il mo. lu.-iimi, which arc dcriicd ^jloly from examination of the 'J3 cases o! definite fiinosis. Of the 1 :>o radiographed. G2 presented r:t!io^raphh-rsl aigus of a diffuse fibrosis, aiul in a farther there i:ro suggestive radiological changes not definitely diliiL-e lihrc-is. In 10 oi the farmer 'roup and 3 i f the latter the changes were possible referable to prior work iu other diis.lv wcupulhm.-. or to other cause, and they arc therefore excluded, leaving 02 cases of fibrosis and 22 with signs suggestive of early changes in the lungs due to asbestos,-- sufficient radiological confirmation. IVunt inferences should lie drawn from these figures?--Certainly not that 2G.S! per cent, or roughly 1 iu 4 of those at present exposed to asbestos tliiit in their daily work have fibrosis of the lungs. As mentioned previously the sample examined is loaded with a greater proportion of workers employed o years and over than obtains in there sections of the industry at the present time (Tables 1 and 2 above), and as shown iu Table 3 below the incidence of fibrosis increases with the lengtii of employment. Therefore in order to obtain an approxima tion of the general incidence rate of fibrosis iu these sections of the industry a correction must be applied on tlti3 account. Applying the rates shown in Table 3 to the figures in Table I, it appears that the general incidence rate of fibrosis of the'lungs amongst those employed in those sections of the industry is rather less than 1 in S, or, excluding those employed under 5 years, rather less than l in 3. un ft age distribution since, ns will jo seen later, the itiwider.ee of fibrosis is uuafiVeted therche. Sex has no effect. These general incidence rales arc convenient merely as affording a rough indication of the inherent risk associated with exposure to a?!-estos du*: at the present time. They have no permanent value either as an index of the general risk of fibrosis in the industry from year to year, or as a measure of the risk in any particular factory or group of employers. This must lie so since not oniv will the distribution of workers in the industry according to process and length of employment vary from year ro veer in accordance with trade develop ments, but the increasing application ot methods for the suppression of dust will have a cumulative effect in reducing the fibrosis incidence rate in future vears. Effects of Aa* end Lenoth at Enrplnumctrt.--Table 3 shows the di.itril.ution of the workers examined according to iongth of employment, and Table 4 their distribution according to age. together with the incidence rates oi fibrosis in .each case. T.iltf.E 3.-- Tr.ci-U'ncr of Fibrosis refatirr t) f.civjfh of Emjdoriiieot. . Yean Employed. : n-4.............. ... 10-14 .............. i*-l? ............... -.ml nvrr .. , Tuir.U N'uw^f SO Ml 54 -5 Cl -TG3 i Cam* of J*i broil*. Average &; in ysir. , Group Of Group less Xu&ir. , lacid`ii< for ! cent. ,. '0 _1 24*2 , :g 30-3 ; ac-o C7 32! 3-ei | ;o*4 16 :.3 <1-0 ; 4H-3 IT <W-0 04-4 2* T OS Sf* - :io*i <14 0 3733 u T.U1U-. I.-- / r -if i tUt'-'.'-i'' rrtfihrr .1./;-. . Ay Grotijt. lh>tou> 20-59 ... 30-09 .................. <0-49 .................. 90--39.................. CO and over ... Total* Nnm<K*r - 1 C .' o( , li'l'CMS. 1 Atemp* IctVjjtK ct * * .' l in >c.\ri. N'.=.Lcr. Inrul nee |*cf CVH4. CJf ol ViUfdU. c ... 13 i 130 100 I <7 r9 | U . 1; 30 31 U 9 _ 'J'3 30*9 Ci-U 3T-> C4*3 3'S c-t 9-J 11-3 9*7 10*0 MM `7 !?* Hi lev u*:: :c3 >3 t SC * i 7-3 ,r.-. These tables indicate lbs :i<iinvj im|imtanc of length of dap1'-.. mem (and hence length of cxposuio :o dust), and Uiu negligible'effects of a"-.-, on the production ol iihrosis. Thus age groups 30/30 and 30/39 (Table ) have incidence rates of V) per cent, and 37.!) jwr cent, respectively, nut a wide difference, since the groups include workers in various processes exposed In different concent rations of dual. Moreover, the average length oi employment. in these two groups; ext-hming the eases of fibrosis, is almost identical, but omsidcnihly less tliau the average length for all the cases of fibrosis (.13.5 veers). It appears also from the same Table that no special susceptibility to the development of fibrosis is sit-v-i by youtig pers-ua, unless it is considered '-hat the figure of r.7 years, the average length'of employment of the case* of fibrosis in age group .0'39, has beer. :i:a;".enci. by inerraMai su.-ccpiibilicy of age., under 20. As. however, the avoir.go age of this group at cases of fibrosis is 2>i.7 y-.ir3, and also Ives use die establishment of filirewis (bus uufc. necessitate immediate retirement from work, this is largely dis^mm-d. Column 4 of Tabic 4 nl.-o shows a gonrml irregularity whirii, in itself, points strongly to the negligible effects ofV.gv in the production of fibr.-.i-. Turni-ig to the effects of length of empmynrnt a very different pi- .are is seen. TaHe 3 shows that after 5 years' exp. ..mi re. -he incidence rue mounts rapidly, and after 10 years increases aImo-4 i:i ircnmetrical progression. Effect of H er/- i;i .afferent f'-e.-r.TImtc are insuperable diiT.-alties in ascertaining trustworthy figures uf the jinrs- incidence of fibro-i.- ni.vuurst workers in particular ashotvs processes. Tliis ;s the result of the irwt practices in ihc Midustry of housing many pn--<-s in one roum, and of wm Ixrs transferring from one process to another. Tin*- two factors, the infin'-MO of dust from itoighhonring processes. nd prior v.vrk in other asbestos proc-i.-s-es, operate to i-bsrnre the effects due to work in my -me process. By distributing the workers, however, according to the process in which each has been longest emph-yed am; Trotijiing similar pr..vsses together, it is to draw ceriaii: broad conclusions as to the rein live rtff.vt of work in diimrem processes. Tn this wav groups were obtained a <nil<ws:-- (1) Crushing, opening, disintegrating and mixing. (2) Carding. (3) ftpinning, twisting, dnnhtiug. plaiting, etc. (4) Insulating mattress making. (*>) TVeaving and associated pm- w~m. ((>) Miscellaneous processes .'.mi r.aiuining unclassified worker.. The out standing point l.ruught out in ihi< wav is the rclativclv vrrv hr.v incidence rale of fibrnys in gn.ip 3 (tvra-.d " i-piunrrs " for i-.i::vc:::.-<i;'-, .- compared wit!-, i-acti oi tlv other groups i'l,,-iv is Mime itid seat ion :i I -- amongst " spinners '.be uirruro ;it-. io:: r :o li.-vol-ip. >tu-!v o'" tIf grams, also, reveals furtln-r inhurtn.us <. .u-i , u...\ M.-riuver, i- tions of the dust rontci-l lb" or ia ;it.- act : b. ::d......I ,!' tia-to pr-v in I lint of v.lbers.tu the v-ric::- .. rv.nr.s sl-.-.-. ifi,. cvobi. ;.ai of du-l -a ;r 3 is .'ll..-3 IvhllUiiv hue (T d i v; . G2734 12 In fact, the liirtorv, aw! the medical .mil radiological fvnLures of i!ic eases of fibrosis, together with the rvsuk.i of comparison o! the dust cow:??, ail con tribute in mjiuc derive to tin: view tli.it with ommar.ilivcly low concern ration of duat in the neighbourhood of a process, the resulting eases of iibrusis amongst the workers in time process are longer in developing and remain longer in a milder stage. It follows, therefore, that in such esses chcjrnte of accumulation of dust in the lung has not 'areally oxcectied the rate of elimination, and .a further point of great practical importance emerges, namely, that in order "to prevent the full development of the disease amongst asbestos workers within the space of an average working lifetime, it is necessary to reduce the concentra tion of dust in the air of the workrooms to a figure below that pertaining to s. spinning at the time over which these eases wore exposed. Not only does group 3 show the lowest incidence of fibrosis, but it forms the largest individual! group in these sections of the industry--about one third. Relative Dustiness of Various Asbestos Processes.--While some reference here to the varying amount of dust evolved by- the different processes is uccessary, the causation of these differences and methods of suppression of dust arc dis cussed iu Part II oi this Ilcnort. Different asbestos processes do cause the evolution of different amounts of dust iuto the air of the workrooms, and, under present conditions, the difference between the least dusty and the most dusty processes is very pronounced. In souse processes the production of asbestos dust is insignificant; in a second group dust is continuously evolved bnt in relatively low concentration, as in spinning; in a third group the evolution of dust is continuous and in high con centration. as in dry cloth weaving: and in a fourth group much dust is dissi pated in hursts of short duration, as in emptying the fibre from settling chambers by hand into hag*. Seme addition a 5 data r?TM. obtained hr means of a limited number of determinations of .he dust content of the air at the breathing level of opera tives engaged in various processes, with the aid of the Owens' Jet Apparatus. The figures iu Table 5 which were calculated from some 50 determination?, give a'rough idea of the general dustiness of the processes concerned, and also of the effect of localised. exhaust ventilation and damping in reducing the concentration of d:t*t in some of them. The counts in other processes are expressed proportionately to the spinning, plaiting and braiding group, taken as unity. It will he seen from this Table that the dustiest processes are opening (with old fashioned ter.=v.O. sieving {with ::o local exhaust ventilation), and shovelling or otherwise handling aeliesros fibre, with a e<'mt'ira?ive figure of 2.34. The heaviest counts of all were found in this group, in sac!: filling 'ey baud in a settling chamber. Th-* comnamtiw figure here was 0.54, hut the record was dense, wi'h much clumping rn?*ther of the dnst particles, with the resuit that the totai dut count arrived at was u.ndnnhredlv too 'nw. Next in order is drv cloth weaving without the application of localised exhaust ventilation, with a figure of l.fia. This is undoubledlv a dnstv process, and although local exhaust ventilation reduces the count at the breathing Icrel of the weaver, much dust still escape* into the wpritroom. Weaving clotii wet, not merely damp, reduce? the fir.st count to a remarkable degree. Column Table S.--Relatirc of rarions. Prr-rc**cs tv* Effects of Localised E.vhavst Vcr.tiiaT'on ova Datr.p Metl-oefs in soprrrssma Dust. flejuHm:;. PUmnr. CWireit?in: s.'!. '.sw-nl I C.uh T>-r. U*ni V.-fttll. ItlOtt. : witi Mt* -t1U. \-f\ Vi:'- fi*n- 1 Itamt. T Wet. Dv\ m till >ntt!. iUtirw ilakiss. 0r<*"*nc x tPilnAr.tft stti-ovaiti`1 f n! ii* | : battHlir.C I Sfcrr. Ore.* | Tv:.n:n with ! "flit sv-r; 1 v\i.*?tist Tf*uU r.tti. r, nt.i- atlOU. * Mints. , Jn-- 01 55 of :: ".i.tt'.rev 03735 13 7'for band (i.c., narrow) weaving, \rc:t Is not accurate sim-c tbc figure luii raked by dust i'i\jui a m-igliNnuing <li\ cloth h.-om. Matlrea- making without any pi-ovuutiuus. =ueh as oxliaiut ventil.ui.m, or damping llunr.-, tables anti doth, follows next willi a figure of l.-j footnote Table a). A|i;ilie:ui''H of exhaust ventilation, and damping i^dieos the figure considerably, but it may le that the figures tn columns l) and 10 ate too Ion*, >imv counts for some subsidiary proc-c.-scs, such as buttoning, sowing, and cutting- out. are not available. It will be observed that carding, although essentially a. very dusty process, produced a comparative figure of only 1.17. Tins is due in part to partial enclosure of the working parts of the carding machine, but is mostly the result of the application of local exhaust ventilation. Moreover, the figure does not take into account the extremely dusty opemtiou of stripping. * Rotative to the comparative numbers for the other different processes, the figure of 1 for spinning, plaiting nod braiding is probably rather too high, owing to contamination by dust from neighbouring and more dusty processes. Samples of asbestos vary much in chemical eonstuuwuu and physical pro perties, and of the three main varieties, chrysotilo. croc-idclite, and amoks, the latter two, in the opinion of experienced workers, usually jgiycrise to more`dust than chrysolite in tJio textile manuf.-ttluricg processes! *^o evitlengfTraffJuai to indicate that any one of the three varieties is more, or less, potent than the others in producing fibrosis. other factors, such as concentration of dust, being equal. A peculiarity of the asijestos fibre is that it first fragments longi tudinally, atitl apparently this process can go ou indefinitely, since there is no ultimate* fibre comparable* ro a vegetable fibre such as cotton.* A Concentration of Dust and Lennth of E.r/wurr Xtccssary to Products Fibrosis.--From the data so far examined it seems clear that fibrosis of Che lungs is a definite occupational risk amongst asbestos workers as a class. Furthermore, it appears that the risk falls most heavily on those longest em ployed and on those engaged in the more dusty proteges. _ Some iurthcr consideration of these two important factors, length of em ployment and concentration of dust, is desirable. Obviously, to some extent, they arc interdependent. since, assuming that a specific quantity of asbestos dust must la- inhaled to produce a generalised fibrosis, the fibrosis will result from exposure for a period o: time varying with the coacenu-atiou of dust in the air breathed. Simson." reports the case of an asbestos mil:, worker in South Africa, exposed for 12 months to a very dusty atmosphere, wbo died from a rapid tuberculosis; sections of the lungs' .-bowed, apart from the chances due to tuber culosis, a moderately marked imrc-is. Burton Word an-.i h'agc'* report the case of an asbestos spinner, employed 13 mouth*, who died from a generalised tuberculosis, 5 mouths after erasing work. In this case a little fibrous ti-suc was generally to be seen surrounding the asbestos fibre* found in the lane r tissue, but there was no gross fibrosis. It seem.- probable, therefore, aithouuh further research is very iicvessnry, ri:nt not only is a certain minium! quantity of the dust required for the production of a generalised fibrosis, but that inhala tion of the dust in high vmceat.-nuvii results in she production of a mure inarbvi degree of- fibrcsi* in a shorter time, than when tim concentration is low. Investigation of this important matter--concent rat ion of dust and length of exposure mressarv tn produce fibn.-is--from the tii;iit ::L side is beset '-.tin difficulties. one of tlie nn*t confusing b-.-it-g that the axis'.once tif a cl-ii'caiiy recognisable diffuse iUirn-is is quite couip.u!<!, with continued work in tbe industry, and. therefore, the eases m ii-uvi-is <!:.-- i-tor.-d in sitci* an in\cstia itu it as litis are in various slaws of the- d:.-ca-e. \v:i.i mo lv.-uit that th-a p-.-mt at which ibev first l-ecamc rov>gui.-ab'C clinically eanuot bt- ascertained Despite llti-. some inidiiniac mi; o; the u.;.Hint the IcU'-C-h ptnanv U> .t-lvsl<-- :u> i-sarv lo [mxhuico In -...r.c- inwr-v:\ -ai,.: riaicciilialii.it of ;hc bu-; in me air. .. iii.i.: icr:.:iu k.w anti .'i:-ab .na:.-. bil ol it a i tied. -xy 03736 11 Table G shows the average ngr rs;.<* length uf employment of the cases of fibrosis in (-lie groups of processes previously dealt uilh (p. 11). Taiu.i: G. Froeexs. C.ue* 0( Ktbrooi*. Avrrngo A#u. Avern^e o EnipU-ym<ut I. Cruihin;, oticniti^, disinlrgrAtiiig, mixing J. Carding 3. Sliiiiiiiut;, twisting, doubting, planing, kc. 4. MalUrti making.......................................... 3. Weaving ;tiul nsiociai-'fl processes G. M uecli..uc-jus processes mid renaming classified workers. ... ... ... ... un- ! 39*G 37-0 as-j sa-a 42 * l V i i ; ; l 1 10*9 13*2 1ST 13-0 12 -T 13-i |i Total*..................................... ... i 13-4 The much longer average period of employment of tlic eases of fibrosis in group 3 as compared with the other groups will be noted. There is also least- exposure to (Inst in group 3. It seems, therefore, that in tills group a longer period elapsed before tuo fibrosis developed, or that it progressed less . i rapidly. i-' This is the more apparent if the incidence rates of fibrosis amongst workers employed in the processes in group 3 are compared with the corresponding rat-js for workers e:'.ip!o\cu ::i the more dusty proev'-cs comprised in groups 1, 2, 4, 5, taken together. These rates are set out in Table 7. TaulF Comparison hifreer n the Incidence Hates of Fibre-sis amennst Workers employed in Group 3 (Jess dusty processes) and the Incidence Hues rmonyst MVnUi-j employed itt Gcirvp* 2, 2, /, 5, taken irujedter (w re dusty precedes). Yt.uu Uuruivu. Group 3................ Cranpi l, i, 4, 3 (l.t.-n lutfeilicr). 0-4. 5-3. j 1C.11. 13-19. 20 itttd over. |1 I ! r*-*ir.)| 1`|MUlMtT<(' | I m" K ^ si | s! 5 ii * ^2 !i 1: X S* W i1 si 93 2 ? j :^ /. X 'J 1L1 s * z l *C . "* &*: 9 i * J -J: -5=' . s * ;5! i d =i 9 57 | i ;-lPer Per j P:r \ Per cent. crut. 1 cent. i 'cat.! rent. 20 0 -- to 2 5*0 :o i i ! *'T tl * 4 :o-4 : G ;t i 4 oC-7 i r47 0 -- 02 :t 3S * 7 K * hs-o ' 14 i * ,s7'11 U f M 34 *C i!, !1 Group -1 ** iwi^ctti*. UMul 'i;'*:, Grou|* 1,2, 4, -* C r u*ltui. wt~, vnrdm^, etc. tonkin:* and vcnviin* *kI a***ciat**d jwodi'fct. It will lie -ecu that, after *> years' employment, the rates arc consistently mucli higher amongst r!:r>employed i:i the more dusty protv.v.os, ami. w her-, as the rate is high from ai:c>ui G years onwards in tlie mure dusty pr.r.vs-es, :t :s not until about ihr 1 ii ycaroi 'tup;.-\ is rcrn iicd in the i*-- <m.-ty -- that the rate f*u tin: latter i><\ macs iii-a!:. ami ar.iuovimutes 10 that reached si'.-.r about " Years' cmp.nvi i l ;;i '.!:> mure dn-.iv nr.. Exposure to dirk'.vnt c-.'iei ntrutinu:; of dust. toget her with Cue e*. . . the I'CCogn:t id'. -,i '.no v..:CS ui hhin-is ill diuereur stages ul ti e it nffonl .v.i c c; i;<i ;t-1 .i uii-'e diih-r'.ma hugths ul en:p."_ m. it 1 (Il\hlu.;l c i o: .. 'u.u 'r.:sa, fie.;-.: vc-aiv. i<> i.'. v- no. c`. , cirlin !ie r.i . .>1 :.-i\ -1.-. . u with le-s ti'.ui > y::::'- .\p I , 11. -i a.-, U.uiid at. ; 1" sii.i i it v ui -.a-a cue- n` :r-i; j s 02737 exposure to high concentrations of du>t r:nmot be ruled out. Three cn-es wcio round with `J, .if and r 1 years Wnrk in arlie*:*'*. respectively, but 1.1 c.'.cn -i;-.re was previous e.\[jusuiv to utiicr uu.ita (see p. W). Support Hu- this view is provided by (I) Ihofe-Tior Beattie's experiments previously mentioned, which demonstrated that the lungs oi' guinea-pies ex posed for id and b7 hour* to asbestos dtlsi showed " dull lute ecl!lll..r puilifcriitiou, though uot very extensive, and this is certainly a preliminary ttu-c iu tiro production oi hbrosia ' ; (t!) ejiiuson's ease mentioned above, and hi.> report iu llic stmc paper on the lungs oi a guinea-pig exposed by Mavrogurdato, to asbestos dust tor 1U0 hours duriug a period of oO days, tin the death oi tiie animal (t'roui causes ether than asbestoses) sime ;>ti mouths later, .-eettuus of the lungs showed a slight generalised iibrosts. In commenting on tlie amount of fibrosis found, be states that " a comparison between the human eases aud the experimental animal showed that the iihrosia was more rapid aud extensive isi the human discs than iu tbe experimental animal," and again ` the amount of fibrosis in two of the human eases was quHe rapid, and it due to the preseiue of asbestos dust, the initial rate of production was rapid when compared with present day non-inicvuvc silicosis ou the ilu.ud (h) data frnui this investi gation, in which- hi oi the alio workers showed, signs suggestive ot commencing fibrosis (p. 10). Oi these Id had been employed lor less than 7 years, and 0, for between 4 and a years. To sum up, therefore, it appears probable that concentration of dust and length of exposure as factors in the production of fibrosis are interdependent within certain limits. While it seems necessary for the production of generalised fibrosis of the lungs that a definite minimal quantity of dust must be iuiintcd, the lower the concentration oi dust iu the .air breathed, tlio longer the lapse of time iHjfore tire fibrosis is fully developed. and within a certain limit, the . higher tbe concentration or dust, the sooner the fibrosis becomes fully developed and the more intense the involvement of the lung tissue. If this hypothesis is correct, and the evidence norms to it, the practical inferences .ire'ot very great iinportauce, since il follows that the application of measures resulting iTi the reduction of the concent ration of dust in the air in the neiglibouriiomi of dusty asbestos processes will cause, firstly a great in crease in the length oi time before workers develop a disabling"fibrosis, and secondly, the ainir-t tocai disappearance of tue disease, as the measures for the suppression oi dust arc periected. Disablement juvrecc't b>j the A.'bentos Fibrosis.--Regarding the amount of disablement produetd by the deveivpniciu of pulmonary fibrosis iu asbestos workers,--for a rtiniiu-r of years this ts surprisingly slight, even more ?o than is generally the care in silicosis. Tliis is partly'due to the character of the disease, ami partly to tlx nature of the work, which in the majority of there processes does not involve mud: physical exertion. The affected person may, and often docs, continue at work with occasional intermission*, lattcriv. due to exacerbations of bronchitis, until the condition is .advanced, althougii he suffers increasing inconveniences from shortness of breath, chi exert mu. times a tcnnin.al broncho-pneumonia. or ot her acute infection, commences hiio still at work, and there is no long period of invalidism. There is :io doubt but that iibrosis of the type produced by a*lvtr.s car: of itself lend to complete disablement and to a fatal tcrr.iiuatiou, aud this w the absence of a su[ten:c!tied tuberculous itiicvtins*. Particulars have !xvn collected up lo the end of 19:19 oi 10 cases n: ".hi;!: an .advanced detrrvv of ;hc aslvcsto* fibrosis wkm.ut tubercido-is ti e prim.arv cause of de.tlli. In 0. the cause or ileath was verified bv po.-t mortem examination a mi in the kT'i. repealed (-linienl. radiological and ex amination;-. cnnitrincd the diagnosis. Tu an lllii e.asr. post morteni ex.-a showed liial a l<-iwr pi-.-.n::bad Minrnvncd nm-n hiau* .alrea.iy y.-:'. of a miierr:U- decr.v to : be .isi-csl-vs nnro-is. V, itl; one excel'-,o.a;l ...i - death* oteHM-.-l :n `.be ye.V'* 7927-lib. The Icntpli of e\po-;;r.' t``il vcnr-i. c::s '-no. dust in there case-.. , ar;c<: net . v . . . <* 0 373? u> It is not suygc-;<<! tl;r.: these few fatalities, in whieii the cnn.-o of denrh has been verified" by lriel enquiry.. .1 re .my criterion of the laic 0iVcci of the disease 0:1 the mortality '.ales of a.-i'osfos wuiker>. Others ore known to have occurred m whicli the. existence of the asbestos fibrosis !i:is been determined in life, but 11a post mortem examination has Into11 (lOssililc. Progress <tud Dunttiort of chr. Disease.--The rale of progress anil duration of the disease varies within wide limits. Willi continued exposure to hiuh concentrations of dut, the fibrusis may be fully developed in from 7 to 9 seisrs, and may cause death after about 15 years exposure, exceptionally in a shorter period. On the other hand, with exposure to leas concentrations of dust, the |ieriod of mnluratiou of the iiliru.-is may lie extended to 15. 20 or 25 years. There are definite indications, derived from the industrial histories and ex amination of workers, that a diminution in the convent ration of diut in the air breathed, either by change of employment from a highly dusty process to one less dusty, or the effect of methods taken for the suppression of dust, results in a prolongation of this period of maturation of the fibrosis, except iu the late stages of the disease. While this is so, the existence of a clinicallv re cognisable degree of the asbestos fibrosis in any individual is an additional adverse factor in the prospects of recovery from any acute infection of the lungs, such as pneumonia or broncho-pneumonia. Association of the Asbestos Fibrosis urith Pulmonary Tuberculosis.--Aj previously mentioned (p. C), silicosis, the fibrosis of the luugs due to the inhalation of free silica dust, has an tuthappv association with pulmonary tuberculosis, in that there is a much increased liability to the supervention of the latter disease amongst silicotic.-*. It is of importance, therefore, both from the iioint of view of die individual worker, and iu its bearing upon the scope of the preventive measure required, to enquire whether there is a similar liability attached to the asboatjs fibrosis. It will be remembered that in this investigation the examination of workers was restricted to those at work at the time of the examination, and, therefore, a number of advanced cases of fibrosis, and a mifaiicr of eases of pulmonary tuberculosis--with or without an asbestos fibrosis in addition--who had either given up work or who were olf work temporarily, will have becu missed. Moreover, the su[>ervention of & tuberculous iufcctiou ou a lung already the subject of fibrosis produce* an increase in symptoms, previously unnoticed or disregarded, and induces the worker to seek medical advice. JETc :* then appropriately advised m give up his dusty employment, migrates from the in dustry, and may or may not accept sanatorium treatment. Thus there tends to be a drift of stick eases from the fibrosis producing industry. In fact, dttriug the course of the investigation, in term;: lion was obtained of a number of person*, previously employed in asbestos, who were either at home or in sanatoria, suffering from chest complaints. Precise information as to the incidence of pulmonary tuberculosis amongst asbestos workers cannot be obtained therefore, iu die absence of periodical medical examination* iu the industry, without prolonged enquiry involving the search of the reeords*<if local sanatoria, tracing workers known to have teased work iu asbestos, and examination of death certificates, and of the sickin'?* records of firms, where these are kept. Nevertheless, with these reservations, the data obtained iu tiiis investigation did not disclose auy outstanding susceptibility to pulmonary uilierculosie, eitucr amongst asbestos workers as a class, or amongst the cases of fibrosis. Suunitiirij.--The outcome uf this itivtstig.itir.u is to establish the exi-temi of a detinue occupational risk iu the a.U-to industry. '1 his takes me 1 a distinct tvpc : fibrosis oi the lungs, resembling silicosis in its main elinn-: aspects, but differing irom lhat disease tit the mode ot distributum oi :. fibrous tissue in :!ie ium;?, in its radiolugiral features, in tin* .niiamv'i mie development under aver.mo .'m!iiu*us in tin.- .cvintry. and as lar is die 1 .. > j^O**-*. ill il Inner OlKilnluv Co lilt* 'UjH.TXi*:;! i* ll *'* I.li'f: > Ui' "t" T!u* uiin.'is urovinu.ir e(1 t:it'!i!r;j 1 tun hhi ol n-'t tlu>l iti i*r *vr luco^-vn 'i.n .* k .:i ...la u*<. ::nvi .* .UUsdvaio<l NVlil ' III .*1 t c r- w,.. 037311 ir of exposure to it. Thus the incidence rate. is highc-t in the most dusty p.-occssos and .uimiig-t tln3e longest L-::i:>iv;.e'.i. Age .Hid sox have no apparent ioliucnre. ou the piodui ::un of ttie disva.-c. 5.--Factous D&rm'.MixixG rut 1`uesext Recognition' of tue Asuestos Ftuuosis. It is of interest to consider why it is that lids disease has ouly recently attracted notice and become a problem m the industry, although asbestos was known to, and worked by the ancients. . Many factors contribute to this positiou, some dependent on the nature of the disease, some mi the phenomenal expansion of the industry, other* on the advance of medical science. While asbestos 1ms been known and spasmodically worked for hundreds of years, it is ouly in the past TO years or so that it has 'neon commercially exploited to any extent. Not only that, but it is lc than do years since the great expan sion of the induslry commenced. Even after a number of years or steady expan sion, tlie industry is still comparatively small, and the workers employed in the essentially dusty" processes relatively rev.-. % " The insidious onset and unobtrusive signs and symptoms of the disease in its earlier course, its covert advance by imperceptible stages, its points of resemblance latterly to fibroid tuberculosis, with which infection it is sometimes associated, and the migration of those affected from the industry, have all com bined to delav its recognition as an entity, and to obscure the causal agent. Knowledge of the effects of specific dusts upon the lnags lias been greatly extended it: the past 20 years, hut research has been mainly concerned with the more important and widespread risk associated with the dusts containing free silica, and enquiry into the effect? of other dusts had to wait upon those investi gations. 6.--Pntvsxrivi MiASCKis. The necessary preventive measures include, first, these directed specifically towards the suppression .mu coutrol of the duc evolved in manufacturing pro cesses, which are examined in I'crt II of this Heport, and secondly, measures directed inwards those employed in the industry. These latter include the control of the disease by periodical medical examine tion of the workers, by which those unfitted by health reasons arc prevented from "eulering the industry, and cases of fibrosis and pulmonary tuberculosis are detected a; the earliest possible moment. The ultimate and only reliable test of the effectiveness of the preventive measures adopted in the industry will be found in the statistics derived from the records of periodical medical examina tion of the workers. They also include the education of the individual. a in other dangerous trades, to a sane appreciation of the risk, and to his personal responsibility "in the prevention aud suppression of dust. The protection afforded by vcs:nr.tt-v.-.> is only partial, and there is a real danger that the use of them mac ,-:ve a >ci:-e of fais-* security. .Asbestos dust fioating in the air contains a matorttv o: particles a: tiilfbrder tl. and und.-r. many being only 0.3u (..iL.? inch) in 'size. In practice, tha discoiur'ar: 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 tho large par ticles which can enter the rang, they cr.r.rof !>c said to 1-c valueless, but can only lie recommended as a strnnd line 01 defence, anti not in substitution fur other preventive measures specifier.:!v Uirc.u.u to tlie control of dust as near r.s possible fii its point of origin. Under very exceptional oir-.unc-tuncos risen; may be seetic for the use of the ctucien: tvp. of breathing appar.-ius, comprising a mask or in-liact with a long tube, enabling the wearer to breathe purr air from a distance. 7.--TUK OcTt.ccu. From consideration of the nature of sin- pre-tv-:es in tin- u~bo~tos in.-iu.-try. and other :e;:lUu>. it :i thr: rut! ;.vv,.;.; jve UT.-.r-.r?' good. Tl:.at is to s.iy that ::: the >p::re ui .1 >h, id.-, er : 1,.^::.c , ->f v . t OS^ + O IS energetic application of preventive measure# should be apparent in a great, reduetion Hi l lie incidence QI liiifu=: All immediate temporary ri*o in '.lie incidence rate is probable. tine to the accumulated damage, partly a legacy ot tile war yeni#, but with the paM.ni'' ut' the peak, a steady fall .-.uoiiU! ensue. Much gencious as>isunee lias boon reeciveil from many source# during the course of tins investigation; these are gratefully acknowledged elsewhere. Special thank* are tine, however, to Dr. K. \V. Twining of Manchester anti Dr. N. Tattersnll of Leeds for their indispensable ex perl ass is tame in the elucidation of the radiological features, to Dr. W. E. Cooke. 1'rofesstir M. J. Stewart, and Dr. Rood house Gloyne, whose researches iu the same Odd arc well known, and to Dr. T. M. D. Grieve for information from an unpublished study of a group of asbestos workers. Referexce*. 1. Seiler, H. E., Brit. Med. Jal., 1923, II, 952. 2. Departmental Committee ou Compensation tor'Iudustrial Diseases. (a) Minutes of Evidence, Appendices and Index, 1907. Cd. 349G, p. 127. .... (J) Report. 1907. Cd. 3+93, p. 14. 3. Cooke. W. E,, Brit. Med. Jul.. 1924, II, 147. 4'. Cooke. W. E.. Brit. Med. Jni. 1927, n, 1024. A. McDounld, Stuart, Ibid. p. 1023. ' G. Badhatu, C.. Studies in Industrial Hygiene, No. 13, Report of the Director- General of rublic Health, New' South Wales, 1927. 7. Cooke. W. E., asid Ilill. C. F., Jnl. Royal Micros. See. 1927, 232. 8. Cooke, W Z., Brit. Med. Jni., 1922. II. fi?. 9. Gioyr.e, S. Roedhonse. " Tubercle ", 1929, X. 40+. 10. Stewart. M. J., and Iladdcw. A. C., Jul. Path, and Bact., 1929. XXXII, 172. 11. Sitnson. F. W., Brit. Med. Jnl., 192S I, F?ii. ............... 12. Wood. W. Burton, anil Page. D. S.. * Tuhcreie ", 1930, XI. PART II. _ '. . Processes Givntr, Rise to Dost ,>ntj Methods for its Scttuessios. 1.--IXTitOUCCTlOX. The asbestos industry has developed greatly in rcccut years and continue? to expand rapidly, mainly because of the Jeniatuis of the motor, electrical, engineering aud.'juilding industries, and ot the increasing attention now pijid to the insulation of steala plant to promote fuel economy. Asbestos products may, tar convenience, be divided into seven main groups:-- Textiles. _ (a) Yarn and clotii. Non~Tcrii!<-i. (h) Miilboard. papier, asbestos-crmcr.: sheets, tiles, and other huilci- iug materia!*, sheet mnt.rir.! of ruhlvr nr liituminou* mixture's c-oulam ing asUaUos. (c) Insulation materials and article#. (d) Brake ami clutch lining#. Ic) Packing and joint incs. (J) .\#!i;**i;:*.eMv*'rv.i eic, trie conductors--electrodes, table.* and wiring, rod* f.:r elec'.rn- maenm- ry. (n) M n-eelluno-jii*. moulding *i i 1 eic.trn.il .mil <"'i'-.r is Some liber:/ed to:-''* in . co '.cm:!!' mv.-texC:o g:-> ! c dv'C . i oivne-.i mr-l.. n up :;;;i t .i i m a nue . i. 0374 t I'J \ condition, uiMiiijml.itcd. umni'icd with other material*. in large quantities in the'factories included in group* (), (id, ami (r), and to a much sniaiier extent ill some ol Llie other lactone* ami work-hop--. (a) Asbestos yarn is woven into doth tor insulation mattress coverim-s, insulattng wrappings, iilioritig material, lire curtains, firc-simiihcriug blankets and firo-re*i.*iing clothing. Narrower woven material is produced tor belting for conveyors, brake linings and insulating U|h\ ,'iomc aslicstos ciotlt is rubber-proofed for u*o in the manufacture of steam packing and jointings. Besides its main use for weaving, asbestos yarn is braided and plaited tor use a? packing, and :. t for insulating material. Spools of yarn are supplied U> factories in whieit . trie cable or eicetrodos arc made, and polislicd liireacl for the couipletiou ot ...candescent mantles. (i) Asbestos millboard and paper are manufactured from pulp containing short librc asljcstos, by a wet method, like ordinary millboard and paper. Asbestos-cement sheets." tiles, gutters, ]>ii>cs. etc., for building and similar pur poses arc made from wet mixtures of Borland cement and short (lbre asbestos. A synthetic composition sheet is made from a rubber mixing, for use as jointing. Bituminous mixings containing asbestos arc made for swucliboard paneiling, and other mixings for floorings. (c) Insulation materials indude filorizcd asbestos; "magnesia," so-called containing about 15 per cent, ol' fihomed asbestos and r;> per cent, of magnesia, and other finely divided mixtures composed partly of fiberized asbestos, used as insulating cements or plasters; Gberized asbestos stiffened into thick sheets, like mats, for lining bulkheads of ships; shaped sections and slabs, moulded from * hberized asbestos or mixtures containing it, or built up of corrugated asbestos paper so as to enclose air cells; mattresses, made of asbestos doth and filled with fiberized asbestos, magnesia, or other filling. (d) Bralce and clutch linings are cliicliy prepared from impregnated and heat-treated asi-vsco? doth, but a !.*.- from moulded asbestos material. (e) Plaited and braided asbestos yarn, proofed asbestos cloth and com position sheet are used in making packiugs an,! jointing?. if) Electrodes lor welding work are plaited "with asbestos yarn or covered with a paste containing asbestos. Some electric cable and wiling required to -withstand heat arc plaited with asbestos yarn; field coils for electric machinery may be wrapped with asbestos tape. (a) jlix-ollancous mannfacturud articles or products. composed wholly or paxdallv of asbestos, include, in addition to moulded electrical and other goods, asbestos" putty and pawner, rubber hose plaited with asbestos vara, and ir.ar.v others. Apart from manufacture, certain work is earried on iu premises subject to the Enc-ory and TVorkshcps Act?, as well as in other premises, which invoice* use or manipulation of asliest os or products containing it. The insulating of boilers, pipe?, engines, and parts o: ships is the most important. Much of this work is done on board ship by contractor? who employ a considerable outdoor staff. 2.--PrxrtisES. The factories aud workshops included in (/?) to fy) number at Is.ist I GO. of which IS arc textile factories. This total i? based"cu lists supplied by the District Inspectors. It d<v* not include the large number of works where there is incidental"use of asbestos packing and v-iniing. ad-esiiis-carcred electric cable. or other fiui3hou goods, required for completing oilier manufactures. There is only one works in which the emrilovces concerned with asm-st-? exceed 500. There are many small premises in* which but a few employee*, in some cases only one or two. are employed. A small " ask-sto* " department is found-in a number of important factories. Textile departments arc usually well housed in modern buildings. A few of the older textile factories have been improved recently 1>y tlie addition of modern building?. In one ease a bad!', licti:-.-.; -mail coik*w:i is in prom.-ss of removal to newly cctistructru premises. The a-i-v-tos-eC'mcnl 5In.1'. ! fa.i forces modern nremiiv* of large fit'-- i-c:. loft v and spacious, ill ; ::o maul, siu-_!e =;o:. v The cable and e!i-r:i lactone? arc a I*.* modern .::.U generally .-'.:i:.b.'e. 03742. 2U Sonif! small works, more parl;._uh:rly tii e engaged in making l'oil; r tcai^.tions, arc un-aiint'actory. A few arc lucre o;>cii-su!cd .~lio!. .-Midi premises arc dillicult to keep clean. Some works arc (tmge.sivd wit.li plant and stocks of material. This tnnv result from inadequate ae:uiu::'.edai ion or a temporary failiug-off jIt i|1R Jcniaml. hut the effect on deaiiiitioi is had. The duat evolved in ninttulucLuriug pro cesses is more dillicuii to control it the premises arc unsuitable, particularly ij crowded with plant or material. Cleaning is nol easily accomplished and'ihe dust is more concentrated. Ventilation.--The arrangements provided for ventilating asbestos works vary as in oilier industries. Dust removal systems, whore used, effort a measure of general ventilation. A number of workrooms in textile factories are ventilated by plenum systems, the air supply being warmed in winter. -Over head extracting propeller fans are but little used now and would be unsuitable. In one mattress making room extraction fans connected to large overhead hoods are used. Extraction by downward diaplacement, the air being drawn through openings iti the tloor, or near llocir level, has not liccnVuct with, but has been considered for some weaving rooms. This system, if designed of a capacity sufficient to effect a high standard of general ventilation, would tend to reduce the dust in the general atmosphere at breathing level, and, with other safeguards, be a possible alternative to localised exhaust ventilation. It could not be success ful without efficient heating, owing to the rapid vhangs of air entailed. Sepamtion of Processes.--In many works several processes are carried on in the same room. lu the absence of effective means of preventing escape of dust into the air, many workers are subjected to a risk from which they would other wise he immune, nr to a greater risk titan that arising from their own work'. In a few textile factories crushi:-.^ and opening plants are placed close to spinning and carding machines. Sptnnttig frames arc installed close to looms and we: and dry weaving arc carried mt r!o*e together. Iu non-textile premises there is more effective separation of dusty work "and processes from non-dusty. 3.--DF.scntrrrox o? Processes a.\d Preventive Meascbes. A complete account of manufacturing methods is not attempted. Attention is mainly directed to die dust-producing processes, a description of which, in broad outline, lias been deemed uecc--ary to make clear the circumstances tinder which exposure to dust arises, anti the character and object . of the remedial measures already iu use or here recommended. Somewhat important changes are on foot which, it is confidently hoped, will greatly reduce exposure :a dust in certain hitherto dusty processes. On the other hand, certain developments, c.g., speeding np of textile machinery, and the increased use of asbestos in various industries, may intensify the dust problem, if adequate measures to deal wirh the dust are not taken. TxxTtr.Es. (ttj Tara and Clotli. The manufacture of asbestos yarn and cloth proceeds on the whole like that of oUicr textiles, but- there are some important differences. Fibcri/cd ami other asbestos material is freely handled in various operations, in gathering '* waste," and in cleaning.' Exposure, in some degree, to asbestos on.~t. is common throughout, ail the factories, but steps have been taken, extending ow< many rear*, to deal with dn-l produced at various point-. though the tns.cs.-arv degree of efficiency has. generally -prtkiag. not been reached. Exhaust vent :la- lion plant- used in the bc>t-equipped .idtesirn factories for removing dust apt-.mr to i)e as efficient as these. astd in (,r textile industries, ami to have been unpin-i over a wid-. r ('.eld. As regard- .>tU< r .-afeguar:!.- against, dust, c.g., rub-t;:a:u-.u of mechanical aiduml- f..r handwork f..c" tv-ding tin; machines in nniiau::::. y Opefat ioCis. .-iTeiru:. ieu:-.'.:c of -a..':, him-. vacuum. imciIv.i-.U ot cV.;;n"g. .e development, ius 'Kvn mane. dc *!?-. m.* :--r varti. bar u.-.d!v tir.lv crust <**:. ami ,u i I eases " iprued " 'd .'vi.'e.l '.. e I- :. 'dy :.>r circling. :i h.-- lore pro, an- v.o... I '>' . .!.!.rrv ouiud mm It hainlv.I, --.--i: in:; i|n i.-;i> \c ir.mi .: ...i ;,ra hr , -r i ;,!I-.ix rushing, hut pi\ 5374-3 2t Material for yarn is not u.-ua'.lv lr.".t.-.d in disintegrators, Imt in ii:o-l factories those niMcliini'i arc u.-eil nr ;ii-c-.i. inwu-le .i-hosto? vara. etc. Cru.-his' flattens out .Hid breaks ix; > ll.c !:i ::;v:I v. i;Im lit (iniilaging l liT id'rea. It. |a cav.'lliplislicd either iii a large cd_-e 11::i!ior, ur in a su'.rdl |iu mill m tiio mortar litiKii: type. The material is eimaied u|"'it the Ilnur close to the machine, the contents Of several sink:, suiimiimes Lein.; spread on the floor to obtain a rutigli " mixing.'' The crushed material is either taken from the machine hy hand, or distiinrgotl thruugh a bottom delivery slide. UsUallv idled into racks nr skips and. it noer-sarv, weighed on a porlnhle weighing Machine. A few edge runners discharge uixm short inclined laltitrs and cite material tails automatically into the sack or skip. Edge runners give rise to dust of considerable amount where short fibre is crushed; suinc are enclosed and have exhaust applied. This is always neces sary. I'an mills arc not enclosed and also give rise to dust, though less ia amount. Handwork, e.g., sack emptying and filling, mixing, shovelling and feeding machine pans or lattice feeds." gives rise to dust, sometimes of considerable amount, and is done without exhaust. Application of exhaust draught would be facilitated if feeding wore cauc from a higher level so that sacks might be emptied under enclosed conditions, i .e. in a sack emptying apparatus. Automatic deliver}' and reversible bageinz lattices eliminate dust produced ia hand iilliug of sacks, but require to be cdictsatlv enclosed with, exhaust draught applied. An opcu travelling band passing round an electro-magnet is used for separating loose iron, tbe asbestos being delivered to an elevator. Enclosed apparatus should be adopted. Enclosed rotary sieves (rotaries) or long oscillating frame sieves arc used for roughly griding crushed materiel, llotaries should be mechanically fed and the asbestos collected under enclosed conditions (not always done) and exhaust applied to the machine enclosures, otherwise unnecessary dust is created. .Some oscillat ing sieves arc very open, the material being allowed to fall on the floor, and being filled into sacks Jv hand. Very dusty conditions are then inevitable. Efncienc enclosure with exhaust draught applied aud, to avoid baud ailing, automatic delivery aud bagging lattices.'aUo enclosed and exhausted^ as used in some cases, are generally practicable. Crightou openers, sack,.-. .1 centrifugal machines, are used for opening crushed asbestos, preparatory to carding. Careful mixing or blending of crushed material is effected by spread:.? i: evenly in layers on the iloor over a considerable area--cotton may be'auded a: :L:.- v.ag.-'it required--and when feeding, taking a vertical cut through the muss. Admixture with a small p'-oportion of cotton may also be achieved by blowing it into the feed opening. The opened material is delivered upon a lattice and colic, led either in a lame container or in sack.-. shovelling anil particularly mixing on the floor. Mixing is a great hindrance to'eliininatioa of hand work; it is asserted that jwr yarn results i: it is not done and that machine mixing Las been tried anti give less satisfactory results. If retained, it should he done at a higher level than the opener, under a large exhausted canopy and the mixture ted at a scries of chutes. Deliver.' lattice* should ba well enclosed aud exhaust applied, as now done in some crises; otherwi.-e dust is evolved. Opened material not required at once, may be stored in open bias ia the workroom, involving emptying r.r. i idling sacks or skips, which ncvc.-.-arii}' cause dust. This storage m bath should be avoided; alternative arraiiu.-meiUs might be adopted which avoid dust. c.c., ;.iiv,,- waste from inter processes, is opened at endosed kittitv-icd teaser? or .'liL-ys, ;:,'it infrequently of primitive dv.-igti. worn out, and emittuig I'lUt It avlwitli.-mimiug that a fan is an integ-:;! par; of the machine. Tlie.-v! -.-Li a Dust may U: emitted .it fv.l feed is irregular. Ex:.au.-i i; also I i_t.ii:-' iVo'iiut i a I;:I! hr :or iuvn dia;.' i ' suggested for Cngin-Mi ;i;.:(< not is used fur a?l.>to< opening ntvuer :aua:::r?. particularly :. :: - .;i v .it t ''red latlivi- fur lids re.a a di:-:. Tl.-.- i is i-ither di- . - r '.I. .. I.'JI" u:i.:::u'e: t:, 1. : 'l'i: D3744 22 Hopper lattice feed;. cue largely ti.-ccl with opening machines; the hopper lip.-, arc alKn.ll 3 feel U inches above lluor level. Much dust is produced m'shovelfeeding as it is dillieult to avoid scattering at tlx lip. An enclosed lattice, led at or just below lloor level,with localised cxli.iu.il applied lo liic enclosure is more satisfactory. Single disintegrators, or two or ihrcc machines in series arc used for break ing up textile or other asbestos waste, more rarely for opening crushed asbestos1. Present arrangements for preliminary hand sorting of waste are unsatisfactory: it should be accomplished at a covered bench, suitably exhausted. Whereas in some eases, the indraught at the disintegrator feed openings caused by the rapid rotation of the rotor is not sufficient to remove dust, and because, at any rate, as soou as it is stopped, escape of dust may result from reversed air currents, exhaust should lx applied here also. Disintegrated material is blown into chaml-crs, a blower fan being in some cases connected lo the delivery of the machine to create a stronger draught. Air pressure in the chamber is relieved in different- ways, the sides may bo covered with sacking, allowing much dust to escape, % " relief'balloon " coancctcd, or exhaust applied. Chambers connected with disintegrating and teasing machines vary in sire, some are little more than a Large box. others ;fre more roomy. Some, but not all, are separated from the workroom. They are entered for emptying, the material being filled into sacks or skips by hand after the machine is stopped or die flow of material diverted to another cluimber. Work in clumbers is very dusty and its elimination is most desirable. (See page 2G.) Carding.--Considerable developments have taken place in recent years. One or two important new cardrooms have been started, ilany new machines, including some of foreign construction, have been installed. The machines, of large overall dimensions, are of the roller and dearer type, iloderu cards arc of high class construction and fitted with two doucr cylinders supported on a carriage, which can lie nuked into or out of position, cor fine yarns, a breaker and a finisher, constituting a let, is used, connected by lattices, lap sliver from the former being automatically fed to the finisher card". In cases where the sliver is collected in cans, a Derby doubler is used for prepar ing laps for finisher cards. Single madiines and breaker cards arc equipped with hopper lattice feeds supplied from skins or sacks, handfuls being dropped in, and skaltcn apart as fed*or the sack emptied into the hopper. The asbestos falls intermittently upon a creeper feed which conveys it to the " licker-in " feed rollers, between* which point and the dolier the material is ur.dcr enclosed conditions. The material is combed from the open doners of finisher cards, as a web or " sheet ", the sheets from the two doffers usually being combined at a con denser, and tit: resulting sliver yarn wound iuto spools. Occasionally, combed web is collected without being condensed, the condenser carriage being with drawn. In other carding, the silver may be obtained as a lap. Admixture with cotton is usually accomplished by carding the two materials together, a cotton hip being mounted above the creeper feed, and cite 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 cardrootns. Suppression of dust cannol_.be realised unlcs* machines arc maintained dean and in' satisfactory repair, and _l1" -.-is-uffective enclosure of various parts. Above all, localised exhaust muse be applied .it well-defined points of dust emission, and improved stripping arrangements pro vided. Wide sparing of macliiiics is_ajjp_i:e>inil>le. The lipper parts of' modern machines arc. usually provided with well made woode:n covers and the lower part.-, arc enclosed '.view in metal. The frames arc well enclosed at the sides. A liiaucd metal cover. fitted in some cn-vs. ;uv- vents cseane of ilu.-t produced by movements of '.be feed lattice. A curtain of fabrtc is less r-arisfactery In older tvpcs. par: r.i.iriv. the wooden covers may not fit satisfaci-'irily. the cylinder* may not t >::v aliened with ike 'nine .me! other defects nine ncfmHit fi.r -i!o c?-. ape of d !> . si.tl emit nd'.dile '.'V .Vu.tn-'.. Sue!: di-tett'i .d.-in r.vp.- : u-ts arm comlca-ar-i ;;i connectin'.1' I, :ud I i-i-1 are not cncle-ed. 1 i? evolved at doucr at uvt'.'v 0374S 23 Locali.-ud c\Ikih.tC ventilation was first, .tppliud to carding machines many years ago. .Methods ;nui apparatus have smou gradually improve! .i:ul uoi'u ^kavci lit! iwi'.uusl draughts aiv now used. One lar'go firm h:nc achieved much success l>v -aumlunlisiug thoir pruc'-ico as n.-ards points of application of exhaust draught, ilol-u of air guides, si/c of branch ducts to air guide* and duct velocity. Exhaust is appliod'ut (u) tlsc proscr at the creeper feed; (M icon roller at lickor-in; (c) top of cylinder; (d) each Joft'er. air guides or hoods being fitted at these points with connecting branch ducts. Muff couplings, u.-.-d an branch pipes, facilitate easy dismantling. Branch pipe sizes and duct velocities arc liberal. The improvement realised by applying powerful exhaust at each of the |Kjiuts TiienUnnctl, at. all of which evolution of dust is important, shows that tliis practice dumb! he followed generally and given point to the view- expressed by some occupiers that carding can be carried on practically dust-free. Apart from' the utave case, exhaust is applied in nearly all cases to the cylinders; in a moderate proportion to the creeper feed; in a few. to ore doiTor--the top. and in one or two only, to the bottom doffer. But. apart from dust-emitting points not provided for, the results may be inadequate. Carding machines are occasionally installed and put into use without exhaust, tlti^ should never lie done. Efficient results are not possible unless the exhaust draught is applied as closely as possible to the dust-producing points. Transverse air guides, with branch duets connected at each etid. are apparently more efficient than pyramidal hoods of the usual type. Ducts of adequate diameter and high duct velocities are essential. The usual air guide for the cylinder, provided to effect removal of dust both during carding, and stripping and grinding (though proved inadequate for stripping) is placet! a little a tare an opening in the crown of the cover. Turn branch ctucts. as above, and in addition a larger central branch duct (for use during stripping) arc connected to it. The shallow space below the back of the air guide is clo-ed up during carding by a wooden hinged piece--thrown back for stripping--and the dust produced at the cylinder is prevented from escaping by inflow .of air from the room, at the front. The dust-laden air is withdrawn at the side filters. Tn stripping, inflow of ,qjr cn raying some of the stripping dust takes place from below the lifted cvfiadcr cover'; the central branch duct, kept closed hv a blast gate during carding, is then fully opened to provide a greater air volume. In one factory, a circular doner cleaning brush runs continuously above the doffer comb. A pvrnmidnl exhaust hood is provided, but much dust escape*; unless fullv efficient cxhnttt is devised an alternative ;o this cleaning, if reallv ner*snry. should be found. The collection of ecntbrd weit. previously referred to. is done without exhaust and dust is produced. Collection might be effected hy exhaust draught as applied for removing side waste at condensers. Notwithstanding the use of covers for card lattice feeds dustv conditions arc produced and exhaust- draught should be applied at this point also. Stripvinft and Grindinn. --C a rd " stripping " or cleaning is done when (he machine is opened out for grinding, which ((`How? denning and takes place at each machine, a taut orsrc a week, but -shorter and longrr intervals .i!o obtain, tnone important faetorv (be two processes are combined in one operation. Bailer and clearer cards must be opened out. i.e.. the lattice few! and breast, and con denser and doffer carriages are drawn back, the cylinder covers arc mir-cd. and the various small rollers, which are cleaned and ground at a special machine, removed. The evlinrier is first cleaned, with the doffer*carriage drawn hack; the carriage is then replaced and the doffers. run at a graailv increased speed, denned in (urn. Cleaning takes .atauc ten minute* and is usuallv done <n working hours, but in one case, at least, after. Tito men pre** their " strickles " or fiat hand brashes ntaut 12 inches long covem! wiih card ohvhing. against r he wire- covered surfaces. Much of the debris is heave and falls to the floor. Bust is evolved in a dense cloud, soon- being removed at rbe evlimler exhaust hood. Tn one cae floor openings, beneath the machine, .ir- connected to (he c'-haiist. Present exhau-f .arr.an"-'incn:; are aliugether inadequate, par! ictderiv o ^ regards the non mu dour1- d-y.f i< (lie ref. re carried int.i : ,c- '.era: atmosphere ot mom. ! re < leaner; w\-r -'*!' i i:- lov. or " hehno-.- Tn a few cases mor.. --ivo ...(. i.-d;.-n machine i< .alaiosi. 'Hiivtv "Ce-.o.iv! ivii'i high rrmo-cm x 0374 6 2-1 work! when: cleaning takes place ufler working hours, an auxiliary oxi aiu' system, villi a hood lor ihc bottom tUifier, is brought into use. } Grinding which lakes several hours. is art auh-iimtic process effected l>v nbrnshc cove red rollers driven by the machine. The small amount of dust produced is chiefly of a metallic diameter. In the factory where grindins' and cleaning arc combined, the dolTer exhaust arrangements arc fu>t rc-couneeled. Much less dust is evolved and appears to bo dealt with more cfiectivelv. This firm consider that hand strickling he fore grinding should nut lie allowed. Their methods mnv. however, not be gencrnriv appiicablc. A little strickling may be necessary after grinding to remove smail piece.? of debris. The trade recognise that present conditions are not satisfactory and experi ments are lacing made with the object of developing improved appliances. In one ease a revolving brush is being tried, with independent exhaust draught applied by flexible connection?; it is said to give promise of success. The brush is narrower than the hand strickle and less dust is evolved at a particular moment. In another case, a vacuum fltring is under consideration. Previous use of vacuum stripping was given up because of rapid erosion of the metal pipe licnds and other parts. Unless effective dust suppression is realised for stripping, all workers, other than strippers, should 1 excluded while it is in progress and for some time afterwards, and the room well ventilated. The machine for ctcauing and grinding the smaller rollers, which gives rise to much dust, should lie fitted with efficient exhaust arrangements--a straight forward matter--and as completely enclosed as practicable to collect the heavier debris, precautions which are not always taken. Tim machine is cither installed in the carding room, or in a room adjoining. Independent machines should bn provided to deal with rollers of different lengths, otherwise inconvenient adjust ments, liable to lie neglected, have to be made. Card Side Waste Treatment.--The irregular " selvedge " of carded fibre, separated a: the tw-o sides of the finishing card, being unsuitable for sliver yarn, is removed by suction draught to a " sin'o-ond " machine, which prepares it for further use. The material is blown upou perforated cylinders, the air escaping at ti:e side and the material being discilarged on tlie floor. The process produces dust, particularly when the reeding is irregular, the air then having a free path betweeu the cylinders. The material should lie delivered under suction and net under pressure, a " pressure " machine being unsuitable. Spinning and Doublin'],--Yarn is spun at flyer or ring frames which may carry op to SO spindles, 40 on each side. * Much piecing is required owing to the comparative weakness of the fibre. A fine metal thread is pun with asbestos, for brake linings and certain other purposes. Mule spinning is not practised in this country. A large amount of doubling is carried on. Spinning, more particularly ring spinuing, gives rise to dust, continuously produced bv'tlie " ballooning " out of the fibre owing to the rapid rotation of the spindles, which may ran at speeds of 1.700 revolutions per minute, and intermittent))*, when the yarn breaks. Doubling is less dusty than spinning. While the amount bears no comparison with dint produced in carding. a::d is less than that from dry weaving, the workers arc continuously exposed to some dust, more in some factories than in others, doubtless due to differences in working methods or materials. Exhaust draught fur its removal has not been applied hitherto, but experiments in one factor)* have been so far successful that the firm are prepared to equip all spinning and doubting frames with exhaust ventilation* plant. cmh<nlving (i) exhaust duels parallel with the frames, niiove the :i:i rollers, with shaped hoods at intervals, each to deal with a small sroup^of spindles, and (ii) for more eileetive rour. atration of the draught, panelling for tiie ends and lower pail? of tiie frames I'cncnth the spindles, capable of being casilv removed wlieu necessary. Such safeguards may nipiiro'somewhat wide application unlC'S special general vem ikitr.n is provided. Warpiua. --Wa r;' leam; : are prepared it: :!:c usual wav from creeling : a ires. a small evolution of >hi.-i ui,urri:.g at the frames and beaming :ua >ine?: localised exhaust ven:ih;::"n ,-..uhi 'i.irtih : .iMiiliii! euVvlivoiy. A par.; :n;;v itil spare. im-rh.'vat: i.-t.-il cre.-.-w i.-,-. u ii.h extr;n-l ion at low level etwee I impi'O' Client. 037^7 25 U'i/idinij.--Many winding utnidiiiics arc us--".t, varying from m;ilccsliift Ivi'cs of primitive con..:ni,.tiuii. at ulm-ii '.lie limit ice obtain of (]l0 f;'iril in the hand, tu modern muvrr.-::l 'viihIits for -viir.lntg " choose.-*." ]'i:~c "mae be evolved to some oxti'Mt. pari ieitlnrly i:t fmimxtic.n with the above practice", which could lie cliri.ltmto*l. Appliiation of cxlinitil draught will thou probably not l>o uvsary, oteept. in particular cases. Plailinrr au<! lirai<linn.--nailing and braiding. also carried on in entitle packing and electric; cable factories, and clone at machines of normal design, cause some evolution of duel, except where the yarn is impregnated with " grease.-' While the amount of dust is sometimes less than in spinning. t!ie difference is not material. But there is perhaps ly~i exposure of the operative under ordinary working conditions and precautionary measures other than localised exhaust vcntilatiou may suffice. Wertointt.--Looms vary greatly in sire and general arrangement. As many as 140 looms may be found" in a single room, hut this is exceptional. The clear space between machines may net exceed 13 inches. Some looms are independently driven hy electric motors. Cotton warp or weft is .-outctimes used. Tliiu cloth, for mattress covers, filters, clothing, etc., is woven from a single warp beam ;it a simple type of loom. Belting looms, for thick belting and brake lining material are complicated, seveval warp henras. arranged*in tandem under ths loom, or in some other convenient way. being required. These looms arc narrow, bat often very long. Tape looms arc" also narrow, unless several tapes are woven together when several shuttles, in liuc, working in unison, are used. Cloth is beamed at tlw front in the usual way, but belting may be led under the loom, aad coiled high above it, at the back. Host weaving is " dry," but some weaving is done wet, either warp or weft, find occasiomdlv botJi lxring wetted. We:'weaving is accomplished mere easily and a closer weave obtained, hut rusting of heald fittings, and the subse quent drying entailed and the less satisfactory appearance of the material are disadvantages. Thoroughly tin- fabric is required for brake linings and rtii/.-erproc fed material, and wet woven cloth may !.e strongly objected to on this account. Considerable evolution of hue dust- occurs in dry weaving as a resuit of (a) the forward movement of the slay in " beating up",""this source being close to the operative. (A) the repeated contacts of the rising and falling warn threads with their ueighlours, this source being the :r.n?c important from a quantitative standpoint, (cj the disturbance of " dust " or " fluff " on machine parts, especially those in motion. A fine dust cloud r.iav be observed behind the healds above the warp threads, linen loss dust is produced in we: weaving. Some " dry " looms are now fitted with localised exhaust usually applied to deal with dust evolved by IjojJWVi aad (b), in some cases (<7) only. (nl A flat horizontal " hood " is fitted in front of :iio operative, just above the cloth, the opening facing towards tire hcaids: (b) cither an upright pyramidal hoed, placed transversely, or horizontal fiat hc^ds. oue cn each side facing each other, are filled close behind the healds. The second arrangement is the mere effective for narrow looms, as the " scisscrz-iike " action of the warp threads appears to 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 (b). It may lie impracticable to apply the draught to all dm-t-producing points bellied the healds. narticulariv a: long looms, hut greater sneecss would have been achieved with more powerful draught and huger air displacements, as is sow being recognised. The methods deserilfd for dealing with the dust created by (h) must ho less successful at clolh looms of orciinarv width. A few such looms in one factory have recently been enuinwd with large " imnr.et '* hovis. ixttctl transversely, clow down over the machine, covering the sl.iv. recti and healds. The hocp, nr.-- of hcTuiriihi-ricitl section, wisii extensions over the s:.u!'.h Imxcs. An in;er*i.-il clcctrie light fitting, and hinced sections, faeilirate working. A nnwerful draught. snitablv apnlied. should prevent r<ea:v of dust, "t-ucrsiw! within Tn another taw. experiment ;= mid iiave shown that a trnns-cersi: inviiu;-.! hard facing the operative, plac'd hi . iwarp : car the front of ;ii-- ran Is* more effei-iivc for re h:e;ng d"si i vit va; iii the niv ''real1-';!. present arrangcmi-nt.'. am; li.o uc- de-igu ;s lie ;* -t:ttit1. 03748 Application of clTicicnt. dust removal arrangements to weaving clenrlv 'difficult. Tin; exocrlient of installing individual machines or small fr^!i;,', 0y machines in suitably ventilated small rooms or cubicles, as sug'-ested unde" W.-irpinpr " docs not appear to bine been tried, but might be considered it localised arrangements arc not sufficiently effective. Long narrow- sheds, for a single line of looms, ventilated as suggested, might be a possible alternative Cloth Picking, E.tn mining, Measuring.--There u|)crations involve mtiniivout the mils of cloth and tend to produce a small amount of dust. If earcfuUv done, so that very little dust is created, other precautions may he unnecessary. ` Now-Textiles. Fiberized asbestos is not used in some of the non-textile factories and exposure to asbestos dust may bo slight or even negligible. Dust is evolved in factories or departments where such material is prepared for subsequent use. or for sale, and also in departments where fiberized material or dry mixtures containing it are manipulated in preliminary manufacturing processes. Again, finishing processes, involving abrading or cutting at high speed, mar be a source of dust*, but such dust may contain only a small percentage of asbestos. The application of exhaust draught, where suggested in tfhe following description of processes, is in most cases'a straightforward problem, comparable with manr others met with in non-textile factories, e.g.. woodworking and grinding, where machinery similar to that described is used. Filerising or Oprninrr.--Fiberizing is almost exclusively confined to works in groups (i) and (c). Ituch of the work is done under less supervision than iu textile factories and unsatisfactory machinery is more common. Primitive teasers (" devils ") are. used in several mattress-making works, ana chamber work is also au unsatisfactory feature (see p. 22). In some asbestos-cement sheet factories, crushed material, from edge runners, falls into worm conveyors below, which transfer it automatically to disintegrators. In one large works.* the process is being entirely enclosed;'the material from the edge runners, which are lattice-fed. will he discharged upon a conveyor and raised"!>y 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, and blown to a hopper fitted with bottom rotary delivery valves, the air being re-ciicuiateu. The material is bagged at lattices. Direct supply to a manufacturing point is another improvement now being tried. Such pneumatic conveyance should be practicable in many eases. Localised exhaust at feeding and discharge noiuts of these systems is*necessary. Vacuum methods for filling sacks may also be practicable. If chambers are 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 doore. (b) Millboard, Paper, Sheets and Tiles. The wet mixtures for millboard. paper, and asbestos-cement products arc prepared iu a beater, as used in paper mills. Dry filierizcd asbestos is emptied into the beater trough, the melts being shaken to some extent. Evolution of dust occurs before the material becomes mixed with the circulating water. Occa sionally a sack is emptied before the water is turned on. Several stints are required for a charge and the process is repeated a number of times tiaiiv Precautions arc r.ot taken at present but the dust might he avoided -v (</) mechanical feeding under enclosed conditions, as appears to he done in >->u:e foreign Merits, (l) applying exhaust draught, (c) feeding in small quant" : > and in such a wav that the maicr'.ii is wetted at once. Finishing process-'* on a gating, pressing and (iriltr. so tv.c-ist as to prevent oust tns-c.-ment sheets include sawing to size, arrie-l on. in some 'act"-ries v.-;;!i the matrrta: nd this practise should he adopted g.-v.oT.ily 037 4 if 27 Otherwise mm li dust is ji<!u*-vI i:i jar. mg. ..living In the rapid ailiin^ >p. cd. and localised cxh:iu:l. i . nctc.-saiy though lift .ipidicd. rMuiilnrly, turning, filing and Mitor.l liirg ni'(lry .I'bcslos-cvnicut pipes, at InLUCs, m;iy require exhaii-l to rciuuvc the du.-t pnidm e. I. - byiilhotie i-iiinjMi-tLitin sheeting. sometimes made in a rublie.r department, is produced fmm i|,iti"ii consisting uf libcrized asbestos and rubber, mixed with solvcm in kneading mailuncs. Dusl i> produced in feeding liic mixer wall asbestos, dune in an ujieti manner l>y hand. from sacks or skips, the sacks being shaken out, or from an n;v:i laltiee feed. .'iubsequont pro. esses arc dust tree Exhaust should be applied at tliu feeding point. - (c) Insulation Materials and Articles. Canrposiiwus.- " Magnesia," the most important insulating composition, is produced on a large scale by the principal manufacturers, by enclosed methods with pneumatic eonuyatne or tlie mixture to automatic suck'fillers. Weighing and feeding the filierizcii asbestos gives rise to dust for which exhaust is necessary. Eibemed asbestos or `` magnesia " is a component of many insulating com positions which may also contain clay, kiesclguhr, fossil meal, flax, hemp or jnle waste ami other materials, llic proportion of a sliestos in the tinal product varies widely. In many small works the materials are mixed " dry," liy baud, in an open manner, involving sack emptying and nlliug, shovelling and weigh ing. Enclosed rotary mixer* emild apparently lie used for such work with exhaust applied at feeding points and the material discharged and bagged under enclosed conditions. If hand work is retained, exhaust should be applied. Consolidate'? Sheet-.--Largo sheets resembling thick mats, built up of layers of hlierizetl a-bsstos. are conmi I Ula ted with silicate of soda, sprayed on in manu facture. The sheets may lie hacked on one face with miikiourd. or sunp! icd without a backing, lying fated when fixed with niiiibairr! or asbestos-cement sheets. .' TJie sheets are produced of the required sire anil shape at work benches, or built up ou the table of a machine, capable of stow reciprocating movement, and fed from a hoptvr above. In the former case, the fiherired material is taken in handfuls frum skips and spread out in the forms, the surplus being scraped away and falling about at the sides of the work lynches, and on the doors, a considerable quantity being scattered. Dust, produced in mnniijukilii'g the dry fibre, before treatment with the silicate of soda, is largely avoided at the "machine. Efficient localised exhaust should be .ipnlied to the hand process with improved bench arrangements, tc prevent scattering. Hand sawing of piled sheets, causes evolution of much dust, owing to the considerable depth of cut. Localised exhaust alone, not vet applied, may prove insufficient. Sections and Stub*.--Moulded insulation is made chiofiv in two forms, sec tions--semi-cylindrical and moulded ho!l...v to suit v.iriouj. pijio sizes--am! sinus, which arc rectangular and .-did. These products arc usually moulded wet. either by hand or ntaehiucrv. from a paste or cream, prepared in a mixing machine or tank. Feeding of dry material involves evolution of dust which might be avoided l*y one of the methods suggested fur feeding I .eaters in millboard milking. Sections an- made at one factory by a dry [in- (-.. at a machine i tali herein ly enclosed. Feed hoppers. filled from skip*. deliver the uslystiis to iuter.ial lattices wliicli in Him supply a travelling band, at which the section is rolled by hand. Involving brushes which clear the lattice and -pread the material evenly on die baud give rise lo mm !i dust, and dust is pro.iuaai at the hoppers, and in rolling and brushing awa\ siiia-rlli'.ims >.-r-ini I'xiiau-t ilraught. not li111icri't-.- applied, is to !" provided at the exjv-vd bru-'i .mi! tile nmehilie is ;> h-e :acn; vlic'ct ;ve1 v enclosed. An enelo-cd " ire.; is a iso uv.c.--n rv. The ~-clions al.d are miner,! lo -iV^- with emukir nr ben: -ir - ' Tl-cli da - ` : n't.. In. .1! . I , \ ii.ie - l I r.i :-C i - . 1. J ; >1!. d. but : i: VUI.-S ij.i :b. unit (.hr. :i`.i r -.-.ms a.- : :n care- in pairs. ;..c :ri :n one <>|"-r:.l nie,, ; an : . wit;: eanan.-t I.i.hI. ai-.ie and below 03750 and Laiul --aws can lx: enclosed below die. table- and inverted hoods filled, the exhaust isv;!;t being a ['pi ie(i .is fur v, mxluoiUi ng machines. Kllicieul arrange* incnts should be readilv prat in-alilc fur all sawing work here. Afattressa.--Mattresses arc manufactured by pruel lenlly all firms who produce insulation rrouisil.es, though only oei:iM<>u.-illy by some. .Malire>-es ior largo contracts arc made in Lite eviiitrttvturs' ptoniiics. their outtloor staff taking necessary mensuremeuts aud preparing rough plans. A iu.itt.ress has sometimys to be made on site. Mattress making involves, broadly speaking, the sequence of processes associated with the making of domestic mattresses. The won; is almost cntirclv hand work. Lengths of aslxutos doth for covers arc cut out ou a wide Lcnvii and sewn tip, by treadle or power driven machines, to an extent depending on the method of filling. Large mattresses may lx* sewn along one side only or Wh sides may he seamed anti filling done front belli ends, Before filling, covers are turned inside out. liupnlies of filling material, which usually, hut may not, contain (MerLed a-djestos. are brought, m sacks or skips, from chandlers, or"taken from open bins, in the"room, kept supplied from thc*cliatubers, or from sacks of material supplied by outside firm*. Filling is done by hand, scoop or shovel, and quantities may lie weighed. The end filling of long double-seamed mattresses, referred to above, necessitates the workmen mounting on the bench to empty the material from skips into the openings. After filling, the mattress is levelled or beaten, to make the filling lie evenly within, the hand or a flat wooden beater being used. Finishing processes include final sewing, stubbing or buttoning, fixing on hooks, etc. The w.oorre is largely done without regard to the necessity for suppressing dust, All beneear* arc entirely open. Localised cxlmust draught is not applied. One firm have improved conditions considerably by the following pre cautions : -- (a) Keeping floors and l'cnches damp and sprnving covers before filling. i-Josc connections and spray finings arc provided. (b) Sub-division of department into SevernT independent workrooms. (c) Exclusion during "fining of all workers not so employed, the excluded workers proceeding to another section. (d) Mechanical ventilation of each room by cross ventilation, embody ing plenum supply (warmed when necessary) at one side and low level extraction at the opposite side, the air being changed between 10 and 20 times per hour. (e) Enforcement of use. by fillers, of respirators. These precautions do not include application of localised exhaust ventilation, without which malt re's filling and beating must involve some risk of inhalation of dust. For small nutirc*;cs, a wide double sided eannpicd bench with exhaust draught applied ac gra(i:i_'s along the centre line might be used. :he filling material being supplied within the canopy. Such a bench may not perhaps be practicable for the making of large mattresses but the jiossibiliiy should be explored. Otherwise at icas; the precautions referred to above should Iv adopted. (d) Srsita and Clutch. Linings. Pcto re being impregnated. l!-.u dry a.-lvsH's cloth. known as '* grey." may lie Calvin lured at squaring !*s .'ini in all wi.-es the coils are cased out to separate them a little, so euur::ig :hi't\.ut;ii tivatnv: ! by i!n- liquid. A little du-L is lirudtu ci! in these o:wain::> i.11 in.-iilik tent tu render special pie. ".it: umary uien-uivs lu-.-'-.-'-iry Other prepnrnt-.ry wak .-i: " givy " arises in tin- malting of sn.i i.il I;11;:i;-. I.ecu'b- .u . : >lu :ihairimcvtl to ring -nry.-, .0 ICMipi.m- . :11 : i nt w;th .'iiv: r I::.1 racial ,/lgcs -ewa ' at a wire i nine. a- a- a a--,.- u:v;;*ig. iJml occurs m nn: ' a C '.'.a 1.111< :'i:. a \ i n .pi-r I : a. h I i r. ,; !i i. ..ii~ c; c\ii..'ia ri'acge!::. a: - :u : c in ni: 'i.fi : .it :r.a ...,n i uiiacr c\i,.;a. l r.cgal. 037 5 i 20 Dry impregnated mate-rial is -!i:i1 .iml mainly liy nowcr-drivcn machines, eg. knives. ri renin r and yuilutinc, cutting piv-*c:-, Itv.iraulie squeezing presses nmi band saws. Calling and si mg expose ends <>i` wire and leave rougii edges; trimming nmi sinrmi liing. ilmio nn grinding u heels and 1 in i.-hors, arc necessary to <.*1 <.it: ex.ul -i/r .nut lini.-b. All llie operations, except .-quiv/ing. produce waste. anil du.-c is created in sogio. The du*t is heavy :;ml stivhv ami less likely to lly about than dry asbestos dust. The amount is considerable at sawing and grinding macliiucs and localised exhaust draught, to remove it. lias bccu applied--in some cases with much success--and is always necessary. Liveried hoods arc Ailed at band saws, just below llie Cable*, the dust being drawn through the small openings in the table guides. A powerful dratm-ht is essential. Grinding and lini.-hing whirls include. in addition tu ordinary single-disc machines, t'.vo-di.-e and vertical spindle segmental grinders, used for flat linings. The hoods by which the draught is applied to all these types are similar to those applied to the same machines when used for metal grinding. The position is similar as regards linislicrs. a hood being fitted in line wtjh'and at the back of the band. A baflle plate to prevent dust being carried past the hood by the high linear speed of the hand is a necessary addition. Special linings and anti-friction bushes arc moulded from disintegrated impregnated waste. Some dust is created in the filling of moulds and efficient localised exhaust draught may lie necessary. The articles arc shaped and fiuislied as just described. Bushes are turned and bored in lathes, with production of waste and dust, but exhaust draught is not at present applied though possibly necessary. (e) Packing and Jointings. Engine packing is either (.) " cloth " packing built up from cloth, usually rubber proofed on both sides, handling of which rie-es not cause du.-t, and (b) rope " packing made from yarn, at braiding and plaiting machiaeiy, as used iu textile factories, (ti) Negligible amouuts of dust may arise ai the spreading machine, from the at:proofed cloth, and, in ho'lBtng up, from material proofed on one side only, (b) " Cheeses " of yaru are first rewound on bobbins for the braiding and plaiting machines. Simple winding median isms are used. Some little dust is produced; special preventive measures will usually not be necessary. Flat packing, known as " grummet," is made, on a small scale, from asbestos yarn, threaded on a needle and wound in and <mt by hand, ss balls of wool are wound. This apparently insignificant process causes suli'cient dut to cover in a short time the hair and clotuiiig of the workers and should be done at a canopied bench provided with localised-ettinuut arrangements. (f) Asbestos-corersd Electric Conductors. Electrodes.--Electrodes arc either wrapped with yarn, the usual method or passed llirongli paste containing asl<ostos fibre, yarn being wrapped upon this coating. The former method is usually achieved by a small high speed strain!big mud line fitted with a flier ca trying the spools or bobbins of yarn, the wire travelling axially through the flier. Treatment with consolidating liquid, straightening and cutting to length follow, ail done at the straiidiiig'maciune. Alternatively, single ciocr.-odes may ho wrapped by a simple winding mcvhanisiii. hand-operated or power-driven. Taste-covered elect roues are also made singA at small extruding machines, a tlier for feeding the yarn being lilted behind the extruder. After drying, a short length of the covering at mi.' end is ground away, leaving the bare r.tctal necesi-arv for making e!.-vtr:,..! eon:.act in :lie la-lder. when in uj-c. Small abrasive \viiv?i>. ai:a:it entirely onclrwd, are Small aaicaiats of durt arc tir.ijivlv! t rr.ta .liar... though ifsa.f;,:. :;t ;>r. ablv to require the nrif.ot am ci sirviul pia-cau: a.a.-, 'barb iit i- ;u-...q:.. , iu grinding end.-, .r.ui e'fu-ter.L c'chr.ir-l .v.H-ial :c.;i ia e- .--it ii; pr. e::i ......... . fa. where jir-ivuieii, ;> ; apab'c .. i iuuuw.a! ihe:-!.. .1 i f bared end. ac r 'ct' i u n i: If nr.. : ;ui pert: r : - ted ; : n. - . . end are being marie . ml give uiorare 01 -ae', Q37 SZ s* / 1 1 t \ \ :ju Tivpor.Uniy proci">->cs hi paste making include (i) ilry grinding yf libcrizcd asbestos by >m;dl lerlic.d u*c grinding wnc\.l>. led .it I la- cv-uln.- uum ;l |lt,.,,H-r a!*ovu mill di'ch.tigcd from tin- periphery in:-.. .. Ixi\ l>dmi. and (ii) hand of the ground materials at a L-i-ncIi, involving emptying out of dry material into pans. Dust is pri.dtn.fi. the umo-.iul being cmiaidi-raMi: in grindin'-. Little precaution is taken. The prueess.-s might be accomplished under almost cnrirvlv enclosed conditions, eilicicut c\li;.ust draught being applied at points where dry material is exposed, e g., in feeding. Hcwittdir.g of yarn is sometimes necessary and primitive arrangements nftvv be used, the practice referred f. on page ill L-'mg fi.llmved. and as a considerable amount of dust is protlueed, the practice should lie given np. Cable and Wiring.---Asljestos-covercd cable and wiring constitute a small percentage of the ouiput of the cable factories. The yarn is braided and plaited on the conductors at machines, not reserved for " asbestos " products, similar to those previously do'eribed. Kev. hiding of " ciicesos," as received from asbestos textile factories. is done at universal winding machines. The amount of dust evolved is small, and special pn-esutionary measures are apparently aot required. Ficid-coil Wrapping.--Field coils for electrical machinery are wound with asbestos tape by hand at ordinary work benches. The process dee.? not give rise to appreciable quantities of dust. (g) Miscellaneous. Moulded Goods.--Some electrical insulating fittings arc moulded from varnish-impregnated fiberized asU-stos, prepared after thorough drying iu a mixer and ground iu an edge runner. Alternatively, impregnated scrap, ground iu a nimbler, may be used. The preparatory precis*.* on (fry or practtcailv dry material are intermittent, and involve sack emptying, shovelling, weigning; filling aud emptying shallow trays. Titov are carried on in an open manner witheut special precautions cxrep: that as regards grinding, hanging curtains may bo used at the edge runner, and the scrap rambler is enclosed. Dust is evolved in the processes mentioned and localised exhaust ventilation should be applied to effect its removal, with, in addition, effective enclosure of some hand work, eg., emptyi:ig of Lays into air.chines could be o'ouc inside a cabinet provided with internal arrangements for securing the trays and an external luuullo for turning them over. Localised exhaust may be necessary for iinal trimming if done at abrading wheels. Mcuicicu articles made in other trades may contain bat a small proportion of asbestos, although a large quantity may be used. In otie^cnse the asbestos is sieved after drying, bet it ojicratious being done iu enclosed machines, aud, in addition, dry mixing, done iu rotary machines, and paste mixing, on open rolls, as in rubber works, are also required. Processes carried on with some risk of exposure to dust include emptying of sacks into bins, filling of trays for drying, feeding at the sieve elevator hopper.-*, the dry mixer, and the rolls. Localised exhaust is applied at (-0 titc elevator hopper. t'A) the storage chamber above an intermediate bagging i<oint. {c) the dry mixer, and <d) the rolls. More efficient arrangements appear to be desirable for (1 anl (r): the feeding of the elevator might U- done under i-aeh*rcd conditions if a cabinet as mentioned above were provided into which the trava could be inserted, l-ocalised exhaust is necessary at storage bins. Final trimming of rough edges is done under efficient exhaust draught. Other processes of comparatively minor imixirtanee. e.g.. aslx-stos putty mixing, in which there is minding aid feeding <<|' dry material in preparntnrv urocesses. will call for pn-raution* as previously tloscrilvd for similar work. 4.--Sacks. In a few c:isi.-s sacks *.f .-aih-lolh or oilier closclv wv.vvn material are used inside the fai-t-ries. >m-h ks are nua-h in be prmVnvd t<* those made of ordinarv material, which is " Ivakv " and gives rise to dust iu handling. o Car.-.NiN-- ei' Woi-.:;s. ?i.\f.-:nxn:v vxn S\t:xs. i.'.'.-li-'- kc -.o a nmtv ,!.-.-niv (:< lliart others. hut hi.-h- ;- am! - ,,,.. t ' ;: . desk-.!'. generally! \Yr>-;>lv c-iv::s':: _ :-v dry 1 !. ,i.. ,. , i -Mit ;> mere i-ticct u ely -iom- i" -...i:-e 03753 31 case's dial! ill others. Casual cleaning may also ho flour* during t!::* week. The du?(. which gathers in a -.wok renders t-lc-rtuia very liiisly operation. Vt 11 i workcis niav ho seen <ii carding machines l-ia-liing dn-t into the air from the covers, etc.,' in considerable amount., near other workers. Some firms !ia\o instituted more frequent regular cleanings anil more satisfactory method.- In damping 1'ct'm-e sweeping. Vacuum nirnr-meiInchs have not lieen adopted anti stu-h methods seem to he regarded as impracticable. hut this can hardly he accepted.. L'ortaHe vacuum set* are constantly u-e<l with great advantage in other da--es of work.-, e.g7, electric cable factories, by adult cleaners wito keep tlie machines, plant, service pipes, cfo.. thoroughly clean. If vacuum methods are not adopted, well organised daily cleaning, by adult-../ using damn methods for floor cleaning, should ho the rule in textile factories. A tea ter supplv with -uitaMe hose and spray connections should lx* provided. 1 Debris produccd-in nslic-fns-cctiicnt'sheet works under moist conditions atav become dry ami cause general dusty conditions. Cleaning itouId be so frequently done as to prevent this. Tlie cleaning under machines such as looms and cards entails collecting waste of considerable value, done at present hy band. Vacuum collection should be possible: in principle, it is already used for removing side waste at finishing cards. The sound principle of collecting card waste, "through floor openings, has been adopted in ouc new factory, and might be followed in others, with automatic collecting arrangements. Sack cleaning is done in a few large works in enclosed machines, involving some risk of exposure to dust in filling and emptying, notwithstanding the provision of localised exiuiust ventilation. A type of " exhausted " machine which does :io: involve such work i- to l preferred. 6.--Summary Ajm Kr.rn:.ciE.xnATyixs_. Asbestos factories and workshops cover a great variety of processes. The premises differ widely in structural feature; aiid are congested in many ea*cs with tuachiaery or material. Procvsscs are largelv carried on in che association. Dust is produced at many kinds of machines, in hand-process work, and in simple incidental operations, particularly in emptying settling chambers, and in nil handling of " .Tuvri/od ' asbestos. Iu textile factories, pure asbestos dust is continuously produced, ia differing amounts, at all the principal machines. Card stripping, a very dusty epc-rr.tioif is usually effected by hand strickles. Hand mixing of different grades .v.ni varieties, incidental to epenirg prove--c*. is also dusty. In non-texti!c factories, pure asliestus dust is jirr.duerd at opening machines, in feeding machines, in making insulating mattres-vs (a dusty bund process*. .'.:.d in incidental hand work. Dust, though rarely pure asi-esto.-. is predtuv.! In finishing opera lions, eg . sawing, grinding and ithcr aiuauing :>f asi.-ostos products. Tl'.o appropriate met in a Is for stipprvs-iou of dust may only he fully deter mined when the harmful i-ife: t.< of comparative!-.- ln-.v ootKcnlrnthms of a.-I-cstos dust are duly c.pproriateil. Very dusty processes will not fail to he recognised, but in processes such as spinning ind Waving. in which in other textile trades special methods for dust cmirol are not renui'-e-i. duo precaution; are ai-o reco*snry. The n;!-esio matinfr.rtnrer* are clear!v rouii-e-.u-'d with the ncre-s-of attaining condition* in (iieii- imiiMry whirl: will -ensure much h-* dust ii. atmosphere than van safely i-e tolerated in many comparable Unde* tint u-iag asbestos. The principal method- for .!> i.-m;v<d ot dust an*:-- {u) ap*'iiv.:i:i',i nf i,\i.ai:>: drangii; r.t du.-l p">dt:r:,*g p.unis- ib) si'.''-lit'.it:oi: of ei:>-!'"-.-d "mri:.ani.s! ::n*r hods for hand convey.. ".-.* and for rla-tv !v:::d v.o-k .-..-rn"* : (r) ciTvctiv-- (* -a of .ins; -:*.*1:*g !i:::t-;.ir.e and rlr.r.t. (tPl c;:l-1: 11:: I < : i o' mr'd'-d- dr. 0 3? 32 recoiii-teiieatio its. (1) Application of Efficient Localised Exhaust Ventilation at dust-producing points. Tliis measure, of Lite greatest importance where manufacturing and incidental processes occasion escape of dust not controlled by enclosure or oilier measures, is necessary for :-- () Ditst-pradncing machines, o.g.-- (i) Crushing, disiutegr.iting, teasing and otfier opening machines; sieving machines; fibre grinding machines; city mixing machines; rolls fed with ary mixings. (ii) Carding machines (to suppress dust from cylinder and doiTcrs, caused liy stripping and grinding, in addition to that pro duced bv carding): card side waste exhaust machines; looms for dr}' weaving; stripping aud grinding machines; other textile machines, if the dust evolved renders this preventive measure necessary. (iii) Sawing, grinding, trimming, polishing and other abrading machines, used on dry asbestos products. () Feeding and deliver}' lattices, or other conveyors, at machines or other plant; feed hoppers at elevators; bagging lattices: feeding of dry material at wet mixing .machines. (c) Chambers, containers, " cyclone " hoppers, or other enclosed space into which iiberirod asbestos'or mixtures containing it arc delivered, or pass. (tf) 'Work benches, e.g. for mattress making, waste sorting. (c) Various hand operations. e.g,, sack emptying and ailing, weigh ing, mixing. This is the principal measure hitherto adopted, and is probably '.hat most generally applicable. Ff has keen applied to some only of the above machines, and appliances, but not to hand work. The methods of applying the exhaust draught, and other associated factors, arc becoming more effective, but there are lew fully satisfactory plants. Special difficulties remain to be overcome in some eases,'c.g.. looms] mixing, mattress making. If not surnicuutcd, an alternative, viz., general ventilation of a high standard applied so as to draw the dust-laden air nwav from the worker, should be provided. (2) Substitution of enclosed mechanical methods for hand conveyance, and for dusty hand work generally. This measure-- (a) avoids depositing material in chambers, intermediate filling and emptying of *nc! or skips., ha ml (ceding of machines, and other incidental hand work; {b) permits of final filling mu! weighing, under the least dusty con ditions, of materials for disjmti-h; (c) rendev* exhaust draught more effective, or, in some cases, unnecessary. It i? already employe-.! to some extern, and its further application, wherever possible, is greatly to be ik*ired. {?,) Effective enctcrurs oi dust-prcclucir.g machines and plain. I'm piv'C.i: e-. " {;:'* !'. v-''vt r- "I.-vl bv exhaust drr.u.gnt, or i-. . .11 11 o c!l'.-. U'l'.t. 03755 (4) Substitution, of wet methods for dry. To reduce (ho dust given off in certain proccs~e* and work, c.g., (a) a considerable amount oi weaving; () matin-.'** mailing, by wetting the covers before filling, and by frequent wetting of floors and benches; (;) final jawing, and other machine prucesses, in asbcslos-ifiuciit sheet ami Lile fat-lories, before the prepared material has had time to dry; * (rf) works' cleaning, by damping floors and benches, before brushing or sweeping. This measure might be adopted to a greater extent than at present. (5) Elimination of certain dust-producing appliances. Certain appliances are used in a few works, sometimes with a measure of precaution, but which emit much dust, difficult or impossible to control by eilieient enclosure or exhaust draught. They should n<-t he rettfined unless effectively modified. (a) exposed doffer brush at carding machines; (5) card side waste exhaust machines, delivering uuder pressure; (c) certain willeys and leasers, 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 so as to avoid exposing worker.'* to risk from processes upon which '.Lev are not engaged. In particular, there should be effectual separation of-- _ (a) opening, carding and weaving, from each other, and from any other process; (b) spinning, doubling, plaiting and .similar processes, from work not causing (lust; (c) mattress making, from all other work; (if) chambers, containing fiberired asl-esto? in bulk, and dust settling chambers and apparatus, from any workroom. The reparation of mattress making should be adopted in existing works, and oilier separation referred to. as far as practicable. ` (8) 77icla spacing of duot-prcdv.cir.g machines in new factories and, as far as practicable!' in existing works. This measure would bring nl.*ut permanent rcriuet-.on of dust concentration in the air of the workroom as a wiinlc. and provide unpeeved cleaning facilities. (9) Use of sacks of close texture material for internal work. (10) cleaning system with wide us? of vacuum methods. (See also v'4j.) (11) Storage of asbestos and other goods to be outsids workrooms. (12) Exclusion of young persons from specially dusty work. S'ntc.--lk:uii r.!.;r pi mca-iiivs if., Part] v. :!> 11 :i ;:. i -..line <-i' : c-p;;-., is bni-lly d:-ru.--ed. .,1 :;u.ir rv;:i .: - Hog.i;:.".! ;i: t i i: s -m.-try 03756 :u Notv. u.n Kxu.uwr Vi..\; u-vri'jx in A.->ui:.->tos Woi:k>. Some.exhaust pl.in;s are eaivfullv designed and rca.vjiialilv vflUnotit, but <Ofi:C arc ill-designed and ic.-bh-v.-nc ; others. .lynn, do not olicct witnw.il oi' <1;;#! to a Sidl'icii'iit cxiant. 'L'I:o ir-niurlit may nut I'e applied as closely as |H.i'>d'lc to the dust-produciug ]min:.-., ur may be t`>o weak. The emission of a visible du.-i cloud at a point wlierc vshaiisr. is applied is a clear indh at ion of inadequacy. Extensive alteration* ot` existing plants may produce serious loss of cfficiencv. Exlmnst provision (or new* maehincrv and processes should, therefore, yoncnUlv speaking, I<c made independently. While advantages result from Herding with malty dual-producing ]n.unts, hy a single exhaust, plant, a number of solC-eontained plants, with itu!e;ctiile:it fans and .-ottiiag apparatus. is often more ctieetive. Exhaust ventilation applied on a large scale entails continuous removal of a considerable volume of air from the room. Tito supply of fresh air muse Ijc ample or the efficiency of the exhaust tout ilation may he reduced. In winter, the workers are liable to bring aiioiu this result by closing windows and doors. T4- Plenum ventilation capable of supplying the volume extracted, the incoming air being warmed, may therefore be desirable, where extensive exhaust plants ere installed. ' Efficiency of au exhaust ventilation plant may bo greatly reduced by in\ efficient dust-settling methods. Each fan should discharge into an independent \ settler. Settlers adopted in asbestos works include cyclones, large chambers ` connected with cyclones, large chambers enclosed with sacking or other filtering material, and bag filters. Cyclones and e-handers are usually well separated from workrooms. Rag filter* are now being commonly adopted, for small' instal lations. These filters'and " balloons " arc sometimes placed inside workroom*, a bad practice- They arc best placed in freely ventilated rooms, effectively separated from workrooms. Filtering fabrics for *ctrliug dust gradually become clogged; and as this effect increases the exhaust plant become,-, more and more inefficient. the volume of air moved by the fan being reduced. Such acttlocs must therefore be kept clean. The usual practice is to bent the filtering material. Arrangements for shaking hags from outside, or automatic shaking apparatus arc ni provided. Ashcsio* dust dues not appear to be so difficult :d deinch from suitable filtering materia! as some dusts, but much dust is produced in heating. Efficient shaking arrangements, avoiding this exposure, should I'e provided if tin's method of settling is retained, t'ome firms strongly support the view that it should be given up because o: the diificultv of maintaining the exhaust plant at the highest efficiency. The matter merits careful consideration. In particular, the efficiency of the exhaust plant should he kept under constant o'oserv.uiou by a responsible person. Cyclones should Ire of adequate dimensions. The combi nation of chamber and cyclone is used extensively, the fan discharging the air i:it* the chamber, to which the cvclone inlet is connected. The efficiency of this arrangement should remain practieailv constant. E. R. A. MEJcEIVETTIEE. CHAS. W. PRICE. I-.'th March. 1930. 03757