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f.'rvtca Copyright lu-smc>l REPORT ON EFFECTS OF ASBESTOS DUST ON THE LUNGS. ami DUST' SUPPRESSION IN THE ASBESTOS INDUSTRY PART L PA FT II. Occurrence of Pulmonary Fibrosis and other Pulmonary Affections in Asbestos Workers Processes giving rise to dust and methods for its suppression t BY n * E. R. A. MEREWETHER. M.D. f HJi. Kimna i AND C. W. PRICE laf liwftnor U K* LONDON: PRINTED AND PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE. To be purct-i-cd direetlv front H.M. STA'l ;ONEIYY OFFICE at tle following audratet Adatral H<w. !<trgv-av. IjmuImi, W.G.I: tao. Georgs Siren, Eciinr.i-.rgn, York Suen, Mainl^ier; i. St. Amir.-w\ Crcvest, Cardiff: 15, Donettnll Square V.Vji, Ret fast; or thraugtt any i <ks>,Uer. *930 Pnn- it. td. Si Asbestos Information Association ]| PLAINTIFF'S EXHIBIT - * 0 CONTENTS Fat* L F** L tsraaaocno* -- -- -- -- ---- -- -- -- t Inenw (umnUnrnwniUm- -- -- -- -- The VitM of Aakaataa -- -- -- -- -- -- -------- * X Score or mo Itrannw -- -- -- -- -- -- -- -- -- -- -- Tka Popalollaa atriaii -- -- ---- -- -- -- -- -- -- -- Solaatioa ol Werkoro tar Tnaimrina -- -- -- -- -- -- -- -- -- The CUaiaai Frami-atf-m io4 Staadarda adapted -- -- Xadiagrapkie gynotinaof tka Laage -------- * T I 4 Xbsvt> or na Imoitr -- -- -- -- -- -- -- -- -- -- -- -- iibootnoio Ttio Pnliaoaaip Flbfooia at Uhootoe Worfcam Tka Aofcootno Badiaa ---- -- ---- -- Tka laaidonoo of fiiaaaifFfbrooio faikata WoHtan ISaaio of Ago aad length of Taplnyiarnt -- -- ---- ---- ---- ---- -- -- -- -- --.-- ---- ---- ---- 10 XCooO of Work ia Diforoat Piccobm -- -- -- -- -- -- -- -- u laiaMra OealiaaM of Tarioaa iiWna Fnaaa -- -- -- -- -- -- -- it Coaoontratfaa of On* and length of Sxpoaaro aroanarp ta predate Ffknaii -- -- u DUabkarat predated bp the ijbaotoa Fibroaia -- -- -- -- -- -- --' it Fragi-- aad Daratfaa of Iba Diaaaao -- -- -- -- -- -- -- -- -- it iiooriotioa of tka Aobaotoo Fibreoil with Fnlitnorp Tvbmeloeu -- -- -- -- ia anair - -- -- -- - - - - --lt K Ficraaa amaannaazb hum Baeoarmo* or attMiwi Fnmoaia. -- -- -- jy t. fumm lUtsmaa -- -- -- - -- -- -- -- ' -- -- -- -- -- ip . T. 1b OVROfll -- -- -- -- -- -- -- -- -- -- -- -- -- jy Fur XL L Isnoeesioa X hmai -- -- ---- ---- -- ---- Teatilatiaa -- -- -- -- -- ------ -- ------ -- Ik u -- -- -- g 1 Dneairno* or Faorsua in Pirann XUucas -- (a) Tara aad Oath -- -- -- -- -- -- Op-oia* -- Carding. ---- -- -- -- -- Mrippiag aad Crtadiag -- ---- Card Side Vito Trralanat -- -- -- Spiaaiag aad Uaakiir. - . - -- Warpiag. Winding ---- -- Plaiting aad Heading * -- -- -- . -- .Wearing -- -- -- - - .-- Ckdk " Pirling," Kaaanning, Umnariag -- .1 a s 3 8 a s r s 3 Kw-Toma , _ -- -- -- -- Ffliariting or 0proinf -- (l) ViUhosrd, Pspor, Shoots sad TUoo (<) lasaiaiioa Materials sad Artklos -- Coatpotitioat _-- Coawliiloml ShocU ---- gootioao sad SUU -- -- (d) Drake sad Clatch I.iniag ,, _ (o) Packing sad Joiatiaga -- -- -- (/) Atkootns uoTtroH Xlactria Coadaefto PIsotrailer -- -- _ -- Cshls sad TOring - . _ Ffaid-Cail Wrapping _ _ it) MlwoHinirni MoaliUit Goods ~ . . . Psoa IS M M rt IT tr IT N n M n so M M M SO 4 Socks -- -- -- -- -- -- -- -- -- -- -- -- -- -- jo 4 Ckaumre or Woaaa, Use*mn tn Stan --_ -- -- jo 4 InauT on RaeuaiBiMStom Von a Xmnr Tcmunn a Asmtoo TToass -- -- --. jj - . . _ ]4 This Report was laid before Parliament on the 24th March, 1930, but has not been1 published os a Command Paper. 03 A > S Tha llitfht lion. J. R. Curios, M l'-, Hi* Majesty's Secretary of State for the Home Department. Homs Orrrez, 17tk ifarch, 1830. Sib, I submit herewith aUeport by Dr. E. R. A. Meriwether and Mr. C. W. Fries on their inquiries into the health conditions of the asbestos industry. Dr. Meriwether's investigations on the medical side are of great scientific value. They the facts that the inhalation of asbestos oust over a period of years results in the development of a serious type of fibrosis of the 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 ago or sex. The remedy for these conditions is to be found, as in the case of so many industrial diseases, in the suppression of dust. The second part of the Report indicate! that this point has only recently been appreciated. In the non-textile Motion of the industry, no serious difficulties arm u regards tha application of exb.in-<l ventilation. For the textile section, it is evident that a good Heal of experimental work will have to be carried out before completely successful ventilating appliances are evolved effectively to remove all the dost. I have the honour to be, 8ir, Year obedient Servant, GERALD BELLBOUSE, H-M. Chief Inspector of Factories. Report on Effects of Asbestos Dust on the Lungs and Dust-Suppression in the Asbestos Industry. PARTI. THE OCCURRENCE OF PULMONARY FIBROSIS AND OTHER PULMONARY AFFECTIONS IN ASUESTOS WORKERS. L--InraoBoenoK. This Report is bsssd upon ths dots obtained in an sxtensiTe investigation daring tbo years 192S and 1029. Ths inquiry was initiated by tbs Factory Department of ths Hams Office following the discovery in February, 1923, m' a csss of nan-tubercular fibrosis of the lungs in an asbestos worker, of sufficient severity to necessitate tmtmeat in hospital (Seiler's Cass'). Prior to this, this Department had knowledge of only two deaths of asbestos workers, about whom there was expert opinion that the inhalation of asbestos dost bad at least contributed to, if net caused, the fatal outcome. Ths first of vthese, now referred to as tbs " Montagus Murray Cass," occurred in 1900, but all that is known concerning it is contained in tbo evidence given by Dr. Montague Murray in 1900, before ths Departmental Committee on Compensation for Industrial Diseases'. In this case post mortem examination confirmed the clinical diagnosis of extensive non-tubercular pulmonary fibrosis. The sc-.-nnd (Cooks's Case*) occurred in 192*. Here, although Cooks' and Stuart McDonald* were of ths opinion that the longs showed a progressive dust fibrosis together ^ with a chronic tuberculous infection, the etiological relationship between the -inhalation of asbestos dust and fibrosis of ths lungs would have been strengthened by the absence of a tuberculous infection. An early sur-ry of the industry in 1910*11 by the Department did not dis close any mdse of the existence of s serious health hazard in ths industry, bat some experiments on animals conducted in 1913 by Professor J. M. Beattie of Sheffield University for the Deoartment showed that the inhalation of dost will cause a mild degree of fihrtsis. When, therefore, investigation of Seiler's Casa showed that other industrial and infective eanses of fibrosis could be definitely excluded, the necessity of . deciding whether ths supervention of this disease in an asbestos worker was an exceptional occurrence, or evidence of s grave health risk in the industry, was apparent and the investigation referred to was undertaken. 1.--Errieia or Ixsitaxt Dun Uron m Lungs. The most important local effects which may follow tbs inhalation of dust include pulmonary sad branchial catarrh, asthma, bronchitis, fibrosis of ths lungs, and secondary changes, such as emphysema, local or diffuse. These changes in ths lungs, whies may bo looked u[>un as a measure of the efforts of tbo living times to repel or incarcerate die irritant particles of dust, ncccaarik cause interference with the general efficiency of the lungs. The impairment of functional capacity, may bo slight or severe, and temporary or permanent, de pending on the variety of dust, and on other factors, such as concentration of dust am! length of exposure. Moreover individuals whose lungs have been affected as the rwmlt of the inhalation of wane duals, show an increased susceptibility to the supervention of respiratory iufeetioii*, sorb as tuberculous or pneumonia. Fibrosis of the lungs is recognised in bo the most important lesion caused by Uir inhalation nf dost, and the prut- -now of workers with a dust filtresis to bo affected kith |Nilnwinary Uils-reulodi* 1ms been shown In be the main <uu*c of tlto iuiTuuscil usiriaiity rate Thmii the latter disease in ivruiu dustr oecnnaCions. AS 8 This triad--exposure to dust, fibrosis of the lungs, and high mortality rate from pulmonary tuberculosis--was found to bo common to a munber of lat;; and important industries, -and in all of them the dust incrimioatad was free crystallino silica (SiO,). Theso features were not observed, however, in other industries in which, while there was exposure to siliceous dust, the silica was found to exist in the combined form as a silicate and not in the fret condition. Thus, shortly, free silica came to bo regarded ss the pre-eminent causa of industrial fibrosis of tha longs and aa a notable factor xo.tho production of the " mortality rate from pulmoimry tuberculosis in certain industries. Whilst the pulmonary fibrosis produced by free silica (Silicosis) has been, and ia bring, minutely investigated, the potentialities, as fibrosis producers, of dust ether than free silica have not bean fully explored, although it appears certain that some other inorganic dusts can, and soma cannot, produce fibrosis under the conditions, mat with in. industry. That a serious, even fatal, degree of fibrosis can be produced by soma of thee other dusts baa not bean generally appreciated, although Bad ram in a thoughtful paper* has drawn attention to this print, in reporting a fatal case of pulmonary fibrosis caused by dust of aa orthoclase basalt containing no free silica. 71* Natim of Atboito*.--Tha fibrous minerals commercially known --a fall into the latter group, the silica being combined with metallic bases, mainly magnesium or iron and, to a last extant calcium, sodium or aluminium. Tha term is a collective name applied to a variety of silicate minerals which differ from each other in chemical composition and physical properties but nsoiuble one another in their finely fibrous nature and flexibility. Their value depends an the facility with which they can be split up into long and flexible fibres for spinning ana weaving, on their resistance to beet end acids, and on thair insulating properties with respect to heat end electricity. Varieties of possess these characteristics in differing degrea. Practically speaking, all that goes under the name asbestos in commerce ia either fibrous serpentina, or a fibrous mineral of the hornblende group, of which the most important are erocxdolite, smosite and tremolita. Serpentina asbestos or chryaotile is enentiaQy a hydrated ailicate of magnesium, containing little iron and practically no calcium. ' Tho hornblende varieties contain lass mag nesium atv* usually more calcium, aluxnininm and iron crecidolite and amorite being mairny silicates of iron. 1--Scars or m hrmnutioM. Ashestns is very largely naad in industry, bring an importune constituent of many different produ u. The diversity of industries concerned made it essential that soma restriction of tho field of investigation should 1 derided upon. The manufacturing procurer affected faff own dr lam sharply into two groups (1) those ia which than is exposure to pure asbestos or asbestos mixed with a very small percentage of cotton or other vegetable fibre, and (2) in which then ia exposure to a mixture of dusts, of which asbestos is but one. Tho former group comprises, ia tha main, the textile broach of the industry, a brunch manur.icturing insulating materials from practically pun aad some prelifr iuiry processes ia other branches. The htti-i- group includes a number of processes in which the proportion of aslH-(-s i:. die dust evolved ranges from a negligible quantity upws.rU*. Since i. ia impossible to evaluate the effect oa the lungs of dusu, of which a.d.stos Just is only one comooneat, until tho action of dust itself was determined, the examination of workers for the purpose of this enquiry was restricted to workers employed iu processes included in group (1), in oilier words, to workers aa nearly as (nwuldc rxprswd to the influence of pure aaUulu* dost. Knrthcntstre, tls* effects of previous exposure tn other irritant dusts, mrh as lluU of free stiit-n, hail tn be excluded. r Tho Population at Risk.--Tic gross number of workers who may 1m exposed to tiio inhalation of asbestos dust to any extent is unknown, and, owing to the great variety of processes concerned, there are insuperable difficulties in ascertaining tliis ftgore. Nor, in fact, would enlightenment on this point be of any particular value. It is otherwise, however, with respect to the figure representing the number constantly exposed in the course of their daily wont to tire inducnco of pure or almost pure asbestos dust. Some information ou this point is very desirable to check the adequacy of the sample of workers examined, and to envisage the problem confronting the industry. While only a rough approximation ia possible, it is believed that about 2,200 ia the present number of persons ia this count- ' exposed ia their daily work to the inhalation of asbestos dust, either pure cr admixed with a small proportion of cotton. It should not be overlooked that this figure dees not inrfnrin the considerable number of workers exposed to the influence of .mixed dusts of which asbestos ia but one, and commonly not more than 20 per cent, of the mixture. Of these 2,200, the sample examined numbered 363 (excluding 11 for rensoae referred to later) or 16.5 per cent. Solution of Workon for Examination.--The selection of workers for examination was not left entirely to chance, since it was early evident that the proportion of those employed 10 yean and upwards in the industry was very . small; therefore, in each factory those longest employed were preferred, since the importance of including a sufficient sample of this group is evident. Regard was also paid to the other end of the actus so as to obtain information as to the length of exposure to dust necessary before effects are manifested, and also to the process on which the worker was engaged. By balancing the component groups of the sample in this way as the enquiry proceeded, 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 the sample do not bear the same relationship to each other as the corresponding groups .of the industry under review. The sub joined Tables will make this dear. Table 1 shows the distribution according to length of employment (not necessarily in ons factory) of 775 workers, the total number engaged on those processes m several factories. Table 2 shows the sample of 3G3 workers distributed in the same way. Tabu 1. Tabu 3 Ton Xaatar. hnml of TataL Ton omolooU. Kmmtmt. PWMSUg* . at TataL *-t ... _ 10-14 .... -- l-IS ... M m4 or -. fatal* ... OS es-stoo . St M 4 3*1 IT t-t ns j isa 0- .... M10-14 ._ l-lt SO aaS mr TMala - - 141 _ S4 _ ts ... ____ ____ -- | 3S3 14-4 3S*t m*s 7*T H 10# The enormous preponderance numerically of workers employed under fire years is striking, as also is the very low percentage of workers employed 16 years or longer. Comparison of the two tables shows that the effect of the method of selec tion of workers fur examination in that the number examined in each snccaaivc five years employment group is a progressively greater proportion of the total number which could have been examined in each particular group. ens . At r t t 1 .1 : . ii Jl il i: i I il u I: I i * i H With a solitary exception all than remained ware at work on tho day of examination. . Tka Clinical Examination and Uluurfnrdx ndoi>ted.--The nature ami * purpose of the inquiry wore explained to cadi worker whom it was proposed to examine, individually, and hia or lier co-operation ubtained. Each in* dividual's previous industrial historr, ; abeequent to leaving sdtool, was noted ill detail. This*was essential in order to exclude, e*|>ccinily, tlie effect of provious work iu any of tlie numerous prwtsscs involving exposure to free silica .dost, and, to a teas extent, tho effect of other dusts. Similarly, the in* dividual's medical history was scrutinised from childhood onwards, to determine the physical level on entry into the industry and any sobeequent changes. Particular attention was paid to accounts of pulmonary ailments, soma of which, like asthma and bronchitis, are common enough amongst the general population,.yet are also non-specific signs of irritation caused by the inhalation . of dost, whilst others, like influenza and pneumonia, are occasionally followed by a degree of pulmonary fibrosis. War service, if any, was gone iuto, especially as to whether there was any history of the worker having been a gas casualty at any time. Tho family and personal historr in respect of pulmonary cober* culosis was enquired into, and also as to any dose association with known cases of this disease in friends or relatives. In approaching the pertinent subject of symptoms, great care was taken to avoid leading questions, sspeciallr in eliciting information as to the existence of any undne shortness ot breath. The actual details of the physical examination do not call for comment, inasmuch os they followed the usual lines of a detailed examination of the chest, with observations of the geneml health and of the condition of the upper air passages. Hefercnce most be made, however, to the standard of normality adopted in assessing the state of the longs. The appraisement of any departure from the normal necessarily pre-supposes the existence of such a standard. Every clinician has attained, as the result of experience, his own dear conception of U normal chest, hot it is not often that he finds it n.-emry to deans this state in so many words, in fact it seems scarcely possible to do so, and this for several reasons; the heart and lungs function efficiently within wide limits of applied strain, and, although vastisn of past disease may bt present and apparent on examination, they will bo unimportant if they will never tax the organism beyond these limits, are non-progressive and do not predispose to other disease. Age itself has recognisable effects, but tor this reason alone, tbs chest cannot be considered abnormal. There is obvious disparity between the standard of physical fitness required far an air pilot and that required for life insurance at ordinary rates; in dividuals reaching cither standard can be classed as " normal,'* yet many attain ing the latter standard havr never approached the former. Thus, within limits, various gradations of normality may be distinguished, and correspondng standards constituted without inaccuracy, the precise status of any standard Being determined by the purpose for which it is establiihed. . For the purpose of this enquiry the standard adopted 1* is been that evinced in any large group of persons living under similar environmental conditions, spart from work in dusty occupation*, as thoea of tlie group being considered. Thi. is neither a high standard nor a very low standard, but the average stan dard of normality displayed amongst the iudiu.rinl population of this country. RxJioanipkii1 Exnminathn of tko I.vnqt. - In addition a earefal radiogrnphii- examination of the sheet was made iu many (133) cases, tho necessity for which in investigations into the effects of dust u{mn tlie lungs has been emphasised repeatedly by various ; .ithoritic*. It was not, of coarse, feasible to ohtaii. technically sufficient radii--rams ot .-ill tlie workers examined, derived a* they were from factories arnttew mrer the country, some in districts remote from a radiologirnl centre. Tlie in of selection was dictated by the needs of tlie situation, with the object of n-idnliug ituilrriai points germane to tlie investigation, c.g., tlie elucidation ... ttmiplirnlir.g affections, in measuring the 9 extent and pragma of tk lotiona and locating the point at which tho earliest radiographic signs appear, and finally ar a chock upon the human factor presented lqr the cxnmiaT himself. 4.--Rxsoits or ms IxQnitr. Ta anttct|iatc, examination of the data eoQeclcd in this investigation leads tn the conclusion that dm inhalation of asbestos dust over a period of years results in the deveU.poa* of a serious type of fibrosis of the lungs. Asbsstosia--tie PJmowarj Fibrosis a/ Aabostoe Workers.--It is helpful to visualise fibrosis of tho tangs as it acorn in asbestos workers as the'slow growth of fibrous tissue (scar tissue) between the air cells of the luug wherever the in haled dust eomes to-rest. While new fibrous tissue is being laid down like a spider's web, that deposited earlier gradually contracts. This fibrous tissue is not only useless as a ratatitnte for tks air cals, but with continued inhalation of the causative dost, by its invasion of new territory and consolidation of that already occupied, it pednslly, and literally, strangles the essential tissues of the lungs. In common with, other essential organs of the body the lungs have a large Toamo of tissne for nee in emergencies end to permit of a diminution of functional capacity don ta advancing age or dimaso. For this reason, end h--fibrosis of the tangs is essentially a local disease, it is only when the fibneis progresses to tha extent of obliterating this reserve, that undue shortnms of breath on any extra effort draws the worker's attention to the fact that his health is not what it should be. The ether symptoms of the disease such aa cough era equally naaraumiag, and are readily ascribed to some common and trivial cause. From this point tha progress of tha diaesse is more rapid, sines it is now encroaching on the remaining sound tissue of the longs, already only just suffi cient to maintain him ta his ordinary daily activities. Ultimately, if no seats respirator infection has precipitated a. fatal termination, a stage is reached .whan the lungs can do little mors than maintain life, and the shortness of breath bananas extreme. In its main features, therefore, the disease reenables silicosis, as might be expected. It differs from silicosis, however, in the mode of distri bution of the fibrous tame in the lungs, in its more rapid development, in its radiological features, sad, there is some reason for believing, in a lessened auseeptihility to the subvention of pulmonary tuberculosis, the liability to which disease is so <l**"**1y aa added hazard in silicotic. Tie Asbestos Bedim.--In the Inngs of those exposed to asbestos dust, angular particles derived from asbestos,' and spicules of asbestos" are found on microscopical examination, and also numbers of pscnlinr bodies described by Cooke and Hill' and Smart McDonald*. They an yellowish brow in colour, of elongated, bead-like farm, often with balboas ends. Cooke* and Uo.rihouse Gloyne* independently demonstrated a mineral core in these bodies, evidently derived from the asbsstra fere. Stewart and Haddow" hare also demonstrated their p.esence in the sputum of asbestos werksrs. These bodies have not been found to occur in any other human affection. They have been found in the sputum within cooperatively short time after exposure to asbestos dust, and in the absence of dinicel or radiological evidence of pulmonary fibrosis, their presence cannot be taken at present ss indicating anything morn than previous inhalation of asbestos drat. Tie J*ridnet ef PrHtemnro Flhroris t Alberto* Workers.--The extent of the rink tn health associated with exposure to asbestos dust under present indus trial conditions may now he considered in detail. Of the 374 workers of both sexes examined, 105 were found to have a diffuse fibrosis of the lungs attributable to the initiation of dust. Ten of these, andone ot1er in which there were earlier signs of the same condition, have been exrhwtni from fnrtlwr consideration, inasmnrh that it was frit that previous work in nthnr (lusty orcinatioos. sorb as qnar-ying, and rent mining, may have hsvn the prime or a contributory factor in tho development of the pulmonary lesion* found. If * A A I - 10 Thus. OS of 303 workers, or 30.2 nor cent, allowed a its fibrous due to asbortoo dust.' An additional 21 were found with prccurm. ^as of tkis disease, but are given no weight ia tho general conclusions, wl;ui are derived solely from examination of the 93 cases of definito fibrosis. Of tho 133 radiographed, 03 promoted radiographical signs of a diffuse fibrosis, and in a further 23 there were suggestive radiological changes not definitely fibrosis. In 10 of the fonosr group and 3 of tho latter the changes were possibly referable to prior work in other dnsty occupations or to other cause, and they art therefore excluded, leaving S3 eases of fibrosis and 23 with signs suggestive of early changes.in the lungs due to asbestos,--sufficient radiological confirmation. . What inf*"1"1*** should be drawn frum these figures 1--Certainly not that 28.2 per cent, or roughly 1 in 4 of those at present exposed to asbestos dust in their daily work have fibrosis of the lungs. As mentioned previously the sample examined is loaded with a greater proportion of workers employed 3 years and onr than obtains in theso of the industry at th.: present time (Tables 1 sad 2 above), and as shown ia Table 3 below the incidence of fibrosis increases with the length of employment. Therefore ia .order to obtain an approxima tion of tho general incidence rate of fibrosis ia those sections of the industry a correction oust bo applied on this account. Applying tho rates shown in Tablo & to the figures in Tania 1, it appears that the general incidence rate of fibrosis of the hnigs amongst those employed in these sections of tho industry is rather lest than l in 8, or, excluding thorn employed under 3 years, rather lea than 1 in 3. Farther corrections would have been necessary if the ample had included an undue proportion of workers from the more dusty processes, but this was found not to be the case. Aim no correction is required on account of differing age distribution since, es will be seen later, the incidence of fibrosis is unaffected l thereby. Sex has no effect. 4 4 These general incidence rata are convenient merely as affording a rough indication of the. inherent risk associated with exposure to dost at the present time. They hare no permanent value either as an index of tho general 1 ride of fibrosis in the industry from year to year, or a a measure of the risk ia any particular factory or group of employees. This must be to not J* 4 only will the distribution of workers is tbs industry according to process and length of employment vary from year to rear in accordance wish trade develop 4 ! ments, bat toe increasing application of methods for the suppression of dust will hare a cumulative elect ia reducing the fibrosis inridence rate ia future I . years. ." i Effocts of Aft and Ltnftk of ffwpkywear.--Table 3 shows the distribution of the workers examined according to length of employment, and Table 4 distrib ution according to sgs, together with the incidence rates of fihresit ia each caa. TsJU S.--IncMenct tf Fikrouo rrlatkt to Ltnftk of EmfUgmtnL Yu* 4-4 II ___ m 1S-M lfll... IS *"*r 11 Cmm af FlbraM Avana aa ia raan. ' Mm Qraap Isaidaaai par 01 ^T U" ! Otnomot (ML afrikrada. j i e o HI M S4 f ST a j . is tl 1 . IT t -- ** tt'S M'S SS'I } S4'4 U- 1 41' se*s M-4 M'S 4S*4 4S'S Si'? Taisia ... j SI j M ! M'S M1, M'l 41*4 l 11 % ip Craap. Up to IS *0-*9... SO-SO _ (Ml,, MSS ... to ml mt ~ Tiuii M Tails !.--iurJtiriue of Fihrusio- retalire lu Ay*. ifsuitor SuaiaaO. ts 1M 1M 4T ts u ses m Cams ml fibrmtis. iMmth o( mpltyaisi im jwn. Nmator. 11 SO SI 11 s ts Qraap Of Grain lata In'iUtira liar . *tot. ... i riiam. _ a so-* . ** 37-0 a-* -t S-l IPS T IS-#.. M-< T*S Of caa at Fitmil. '_ 7 lt-S U-t 10-* 18-J 13* TbtH tables indicate tbs outstanding importance of length of smploynient (sod hence length of exposure to dust), and the negligible sheets of age, on the production of nbroeis. Thus age groups 30/39 and 30/59- (Table 4) bate incidence rate., of 30 pr omt. and 37.9 per cent, respectively-,' not a wide difference, since the groups indude workers m various processes exposed to different concentrations of dust. Moreover, the average length of employment in theee two groups, exdudiug the eases of fibrosis, is almost identical, but considerably leu than the average length for all the cases of fibrosis (13.5 years). It appears also from the same Table that no special susceptibility to the development of fibrosis is shown by young persons, unless it is considered that lbs figure of 8.7 years, tbs- average length of employment of the cases of fibrosis in age group 20/29, baa been shortened by increased susceptibility of ages under 20. As, however, the average age of this group at cases of fibrosis is 20.7 yean, and also'because the establishment of fibrosis doss not nscessitata immediate retirement from work, this is largely discounted. Column 4 of Table 4 also snows a general irregularity which, in itself, points strongly to the negligible effects of age in the production of fibrosis. Tuning to the effects of length of employment a very different picture is seen. Table 3 -shows that after 5 years' exposure, tbc incidence rate mounts rapidly, and after 10 years increases almost in geometrical progression. Bfftct of Work tn Jifftreat Processes.--There are insuperable difficulties' in ascertaining trustworthy figures of the precise incidence of fibrosis amongst workers in particular asbestos processes. This is tbc result of the common practices in the industry of boosing many processes in one room, and of workers transferring from one process to another. These two factors, the influence nf dost from neighbouring processes, -and prior work in other asbestos processes, operate to obscure the effects due to work in any one process. By distributing the workers, however, according to the process in which cr h has been longest employed and grooping similar processes together, it is possiMe to draw certain broad conclusions as to tbc relative effect of work in different processes. In this way groups were obtained as follows:-- (1) Crashing. opcning, disintegrating and mixing. (2) Carding. (3) Spinning, twisting, doubling, plaiting, etc. (4) Insulating mattress making. (5) Weaving and associated processes. ^1) Miserilaneooa processes and remaining unclassified workers. _ The outstanding point brought nut in this way is the relatively very !jw inridr'.ve rate of fibrosis in group 3 (termed " spinners " for convenience) as compared with each of the other groups. Then is soma indication also tUt among*.* " spinners " tho discajs takes lonccrio derelop. Stmlv of the radio- gram*, a1 , reveals further indication* confirmatory of this. Moreover, cstimalions of dost content of Uu> air in tho neighbourhood of there processes am! in lit ' il*ni in the vari. us groups show that tho evolution i f dust in sroun 3 is aU intlvdv low (Tald,- 3). *` / > . V * ' ~1 In fact, the history, and tbo medical and radiotesical features of the cases of fibrosis, together with tbo results of comparison of lbs dust counts, all con- tribute in some degree to the view that witb comparatively low concentration of dust in tlio neighbourhood of a process, tbo resulting eases of fibrosis amongst tbo workers in that process are longer in` developing and remain longer in a milder stage. It follows, therefore, that in such cases the rate of acoin.ulatioa of dost in tbs lung not greatly exceeded the rate of elimination, and a farther point of great practical importance emerges, namely, that in order to prevent the full development of tbo disease amongst asbestos workers within the space of an average working lifetimo, it is necessary to reduce the concentra tion of dost in the air of tbo workrooms to a figure below that pertaining to spinning at the time over which these cases were exposed. Not only does group 3 show tbs lowest incidence of fibrosis, but it forms the largest individual group in thess sections of the industry---about one third. Bmatin* Dustintu of Various Asbtstos Proesssu.--While some reference ben to the varying amount of dust evolved by the different processes is necessary, the carnation of these. differences and methods of suppression of dost are dis eased in Part II of this Seport. Different asbestos processes do cause the evolution of different amounts of dot into the air of the workrooms, and, under present conditions, the difference between the least dusty and the most dusty processes is very pronounced. In some processes tho production of asbestos dust is insignificant; in a second group dost is continuously evolved but in relatively low concentration, as in spinning; in a third group ths evolution of dust is continuous and in high con centration, ea in dry doth waving; and in a fourth group much dust is dissi pated in busts of sort duration, as in emptying the fibre from settling chambers fay hand into bags. Soma additional data wars obtained by means of a limited number ox determinations of the dust content of the air at the breathing level of opera- tivas engaged in rations processes, with the aid of the Owens' Jet Apparatus. The- figures in Table 5 which were calculated from some 50 determinations, give a rough idea of the general dustiness of the processes concerned, and also of the effect of localised exhaust ventilation and damping -in reducing the concentration of 'd -<t in some of them. The counts in other processes tre expressed proportionately to the spuming, plaiting and braiding group, talrn as-unity. Tt will be seen from this Table that the dustiest piocesses are opening (with old fashioned teasers), sieving (with ho local exhaust ventilation), and shovelling or otherwise handling asbestos fibre, with a comparative fieure of 2.34. The haviest counts of oil were found in this group, in sack filling by hand in a titling chamber. The comparative figure here was 8.84, but the record was dense, with much dumping together of the dust particles, with the result that the total dust count arrived at was undoubtedly too low. Next in order is dry doth Shearing without the application of localised exhaust ventilation, with a figure of 1.95. This is undoubtedly a dusty process, and although local exhaust ventilation reduces the count at the breathing level of tho waver, mueh dust still escapes into the workroom. Waving doth wot, not merely damp, reduces the dust count to a remarkable degree. Column . Taolz 5.--Rtlativt Dnstiuoss of various Proeessts and /. *ts of Loealisti Exhaust Vsatiltttiou and Damp listhods in supprassing Dust. Ofimmimt IwwMiaa. fUitint. will--1 W--1 MhawM twriU MNM. TO t Wfeevia CJwtL Canliwc. with teal nrim-- Off. vatiW Will--'; With MM. i--1 : WM Min-- Mlnwu m intil. mlik Mt-- ' M<--. a c> Wl |1-1T !<* |*J -as~ ' BraSL ' ~ jDm. with 1 1--1 I **hw-- i Wti. VMtiU , m' -! SI XMm Ibkiae llr?, with--t laral nkant OtT* with nhamt MWt:l- Omit.* with ttkmi rnii iU Mi--. a : mu !** M is Oa--iag l kaaeiiac O-- V, with--t hk-al nluxt twatilMi--. nn S-J4 * Nat* tllat h4 ihw-alnwM mitibta., mu ifwitl pwnl mtihliM M the nitmi --1 1. , -- Mt --ali--l-t Ih- Ht  ` 13 f Ii 0 I r1. . < i %* i i i r 7 lor land (i.o., narrow) wcaviug, wet, is not accurate since die figuru lias been raised by dust from a imigiiiwuriifg dry doth looui. , HaUnaw making without any precautions, such as exhaust ventilation, or damping floors, tables and'cloth, follows next with a figure of 1.83 (See {footnote Table 3). Application of exhaust ventilation, and damping reduces the figure considerably, hut it may be that !lic figures in columns U and 10 are too low, situs counts for some subsidiary processus, such as buttoning, sowing, and cutting out, are not available. It will bo observed that carding, although essentially a very dusty process, produced a comparative figure of only 1.17. This is duo in part to partial ondesute of the working parts of tbo carding machine, but is mostly the result sf the application of local exhaa- ventilation, hloreovcr, the firuro does not take into account the extremely dusty operation of stripping. Belative to the comparative numbers for tho other different processes, the figure of 1 for spinning, plaiting and braiding is probably rather too high, owing to contamination oy dust from neighbouring and more dusty processes. Samples of asbestos vary much in chemical constitution and physical pro perties, and of the three main varieties, chrysotile, crobdolite, and amosice, the utter two, in the opinion of experienced wonters, usually give rise to mors dust than chrysotile in the textile manufacturing processes. No evidcues was found 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 asbestos fibre is that it first fragments longi tudinally, and apparently this process can go on indefinitely, since there is no qlriTwntu fibre eomparable to a vegetable fibre such as cotton. Comcontration of Dust and Lon nth af Erposvrt ,Vecssory to Product Fibretit.--From tho data so far exa :iined it seems dear that fibrosis of the Inn).. 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 thoso engaged in the more dusty processes. ' Some farther consideration of these two important factors, length of em ployment tad concentration of dust, is desirable. Obviously, to seme extent, they are interdependent, since, assuming that a specific quantity of asbestos dust must bo inhaled to produce a generalised fibrosis, the fibrosis will result from exposure for a period of timt varying with tbs concentration of dost in the air breatkod. Siiuson" reports the ease of an tsbcitoe mill worker in Sooth Africa, .snored for 12 months to a very dusty atmosphere, who died from a rapid tuberculosis; sections of the longs shewed, span from the changes due to tubereuloais, a moderately marked fibrosis. Burton Wood and Page* report the care of an rebretoe spinner, employed 15 months, who died from a generalised toberculoeis, S months after ceasing work. In this case a little fibrous tissue was generally to bv seen remanding tha asbestos fibres found in the lung tissue, but there was no gross fibrosis. It seems probable, therefore, although further research is very necessary, that not only is a certain minimal quantity .of the dost required for the produrtir. of a generalised fibrosis, but that inhala tion of the dost in high concentration results in the production of a more marked degree of. fibrosis in a shorter time, than when the concentration is low. Investigation of this important matter--concentration of dost and length of exposure necessary to produce fibrosis--from the clinical side is beset with difficulties, one of the most confusing being that the existence of a clinically neugiiisal'io diflva fibrosis is' i itc compatible with continued work in he industry, ami. therefore, the ear'. af fibrosis discovered in such an investigat-in re this are in various starts f the disease, with the result tliat the point at which they first become recognisable clinically cannot be ascertained. Despite this, some confirmation of the byrothesis that tlie length of cvpoenrv l a*U*4/M dust nwvssnry to produce iuinwis varies inversely with the cwncrulrnliiHi of thr dust in the air, within certain low and high limits, may be Jilaimnl. A7 k 'l rii 1 '!! * i 1 i. 4i i i i i li Table C sbowa the average age and length of employment of the case* of fibrosis in the grutipa of processes previously dealt with (p. 11). Tabus G. Cun ai Fibraain. I. Ornakiag, disiatagrating, auii( a Carding -- ... ... -- 3. Spiaaiag, twisting^ daabliag, plaiting, lea. 4. Mallraw Baking ... ... .......................- a Wanting-ukI ittmriiuad pramaaa .TM a Siltatllittv. praaaaaa and rftiaing an- alaadM vnriian. Tataia ~ ,, _ -- Atnraga Ago. <3*1 JS-0 37*0 3S*1 43*3 . * Average Length ot lapltjrntnl l<i*0 li-t 13*1 13*0 IS*I 13-3 13*3 Tbs modi longer average period of employment of the cases of fibrosis in gronp 3 as compared with the other groups will be noted. There is also least exposure to oust in gronp 3. It seems, therefore, that in this gronp a longer period elapsed before the fibrosis developed, or that it progressed leu rapidly. This is tbe more apparent if the incidence rates of fibrosis amongst workers employed in tbe processes in group 3 are compared with the corresponding rates for workers employed in the more dusty processes comprised in groups 1, 2, 4, 5, taken together. These rates ere set out in Table 7. TaBX T.--Comparison between the Incidence Ratu of Fibrosis amongst Wariers employed i* Group 3 (Jus dusty processes) and the Incidence Reus anmnyst Workers employed m Groups I, 3, 4, 3,'taken together (more dusty processes). Tina Inum. 8-4. 3* 1044. 1S49L Sand area f r A A * Amtu^m i 1y i 1f i* i 1f * Js 1 i* <3 ii i 1 1 SS <3 4 a a 1 QfMp3-- -- 33 Omapa l, t, 4, S 4T (taken tagiikar). Far S 40 Far % 3*0 30 Far cant. t S*1 It M 31 33-T 43 S3 4S*t 14 Far cant. 4 St-4 * Par cant. 4 4*r S Sit 13 11 14*4 Qmp 3 m Spiaaiac. Wriauag. 'ia#klBg, plait >, tic. Ccaapal,34.SUcakiag.ta,B<diag. nan atakiag lad waring aad maiiltl pracruca. It will be seen that, after 5 years' employment, the rates arc consistently much higher a-nongst those employed in the more dusty processes, and, whereas the rata is high from about 3 yean onwards in the more dusty processes, it is not until alxmt tin*15th year of employment is reached in the loss dusty pnax-vses that the-ratu for l.' latter leomu* high, and approxitnair* to that readied alter about 3 years' employment in the nioru (lusty processes. Exposure to dilTcrcut concentration** of dust, together with the effect of the recognition of the cases of. fibrosis in different stages of the disease, also afford an explanation of the widely differing length* of employment of in dividual case* of AIirimU, which ranged from 3 yean to over 30. While no definite case of fibrosis cl**trly due In aslutUt* dust was found among-.: workers witli lex* than 3 yront <*\pimiiir. the pnmiliility of such cases occurring witli exposure to high concentrations of dust cannot bo ruled out. Three cases were found with u, ;t| aud 41 years work iu asbestos, respectively, but iu eucu there was previous exposure to other, dusts (see p. 10). * Support for this view is provided by (1) Professor Beattie's experiments' previously mentioned, which demonstrated that the lungs of guinea-pigs ex posed fur 43 aud U7 hours to asbestos dust showed " deliuiic ceilular proIiferatiou, though not very extensive, aud this is certainly a preliminary surge .in the production of fibrosis (2) Simsou's case mentioned above, aud hts report in the same paper on the lungs of a guinea-pig exposed by Uavrogordato to asbestos dust for 100 hours during a period ox 50 days. On the death ox the mI (from causes other than asbestosis) some 32 months later, sections of the lungs showed a slight generalised fibrosis. In commenting on the amount of hbrosis found, be states that " a comparison between the human eases aud the experimental animal showed that tbo fibrosis was more rapid and extensive in the >""" cases than in the experimental animal," aud again '* the amount of fibrosis in two of the human cases was quite rapid, and if due to the presence of dust, the initial rate of production was rapid when compared with prraent day nou-iufective silicosis on the Band (3) data from tnis investiI nation, iu which 21 of the 303 workers showed signs suggestive of commencing I fibrosis (p. 10). Of these 12 had been employed for less than 7 years, and C, j fqr betweenJjtndjS years. To sum up, therefore, it appears probable that concentration of dust and1 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 miuimal quantity of dust must be inhaled, the lower the concentration of dust in the air breathed, the longer the lapse of time before the fibrosis is fully developed, aad within a certain limit, the j higher the concentration of dust, the sooner the fibrosis becomes fully developed and the more intense tlm involvement of the lung tissue. If this hypothesis is correct, sad the evidence points to it, the practical ' inferences are of very great importance, since it follows that the application of measures resulting in the reduction of tho concentration of dust in tlm air in the neighbourhood of dusty asboOos processes will cause, firstly s great in crease in the length of time before workers develop s disabling fibrosis, and secondly, the almost total disappearance of the disease, as the measures for the suppression of dust are perfected. * DiaaiUnunt produced ij tkt A sbtstet Fibretit.--Regarding the amount .of dtsaMsnwnit produced by the development of pulmonary fibrosis in asbestos workers,--for a number ot years this is surprisingly slight, even more so than is generally the case in silicosis. This is partly due to the character of the disease, and pertly to the nature of the wont, which in the majority of these processes does not involve orach p' ysical exertioo. The affected person may, and often does, continue at work with occasional intermis ions, latterly, due to exacerbations of bronchitis, until the condition is adY :uced, although he suffers increasing inconveniences from shortness of breath, on exertion. Some times a terminal broncho-pneumonia, or other acute infection, commences while still at work, aad there is no long period of invalidism. There is no doubt but that fibrosis of the type produced by asbestos can of (Uoolf lead to complete disablement and to a fatal termination, aad this in the absence of a superadded tuberculous infection. ' Particulars have been collected up to thu end of 1029 of 10 cases in which an advanced degree of the asbestos fibres;.-. witlout tuberculosis was the primary cause ..f death. 1* 0, Uiv cause of death was verified by post mortem examination and in tlie H . rct'cnlcd clinical, radiological and sputui.i ex aminations confirmed the din^ ioais. In an 11 111 case, post mortem examination showed that a lobar pocnmui i.-i had supervened ujsm lungs already the scat of a modemte degree of the asbestos fibrosis. With one exception, all these deaths occurred in tlia years 1027-29. Tlic leuglh nf rx|awurv to arlmtns dut iu these eases varied belvvucti 9 and !M years. ^ It is not suggested lli.nl these few fatalities, in which the eau*c of death has been verifi* J by stria enquiry, are any criterion of the true effect of Uic disease on llie mortality rates of asbestos workers. Others are known to have occurred in which the existence of the asbestos Qbrosis has been determine-.! in life, but oo post mortem examio.tioa has been possible. ~ Progress and Duration of the Disease.--The rate of progress and doratioij of the disease varies within wide limits. With continued exposure tu high! --~!cntrat>ons of dust, the fibrosis may bo fully developed in from 7 to 9 year*-J mar cause dcatk. after about 13 vcari exposure. exevi ' re are definite indications, dcrii from the industrial histories and lination of workers, that a jEssoat [air breathed, either fay change oTship aisut from a highly dusty process f one less dusty, or the effect a tn for tbs suppression of dust, ref 'pBbm-alhtnk fibrnsi^lxcept in stages of ths d is soT tBe^exTstcncfot i elinieaJly re- degree of the ssbestee fibrosis in any indiridual is an additional j adverse factor in the prospects of recovery from any acute infection of the j lungs, such as pneumonia or broucho-pneumonia. # Association of the Asbestos Fibrosis with Pulmonary Tuberculosis.--hs previously mentioned (p. 0), silicosis, ths fibrosis of ths lungs due to the inhalation of free silica dust, has an unhappy association with pulmonary tuberculosis, in that there is a much increased .liability to the supervention of the latter disease amongst silicotic*. It it of importance, therefore, both from the point of view of the indiridual worker, and in its bearing upon the scope of too preventive measure required, to enquire whether there is a similar liability attached to the asbestos fibrosis. It win be remembered lliat in this investigation the examination of workers . was restricted to those- st work at the time of the examination, and, therefore, 4 number of advanced eases of fibrosis, and a number of cases of pulmonary tuberculosis--with or without an asbestos fibrosis in addition--who had either given np work or who were oil work tempo: arily, will have been misaed. Moreover, the supervention of a tuberculous infection on a lung already the subject of fibrosis produces an increase in symptoms, previously unnoticed or disregarded, and i* dneas the worker to seek medical advice. He is then appropriately advised tu give np his duty employment, migrates from the in dustry, and may or may not accept sane torium treatment. Thu than tends to be a drift of such cues fr -m ths fibrosis producing industry. In fad, during ths coarse of the investigation, information was * obtained of a number of peraou, previously employed is asbestos, who were either at home or in sanatoria, suffering from chest complaints. Precise information as to ths incidence of pulmonary tuberculosis amongst workers cannot be obtained therefore, in the absence of periodical . examinations in the indutry, without prolonged enquiry involving the surch of the records of local sanatoria, tracing workers known to have erased wok in and examination of death certificates, and of the sickness records of firms, when these are kept. Nevertheless, with these reservations. the data chained in this did s.c cis.L*#e any censunaisg susceptibility to puls.-nary tttier;ul;sis. eitii: amongst ashes: rs workers as a class, or antongn the cases of fibrosis. dummory.--The outcome of this investigation is to establish the existence of a definite occupational risk in tin asbestos industry. This takes tin* form of a disrioct type of fibrosis of the lungs, resembling silicosis in its main cliuuai aspects, but differing from that disease in the mudu of distribution of the fibrous tissue in the hugs, in its rudivlogicai features, in the enhanced rate nf development under averaue ndiriuns in this country, and as far as the rvidcr.ce gees, tu a lower sws.-cptiliiliiy tu tlwwqnirvcnrioHu'f pulmonary lubcrcu Ionia.* * TW --wIIbi! sad mliuJugicU ilala aUaiiMpt 1m lhi iMTaSi^aliaM will bn |mUwJi<nl lanwlicn. 17 jcs'ou tEd production of the disease. ElugISeit uTtficL PAgw'amPsdPKavc* no "apj>aruu t Factobs Dmjuiwmc nix P&zskmt Rrcocxmox or tbs Ajbxstos Eubosu. Zt is of in' rst to consider why it is that this diurnse has only recently attracted notier ..id become a problem in the industry, although asbestos was known to, and worked bytho ancients. Many factum contribute to this position, some dependent on.the uature of the disease, sonic on ti: phenomenal expansion of the '.idustry, others on the adr**-:ce of mediui- *ei'ice. Whilo asbestos has been known and spasmodically worked for hundreds of ye re, it is only in the past 40 yean or so that it has been commercially exploited to my extent. Not only that, hot it is less than 30 yean since the great expan sion of the industry commenced. Even after a number of yean of steady expan sion, the industry is still comparatively small, and the workers employed in' the essentially dusty processes relatively few. - The insidious onset and unobtrusive signs and smptoms of the disease in its earlier course, its covert advance by imperceptible stages, its points of Tassmfflnnn 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 delay its recognition as an entity, and to obscure the causal agent. Knowledge of the effects of specific dusts upon tbs lungs has been greatly extended in the past 20 yean, but research has been n-iinly concerned with the men important and widespread risk associated with the ousts containing free silica, and enquiry into the effects of other dusts had to wait upon those investi- Pixvxtmvx Mxaxctis. The'necessary preventive measures include, first, those directed specifically towards the suppression and control of the dust evolved in manufacturing pro cesses, which are examined in Part II of this Report, aad secondly, measures directed towards those employed in the industry. ' These latter include the control of the disease by periodical medical examina tion of the workers, by which these unfitted by health reasons are prevented from entering the industry, and eases of' fibrosis and pulmonary tuberculosis are detected at the earliest possible moment. The ultimata 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 woriters. They also include the education of the individual, as in other dangerous trades, to a sans appreciation of the risk, and to his personal responsibility m the prevention and suppression of dust. The protection afforded by respirators is only partial, and there is a real danger that the use of them may give a sense of false security. Asbestos dust flouting in the air contains a majority of particles ox' the order 2iu and under, many being only 0.5* (rt.V*T inch) in size. In practice, the discomfort of constant wear, and difficulty in speech, etc., render workers verv unwilling to use this form of protection for any length of time. Since, however, a high class respirator will trap a proportion of the lam partides which can enter tbs lung, they cannot be said to be valueless, But can only be recommended as a second line of defence, and not in substitution for other preventive measures specifically directed to the control of dust as near os possible to its point of origin. Under very exceptional circumstance* there aav be scope for the use of the efficient type of breathing apparatus, comprising *a mask or helmet with a long tube, enabling the we.jrcr to breathe pore air frem a distance. T.--Tnx Outlook. '"muncilLite temporary riso iu the incidence rate is probable, due to the \ Bcenmulatcil damage, partly* a legacy of the war years, but with the passing ol' the peak, a steady Call should ensue. MV1* generous assistance has been received fruin many sources during the course of this investigation; these are gratefully acknowledged elsewhere. Special thanks are due. Iiowercr. to Dr. E. W. Twining of Manchester and Dr. K. Tattersall of Leeds for their indispensable expert assistance iu the elucidation of the radiological features, to Dr. W. E. Cooke, Professor M. J. Stewart, and Dr. Roodhouse Glornc, whose researches in the same Geld are well known, and to Dr. I. M. D. Grieve for information from an unpublished study of a group of asbestos workers. , Rxxxmkcxs. 1. Seiler, H. E.. Brit. Med. JnL, 1928, II. 982. 2. Departmental Committee on Compensation for Industrial Diseases. (e) Minutes of Evidence, Appendices and Index, 1907. Cd. 3400, p. 127. (ft) Report. 1907. Cd. 3495, p. 14. 3. Cooke, W. E., Brit. Med. Jul., 1924, II, 147. 4. Cooke, W. E.. Brit. Med. JnL 1927, II, 1024. 8. McDonald, Stuart, Ibid. p. 1025. .... * 6. Badhiun, C., Studies in Industrial Hygiene,. No. 13, Report of the Director- General of Public Health, New South Wales, 1927. : 7. Cooke, W. E., and Hill, C. F., Jnl. Royal Micros. Soc. 1927, 232. 8. Cooke, W E,, Brit. Med. Jnl., 1929, II, 578. v *;J.. 8. Gloyne, S. Roodhouse, " Tubercle ", 1929, X, 404. _____ 10. Stewart, M. J., and Haddow, A. C., Jnl. Path, and Bad., 1929, XXXII, 172. * ' " ': 11. Simson. F. W., Brit. Med. Jnl., 1928 I. 8S5. ;p - 12. Wood, W. Burton, and Page, D: S., " Tubercle ", 1930, XI.^ ; |' ,:t` PART II. Paoczsszs Grvorc Risz to Dost amo Mztsoos rox rrs Sctmixssiox. ' L--IsTxonocnox. '* Tho sshvstoe industry has developed greatly in recent yean and continues to expand rapidly, mainly because of toe demands of the motor, electrical, engineering and building industries, and of the increasing attention now paid to the insulation of steam plant to promote fuel economy. Aebestot produets may, for convenience, be divided into seven main groups TtxtiUi. (a) Yam and cloth. No*`Ttxtilet. (ft) Millboard, paper, asbestos-cement sheets, tiles, and other build ing materials, sheet mau-tii of rnhber or bituminous mixtures contain ing asbcslo*. (e) Insula'.inn materials and articles. (4) Br: nd phurii linings. (a) PaV.ng and jointings. (/) Asi-attos-covcrixl electric conductors--electrodes, caliii* and wiring, tv'-" 4 for clertric machinery. (p) Mi-ifUancms, including moulded elertriral and otltcr nmls, 'etc. Smite fa; titries make Imtli textile and imn-tcxtilc goods. Svvnlh>d Oherizod '' i.r., opened nr hrnken-up material in a fi:u flm-k-likc |I 19 condition, is RtAuipulatrd, uninixml with oilier materials, in large quantities in tbs factories included in groups (u), (b), and (c), aud to a muck smaller extent m some of Use otlicr factories and workshops. -fa) ynni ; vroren into clntlt for 'insulation mattress coverings, in- sulauog wrappings, filtering nuilerial, fire curtains, ftre-smotlicriug blanhuu and fire-reri: ? tug clothing. Narrower woven material is produced tor belting I for conveyor*. brake linings and insulating tape. Same asbestos cloth is rubber-proofed for use in die manufacture of stea-u packings and jointings. Besides its main use fur wearing, asbestos yarn is braided aud plaited fur ass as packing, and also for iusolatiug material. Spools of yarn sure supplied to factories in which electric cable or electrodes are. made, and polished thread for tbs completion of incandescent mantles. II (b) Asbestos millboard and paper are manufactured from pulp containing abort fibre asbestos, by a wet method, like ordinary millboard and paper. Asbestos-cement sheets, tiles, gutters, pipes, etc., for buildiug and similar pur- poses are mads from wat-mixtures of Portland cement and short fibre asbestos. A. synthetic composition sheet is made from a rubber mixing, for use as jointing. Bituminous mixings containing asbestos are made for switchboard panelling, and other mixings for floorings. (c) Insulation materials include fiberized asbestos; " magnesia," so-called containing abo* - IS per cent, of fiberized asbestos and 85 per cent, of magnesia, and other finely divided mixtures composed partly of fiberized asbestos, used ns insulating eameuta or plasters; fiberized asbestos stiffened into thick sheets, like mate, for lining bulkheads of ships; shaped sections and slabs, moulded from fiberized asbestos or mixtures containing it, or built up of corrugated asbestos paper so as to enclose air calls; mattresses, mad-.- of asbestos cloth and filled with nbarized asbestos, magnesia, or othsr filling. I (rf) Brake and dutch linings are chicly prepared from impregnated and I hast-treated asbestos doth, but also from moulded asbestos material. (a) Plaited and braided asbestos yarn, proofed asbestos doth and com position sheet are used in making packings and jointings. (/) Electrodes for welding work are plaited with asbestos yarn or covered with a paste containing asbestos. Seme electric cable and wiring required to withstand heat are plaited with asbestos.yarn; field coils for electric machinery may 1 wrapped with asbestos tape (y) Miscellaneous manufactured articles or products, composed wholly or partially of asbestos, induda, in addition to moulded electrical end other goods, asbestos putty and powder, robber host plaited with asbestos yarn, and many others. ---- . Apart from manufacture, certain work is carried oo in premises subject to the Factory and Workshops Acta, aa wall as in other premises, which involves net or manipulation of asbestos or products containing it. The insulating of boilers, pipes, engines, and parts of ships is the moss important. Much of this work is dona on board ship by contractors who employ a considerable outdoor Uff. , N-- * - A--P&xartsu. The factories and workshops induded in (a) to (y) number at least 160, of which 18 are textile factories. This total is based on lists supplied bv the District Inspectors. It docs not include the large number of works where 'there is incidental use of asbestos packing and jointing, asbestos-covered electric cable, or other finished goods, required for completing otlicr manufactures. . There is only one works in which the employees concerned with asbestos exceed 500.- There are many small premises iu which but a few employees, in nne rue* only one or two, are employed. A small '* ashcsios " department is found in - number of Important foctar.es. Textile departrar* <s are usually well housed in modern buildings. A few of tbc older textile factories have been improved recently by the addition of modern buildings. In one case a badly housed small concern is in process of removal u. newly constructed premises.' Tbc u-lotos-cement slwct factories are modern premises of large door area, lofty and sjiariutu, in llie main, single storey Ituildings. The cable and electrode factoring nrv alap modern and generally suitable. * 80 Soum small works, more particularly those engaged in making boiler comtuitions, an unsatisfactory. A few an men opcu-sulcd sheds-. Siu-h premises are difficult to keep clean. - Sows works an congested* with plant -aud stocks of material. "Hiis may result front iu.nK'quatc acuouuuodatiou or a temporary falling-off in lIic demand, but tho effect t-. eieanlincss is bad. The dust evolved in manufacturin'; pro* itnn is man difficult to control if the premises an unsuitable, particularly if crowded with plant or material. Cluauing is oot easily acoompluiicd and the dust is non concentrated.- Fsatffat/on.---Tile arrangements provided for ventilating asbestos works ;| ary as in other industries.. Dus* removal systems, when used, effect a measure p geueral ventilation. A number of workrooms in textile factories are i ventilated by plenum systems, tbc air supply being warmed- in winter. Over head extracting propeller fans an but little used now and would be unsuitable. In one mattress making room extraction fans connected to large overhead hoods ere used. Extnetion by -downward displacement, the air being drawn through openings in the floor, dr near floor level, has not been met 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 dost in the general atmosphere at breathing level, and, with other safeguards, be a possible alternative to localised exhaust ventilation. It could not be -uccessful without efficient heating, owing to the rapid change of air entailed. Separation 0/ PractsatsJ--In many works several processes are carried on in the aamo room. In the absence of effective means of preventing escape of dust into tho air, many workers are subjected to a risk from which they would otherwise be immune, or to a greater risk than that arising from their own work. In a few textile factories crushing and opening plants are placed close to spinning and --rding machines. Spinning frames are installed close to looms and wet and dir weaving are carried on close together. In non-textile premises there is more effective separation of dusty work and processes from non-dusty. 3.--DucsxrnuM or Pxoczsszs aot PnxvzxTrvx Miascxxj- A complete account of manufacturing methods is not attempted. Attention f.l is mainly directed to the dust-producing processes, a description of which, in i!! t.1 ": f .f broad oatline, has been deemed necessary to make dear the circumstances under which exposure to dost arises, and -the character and object of the remedial measures already in use or here recommended. Somewhat important changes are on foot which, it is confidently hoped, s will greatly reduce exposure to dust is certain hitherto dusty* processes. On - II ;! - the other hand, certain developments, e.g., speeding up of textile machinery, and the increased use of asbestes in various industries, may intensify the dust problem, if adequate measures to deal with ths dust are not taken. Tkxroxs. (a) Ysza and Cloth. Tho manufacture of asbestos yam and cloth proceeds on the whole like that -of other textiles, but there are some important differences. Fibcrized aud ether asbestos material is freely handled in various operations, in gathering i1 * waste,and in denning. Exposure, in some degree, to asbestos dust, is common througluuit all the factories, but steps have been taken, extending ovci many years, to den! with dost produced at varians point-*, tlunigh the necessary i5 gf efficiency Ins, generally speaking, nut been reached. Exhaust vcntil.ilion plants used in lU ber*-equip]skI asbestos factories for rvmuvnig dust appear to he na efficient as those used m other textile industries, and t< have Uevn applied r over a wider field. As regards other safeguards against dm-t. ! *H--;:it}:tion of mechanical methods for liandwork for feeding the mac I" "-"V'JJ operations, efficient enclosure of machines, and vacuum nicili>|-> *' `'.caning, lit;..; development has been made. AsUnitw, suitable fur yarn. Tins usually lu l* ,in' 1:1 n`* Cs "ojiriH-d ** (" lils-rizrd ") U-fnrc it is ready fur rordiic*. ' l_o_rTy nro*vf**ro are effected lv machinery, Imt entail hum h *["" ,.,...,.,1,. ing (1 reuMny iriMi) and grading nr sieving follow cnisliuijj. H I *' ' . # Material for yarn is nut usually treated in disiulivrators, but in most factories those machines are usol fur libcrizing waste asbestos yarn, etc. Crushing flattens out and breaks up tlie ipiucral without damaging the fibres. It it accom plished either in a huge edge runner, or in h. snail pau mill of the mortar mixing type. The material is emptied upon the floor dose to the machine, the coutcnts of several sucks sometime* Iving spread ou the floor to obtain a rough " mising." The crushed material is /.isiter taken from tlie machine by hand, or disc' argee! througli a Inttom delivery slide, usually filled iute sacks or skips aud, if necessary. ' weighed on a portable weighing machine. A few edge runners discharge up<m abort inclined lattices and the material falls automatically iuto tho tuck or skip. Edge runners give rise to dust of considerable amount where short fibre . is crushed; some are enclosed and have exhaust applied. This is always neces sary. Pan mills an not sadosed and also give rise to dust, though less in amount. Handwork, e.g., sack emptying and filling, mixing, shovelling and feeding machine pans or Tatties feeds, gives rise to dust, sometimes ot considerable amount, and is done without exhaust. Application of exhaust dranght would be facilitated-if feeding wen done from a higher level so that sacks might be emptied under enclosed conditions, Lc. in a sock emptying apparatus. Automatic delivery and reversible bagging lattice* eliminate dust produced in hand Ailing of sacks, bat requin to be efficiently enclosed with exhaust draught applied. An open travelling band passing round an' electro-magnet is used for separating loose iron, the asbestos being delivered to an elevator. Enclosed apparatus should be adopted. d rotary sieves (rotaries) or long oscillating frame sieves an used for roughly grading crushed material notaries should be mechanically fed and the **" collected under enclosed conditions (not always dons) and exhaust applied to the machine enclosures, otherwise unnecessary dust is created. Some oscillac. log sieves an very open, the material being allowed to fall on the floor, and being filled into sacks by hand. Very dusty conditions an then inevitable. Efficient enclosure with exhaust draught eppued and, to avoid hand filling, automatic delivery and bagging lattices, also enclosed and exhausted, ss used in some cases, an generally practicable. Crighton openers, enclosed centrifugal machines, an used for opening crushed "*<*" preparatory to carding. Careful murine or blending of crushed material is affected by spreading it evenly in layers on the loor over a considerable ana cotton may be added at this stage if required--and when feeding, taking a . vertical eat through the mass. Admixture with a small proportion of cotton may also be achieved By blowing it into the feed opening. The opened material is - delivered upon a lattice and collected either in a lane container or in sacks, automatic boning lattices being used in some cases. Mechanical feeding under - --*"--* contritions, with wrhaust dranght applied to feeding lattices or other eooveyon, should be adopted. Hand feeding gives rise to dust, from sack empty ing, shovelling and particularly mixing on the floor. Mixing is a great hindrance to elimination of hand work; it is asserted that poor yarn results u it is not done and thit machine mixing has beta tried and gave less satisfactory results. If it should bs done at a higher level than the opener, under a large . canopy and the mixture fed at a series of chutes. Delivery lattices should be well enclosed and cxhauit applied, as now done in some cases; otherwise dost is evolved. Opened material not required at once, may be stored in open bins in the workroom, involving emptying and filling sacks or skips, which necessarily caose dust. This storage in bulk should be avoided; alternative arrangements might bs ador-Uv.1 which avoid dust. Son" nuiluriai, e.g.. long fibre waste front later processes, is opened at enclosed lattice-fed teasers or wiJScvs, not infrequently of primitive design, worn out, and emitting much dust, not'* ithstanding that a fan is au integral par. of the macltino. These old machines should uot bo used for asbestos opening. Dust may be emitted at feed points of modern machines, particularly when iho feed is irregular. Exhaust is necessary at the feed lattice for this reason am! also IwcatM! feeding itself causes dust. The material i: either diM-hnrrd u[*>n a lattice fur immediate collection, or blown into a chamber. Tito standards suggested fn^ frighton machine* slsmld 1st adopted. 22 Hopper Lattice feed* .are largely used with 0|)cuii>g machine*; the hopper lip> an about U feet C inches above lloor level. * Much, dust is produced in siiovcl- fceding tut it is diilieult to avoid scattering at tlie lip. Am. unclosed lattice, fed at or just below floor level,with localised exhaust applied to the enclosure is wore satisfactory. "' ' . Siogie disintegrators, or two or three machines in series arc used for break ing up textilo or other asbestos waste, riore rarely for opening crushed asbestos. Fraent arrangements for preliminary band sorting of waste art unsatisfactory; it should be accomplished at a cowed bench, tnitably exhausted. Whereas in seam cases, the indrauglifat the disintegrator feed openings caused by tlie rapid rotation of the rotor is not sufficient to remove dust, and because, at any rate, as soon aa it is stopped, escape of dost may result from reversed air currents, exhaust should be applied here also. Disintegrated material is blown into chambers, a blower fan being in some i connected to the delivery of the machine to create a stronger draught. Air pressure in the chamber is relieved in different ways, the sides may be covered with sacking, allowing much dost to escape, a " relief balloon " connected, or applied. Chambers connected with disintegrating and teasing machines vary in size, some are little more than a large box, others are more roomy. Some, but not all, are separated from the workroom. They are entered for emptying, the ifft**"*1 being filled into aaeks or skips by hand after the machine is stopped or the flow of material diverted to another chamber. Work in chambers is verr duty and Its elimination is most desixabla. (Soe page 28.) Cording.--Considerable developments have taken place in recent yean. One or two important new cardroomi have been started. Many new machines, including acme of foreign construction, have been, installed. The machines, of large overall dimensions, are of the roller and clearer type. Modern cards are of high class construction and fitted with two dofier cylinders supported an a carriage, which can bo racked into or oat if position. .For flu yams, a breaker and a finisher, constituting a set, is used, connected bv 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 machine! and breaker cards are equipped with hopper lattice feeds supplied from skips or sacks, handfnls being dropped in, end shaken apart as fed, or the sack emptied into the hopper. The asbestos falls intarmittentiy upon a creeper feed which conveys it to the " licksr-in " feed rollers, between which point and the dofier the material is under enclosed conditions. Tba material is combed from the open defiers of finisher cards, as a web or " sheet ", the sheets from the two dofiers usually being combined at a condenar, and the malting sliver yarn wound into spools. Occasionally, combed web 'is collected without being condensed, the condenser carnage being with drawn. In other carding, the sliver may be obtained as a lap. Admixture with cotton is areally accomplished fay carding the two together, a cotton lap berg mounted above the creeper feed, end the cotton fed through the feed rollers with the asbestos. The evolution of dust at cards is inevitable and a fine dust cloud may be observed in meet cardroonw. Suppression of dust cannot be realised unless machines are maintained dean and in satisfactory repair, and there is effective endeeare of various parts. Above all, localised exhaust must be applied at well-defined points of dust emission, and improved stripping arrangements pro vided. Wide . icing of machines is also desirable. The npper ;<arts of modem machines are usually provided with well made wooden covers and the lower para arc enclosed below in metal. The frames are well oncloscd at the sides. hinged metal cover, fitted in some cases, pre vents eivpr of dust produced by movements of the feed lattice. A curtain nf fabric is levs satisfactory. Tn older typo, particularly, the *o!e. covers may not fit sniisfactorily, the cylinders may not be truly aligned with tlie frame anil other d fccts may account for side escape of dust, not ctmtroHa! 'c .by exhaust. Such defects slmild hr remedied. Creeper Veils. tloffcrs anti condensers and connecting bi.ttirrs hrtwrm hivnkcr ami finisher ranis arc not enclosed. Dust fat evolved at dofier ronil* and at rrreper feeds. I *3 Localwed exhaust vcntilatiou was first applied U> carding madiiucs n:.:ny non ugo. hlctiuxls aud apjiarattu hare since Iwen gradually improved ami more powerful.csJtaust draughts aro now used. One large firm have achieved such suctt** by standardising their practice as regards poiuts of application of cvImuiv*- draught, design of air guides, size of branch ducts to air guides and duet velocity. Exhaust Is applied at (a) the pressor at the creeper feed; (1*) feed roller at lietccr-iu; (e) top of cylinder; (it) each do/Icr, air guides or hoods being fitted at these points with connecting branch ducts. Muff couplings, used ou branch pipes, facilitate easy dismantling. Branch pipe sizes and duct velocities an liberal. The improvement realised by applying powerful exhaust at each of the points mentioned, at all of which evolution of dust is important, shown that this practice should be followed generally and gives point to the view expressed by some occupiers that carding can be carried on practically dust-free, part from the above case, exhaust is applied in nearly all cases to the cylinders; ia a moderate proportion to the creeper feed; in a few, to one Hotter--the top. and in one or two only, - to the bottom doilcr. 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, this should never be done. Efficient results aro not possible unless the exhaust draught is applied u doselr as possible to the dust-producing points. Transverse air guides, with branen ducts connected at each end, are apparently mote efficient than pyramidal booda of the usual type. Ducts of adequata diameter and high duct velocities are essential. The usual air guide for the cylinder, provided to effect removal of dost both during carding, and stripping and grinding (though proved inadequate for stripping) is placed a little above an opening in the crown of the cover. Two branch aucts, as above, and is addition a larger central brattlt duet (for use during stripping) are connected to it. The shallow space below the back of the air gnide is closed up 'luring carding by a wooden hinged piece thrown back for stripping--and the dost produced at the cylinder ia prevented from escaping by inflow of air from the room, at the front. The dust-laden air is withdrawn at the tide doets. In stripping, inflow of air carrying some of the Gripping dost takes place from below the lifted cylinder cover; the central branch dact, kept dosed hr a blast gate during carding, is then folly opened to provide a greater :ir volume. In one faetoi a circular doffer cleaning brush runs continuously above the doffer mb. A prramidal exhaust hood is provided, but much dost escapes; unless folly efficient exhaust is devised sn alternative to this cleaning, if really necessary, shonld be found. The collection of combed web. previously referred to, is done without exhaust snd dust is produced. Collection might be effected by exhaust draught aa applied for removing side waste at condensers. Notwithstanding the use of covers for card lattice feeds dnsty condition* are produced and exhaust draught shon:.l be applied at this point also. Strrjrpina and Grinding.--Card '* stripping " or cleaning is done when the machine is opened out for grinding, which follows deaning'and takes place at each machine about once a week, but shorter and looser intervals also obtain. In one important factorr the two orocesses are combined in n:,e operation. Roller and dearer cards must be opened out, i.e.. the lattice feed and breast, and con denser and doffer rsrriages are drawn back, the cylinder coTcn are raised, and the various small rollers, which are donned and ground at a special machine, removed. The nrlinder is first cleaned, with the doffer carriage drawn back; the carriage is then replaced and the doffers. run at a grratlv increased speed, denned in turn. Cleaning takes nhnnt ten minntes and is nsnalty done in working hears, hat in onc.case. at least. after. The men press their " strickles '* or flic band brushes about IS inches long covered with card clothing, against the wire covered surfaces. Xfnrh of the debris is heavy and falls to (he floor. Dust is evolved in a dense flood, some being removed at the evlinder exhaust hood. In one case floor openings, beneath the machine, are mnnerted to the exhauit. Present exhaust arrangements- are altogether inadequate, particularly so as regards the bottom doffer. Much dost is therefore carried into the general atmnsnhere f (he room. The Heanera wear respirators or " helmets." Tn a few rases, more effective measures are taken, e.g.. the opened-out machine is nlmmt entirriv endowed with high ennvns-cm-rrrd screens. In the 14 work* where cleaning Ukca place after working huttrs, an auxiliary cxhai. system, witli a hood for the bottom lioffir, is brought into use. Grinding which takes several hours, is an aulotnatic process effected abrasive covered rollers driven by the machine, Ike small amount of uu produced is chiefly of a metallic character. Is Uie factory whore griudiiig and cleaning arc combined, the doffur cxluiu arrangements arc first rc-connected. Much less dust is evolved and apper. to bo dealt with more effectively. This firm consider that hand .trickling bclo grinding should nut bo allowed. Their methods may, however, not be general applicable. A little strickling may be necessary after grinding to remove sum pieces of d&ris. The trails recognise that present conditions are oot satisfactory and exper moots are being made with else object of developing improved appliances. In oc ease a revolving brush is being tried, with independent exhaust draught applic by flexible connections; it is said to give promise of sucems. The brush ; narrower eh* hand strickle and less dustis evolved at^a particular nioacn- Is another ease, a vacuum fitting is under consideration. Previous use of racuu: stripping was given up becaose of rapid erosion of the roctM pipe beads and othc sorts Unless effective dust suppression is realised for stripping all worker:, other than strippers, should be excluded while it to *u progress and for some tier, afterwards, and the room well ventilated. The for cleaning and grinding the mailer rollers, which gives rise to much dust, should be fitted wish efficient exhaust arrangements-a straight forward matter--and as completely enclosed as practicable to collect the henrie: d&ris, precautions which are not always taken. The machine is either installec in the carding room, or in a room adjoining. Independent machines should bi provided to deal with rollers of different lengths, otherwise inconvenient adjust masts, liobls to ba neglected, have to be made. Card Sidt Wait* Treatment.--The irregular/* selvedge * of carded fibre, separated at tha two sides of the finishing card being unsuitable for sliver yarn, u nmoved by suction draught to a " side-end/' machine, which prepares it for farther ntf, The material it blown upon perforated cylinden, the air escaping at tha side and tha material being discharged on the floor- The process produces dnst, particularly when the feeding is irregular, the air then having a free path between the cylinders. The material should be delivered under suction and not under pressure, a " pressure " machine being unsuitable. * Spinning ,md Doubling.--Yam is spun at flyer or ring frames which may osrrr uu to 80 niudles, 40 on each side. Much piecing is required owing to the oomnarativa weakness of tha fibre. A fine metal thread is spun with asbestos, for and certain other purposes. Mule spinning is not practised m this country. A large amount of doebliug is earned on. hitherto, hot expennvi-- ...... prleanptr,eepmarbeoddytoinegq0u)ipevalilaluipssir.dru.:--ru paasrJaid.VcIuwblitnhgtfhreamfreasmewdi-h ~jentil,ation (xi) for more effittiw concentre: - ~. p. 1 *pmclJcs, and war parts of the frames whan nerresary. Si*li r.-- unless special gen.i.i> .mi!;i:i- .i j.r^iiied. Warphf.-\V;n.. Iwams ar- r~=^J in the iwial way from crwefii:- (nm&s a small evolution <11 ilii.i w.urrir.* :: tj,e ,__ . tioffcsaplkn-rdo.oixtlimri'iliurtitnvtr. ;iiltli\kit\imoHl il.u >l c!.r.wl<itahnplteMtf einffectiw.^'* , Pnrtitior effect improvement. at W ievcl v t 25 Winding.--ITany winding machine* are used, varying from makeshift types of primitive construction, at which Uic practice may oliiaiu of holding the yarn in the hand, to modern oniveraal winders for winding " cheeses." . Dust may bo evolved to totne extent, particularly in eonnectiou with the above practice, which could bo eliminated. Application of.exhaust draught will then probably nOt be accessary, except in particular eases. Plaiting and Dmiding.--PhiliBg and braiding, aim carried on in engine packing and clcetrie cable factories, and done at machines of normal design, canso some evolution of dust, except where the yarn is impregnated with "grease." WUIo the amount of dust is sometimes leu thau in spiuning, the difference is not material. But there is perhaps leu exposure of toe operative tinder ordinary working conditions and precautionary measures other than loculi**] exhaust vsatilation may sullies. Wsawing.--Looms vanr greatly in size and general arrangement. As many as 140 looms may bs found in a single room, but this is exceptional. The dear space between machines may not exceed IS inches. Some looms are independently driven by electric motors.- Cotton warp or weft is sometimes used. Thin cloth, fur mattreu covers, filters,' clothing, etc., is woven from a single warp beam at a simple type of loom. Belting looms, for thick belting and brake lining material are complicated, several warp beams, arranged in tandem under the loom, or in aome other convenient way, being required. These looms are narrow, bat often very long. Tape looms are also narrow, unleu MTtral tapes are woven together when several shuttles, in line, working in unison, are used. Cloth is burned at the front in the usual way, but belting may be led under the loom, ud eoSed high above it, at the back. Meet weaving is " dry." bat some weaving is done wet, either warp or weft, and occasionally both being wetted. Wet wearing is accomplished more eerily and a closer weave obtained, bat rusting of heald strings, and the subse quent drying entailed and the leu satisfactory appearance of the material are disadvantages. Thoroughly dry fabric is required for brake linings and rubberproofed material, and wet woven cloth may be strongly objected to on this aoeouat. ' ` Considerable evolution of fine dust occurs in dry wearing aa a' result of fa).ths forward movement of the slay in " beating up," this source being dose to the op-rative, (b) the repeated contacts of the rising and falling warp threads with their neighbours, this sourcs being the most important from a quantitative standpoint, (c) the disturbance of " dust " or " fluff " on machine parts, especially those in motion. A fine dust cloud may be observed behind the healds obo\e the warp threads. -Much leu dust is produced in wet wearing. Some " dry " looms are now fitted with localised exhaust usually applied to deal with dust evolved by both (a) and (6), in some cases (a) only, '(a) A fiat horizontal " hood " is fitted in front of the operative, just above the cloth, the opening faring towards the healds; ft) either aa upright pynunidal hood, placed transversely, or horizontal flat hoods, one on each side faring each other, are fitted does behind the healds. The second arrangement is the more effective for narrow looms, as the " sriesors-like " action of the warp threads appears -to displace most of the dust to the sides. The exhaust draught has effected seme improvement, but all the dust is net removed, especially that produced by ft). It may be iirvracticalilexo apply tbe draught to all dust-producing points behind the healds. particularly at loog looms, but greater succeu would have been achieved with more powerful draught and larger air displacements, as is new being recognised. The method* described f r dealing with tbe dust create * by ft) must be leu occeufnl at cloth looms of ordinary width. A few such Wm* in one factory have recently l**n equipped with large " bonnet " lioods, fitted transversely, don down over the machine, covering the slay, reed and hvahls. The hoods are of hemi*|da*ricnl section, with extensions over the shuttle boxes. An intr-nr.l dcetric light fitting, and hinged sections, facilitate working. A powerful drnnght. suitably applied, should prevent escape of dust, genemin! within, fn another case, experiment is snid to hare shown that a transverse inclined hood faring the operative, placed just Iwlnw the warp near the front of the loom, ran Is* more rffertixe fur rrdnring ilnst eonrenlration in the air brcatlied, than present arrangement-:. ;i.d the new design is Ui lie substituted. I 1C Application of efficient dust removal .arrangements to weaving is cl difficult. Tho expedient of installing individual machines or small grou; machines in suitably ventilated small rooms or cubicles, as suggested it ** Warping '* does not appear to have been tried, bnt might be considcrc localised arrangements 'are not sufficiently effective. Long narrow shells, a singl* litm of looms, ventilated as suggested, might bs a possible alterua: Clotl Picking, Examining, 31tanring.--There operations involve mm oat the rolls of cloth and tend to produce a small amount of dust. If carcf done, so that very little dust is created, other precautions may be unncccunr Non-Txxthjcs. Fibcrized asbestos is not used in some of the non-tsxtile factories ; exposure to asbestos dust may be slight or even negligible. Dust is evolved factories or departments where such materi-d is prepared for subsequent i or for sole, and also in departments where fiberized material or dry mixtc containing it are manipulated in preliminary manufacturing processes. Ag= finishing processes, involving abrading or cutting at high speed, may be a sou of dust, but such dust may contain only a small percentage of asbestos. 1 application of axhaost draught, where suggested in the following descript; at processes, is in most eases a straightforward problsm, comparable with ma others met with in non-tsxtile factories, eg., woodworking and grinding, whe machinery similar to that described is used: Pibtrixing or Opening.--Fiberixiag is almost exclusively confined to wor in groups (b) and (e). Much of the work is done under less supervision th; in textile factories and unsatisfactory machinery is more common. Primiti teasers (" devils ") are used in several mattress-making works, and dumb work is also an unsatisfactory feature (see p. 23). la some asbestos-cement $> eel factories, crushed material, from edge runner falls into worm conveyors below, which transfer it automatically to disintegrator la one large works, the process is being entirely endosed; the material fro; the edge runners, which are lattice-fed, will be discharged upon a conveyor an 'raised by an elevator to large overhead storage hoppers, fitted with automat: * bagging lattices. Localised exhaust draught will be applied at feeding an delivery points, whore dost might escape. Chambers have been eliminated in some large works, with beneficial resdb The material, after being disintegrated or opened, is fan-handled, and blow to a hopper fitted with bottom rotary delivery valves, the air being re-circulated The material is bagged at lattices. Direct supply to a manufacturing point i another improvement now being tried. Such pneumatic conveyance should l> practicable in many caste. Localised exhaust at feeding and discharge point; of then systems is necessary, Vacuum methods for filling sacks may also be practicable. If chambers are retai'-ed, tbs necessity for entering them might be avoided, by providing chambers of small front to back dimensions fitted with low doors, at which not filling would be done, localised exhaust ventilation being applied over the doors. (b) KQtboard, Paper, Sheets and Tiles. The wet mixtures for millboard, pa par. end asbestos-cement products arc prepared in a baater, as used in paper mills. Dry fiberixed asbestos is emptied into the beater trough, tbs sacks being shaken to some extent. Evolution of dost occnrs before the material becomes mixed with the circulating water. Occa sionally a sack is emptied before the water is turned on. Several sacks are required for a' charge and tba process is repeated a number of times daily. Pressutiros are not taken at present hut the dost might be avoided bv () mechanical feeding under en Jowl conditions, as appears to be done in wine foreign works, (b) applying exhaust draught, (r) feeding in small quantities and in such a way that the material it wetted at once. Finishing pmc-csso on asbestos-cement slieets include sawing to size, corru gating, prosing and drilling, carried on in some factories with the material so moist as to prevent dust, and this practice should he adopted generally. Olbunvisc much (hut is produced in tawing, owing In tin; rapid rutting *, sad localised exhaust is wxcwary though not applied. Similarly, turning, filing aud smoothing of dry usbcstos-ceuicut pipes, at lathes, nmy require exhaust to ranwva the dust produced. * Synthetic composition sheeting, sometime* made in a rubber department,' is produced from dough consisting of fiherized asbestos and rubber, mixed with ofrent in kneading inaciiines. Dust is produced in feeding tlus mixer with asbestos, dene in an ojicii manner by lunul, from sacks or skips, the sacks being shaken oat, or from an open Lattice feed. Subsequent processes are dust-free. Exhaust should ha applied at tlie feeding point. (e) Insolation Materials and Articles. Composition*.--** Magnesia," the most important insulating composition, is produced on a large scale by the principal manufacturers, by enclosed methods with pocumatic conveyance pf the mixture to automatic sack fillers. Weighing and feeding the fiherized asbestos gives rise to dust for which exhaust is naoefMary. Fiherized asbestos or " magnesia " is a component of many insulating com positions which may also contain clay, Ideselgnhr, fossil meal, flax, hemp or jots waste and other materials. XIte proportion of asbustos in the final product varies widely. In many small works the materials are mixed " dry," by hand, in an. open manner, involving seek emptying and filliug, shovelling and weigh ing. Enclosed rotary mixers could apparently be used for inch work with exhaust applied at feeding poiuts ana the material discharged and bagged under enclosed conditions. If hand work is retained, exhaust should be applied. Consolidated Skttts.--Large sheets resembling thick mats, boilt up of layers of Aberized asbestos, are consolidated with silicate of soda, sprayed on in manu facture. The sheets may be becked on one face with millboard, or supplied without e backing, being faced when fixed with millboard or asbestos-cement sheet'). The sheets an produced of the required size and shape nt work benches, or built up on the table of a machine, capable of slow reciprocating movemciit, end fad from a hopper above. In the former case, the fiherized material is taken in handfuls from skips and spread out in the forms, the surplus being scraped away and falling about at tlie sides of the work benches, and on the floors, a considerable quantity being scattered. Dust, produced in manipulating tlie dry Atone, before treatment with the silicate of soda, is largely avoided at tlie machine. Efficient localised should be applied to the hand process with improved bench arrangements, to prevent scattering. Bend sewing of piled sheets, censes evolution of modi dost, owing to the considerable depth of cot. Localised rxhanst alone, not yet applied, may prove inenfficient. Sostions and Slabs.--Moulded insulation is made chtefiv in two forms, sec tions--semi-cylindrical and moulded hollow to suit various pipe sixes--and slabs, which are rectangular and solid. These products are usually moulded wet, cither by band or machinery, from a paste or ergani, prewired in a mixing machine or tauk. Feeding of drr material involves evointiun of dust v hich might lie avoided by ono of the methods suggested for feeding beaters in milllmard making. Sections are made at one factory by a dry process, at a machine indifferently enclosed. Feed hoppers, filled from" skitw, deliver the asbestos tn internal lattices which in turn supply a travcllius Imnci, at which tlie section is roiled by hand. Semiring lirnsbes which dear tlie lattice and spread the material evenly on the hand gin* rise to much dust, and dust is pnidincd at tlx* Impfiers, and in rolling ami brushing away sujvriltmns material. Exhaust draught, mil hitherto applied, is to 1 provided at tlie cx]Hod brush and the machine is to be more effectively enclosed. Ao enclosed- " feed " is also necessary. Thr arvtinns and slat* an* trimmed to sin? with circular nr baud saws. Mnrh dust is produced ami exhaust draught is mmimmly applied. Imt is in some now* indliciVot. t'in-ular mws imv! in sumc cases in pairs. for I rimming ends in nor operation, ran lr filled with oxlmust Isaals ataivr and Ivlinv the Ix-m-hes. and band saw* can lie cnclmcd hulow tlic tablet and inverted hoed* fitted, exhaust draught being applied .ik for woodworking machine*. JEilicieut arra: muuta should bo readily practicable for all cawing work here. UaUrwes.--Mattresses are manufactured by practically ail firm* v. produce in*ulation requisites, though only occasionally by some. Mattre*es Luge contracts art made in tbe contractors' premises' their outdoor suit tnk necessury measurements .tad preparing rough plans. A inattrcs* has soiucti: to bo innJo on site. Mattress nuking involves, broadly speaking, the sequence of prove.associated with the making of domestic mattresses. The work is alhiast eutii hand work. Lengths of asbestos cloth for covers are cut out on a wide br and sown up, by treadle or power drircu machines, to an extent dependin'' the method of filling. Largo mattresses mar be sewn along one side only or k sides may he scaraaa and filling done from both ends. Before fiUiug, covers c tamed inside oat. Supplies of filling material, which usually, but may ru contain fiberued asbestos, are brought, in sacks or skips, from chambers, or tak from o]>en bins, in the room, kept supplied from the chambers, or from sac of material supplied by outside firms, rilling is done by hand, scoop or shor; and quantities may be weighed. The end filling of loug double-seamed mottressc referred to above, necessitates the workmen mounting on the bench to empty t om'urial from skips into the openings. After filling, the mattress is levelled beaten, to make the filling lie evenly within, the hand or a flat wooden beat being need. Finishing processes include final sewing, stabbing or buttonin fixing on hooks, etc. Some dost is produced at tbe cutting out bench, in opening out the roll c doth, and at the sewing machine, but far more in taking material from bins c sacks, in weighing, filling and levelling. Beating of the cloth produces tsbestc dust, the amount of which is largely increased if the filling contains asbestc: The work is largely done without regard to the necessity for suppressing dus; All benches are entirely open. Localised exhaust draught is not applied. One firm have improved conditions considerably by the following pre cautions:-- W(a)-Keeping floors and benches u;mp and spraying covers before filling Hose connections and spray fittings are provided. Sub-division of department into several independent workrooms (e) Exclusion during filling of all workers no: so employed, tbe excluded workers proceeding to another section. (d) Mechanical ventilation of each room by cron ventilation, embody lag planum supply (warmed whan necessary) at one side and low level extraction at the opposite side, the air being changed between 10 and 2C times per hour. (*} Enforcement of use, by fillers, of respirators. These precautions do not induuo application of localised exhaust ventilation, without which mattress filling and beating must involve some risk of inhalation of dust. For small mattrssses, a wide doable-sided canopied bench with exhnuse draught applied at gratings along the esntre lint might be tued, the filli material being supplied within the canopy. Snth a bench may uot perhaps practicable for the making of large mattresses but the possibility should explored. Otherwise at (east tbe precautions rsferred to above should adopted. (d) Brake tad Clutch Linings. Hcf'-ro being impregnated, the dr)* asbestos cloth, known as ** grey," may be calcin -ml at squaring r>H and in all cases tin mils art eased out to sep-'-ate them a little, su ensuring : :rough treatment by the liquid. A little chut is produce-1 in t:-sw ofM-rainii* hut irsuflicient to render sficvial prccautiunar measures niiosury. Ollier prqmratory work on " grey '* arises in the m.;ki of special lining*. Lengths of doth are lightly hanm-red to ring shape templates, then cot with chisel nr shears and the radial edges sewn tngcthi* win-stitching machine, a* used in Imnk-hiitdifig. Dim mvtirs in lcimiucr' Stitching. A ranop*-tl Is-nHi fit In I with Incalim'd exhaust arrangement* provided ami I In* machine jdnivd under exhaust draught. *9 Dry impregnated material is shaped and finished mainly by |.<i\vcr-drivcn machines, e.g. knives, circular and guillotine, cutting prcssra, hydraulic squeezing presses and bond saws. Cutting aud sawing expose cud* of wire and leave rough edges; trimming and smoothing, done on grinding wheels and linixl.zrs, are aooessary to obtain exact sire and finish. All tlie operations, except squeezin'-;, ocodnco waste, and dust is created in some. Tbo dust is heavy and sticky and wss likdy to fly about than dry asi<stos dust. The amount is considerable at sawing and grinding machines and localised exhanst draught, remove it, lias bon applied--in some eases with much success- and is always necessary. Inverted hoods are fitted at band saws, just below the tables, the dust being drawn through the snail openings in the table guides. A powerful draught is Grinding and finishing wheels include, in addition to ordinary single-disc two-disc and vertical spindle segmental grindors, used for flat linings. The hoods by which the draught is applied to all these types are similar to those applied to tho same machines when used for metal grinding. The position is similar aa regards linishers, a hood being fitted in line with and at the back of the band. A baffla plata to prevant dust being carried past tha hood by the high linear speed of tha bud is a necessary addition. Special linings and anti-friction bushes are moulded from disintegrated impregnated waste. Some dost is created in the filling of moulds and efficient localised exhaust draught may bnaecessary. The articles are shaped and finished as just described. Bushes are turned and bored in lathes, witu production of waste and dust, but exhanst draoght is not at present applied though possibly (e) Picking and Jointings. Engine packing is cither (a) " doth " peeking built up from doth, usually rubber proofed on both sides, handling of which does not cause dust, and (J) *" rope " packing made from yarn, at braiding and plaiting machinery, as used in textile factories, (a) Negligible ai-ounts of dust may arise at the spreading machine, from the unproofed doth, and, in building up, from material proofed on one side only. (J) *' Cheeses '* of yarn axe first rewound on bobbins for the braiding ud plaiting machines. Simp- winding mechanisms are used. Some little dust is produced; special prevent!,.. measures will usually not be Flat packing, Imown as " grummet/' is made, on a small scale, from asbestos yam, threaded on a needle and wound in and out by hand, as balls of wool are wound. This apparently insignificant process causes sufficient dust to cover in a short timo the hair rind dothmg of the workers aud should be doue at a canopied tench provided with localised exhaust arrangements. (Q Asbestos-covered Electric Conductors. EUctrodtt.--Electrodes are either wrapped with yarn, the usual method, or passed through paste containing asbestos fibre, yarn being wrapped upon this coating. The firmer method is usually achieved by a small high speed stranding machine fitted with a flier carrying the spools oc. bobbins of yarn, the wire travelling axially through the flier. Treatment with consolidating liqui-1, straightening anil cutting to length follow, all done at the stranding nuch:i:v. Alternatively, single electrodes mav be wrapped by a simple winding mechanism, hand-operated or power-driven. Paste-covered electrodes are also made singly at small extruding machines, a flier for feeding the yarn being fitted behind Die extruder. After drying, a short length of the rwering at one end is ground away, leaving the bare metal neressarv for making ricvti icnl contact in the holder, when in use. . Small abrasive wii vl-. almost entirely enclosed, are used. Small amounts of dust an* projected from flier*, though insufficient nruhably to requin* the adoption of |x*cinl pnivuiiioiM. Much dust is produced in grinding end* and efficient exhaust ventilation is cwcntial; present apt^iratus, where provided, is capaldc of improvement. Tim proivs* would l uninivssary if hared rnds^wriT left in niannfartun:. and e!C]vrimutU directed In thu di*-irnl>lc end are being, made aud give promise of success. .Ml l'rwiwniliirj.' pruwMM in pau- making iitehule (i) dry grinding nf lilx.wiini tulmlim by Mini 11 vertical dine grinding wheel.-*, led at liu ivulrv l rum ;i hoi>|<cr * above anil diM liargtai I'pmu Ujc periphery intn u 1ms helmv, mid (ii) hand mixing of Uie ground materials a: a. bench, involving emptying out uf dry material juii> ' pans. Dual' in produced, the amount being considerable in grtndiug. J.ittle precaution is taken. The processes might be uceuiupli..hcd under uiniust entirely enclosed condition*, eMieicut cxliau*t draught being applied at point* when* dry material is exposed, c.g., in feeding. Rewinding of yam is souictiines necessary and primitive arrangements may be used, the practice referred to on page 24 bciug followed, and as a considerable amount of dust is produced, the practice should be given up. Cablt a. ti |i iri'ny.--Asbestos-covered cable and wiring constitute a small percentage ol* the output of the cable factories. The yam is braided and plaited on the conductors at madwtes, not reserved for " asbestos " products, similar to thoso previously described. Rewinding of " chesses," as receive'' from asbestos textile factories, is douo at universal winding randlines. The amount of dust evolved i small, and special precautionary measures are apparently not required. Fit Id-?nil Wrapping.--Field coils for electrical machinery are wound with asbestos tajie by hand at ordinary work benches. The process does not give rise to appr viable quantities of dost. * (g) Macallantoos. Mouldsd Goods.--Soma electrical insulating fittings are moulded from - varnish-impregnated fiberiaed asbestos, prepared after thorough drying in a mixer and ground in an edge ruuucr. Alternatively, impregnated scrap, ground in a nimbler, may be used. The preparatory processes on dry or practically dry material are intermittent, and involve sack emptying, shovelling, weighing, filling and emptying shallow treys. They are ei. ried on in an open manner without special precautions except that as regards grinding, hanging curtains may be used at the edge runner, and the scrap rambler is enclosed. Dust is evolved in the processes mentioned and localised exhaust ventilatiou should be applied to effect its removal, with, in addition, effective enclosure of some band work, c.g., emptying of trays into machines could be done inside a cabinet provided with internal arrangements for securing the trays and an external handle for tsraing them over. localised exhaust may be necessary for final trimming if done at abrading wheels. Moulded articles made in other, trades may contain bat a small proportion of asbestos, although a large quantity may be used. In one case tbe asbestos la tiered after drying, both operations being done in enclosed inachiues, and, in addition, dry mixing, dona in rotary machines, and paste mixing, on opr.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 travs for drying, feeding at tbe sieve elevator hoppers, the dry mixer, and the rolls. Localised exhaust is appliad at (a) ths slcvator hopper, (!>) the storage chamber above an intermediate'ragging point, (c) the dry mixer, and (d) the rolls. More efficient arrangements appear to bo desirable for (a) and (c); tbe feeding of the elevator might be done under enclosed conditions if a cabinet as mentioned above wore provided into which the trays could be inserted. Localim*l exhaust is nocesttry at storage bins. Final trimming of rough edges is done under efficient exhaust draught. Other processes of comparatively minor importance, e.g., asbestos putty mixing, in which there is handing and feeding of dry material in preparatory prnce<<*. will call for precautions as previously described for similar work. 4.--Sacks. In a few cures sacks of sailcloth nr other cioselv woven material are used inside tlf factories. Such racks are much to bn preferred to t!*.* made of tlu*. ordinary material, which is " leaky " and gives rise to dust in handling. 8.__ fllx.vx txt; or Wonsfi. Macimnwiy .vxn Sack :. Some fai-turie* are ke|it in a noire elenuly state than .other*. hut higher standard* and improved uietlmd* are desirable generally. Weekly cleaning hy drr metis*1* is jmiienil in textile fortune*. luit is more effn-tiwly done in s*>nie 31 eases Limit in other*. Caxu.il Henning may olio lie done ilnriiig the week. Tim dost which gathers iu a week render* cleanin'; .1 very dnsty operation. Young workers may be.seen on carding machines brushing dnat into the air from the covers, etc., in considerable amount, near other workers. . Some linn* hare instituted more frequent regular cleanings and more satisfactory methods bydamping before sweeping. Yauunm denning methods have not hoeu adopted and mn*li methods scon to be regarded as impracticable, bin this can hardly be nerepted. Portable ' vaeuuin seta are constantly used with grent advantage in otlier classes of works, e.g., electric cable factories, by adult dernier* who keep the machines, plant, serviee pipes, etc., thoroughly dens. If vacnom methods are not adopted, well organised daily cleaning, by adults, using damp methods for floor cleaning. slwulu be the rule in textile factories. water supply with suitable hose and spray connections should be provided. Ddbris produced in. asbestos-cement sheet works under moist conditions may become dry and cause j^nerai dusty conditions. Cleaning should bo so frequently done as to prevent this. The cleaning under machines such as looms and cards entails collecting waste of considerable value, done at present by hand. Vacuum collection should be possible: in principle, it is already used for removing aide waste at finishing cards. Tim strand principle of collecting curd waste, through floor openings, bus been adopted in one new factory, and might be followed iu others, with automatic collecting arrangements. 8ack 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 exhaust ventilation. A type of M exhausted '* nrndune which does not involve each work is to be preferred. 6.--SUMKAXY ASS SaCOMMCtOATIOXS. Asbestos factories and workshops cover a great variety of processes. The premises differ widely in structural features and are congested in manv cases with machinery or material. Processes are largely carried on in close association. Dust is producrl at many Jrinr' of machines, in hand process work, and in simple incidental operations, particularly in emptying settling chambers, and in aff handling of ** finerized " asbestos. In textile factories, pure asbestos dust is continuously produced, in differing amounts, at all the principal machines. Card stripping, a very dusty operation, is usually effected by hand strickle*. Hand mixing of difierent grades and varieties, incidental to opening processes, is also dusty. In non-textile factories, pure asbestos dust is produced st opening mndiines. in feeding machines, in making insulating mattresses (a dusty hand procr-), and in incidental hand work. Dust, though rarely rare asbestos, is produced in flushing operations, e.g., sawing, grinding ana other abrading of asbestos products. The appropriate method* for suppression of duet way only be fullv deterk -'nod when tho harmful effort, of comparatively low concentration* of asbestos dost are duly appreciated. Tory dusty processes will not fail to be recognised, hut in processes such as spinning and weaving, in whirh in other textile trades special methods for dust control are not required, due precautions are also neces sary. The asbestos manufacturers are dearly confronted with the necessity of attaining conditions in their industry which will ensure much less dost in' the atmospheie than con safely be tolerated in many compareMe trades not usiiig asbestos. The principal methods for the control of dost are:--> (*) application of exhaust draught at dust-producing points-. (b) substitution of enclosed mcehanivul methods for hand conveyance, and for dnsty ha*mI work generally; (t) effective vnehwnre of dust-producing nvu-hines and plant; (-r snikUitiitinn of wet methods for dry. Earh of Uuwc has its particular sphere of utility, and llc jairticniar indit-u' Uons for their adoption are put forward inter n/}* in the rvctmicinl.it.ions Mow. BSCOHMEXflDATIOWS. (1) Application of ECdent Localised Exhaust Ventilation at dust-producing points. This measure, of the,greatest importance where manufacturing and incidental processes occasion escape of dust not controlled by enclosure or other measures, is necessary for:-- (a) Dvf -prodveinq machines, e.g.-- (i) Crashing, disintegrating, teasing and other opening machines; tiering machines; fibre grinding machines; dry mixing machines; rolls fed with dry mixings. (ii). Carding machines (to suppress dust from cylinder and doffere, caused by stripping and grinding, in addition to that pro duced by carding); card side waste exhaust machines; looms for dry weaving; stripping and grinding machines; other textile machines, if the dust evolved renders this preventive measure (iii) Sawing, grinding, trimming, polishing and other abrading machines, used on dry asbestos products. (B) Feeding and delivery lattices, or other conveyors, at machines or other plant; feed hoppers at elevators; bagging lattices; feeding of dry material at wet mi:. >ng machines. (e) Chambers, containers, " cyclone." hoppers, or other enclosed space into which fiberued asbestos or mixtures containing it are delivered, or pass. (d) Work benches, e.g. for mattress making, waste sorting. (*) Various hand operations, e.g., sack emptying and filling, weigh ing, mixing. This is the principal measure hitherto adopted, and is probable that most generally applicable. It has been applied to tome only of toe above machines, and appliances, bat not to hand were. The methods of applying the exhaust draught, and other a odated factors, are becoming more effective, but there are few fully satisfactory plants. Special difficulties remain to be overcome in mm cases, e.g., looms, mixing, mattress making. If not surmounted, as . alternative, viz., general ventilation of a high standard applied so os to draw the (test-laden air away from the worker, should be provided. (3) Substitution of enclosed mechanical methods for hand conveyance, and for duty hand work'generally. This measure-- (a) avoids depositing material in chambers, `internedinto filling and mnptying of sacks or skips, hand feeding of machines, and other incidental hand were; * (b) permits of final filling and weighing, under the least dusty con ditions, of materials for dispatch; (c) renders exliaust draught more effertive, or, in some esses, unnecessary. .. It is already employed to some extent, and its further application, wherever possible. :.s greatly to be desired. (3) effective endoaure of dnst-prodrclng martinet and plant. () To prevent of diixt net coni mllrd by exhaust draught, or (&) tn rriulcr iu itpjdii-alinu inure eflicicul. 3S (4) Substitution o! wet methods lor. dry. To reduce the dust given off in certain precedes and work, e.g., ' (a) a considerable amount of-weaving; (b) mattms making, by wetting the covers before filling, and by frequent wetting of floors and benches; (e) final awing, and other machine processes, in arixattos-cemcnt sheet ami tile factories, boforu the prepared material has had time to dry; (d) works' cleaning, sweeping. damping floors and benches, before brushing or This measure might be adopted to a greater extent than at present. <S) Elimination ol certain dnst-prodndng 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 efficient enclosure or exhaust draught- Thev should not be retained unless effectively aodified. (a) exposed doffer brush at carding machines; (b) card side waste exhaust machines,.delivering under pressure; (e) certain willeys and teasers, particularly old machines. (6) .Abandonment of Settling Chambers In ICacufaetnrlng Processes, to the utmost extent. (Z) Effectual separation ol processes to prevent un- <ctssary exposure to dost. New factorise should be laid out so as to avoid exposing workers to risk from processes upon which they an- not engaged. In particular, tharc should be effectual separation of-- (a) opening, carding and weaving, from each other, and from cay ether process; (b) * pinning, doubling, plaiting and similar processes, from work not causing dust; (e) mattress making, from-all other work; (rf) chambers, containing fiberixed ..diestos in bulk, tod dust mttiing chambers end apparatus, from any workroom. The separation of mattress making should be adopted in existing works, and other separation referred to, as far as practicable. (I) Wide spacing of dnst*predudag machines in new factories and, u far as practicable, in existing works. - This measure would bring about permanent reduction of dost concentration in the air of the workroom as a whole, and provide improved cleaning facilities (9) Use of sacks of close texture material for infernal work. (10) cleaning system with wide use of vacuum methods. (Sec also (4).) (11) Storage of asbestos snd other goods to bo outside workrooms. (12) Exclusion ol young persons from specially dusty work. Vo/p.---Partii uUr jircventivr measure* of a medical nature are referred to in Part I. when: aUills' limited valu of rwtpiraior* a* a ttfr^ainl in this industry j*liri.-llv* ilinniwi ed. Nunc un Exhaust VumumoN in AeasxTUH Woiucx. 8ome eximuxt plant* an canifujly designed and reasonably efficient, but . some an nUlougned and inefficient; others, again, du not effect removal of dmu to a sufficient extent. _ TIm draught may 091 be applied as doscly as possible tu 'the du*t-pn*l-ruir poinls, or may be too weak. The emission of a risible dust eland at a p .t where exhaust is applied.is a dear indication, of- inadequacy. Extensive allrrationa of existing plants may produce serious loss of efficiency. Exhanrt iwuvisit- fur new machinery and proceaan should, therefore, generally . sposkii- '<e mnrir independently, while adventnges result from danlttig with many -reducing points, by a single exhaust plant, a number of self-contained plant* ' independent fans and sealing apparatus, is often mors effective. ;. * a t ventilation applied on a large scale entails continuous removal of eonsiu-iable votntns of air from the room. The supply of fresh air must be l-.>: : ample or the efficiency of the exhaust ventilation may no reduced. In winter, the workers are liable to bring about this result by closing windows and doors. /- Plenum ventilation c&pairip of applying tbs volume extracted, the inoeraing * air being warmed, may therefore be desirable, where extensive exhaust plants are metalled. . df an exhaust ventilation plant may be greatly reduced by inefficient dnat-mttling mctliods. Each fan should discharge into an independent Mttlor. Settlers adopted in aeheetos works include cyclones, large chambers connected with cyclones, large chambers enclosed with seeking or outer filtering material, end bag filters. Cyclones and chambers an anally well tenanted from workrooms. Bog filters are now being commonly adopted, for small instal lations. Then liters and " balloons " an sometimes placet! inside workrooms, n bad practice. They an hot placed in freely ventibi i rooms, affectively --rend from workrooms. filtering fabrics for settling dost gradually become domed; and aa this effect increases the exhaust plant becomes more and more the volume of air moved by the fan being reduced. Such settlers must therefore be kept * dean. The usual pneties is to bat the filtering material. Arrangements for bogs from outside, or automatic shaking apparatus an not provided. (Idlestne dust does net appear to be a difficult to detach from suitable filtering material aa some dnsts, but much dost is produced in boating. Efficient shaking arrangements, avoiding this axposnn, should bo provided if this method of settling is retained. Some firms itrtngty mpport the view that it should be given np because of the difficulty of maintaining the exhaust plant at the highest rfltrinwy. The matter merits careful cnosideration. In particular, the efficiaoi-v of the exhaust plant ehoold be kept under content observation by a Cyclones should be of adequate dimes*ions. The combination of chamber - and cydooe la need extensively, the fan discharging the air into the chamber, to which the cyclone inlet is connected. The dfidency of this arrangement should lumaia practically constant. I. R. A.-MEREWETHER. CHAS. W. PRICE. ""'^Hth March. 1830. * *, i, 38, Hatch, T, Warren, If., Drinker, P.: Modified Form of the Grecnbnrg-Stnitli Impinger tor Field Use, with a Study of its Operatise CTiaracteristic*. J. ImL Hyg, 14:301-311, 1932. 39. Hatch, T. and Pool. C. L.i Quantitation of Impinger Dust Samples by Dark Field Microscopy. J. Ind Hyg, 16:177* 191,1934. I : . - >' : * * r* i i Xf i 60. Holtzmann. F.: Die Eintrirlrang des Asbeststaubes. ZentralbL L Getrerbehyg, 825-226. 1931. 61. Industrial Directory--1931 Edition. Pa. Dep't of Internal Affairs, Harrisburg. 62. Katz and Slater: The Second Positive Ware of the Q-R-S Complex. Arch. lot. Med, 55: No. 1, Jan. 1935. 63. Kettle, E. H.: Interstitial Reactions Caused by Various Dusts and their Influence on Tuberculous Infections. J. Path, and Bsct, 3525-405, 1932. 64. Knopf, A.: The QuantitatiTt Determination of Quartz ("Free Silica'*) in Dusts. U. S. Pub. Health Reports, 48:183-190, 1933. 65. Kruger, E, Roetosld, O., Saupe, E.: Asbestosis. Arch, t Geirerbepath. u. Getrerbehyg, 2:558-590, 1931. Abstr, J. lad Hyg, 14:144, 1932. 66. Lanra, A. J, McConnell, W. J, Fehsel, S. W.: Effects of die Inhalation of Asbestos Dust on the Lungs of Asbestos Workers. A Preliminary Study. U. S. Pub. 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