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f.'ret?a 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 Affection* 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 AND i C. W. PRICE laf iMpKMTirf K LONDON; PRINTED AND PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE. To be pard.a-cd riirectiv front H.M. bTAl lONEIYY OFFICE at tle following suitresses: Ada*'rat Hmiic. !<trgv-av. I jmuImi, W.G.I: teo. Georgs Siren, Erf:ni.i:rjii, York Sucn, Mainl^ icr; i. St. Amir.-w\ Crcvtst, Cardiff; 15, Donettnll S<;uarr V.Vji, Rctfasi; ' or ihrougtt any i <*k.vUcr. . 193 Pnn- it. td. Si Asbestos Information Association | PLAINTIFF'S EXHIBIT - * 0 CONTENTS . futt L P** L tsraaaocnoa -- ------ -------- -- . t Inenw (umnUnrnwniUm- -- -- -- -- -- -- -- -- * Tka VitM al Aakaataa - -- -- -- -- -- -- X Score or mo Itrannw -- -- -- -- -- -- ` Tka Papalollaa atriofc -- -- ---- -- -- Salaatiaa ol Werkoro tar Twinort-- -- -- -- -- Tka CUaiaal rTimi-otfm io4 Staadarda adaptad -- -- JUdiagrapkia EaaanaaliM al tka Laapo - -- ---- ---- ---- -- ---- -- ---- ---- ---- ---- -- -- -- -- -- - * T I I 4 Xbsvt> or na Imoiir -- -- -- -- -- -- -- -- -- -- -- -- iikoornoii Tka Palnaaaiy P&raaia al Ufiaataa Warinta -- -- -- -- -- Tka Aokootno Badiaa -- -- ---- -- ---- -- -- ---- Tka laaidaaaa ol Fikaoaif Flkraoio fa ikada Woricari -- -- -- -- -- ISaaio al Ago aad laagtk al Tnpkiywaiil -- -- -- -- -- -- -- 10 ' IBool al TTark ia Difaraat Piccobm -- -- -- -- -- -- -- -- 11 laiaMra Daoliaaia al Tariaaa iiWno Pracoaaa -- -- -- -- -- -- -- it CaoraniraUaa al Dm* and Laagtk al Sxpaaara araanary ta pradara Pfkreaii -- -- u DioakiawU ptadaoad by tka iakootoa Fibroin -- -- ---- Fmioa aad Daratfaa al tka Diaaaaa -- -- -- -- -- -- tiooriotina al tka Aokaotoo Fihiana aith Palmary Tukoraoloau -- -- -- -- -- --` ---- ---- is it ia . *anaiy - -- -- -- - - - - --lt K Fioaaa mwonnw zb hum Baeoarmoa or tmm Aim Fnsaam -- -- -- jy a. hiiwin SuoiiMi -- -- -- - -- -- -- -- -- -- -- -- -- if . T. 1b Ovnon -- -- -- -- -- -- -- -- -- -- -- -- -- iy a* s 3 L Xaraowiaioa X hmin Tratfloliaa -- -- ---- ---- Pur XL -- ---- -- ---- -- -- ------ -- ------ -- Ik u ----n ----M ' 1 Ocacaimoa or Paorsua in Pirann ftiuna -- (a) Tara aad Clatk -- -- -- -- -- -- Op-aia* Card:an. ---- -- -- -- -- MripfMn* aad Crtadtag -- ---- Card Side Vita TmUanat -- -- -- Bpiaaiag aad Uaahlir - . - -- Waipiaf. Vimlhf ---- -- PWMiag aad llradia* ' -- -- -- . .XTrario* -- -- -- - - .-- Ckdk " Piriiag,** KaaaHaiag, Alm--riaf -- sasr s 3 * Kw-Toma , _ -- -- -- -- Ffliariting or Opening ~ (k) ViUhasrd, Pspor, Shoots sad TUoo (<) Usaiaiioa Materials sad ArtieJee -- Coatpetitions _-- Coawliiltml ShocU -- -- * SootioM sad SUU -- -- (d) Drake sad Clatch I.ieiag ~ _ (o) Packing sad Joiatiaga -- -- -- (/) Atkootns uoTtroH Electric Coadaefto flootrailes -- -- _ -- Cshls sad TOring - . _ Ffaid-Coil Wrapping _ _ it) MiwoHinirni MonItint Goods ~ , . V . . . . Psoa is M M rt IT tr IT N n M n M M M SO 4 Socks -- -- -- -- -- -- -- -- -- -- -- -- -- -- go 4 Ckaumre or Woaaa, Use*mn tn Seen -- -- -- -- -- -- -- go 4 InsuT on RaeaioiBiMStom jj Von as Xmnr Tcmunov a Asmtoo Wokks -- -- -- . - . . _ ]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. Sir, .. 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 FlUltOSlS AND OTHER PULMONARY AFFECTIONS IN ASUESTOS WORKERS. L--InraoBoenoK. This Report is bsssd upon ths dots obtained in an extensive investigation daring the years 192S and 1029. Ths inquiry was initiated by ths Factory Department of ths Home Office following the discovery in February, 1923, nf a esse of nan-tubercular fibrosis of the lungs in an asbestos worker, of sufficient severity to necessitate treatment in hospital {Seiler's Cass'). Prior to this, this Department had knowledge of only two deaths of asbestos workers, about whom then waa expert opinion that the inhalation of asbestos dnst bad at least contributed to, if net caused, the fatal outcome. Ths first of vthese, now referred to as the " Montague Murray Case." occurred in 1900, but all that is known concerning it is contained in the evidence given by Dr. Montague Murrey in 1900, before the Departmental Committee on Compensation for Industrial Diseases'. In this cast post mortem examination confirmed the clinical diagnosis of extensive non-tuhercular pulmonary fibrosis. The sc-.-nnd (Cooke's Cass') occurred in 1924. Here, although Cooks' and Stuart McDonald* were of the opinion that the lungs showed a progressive dust fibrosis together ^ with a chronic tuberculous infection, the etiological relationship between the .inhalation of asbestos dnst sad fibrosis of ths lungs would have been strengthened by the absence of a tuberculous infection. An early sur-vy of the industry in 1910*11 by the Department did not die* clora any endec-- of the existence of a serious health hazard ia the industry, hot some experiments on animals conducted in 1913 by Professor J. M. Beattie of Sheffield University for the Dennrtment showed that the inhalation of dnst will cause a mild degree of fthrtsis. Whan, therefore, investigation of Seiler's Case showed that other industrial and infective causes of fibrosis could be definitely excluded, the necessity of . deriding whether ths supervention of this disease in an asbestos worker was an exceptional occurrence, or evidence of s grave health risk in ths industry, was apparent and ths investigation referred to was undertaken.- - 1.--Errzcrs or Imituit Dun Uroit txz Lungs. The most important local effects which nay follow tbs inhalation of dnst include pulmonary sad branchial catarrh, asthma, bronchitis, fibrosis of ths lungs, and secondary changes, such as emphysema, local or diffuse. Those changes in ths lungs, whies may bo looked mini as a measure of tbs efforts of the living times to repel or incarcerate die irritant particles of dust, necessarilr cause interference with ths general efficiency of the lungs. The impairment of functional capacity, may bo slight or seven, and temporary or permanent, rle* pending on the variety of dust, and on other factors, snub as concentration of dust am! length of exposure. , Mqrcurrr individuals whose lungs hare been affected as the result of the inhalation of were* duals, show on increased susceptibility to the supervention of respiratory infections, sorb as tuberculous or pneumonia. - Fibrosis of the lungs is recognised to bo the moat important lesion caused by Uir inhalation of dust, and the pns- -now of workers with a dust liitresis to bo affected kith |Nilnwinary UihrrciiU*is 1ms been shown to be the main <uu*c of tlw iui-reuscil UMM-iaiity rate Tnim the latter disease in ivruiu dustr ocenna* lions. 1 AS 8 This triad--exposure to dust, fibrosis of the lungs, and high mortality rate from pulmonary tuberculosis--was found to bo conumm 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 obserred, hotrersr, 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 end not in the free condition. - Thus, shortly, free silica came to bo regarded ss the pre-eminent cause of industrial fibrosis of the lungs and aa a notable factor in.tbo production of the " mortality rata from pulmonary 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 rhan 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 fihroeis can be produced by some of them other dusts has 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 orthoclaso basalt containing no free silica. ' Tio Natim of Atboito*.--The fibrous minerals commercially known 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. The 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 ap into long and flexible fibres for spinning ana weaving, on their resistance to heat and acids, and on thair insulating properties with respect to hast and electricity. Varieties of possess these characteristics in differing degrea. ' Practically speaking, all that goes under the name asbestos in commerce ia either fibrous serpentine, or a fibrous mineral of tbs hornblende group, of which the most important are erocxdolite, smosite and trsmoiiia. Serpentina asbestos or chrysotile is essentially a hydrated ailicate of magnesium, containing little iron and practically no calcium. ' The hornblende varieties contain lass magnerium atv* usually more calcium, aluminium and iron crocidolite and amorite being mairny silicates of iron. 1--Scars or m hrmnutioM. Asbestos is very largely used in industry, bring an important constituent of many different produ u. The diversity of industries concerned made it essential that soma restriction of the field of investigation should 1 derided upon. . The manufacturing procsisu affected faff more dr lam sharply into two groups (1) those ia which than is exposure to pun asbestos or asbestos mixed with a very small percentage of cotton or other vegetable fibre, and (2) ti^ ia which then ia exposure to a mixture of dusts, of which asbestos is but one. The former group comprises, ia the main, the textile branch of the industry, a brunch manuPicturing insulating materials from practically pun and soma prriifr ;iury processes ia other branches. The htti-i- group includes a number of processes in which the proportion of aslK-(.'* i:. dm 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.U.^tot Uuat is only ono comooncnt, until tbs action of dust itself was determined, the examination of workers for the purpose of this enquiry was restricted to wnrkrrs employed iu processes included in group (1), in other words, to workers aa nearly as |MMiiliic expmed to the influence of pure aabwlu* dost. Furthermore, tin* effects of previous rxposnre tn other irritant dusts, such as UuU of free silit-n, had to 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 *-t ... _ 10-14 .... -- l-IS ... -- M m4 or -. fatal* ... OS es-stoo . St M 4 3*1 IT t-t ns j isa Ton omolooU. Kmmtmt. PWMSUg* . at TataL 0- .... M- 10-14 ._ 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 snccaalvc 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 those rcuuincd ware at work on tho day of nxamiuatioc. . ' ' Tka Clinical Examination and Muurfnrdx ndoi>ted.--Tks nature ami * purpose of the inquiry were explained to cadi worker whom it vraa proposed to examine, individually, and liia or Iwr co-o;x:mtiuii obtained, Each in* dividual'* previous industrial history, ; absequeat to leaving sdiool, was noted ill detail. This *waa essential in order to exclude, ex|iecial!y, tlie effect of pre vious work iu any of tlie numerous processes involving exposure to free silica .dost, and, to a teas extent, the 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 subsequent changes. Particular attention was paid to accounts of pulmonary ailments, soma of which, like asthma and bronchitis, an 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. The 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, especiaUr in eliciting information as to the existence of any undue 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 genemi health and of the condition of the upper air paoages. .' Hefercncs must 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-snpposes the existence of such a standard. Every clinician has attained, as the result of experience, his own dear conception of ' Uw normal chest, hot it is not often that he finds it n.- -emry to denne this state in so maoy 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 vestisn 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 for this reason alons, tbs ebsst cannot ba considered abnormal. .- Thera is obvious disparity between ths standard of physical fitness required far an air pilot end that required for life insurance at ordinary rataa; in dividuals reaching either standard can be classed as " normal,'* yet many attain ing the latter standard ban* never approached the former. Thus, within limits, various gradations of normality may be distinguished, and corrsspondng standards constituted without inaccuracy, the precise status of any standard Being determined by the purpose for which it is established. . 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, apart from work in dusty occupation*, as Uiom of tlie group being considered. This is neither a high standard nor a very low standard, but the average stan dard of normality displayed amongst the iudns.rinl population of this country. RxJioanipkii1 Exnminathn of tko J.angx. - In addition a careful radio graphic- examination of the ohest 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 ; .ithoritir*. It was not, of course, feasible to ohtaii. technically sufficient radii--rams ot .iU tlie workers examined, derived a* they were from factories aratten-- over the country, some in districts remote from a radiolcgirnl centre. Tlie in *: of selection was dictated by the needs of tlie situation, with the object of n-idnliug nuitrriai points germane to tlie investigation. c.g., tlie elucidation ... twnplirclir.g affections, in measuring the 9 extent and pragma of tk lotions and locating tho point at which tho earliest radiographic signs appear, and finally ar a chock upon the human factor presented lqr the exnmiwr himself. a,, - 4.--Rxsoits or tjie Iwp:mr. Ta antict|iatc, examination of the data collected in this investigation leads tn the conclusion that the inhalation of asbestos dust over a period of years results in the deveU.paa* of a serious type of fibrosis of the lungs. ' Asbsstosia--tie Pdmomarj Fibrosis of Asbostoa Workers.--It is helpful to isonlise fibrosis of tho tangs as it acorn in asbestos workers as the'slow growth of fibrous tiuue (scar tissue) between the air cells of the lung wherever the in haled dust comes ta rot While new fibrous tissue is being laid down like a spider's web, that deposited earlier gradually contracts. This fibrous tissus is not only useless as a substitute for the air cals, but with continued inhalation of the eausative dost, by its invasion of new territory and consolidation of that already occupied, it giednslly, and literally, strangles the essential tissues of the lungs. ' ' la common with, other essential organa of the body the lungs have a large reasire of tissue for aee in emergencies end to permit of a diminution of functional capacity do* ta advancing age or disrate For this reason, end h--fibrosis of the taags is essentially a local disease, it is only when the fibrosis progresses to the extent of obliterating this reserve, that undue short- urn of breath on any extra effort draws the worker's attention to the fact that his health is not what it should be. The other symptoms of the disease such as cough era equally nanranmiag, and are readily ascribed to some common and trivial cause. ., From this point the progress of the 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 acute respirator infection has precipitated a. fatal termination, a stage is reached .whan the lungs can do little more than maintain life, and the shortness of breath becomes extreme. In its main ***--* features, therefore, the disease resembles silicosis, as might be expected. It differs from silicosis, however, in the mode of distri bution of the fibrous dean in the lungs, in its more rapid development, in its radiological features, and, there is some reason for believing, in a lessened anseeptihility to the subvention of pulmonary tuberculosis, the liability to which disease is so <l**"**1y an added hazard in silicosis. ' Tie Asbestos Bedim.--In tho tangs of those exposed to asbestos dost, angular particles derived from asbestos,' and spicnles of asbestos" are found on microscopical examination, and also numbers of pscnlinr bodies described by Cooke and Hill' and Smart McDonald*. They are yellowish brow in colour, of elongated, bead-like firm, often with bulbous ends. Cooke* and Uo.rihouse Gloyne* independently demonstrated a mineral core in these bodies, evidently dcnvr: from the asbsstra fere. Stewart and Haddow" hare also demonstrated their p.esence in the spntmn of asbestoe workers. Them bodies have not been lonnd to occnr in any ether human affection. They have been found in the sputum within comparatively short time after exposure to asbestos dust, and in the absence of dimcil or radiological evidence of pulmonary fibrosis, their presence cannot be taken at present ss indicating anything more than previous inhalation of asbestos drat. . . Tie Jnridnet ef PrHtemnro Flhroris t Alberto* Workers.--Ths extent of the rink tn health associated with exposure to asbestos dust under present indus trial conditions may oow 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 nf dust. Ten of these, and- one alter in which Umiw were earlier signs of the same condition, hare been exchwlni from further consideration, inasmnrh that it was felt that previous work in nthor rlusir orcuimtieoa. snrh as qnar-ying, and real mining, may have hem the prime or a contributory factor in the dsrrlopmrnt of the pulmonary lesions found. * If * A A I - 10 Tliuf. 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 11 Yu* 4-4 II ___ ... m 1S-M lfll... ... IS *"*r Taisia ... j M e HI S4 a tl SI Cmm af FlbraM Avana aa ia raan. ' Mm i :o M f ST j . is 1 . IT . Qraap 01 ^T U" ! Otnomot Isaidaaai par - (ML afrikrada. j -- tt'S SS'I U- se*s t. ** i M'S } S4'4 1 41' M-4 M'S 4S*4 4S'S Si'? j M ! M'S ! M'l 1,: 41*4 l % ip Craap. Up to IS -._ ... SO-SO _ (Ml,, MSS... to sail MT ~ Tiuii M 11 Tails !.--iurJtiriue of Fihrusio- retalire lu Ay*. Siaisr SuaiaaO. Cams ml Fikraai*. Avm|i Ih|Ui o( mpltyaisi im jwn. * - Kaafcar. Qraap Of Grain lata In'iUtira liar . toL ' ... i riiam. Ot caaaa at Fitrai. ts * 0 1M 14 1M SO 4T SI ts 11 Ms _ a so-* ** 37-0 . a-* -t S-l IPS T IS-#.. . '_ 7 lt-t U-t 10-* 10-J Stt ts M-< T*S 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, -end 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, opening, 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 ineidrvic rate of fibrosis in group 3 (termed " spinners " for convenience) as compared with each of the other groups. Then is some indication also tUt among*.* " spinners " tho discajs takes lonccrio derelop. Stmlv of the radio gram*. ' , reveals further indications confirmatory of this. Moreover, cstima. lions of dost content of llu* air in tho neighbourhood of (hoc processes am! in Ih ' il*ni in the vari. a* groups show that tho evolution i f dust in sroun 3 is ;.b lattvdy low (Tal** 3). . V . Jr / > ' ~1 In fact, the history, and tbo medical and radioteeicii 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 n 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.ulation of dost in tbs lung ha 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 the lowest incidence of fibrosis, but it forms the largest individual group in these sections of the industry---about one third. Bmativ* Dustiness of Various Asbestos Processes.--While some reference ben to the varying amount of dust evolved by the different processes is necessary, the causation of tnese. differences and methods of suppression of dust 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 proeessss 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 the 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 short 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 various 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 ere expressed proportionately to the spinning, plaiting aod braiding group, tairn as-uaitv. Tt will bs seta from this Table that the dustiest piocesses are opening (with old fashioned teasers), sieving (with no local exhaust ventilation), and shovelling or otherwise handling asbestos fibre, with a comparative fieure of 2.34. The haviast counts of all 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 denes, with much dumping together of the dust particles, with the result that dm total dust count arrived at was undoubtedly too low. Next in order is dry doth Sheaving without the application of localised exhaust ventilation, with a figure of 1.95. This is undoubtedly a dusty prccr-s. and although local exhaust ventilation reduces the count at the breathing level of tho waver, mnch dust still escapes into the workroom. Waving doth wot, not merely damp, reduces the dost count to a remarkable degree. Column . Taolz 5.--Relative Dustiness of various Proeessss and /. *ts of Localised Bshaust Ventilation trod Damp Methods in suppressing Dust. Sri--< BraMias. FUitilL till--t 1--el efcaeaa --til. MMM. TO t TstiaS Oath. Canties. Tilb larel Hte--a Dry- veliW With--* i With alias. i-ei ; Wal Wet. --in--t -ik-- netii- 1 miik m Mas ' a Mas c> r,, "tfl 1-1T l-* | i-ej -as~ ' BariL ' ~ jDtt. ilk 1 tanl 1 aheera i Was --aliU , m' -! SI Ifettnaa Ibkias Brr. vithaai laral aahaau ama Drr,* *ith nkamt Taat:l- Dana.* *itli nkmi rnii iU alias. a : om !** M s Oeeaiag id kaaMliae O-- V, rithni Isai nluxi aliaa. nn S-J4 * !C--e that kwl ife-fhiinl mitibta., mu ifwitl pwnl mtihliM M the nitmi --1 1. , --a, Mt --aii--l-t Ik- Ht  ` 13 f 7 lor land (i.o., narrow) wcaviug, wet, is not accurate since die figuru lias been Ii 0 I 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 r1. . {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 i %* i 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. ' i 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. i 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 r 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 i i_ I '!! * i 1 i. 4i i i i i li Table C shows the average age and length of employment of the case* of fibrosis in the grutipa of processes previously dealt with (p. 11). . v Tabus G. * ' I. OfMhiaf, diauriagming, aix.iag ... a Carding .. ._ ... ._ .. 3. Spiaaiag, tvittiagrdaabliag, plaitlag. tea. ... 4. Millw flukiag ... ... -.....................- a Waaviag-UKl aaamriitfart pramoaa ... ,TM a til--lliaovt piMnu aatl rtuaiaing ua> aliaiM variiaia. . -* iMtli ~ ~. _ -- Cum al Fil--aia. Ann(i A(a. range Length of laplojrninl U-l je*o ai*o S3' I 43*3 . ** ' l<i*0 li-t 13*1 13*0 IS*7 13-3 13*5 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 . unsnyst Workers employed m Groups I, 3, 4, 3,'taken together (more dusty processes). Tina Inum. 8-4. 3* 1044. 154& Saad one f r A * Amtu^m i 1i y 1f i* i 1 f * 1 rj ii Js i* <3 i 1 1 SS <3 4 a a 1 Piwpl- -- 33 Qmpa l, t, 4,3 4T Ctotae tagaifcart. Far S 40 Far % 3*0 30 Far cut t S*T It M SI 33-T 43 S3 43*3 14 Far east. 4 St-4 * Par not 4 4-r S Sit 13 11 14-4 Qmp 3 m Spinaiac. WriuC laaSlias, plait >hc, tic. Cc--pa 1,1,4, SUr--Siaq.ta,fdias. --It --fciac lad ororiag mat maiiltl procruc*. It will be seen that, after 5 years' employment, the rates arc consistently much higher a-nengst 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 alxuti 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 clearly due In aslutUt* dust was found among-.: workers witli lex* than 3 yront <*\pcwair. 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 pro liferation, 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 hlirosis 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 investi- I 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 . ret'CMcd clinical, radiological and sputui.i ex aminations confirmed the din^ ioais. In an 11 111 case, post mortem examination showed that a lobar pncnmni-in 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 <*x|nMtifV to arlmtns dut iu these eases varied between 0 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. ~ jPreerm 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 'pBfim-alhtBk fibrnsi^lxcept in stages of tht 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, the fibrosis of the 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 up 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 treatnn-ut. Thu than tends to be a drift of such cues frm the fibrosis producing industry. In fad, during the course of the investigation, information was * obtained of a number of persons, previously employed in asbestos, who were either at home or in sanatoria, suffering from chest complaints. Precise information as to the incidence of pulmonary tuberculosis amongst 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.iary tttier;ul;sis. eitii: amongst a*lvs: e* 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 disiioct type of fibrosis of the lungs, resembling silii-usis in its main cliuuol aspects, but differing from that disease in the mudu of distribution of the fibrous tissue in the hugs, in its rudivlogicai fcatnrrs, in the enhanced rate .if development under arrrnsre -ndirinns in this country, and as far ns the evidence gees, tu a lower t-cptibility tu tlwiqnirvcnriou_u'f pulmonary tuberou Ionia.* * TW --hIIbiI sad mliuJugicU ilala UaiiMpI 1m Ibia iMTaSi^aliaM will bn |mUwJi<nl lanwlicn. 17 jcs'ou tEd production of the disease. ElugISeit uTtficL PAgw'amPscx^Kavc * no "apj>aruu t Factobs Dmjuiwmc nix P&zskmt Rrcocxmox or tbs Ajbxstos Funoais. 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 by tbo 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 TSssmMnnn 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-' turn 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 examine- tisa 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, aad 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 par- tides 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 pa**iug 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. Tattcrsall 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 Cowuiittoe on Compensation for Industrial Diseases. . (a) Minutes of Evidence, Appendices and Index, 1907. Cd. 3400, p. 127. . . (ft) Report. 1907. Cd. 3495, p. 14. :. . 3. Cooke, W. E., Brit. Med. Jnl., 1924, II, 147. . .-.. 4. Cooke, W. E.. Brit. Med. JaL 1927, II, 1024. * 8. McDonald, Stuart, Ibid. p. 1025. -1 ` * 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 ->L . 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. 1 ; i;' ' " 12. Wood, W. Burton, and Page, D: S., ' Tubercle ", 1930, XI.^ ; | PART II. Paocxsszs Grvorc Risz to Dost amo Mztsoos rox rrs Sctmixssiox. ', . L--Ixt*qductiox. '* * i; . 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- iag materials, sheet mau-> i;;l 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, cahirs and wiring, tv'-" 4 for clcrtric machinery. (p) Mi-ifUancms, including moulded elertriral and otltcr nmls, etw\ Smite faitnries make hntli textile and nun-textile goods. Sven It,-. I QUtrizod '' atlrslrw, i.r., opened nr hrnken-up material in a fi:> 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) yarn ; woven 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 om 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 '* ashestos " 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 Ituildingx. The cable and electrode factories nrv alnp modern and generally suitable. * 80 Some small works, more particularly those engaged in making boiler com- jusitioiui, are unsatisfactory. A few are mure opcu-sulcd dials, Siu-h premises are difficult to keep dean. - Sums works are congested- with plant -and stocks of material. "Hiis may result from iundi'quate ncuouiuiodatiou or a temporary falling-off in tlic demand, but tlio effect e. cleanliness is liad. Tlie dust evolved in manufacturing pro* itnn is more difTicnlt to control if the premises are unsuitable, particularly if crowded willi plant or material. Cleaning is oot easily accompluimd aud the dust is more concentrated.- The arrangements provided for ventilating asbestos works ;| ary as in other industries.. Dus* removal systems, where used, effect a measure p general 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 are but little used now and would be unsuitable. In one mattress making room extraction fans connected to large overhead hoods re used. Extraction 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 eonld not be -uceess* ful without efficient heating, owing to the rapid change of air entailed. Separation of ProetsrosJ--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 other wise be immune, or to a greater risk than that arising from their own work. In a faw textile factories crushing and opening plants are placed dose to spinning and machines. Spinning frames are installed dose to looms and wet and dry weaving are carried on dose together. In non-textile promises there is more effective separation of dusty work and processes from non-dusty. ' 3.--DucsxrmiM or Pxoczsszs ass Puvzsttvx MiAstrax-v dt * A complete account of manufacturing methods is not attempted. Attention is mainly directed to the dust-producing processes, a description of which, in i!! t.1 ': f .f brand outline, has been deemed necessary to make dear the circumstances under which exposure to dust 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 in certain hitherto dusty* processes. On - II ;! the other hand, certain developments, e.g., speeding up of textile machinery, and the increased use of asbestos in various industries, may intensify the dust problem, if adequate measures to deal with the dust are not taken. * . Tkxroxs. (a) Yaxa and Cloth. . The mannfactnre of asbestos yam and cloth proceeds on the whole like that -of other textiles, but there are some important differences. Fibcrized aud ether ubestos material is freely handled in various operations, in gathering ii "waste,'' and iu cleaning. Exposure, in some degree, to asbestos dust, is common througlumt all the factories, but steps have been taken, extending ovci many yenrs, to dm! with dost produced at various poini-*. ilunigh the necessary i diwss gf efficiency has, generally speaking, not been reached. Exhaust vcntit.i. liiMi plants used in llc bc!-*-uipjtxl asbestos factories fur removing dust appear to ha ns efficient as those used m other textile industries, and < have beat applied r over a wider field. As regards other safeguard* against dm-. c.g.- sn-^titution of mcclwnicnl methods for iandwork for feeding the m;u lnt*- muii.u-y opemtions, efficient enclosure of machines, and vacuum method-* *' `'-caning, lut.e development has been made. Qpr.hiart. --suitahk- for yarn. Tins usually l l* .r"' 1,in,` 1:1 n'l CS "ojiriH-d " (" filswiznl ") before it is ready for ear.ljn*. ' t_o_rTv provf**r* are effected lv machinery, lmt eulad non h *["" ing (lo retmivp iron) ami grading nr sirring follow crushing, m i I ' ' t 1 . Material for yarn is nut usually treated in disintegrators, 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 eiose to the machine, the eoutents 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! through a Inttom delivery slide, usually filled iute sacks or skips aud, if necessary. ' weighed on a portable weighing machine. A few edge runners discharge upon abort inclined lattices and the material falls automatically into tho tack or skip. Edge runners give rise to dust of considerable amount where short fibre . is crushed; some are cncloced and have exhaust applied. This is always neces sary. Pan mills an not enclosed and also give rise to dust, though less in amount. ' ' Handwork, e.g., sack emptying and filling, mixing, shovelling and feeding machine pans or lattice 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 sack emptying apparatus. Automatic delivery and reversible bagging lattices eliminate dust produced in hand Ailing of neks, 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 bting delivered to an elevator. Enclosed apparatus should be adopted. . - f.iwU--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 done) and exhaust applied to tho machine enclosures, otherwise unnecessary dust is created. Some oscillac- . ing sieves an very open, tho material being allowed to fall on the floor, and being filled into sacks by hand. Very dusty conditions an then inevitable. Efficient eodosun with exhaust draught applied and, to avoid hand filling, automatic delivery and bagging lattices, also enclosed and exhausted, as 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 effected 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 cut through the mass. Admixture with a small proportion of cotton may ate be achieved by blowing it into the feed opening. The opened material is - delivered upon a lattice and collected either in a large container or in sacks, automatic boning lattices being used in soma cases. Mechanical feeding under - --*"--* contritions, with wrhaust dranght applied to feeding lattices or other oocveyors, should bo 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 ii it is not done and thit machine mixing has been tried and gave less satisfactory results. If w**'"TM*. it should be 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 exhautt applied, as now done in some cases; otherwise dost is evolved. ', Opened material not required at once, may be stored in open bias in the . workroom, involving emptying and filling sacks or skips, which necessarily canse dust. This storage in bulk should be avoided; alternative arrangements might be adopted which avoid dust. Son" nuilumi, o.g.. long fibre waste from later processes, is opened at enclosed lattice-fed teasers or w i'Ihw*, not infrequently of primitive design, worn out, aud emitting much dust, notwithstanding that a fan is au integral pur. of the macltiao. These old machines should not bo need for asbestos opening. Dust may bo emitted at food points of modern machines, particularly when iho feed is irregular. Exhaust is necessary at the feed lattice for this reason and also Iwcaum: fording itmdf causes dust. The material i: cither discharged u|mn a lattice fur immediate collection, or blown into a chamber. The standards suggested fn^ frighton machine* idmold 1st adopted. . 22 Hopper Lattice feed* .are largely used with 0|)cuii>g machines; the hopper lip> an about U feet C indie* above llnor level. * Much, dust is produced in shovel- fceding tut it is diilieult to avoid sroUcring at tlie lip. Am. unclosed lattice, fed at or just below floor level,with localised exhaust applied to the enclosure is wore satisfactory. ` "' ' . Single 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 are unsatisfactory; it should be accomplished at a covered beach, suitably exhausted. Whereas in eowc eases, the indraughfat 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 dust to eseape, a " relief balloon " connected, or applied. Chambers connected with disintegrating end 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 seeks 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 desirable. (Soe page 28.) * Cording.--Considerable developments have taken place in recent yean. One or two important new cordrooms have been started. Many new machines, including seme of foreign construction, have been, installed. The machines, of large overall dimensions, art of the roller and clearer typo. Modern cards art of high class construction and fitted with two dofier cylinders supported an a carriage, which can bo racked into or out 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', la eases where the sliver is collected in cans, a Derby doubler is used for prepar ing laps for finisher cards. .. - - Single machines and breaker cords art equipped with hopper lattice feeds supplied from slaps or sacks, haadfnls being dropped in, ana shaken apart as fed, or the seek emptied into the hopper. The asbestos falls intermittently upon a creeper feed which conveys it to the " lideer-ia " fsed rollers, between which point and the dofier the material is under enclosed conditions. The material is combed from the open doffsrs of finisher cards, as a web or " sheet ", the sheets from the two dofiers usually being combined at a con denser, and the molting sliver yam wound into spools. Occasionally, combed web is collected without being condensed, the condenser carnage being with- dmtin. In ether carding, the sliver may be obtained as a lap. . Admixture with cotton is usually accomplished by 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 obecrrvd in meet cardroosu. Suppression of dust cannot be realised unless machines ere maintained dean and in satisfactory repair, and there is effective enclosure of various parts. Above all, localised exhaust must be applied at wsD-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 parts arc enclosed below in metal. The frames am well enclosed at the sides. hinged metal cover, fitted in some cases, pre vents evpr of dust produced by movements of the feed lattice. A curtain nf fabric is lew* satisfactory. Ta older types, particularly, the tmvr* may- net fit satisfactorily, the cylinders may not be truly aligned with liic frame anil other d feett may account for side eseapa of dust, not cnntroHa! 'n .by exhaust. Such defects slmuld hr remedied. Creeper Veils, ilnffer* and condensers and connecting bi.ttirrs between hivakcr ami finisher ranis arc not enclosed. Dust fat evtdrrd at duffer romlsi and at rrreper feeds. .- I *3 Localwed exhaust vcntilatiou was first applied U> canling madiiucs n:.:ny non ugo. hlctiuxls aud apjiarattis hare since Iwen gradually improved atid 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. Apart 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 braaeli 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 duct, 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 ia 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 rarriages 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 about ten minntes and is nsnalty done in working hours, but in one.case, at ler.rt, after. The men press their " strickles '* or flic baud 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 centred 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 dnst is therefore carried into the general atmnsnhere of (he room. The Henners wear respirators or " helmets." Tn a few rases, more effective measures are taken, e.g.. the opcned-ent machine is nlmmt entirriv endowed with high eanvae-cm-rrrd screens. In the % 14 . work* where cleaning Ukca placu after working liuttrs, 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, llie small amount of uu produced is chiefly of a metallic character. ' Is Uie factory whore grinding and cleaning arc combined, the doffur cxluiu arrangements arc first re-conuccted. Mucii less dust is evolved ami 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 th*u hand strickle and less dust is evolved at^a particular omcn. Is another ease, a vacuum fitting is under consideration. Previous use of wvcuu: stripping was given up because of rapid erosion of the roctnl pipe bends and othc narts Unless effective dust suppression is realised for stripping all worker:, other than strippers, should be excluded while it is in progress and for soma tint 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 hearie: ddbris, precautions which are not always taken. The machine is either inJtallec is the carding room, or in a room adjoining. Independent machines should bi provided to deal with rollers of different lengths, otherwise inconvenient adjust masts, liable to be neglected, have to be made. ' Card Sidt Wattt Treatment.--The irregular/* selvedge * of carded fibre, Marated at the two tides of the finishing card being unsuitable for sliver yarn, is removed by suction draught to a " side-end " machine, which prepares it for farther ntf, The material it blown upon perforated cylinders, the air escaping at tha side and the material being discharged on the floor- The process produces dnst, particularly when the feeding is irregular, the air then having a free path bstwwn 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 ourr uu to 80 niudles, 40 oo each side. Much piecing is required owing to the oompantiva weakness of the fibre. A fioe nittal thread is spun with asbestos, for V*1" and certain other purposes. Mule spinning is not practised m this country. A large amount of doubling is earned on. hitherto, hot expcnnvi--___ _ planptr,eepmarbeoddytoinegq0u)ipevalilaluispsird.nueir:g* paasrJaid.Viul bwlinthgtfhreamfreasmewdi-h ^?ntd,ation (si) for more effi-uiw concentre; ~ 1 *pmciJcs, and lower parts of the frames *=! wunhlaenss nspeerrcsiaml rgy..*n. iS.ducih.m--i!a:i- .i pr^'filed. irarpi*f.-\V.n.. hram* ar- ,-rrfs.^i in the iwial way fmm ertefing frame5 oiaofcfsasmflekai-rldel .ocixmtilrilait'iiliiuinnitnnIt.r;Iiiultli\k*ilitniiMo>iu(il.wi<.-n>) rcr!ri.r-.gjt+aa:i-|ttrtfhaewnitnhrlnie~wivlmtenffcctiw. .,^_'*_ , . pnrtitior effect improvement. at W levcl v I 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.'' Wi de 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 ba led under the loom, . and 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*Hwiicnl 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 eft difficult. The 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* litui 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 carci done, so that very little dust is created, other precautions may be unncccunr NoN-Txxnucs. 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 fiberixed 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, coiuparabls 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 $> cel 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 enclosed: 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 bs applied at feeding an deavery points, where 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-circulatec; 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) KQXboard, Paper, Sheets and Tiles. - The wet mixtures for millboard, paper, end asbestos-cement products are prepared in a beater, as used in paper mills. Dry fibcrized asbestos is emptied into the beater trough, the sacks being shaken to some extent. Evolution of dost ocenrs 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 tbe process is repeated a number of times daily. Precautions art not taken at present hut the dust might be avoided bv (*) mrehuainl feeding under endosed conditions, as appears to be done in wine foreign works, (b) applying exhaust draught, (c) feeding in small quantities and in such a way that the material it wetted at once. . Finishing pmcrwo 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 ncccwary though not applied. Similarly, turning, filing aud smoothing of dry usbcstos-cewcut pipes, at lathes, nmy require exhaust to renwva the dust produced. ' * * Synthetic competition sheeting, sometime* made in a rubber department,' is produced from dough consisting of fiherized asbestos and rubber, mixed with solvent in kneading machines. Dust is produced in feeding llic mixer with asbestos, dene in an o]>eii manner by lunul, from sack* or skips, the tacks being shaken oat, or from an open Lattice feed. Subsequent processes arc dust-free. Exhaust should ha applied at the 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 pneumatic conveyance pf the mixture to automatic sack fillers. Weighing and feeding the fiherized asbestos gives rise to dust for which exhaust is naecfMary. . Fiherized asbestos or " magnesia " is a component of many insulating com positions which may also contain clay, Ideselgnhr, fossil meal, flax, hemp or juts waste and other materials. XIte proportion of asbestos in the final product varies widely. Ia 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 such 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 fiherized asbestos, an 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-earnest 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 movement, end fed 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 the sides of the work benches, and on the floors, a considerable quantity being scattered. Dost, produced in manipulating the dry fibre, btfon treatment with the silicate of soda, is largely avoided at the 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 deput of cnt. Localised exhaust alone, not yet applied, may prove inanffident. Sostions and Slabs.--Moulded insulation is made chteflv in two forms, sec tions--semi-cylindrical and moulded hollow to suit various jpipe sixes--and slabs, which are rectangular and solid. These products are usually moulded wet, either by band or machinery, from a paste or ergani, premia red in a mixing machine or tauk. Feeding of drr material involves evolution of dust v hidi might lx: avoided by ono of the methods suggested for feeding beaters in niilllmard making. Sections are made at one factory by a dry proves*, at a machine indifferently enclosed. Ford hoppers, filled from"skiiw, deliver the asbestos tn internal lattices which iit turn supply a travclliug Imnci, at which the section is rolled by hand. Semiring brushes which dear the lattice and spread the material evenly on tht* hand gin* rise to much dust, and dust is pnslincd at tlx* Itoppers, and in rolling ami brushing away mijvrfltmos material. Exhaust draught, not hitherto applied, is to 1 provided at the cx]"Hod brush and the machine is to be more effectively enclosed. An enclosed- " feed " is also necessary. Thr arvtinns and sblw an* trimmed to sin? with circular nr baud saws. Mnrh dust is pnsliuvd ami exhaust draught is rnntnuntlv applied. Imt is in some raws indlN'iimt. Circular mws uwd in mnuc eases in |irs. fnr trimming ends in nor operation, ran Is* fillnl with oxlumst l*<d* ataivr and Ivlinv tlie Ix-m-lies. and band saw* can lie cnclmcd hulow tlic tablet and inverted hoed* fitted, exhaust draught being applied .ik for woodworking iiiadiines. JEilicieut arra: owiite should bo readily practicable for all cawing work here. . UaUrwes.--Mattresses are manufactured by practically ail firm* v. produce imeuiation 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 lu seamod and filling done from both ends. Before fiUiug, covers c tamed inside oat. Supplies of filling material, which usually, but may ru contain fibemed asbestos, are brought, in sacks or skips, from chambers, or tak from o]>ca 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 ma`eri*l 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 the 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 bandies are entirely open. Localised exhaust draught is not applied. Qna firm have improved conditions considerably by the following pre cautions:-- W(a)-Keeping floors ana benches u;mp and spraying covers before filling Hose connections and spray fillings are provided. Sub-division of department into several independent workrooms (e) Exclusion during filling of til workers no: so employed, the. excluded workers proceeding to another section. - (d) Mechanical ventilation of each room by cron ventilation, embody lag plenum supply (warmed when necessary) at one side and low level extraction at tbs opposite side, tba air being changed between 10 and 2C times per boor. (*} Enforcement of use, by fillers, of respirators. These precautions do not include application of localised exhaust ventilation, without which mattress filling and beating must involve some risk of inhalation of dust. For small mattrssses, a wide doable-sided canopied bench with exhaust draught applied at gratings along the centre line might be tued, the filli material being supplied within the canopy. Snth a bench may uot perhaps practicable for the making of large mattrenss 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 calcn* -ml at squaring r>H and in all cases tin mils art eased out to sep-'-ate them a little, so ensuriug : . :rough treatment by the liquid. A little chut is produce-1 in t:-sw o]K-r,tion* hut irsuflicient to render sfiwial prccautiun.ir neanurot ih-mt-wi rv. Ollier prqmratory work on " grey '* arises in the m.;ki of special lining*. Lengtiik of doth are lightly hanm-red to rrug shap* templates, then cut with chisel nr shears aud the radial edges *.-wn tngctlu* win-sliu-iitng machine, a* used in Imok-liinding. Dim mvtini in hammer' Stitching. A caiMip'-tl liciM-h fit In I with lm-aliwd exhaust .irnui-rmcaU provided and I hr machine jihiivd under exhaust draught. *3 . Dry impregnated material is shaped and finished mainly by |.<i\vcr-drivcn machines, e.g. knives, circular and goillulinc, cutting prcsae*, hydraulic wjnecxing prases and bond saws. Cutting aud sawing expose cud* of wire and leave rough edges; trimming and smoothing, done on grinding wheels and linixl.ers, are aooessary to obtain exact sitt and finish. All tite operations, except squeezin;, produce 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 exhaust 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 the same machines when used for metal grinding. The position is similar as regards linishers, a hood being fitted in line with and at the back of the band. A baffle plate to prevent dust being carried past the hood by the high linear speed of the bud ie a necessary addition. Special linings and anti-friction bushes are moulded from disintegrated impregnated waste. Some dust is created in the filling of moulds ud efficient localised exhaust draught may banecessary. The articles are shaped ud finished as just described. Bushes are turned and bored in lathes, with production of waste and dust, but exhaust draught is not at present applied though possibly ' (e) Picking and Jointings. Engine packing is either (a) " doth " peeking built up from doth, usually rubber proofed on both sides, hudling of which does not cause dust, and (J) *" rope " packing made from yarn, at braiding and plaiting machinery, as naed 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, (mown as " grummet/' is made, on a small scale, from asbestos yarn, threaded on a needle ud wound in and out by hand, as balls of wool are wound. This apparently insignificant process muses sufficient dust to cover in a short timo the hair rind dothmg of the workers and should be done at a canopied tench provided with localised exhaust arrangements. (Q Asbestos-covered Esctrie Conductors. - EUctrodtt.--Electrodes are either wrapped with yarn, the usual method, or pasred through pasts containing asbestos fibre, yarn being wrapped upon this coating. The firmer method is usually achieved by a small nigh spued stranding machine fitted with a flier carrying the spools oc. bobbins of yam, the wire travelling axially through the flier. Treatment with consolidating liquid, straightening and cutting to length follow, all done at the stranding nudum*. 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 revering at one emt is ground away, leaving the liarc metal Reressarv for making dcvti icnl contact in the holder. when in use. . Small ahrasivu wii vl-. almost entirely enclosed, are used. Small amounts of dust an* projected from fliers, though insufficient prob ably to require the adoption of s|>crial pniwiitiocw. Much dust is produced in grinding cuds and efficient exhaust ventilation is ewential; present apt stratus, where provided, is capaldc of improvement. Tim pnx-nw wutihl l uiiinivssury if hared cmls wrre left in manufacture. and e!C]vrimntU dirvvivd In lliu dr-i ruble end are being, made aud give prendre of success. .Ml l'rwiwniliirj.' pruwMM in jwu- making include (i) dry grinding uf lils.wiini tulmlim by Mini 11 vertical dine grinding wheel*, led at lint ivulrv l rum ;i lioi>|*-r * above anil din liargtai Ipmii Ujc periphery intn u 1ms below, and (ii) hand mixing of Uie ground materials a: a.Luucb, involving emptying mil uf dry nutlcriiU juli> ' pans. Dual' in produced, the amount being considerable in grtndiug. J.ittle precaution is taken. Tliu processes might be accompli.-bed under uiniust entirely tadosod conditions, ellieicut cxliau*t draught being applied at point* when* dry material is exposed, c.g., in feeding. . ' Rewinding of yam is sometimes necessary and primitive arrangements may be used, the practice referred to on page *J4 bciug followed, and as a considerable amount of dust is produced, the practice should be given up. - Coifs a. ti |i iring.--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 ntacb-ues, 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 it 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) Miscellaneous. Mouldsd Goods.--Soma electrical insulating fittings are moulded from - varnish-impregnated fiberixed 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 practicai.lv 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 taming them ever. localised exhaust may bu necessary for final trimming if done at abrading wheels. Moulded articles made in other, erodes may contain bat a small proportion of asbestos, although a large quantity may be used. In one case tbe asbestos la sieved after drying, both operations being done in enclosed inachiues, and, in addition, dry mixing, done 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 applied at (a) the elevator hopper, (b) the storage chamber above an intermediate'ragging point, (e) the dry mixer, and (<f) 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 were provided into which the trays could be inserted. Localised exhaust is necessary 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 Liter* is handing and feeding of dry material in preparatory process!**. will call for precaution* as previously described for similar work. . 4.--Sacks. In a few cases sack* of sailcloth nr other close!v woven material are used inside tlf factories. Such sacks are much to lm preferred to t!..*e made of tlu*, ordinary material, which is " leaky " and gives rue to dust in handling. 0.--Clsaxixu or Wonsfi. Macimnwiy .vxn Sack Some faHitries are kc|it in a more elennlv state than, oilier*. Imt higher standard* and improved metlssl* are durable generally. Weekly cleaning by drr nu'lUsls i* grmwnl in n*\li?e factories. hut is more effectively done in >mc 1 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 dusty operation. Young workers may be.seen on carding machines brushing dust into the air from tlm covers, etc., in considerable amount, near other workers. . Some linn* hare instituted more frequent regular cleanings and more satisfactory methods by damping before sweeping. Vauuum 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 ctauicre 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 card 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 '* mariune which does not involve such work is to be preferred. 6.--SUMKAXY ASS RXC0UUCI0ATI0H8. 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 kisr' of machines, in hand process work, and in simple incidental operations, particularly in emptying settling chambers, and in aff handling of ** finerized " asbestos. ' Za 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. iu feeding machines, in making insulating mattresses (a dusty hand procr-), and iu incidental hand work. Dust, though rarely rare asbestos, is produced in finishing operations, e.g., sawing, grinding ana other abrading of asbestos products. Thu appropriate method* for suppression of duet way only be fullv deterk -'nod when tho harmful effort, of comparatively low concentration* of 'asbestos dust 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 prernntions are also neces sary. The asbestos manufacturers are dearly confronted with the necessity of attaining renditions in their industry which will enmre much less dost in' the otmospheie than con safely be tolerated in many compareMe trades not usiiig asbestos. .' ' The principal methods fnr the control of dost are:-- - (4) application of exhaust draught at dust-producing points-. (b) substitution of enclosed mcehanivul methods for hand conveyance, and for dnsty ha*nl work generally; _ _ ' (t) effective enckwnre of dust-producing ninrhincs and plant; (-T snikUitntinn of wet methods for dry. Each of Uuwc ha* its particular sphere of utility, and llc jwrtiavlar indit-u' Uons for their adoption are put forward inter nii* in the rvctmicinl.itions Mow. BSCOHMEXflDATIOWS. - (1) Application of Efficient Localised Exhaust Ventilation at dust-producing points. . Thu measure, of the,greatest importance where manufacturing and incidental processes occasion escape of dust not controlled by enclosure or other measures, is notcssary for:-- '' (a) Dvf '-prodvciiig 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 * doffers, 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. ' (c) Chambers, containers, " cyclone." hoppers, or other enclosed space into which fiberited ashestoe or mixtures containing it are delivered, or pass. (4) Work benches, c.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 probablv that most generally applicable. It has been applied to tome only of the above machines, and appliances, bat not to hand wars. 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 roam cases, e.g., looms, mixing, mattress making. If not surmounted, an . alternative, viz., general ventilation of a high standard applied so os to draw the . dnsi-ladan air away from the worker, should be provided. (3) Substitution of tnclosed mechanical methods for hand conveyance, and for .. duty hand work' generally. This measure-- _' ' (a) avoids depositing mattrial in chambers, `intermediate filling and emptying of sacks or skips, hand feeding of machines, and other incidental hand work; . * ` (b) permits of final filling and weighing, under the least dusty con ditions, of materials for dispatch; *. (c) renders exliaust draught more effective, or, in some esses, unnecessary. .. It is already employed to some extent, and its further application, wherever possible. V- greatly to be desired. (3) Effective enclosure of dnst-prodreing martinet and plant. () To prevent of dust not conlmllwl by exhaust draught, or (&) tn rrn.l.T iu apjdii-aliiiu iimru eflwwnil. * 3S . (4) Substitution o! wet methods lor. dry. To reduce the dust given off in certain precedes and work, e.g., ' (a) a emuiderabie 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. . 5 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- <cessary 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 menwire* of a medical nature art* referred to in Part I. when: alan tin- limited valu of riatpimior* ax a aafcgiuinl in this industry j*liri.-llv* dnunawwd. I I I i i i ; i i . la** i * *, 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 .: . - >' : * * r4 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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