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FILE NAME State of the Art Literature SAL DATE 1930 DOC SAL016 DOCUMENT DESCRIPTION Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry \ MEA 2012 ors 424 424 34 | , | HOME OFFICE t I 6/6/79 TAJ 6/6/79 454 C K K K ' Crown Copyright Reserved 6 | | oN - 3 REPORT ON | " EFFECTS OF ASBESTOS DUST - . ; ; ON THE LUNGS and . : DUST SUPPRESSION IN THE : ASBESTOS INDUSTRY 7, an yy . 3 - eae a 4 af *3 7" bt at - : re a . ae . t . PART I. PART II Occurrence of Pulmonary Fibrosis and other in Affections Asbestos Workers Pulmonary Affections in Asbestos Workers . Processes its giving giving suppression rise rise to dust and : methods methods for its suppression BY E. A. MEREWETHER M.D. HM Micarena jajetur se Foxzonta AND C. W. PRICE H.M. Enginessing Enginessing Inspector of Factories LONDON PRINTED AND PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE purchased To be purchased directly mni HM STATUNERY STATUNERY OFFICE at the following addresses Adas~-ral Housz Kingsway Danilua 3 C. 129. Guerge Street Edimir i York Suent Manere ce 1 St. Ann 2 peeeee, Cacait, 15. DoncalDoncal Square Wei Peitast or through any wcw her ~ 31.200 1930 Price is td Net Wren et a es ll ep . Sad soe iad 7 fe 4 eae => spt? CONTENTS- . . Par L 1. IntroducTIOS - ---- 2. ESTRICTS OF RBIT.LYT UUst upon the Lowos .. oe I { I The Nature of Asbestos eae a i R| 3. Score or THE TVESTIGATION 2.0 oe lt J The Population at risk - eee pedis bir bet a Selection of Workers for Examination .. ac9 us The Clinical Examinatiou and Standards adopted ~_ Radiographic Examination of the Lunga one _ & RESULTS or the Inqutar 1 eget oo ie onmuwte eo Asbestosis Pulmonary Fibrosis of Asbestos Workcurs The Asbestos Bodies Sad ~~ ~ The Incidence of Pulmonary Fibrosis in Asbestos Workers con i i Pride. 2vo produce Efects of ^ geand Langth of Employment owe Effect of Work in Different Processes cd Relative Dustiness of Various Asbestos Processes Concentration of Dust and Length of Exposure necessary to produce Fibrosis Disablement produced by the Asbestos Fibrosia .. ~ m Progress and Duration of the Disease S ~ _ Association of the Asbestos Fibroms with Pulmonary Tuberculosis Summary - ee - oly & FACTORS DETERMINING THE POLLENT RECOGNITION of the ^ SBESTOSFizzosia -- 17 & Preventive Measures . we 17 selracnmth 7. THE OUTLOOK awe 17 RETIC wee IS Same. Part II cam 1. INTRODUCTION ~~ oo one Ote Z PERMISES 7 - he Ventilation 044 eee } i eh Separation of Processes ONE 3. DESCRIPTION OF Procrasts and Preventive Menten oo Oe Tomtes oe oe et a Yaru and Cluth ... 7 cod eee Opoing one we Carding oo 2 - - ove Stripping and Grinding +. 7 Card Side Waste Trenimient * Spinning and Doublir 7 _ Warping Winding ry om oe Paiting and Brad~-m swe wm WATINE so see oy _ " Chih Pjeking Examining Measuring . Pe an > 4 .? *. . 4, o 3 : . , ' : 8 . Piag . I | TEXTILES meee 20 i . Yiberising or Opening 4007 ee rea a a | . 6 Millboard Paper Sheets and Tiles 2 0 an oe 26 . ww 3 c Insulation Materials and Articles - 9 ms 0 memes 7 . _ Compositions i Consolidated Sheets . ee a 2727 re: | Sections and Slaba - ea ea we, UU IT . Mattresses ow ry owe a me ~ - ~ ~= -_ -_ _ 12 ' d Brake and Clutch Lining a 18 3 . c Packing and Jointings .. a la ei _ - = : s covered Electric Conductors 32 egg Electrodes - +) . Cabla and Wiring 2 = -_ 30 . Field Wrapping meme - 30 - 7 Miscellaneous - - - . - - - 30 Moulded Goods wee 88 4. Jacka wm em ae nae nam ate eee 30 6. CLEANING OF Works Machinery and Sates - - - - - - 30 AND <RecoumeRIecDoA umT eIIDAOTINONSS - .f I a 31 No ox Exaust VentilatION IN Astantos Works .. a. 1 I 04 (7 . x This Report was laid before Parliament on the 24th March 1930 but has not been published as a Command Paper LS os A ost aAt y Jed, 0s sob die sOaciimum em be ine te Dated ont iim ueloat cy S9: ee Oe . TRC sme ome raietry te tne ae ee Denraey cet ~ Lpuranted aa e IS RS ES re ene . The Right Hon J. R. CLYNES M.P. His Majesty's Secretary of State for the Home Department HOME OFFICE . 17th March 1930 Str oe . I submit herewith a Report by Dr. E. R. A. Merewether and Mr. C. W. Price on their inquiries into the health conditions of the asbestos industry Dr. Merewether's investigations on the medical side are of great scientific value They establish the facts that the inhalation of asbestos dust 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 age or sex The remedy for these conditions is to be found as in the case of industrial diseases in the suppression of dust The second so many of the indicates that this point has only recently been appreciated part In the Report section of the industry no serious difficulties arise as textile of exhaust ventilation For the textile regards the application . - of section it is evident that a good real work experimental will have to be carried out before completely successful ventilating appliances are evolved effectively to remove all the dust I have the honour to be Sir Your obedient Servant . GERALD BELLHOUSE HLM Chief Inspector of Factories A om oe on oe rer en (~ cm _ me new Oem .. Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry PART I. : THE OCCURRENCE OF PULMONARY PULMONARY FIBROSIS AND OTHER PULMONARY AFFECTIONS IN ASBESTOS WORKERS INTRODUCTION INTRODUCTION is during This Report based upon the data obtained in an extensive investigation during the years 1928 and 1929 Department of the Home The inquiry was initiated initiated by the Factory Office following the discoverydiscovery in February 1928 of a sceavseeriotfy ttoubneecrescsuitlaater fibrosis of the lungslungs in an asbestos worker of sufficient treatment in hospitalhospital Seiler's Case I'rior to this this DepartmentDepartment had knowledge of workers about whom there was knowledge only two deaths of asbestos dust had at least contributed expert to if opinion that the inhalation of asbestos these now referred to as the not caused the fatal outcome The first of but all that is known concerningMoint tisagcounetaiMunrreaydMurray Case occurred in 1900 Montague Murray in 1900 before the in the evidence evidence Departmental Committee given by Dr. , for Industrial Diseases In this case Committee on Compensation clinical diagnosis of extensive post mortem tubercular examination confirmed the Cooke's Case occurred in 1924. pulmonary fibrosis The second Here although Cooke and Stuart were of the opinion that the lungs showed a progressive dust McDonald fibrosis ... with a chronic tuberculous infection the etiological relationship relationship together between the -inhalation of of asbestos dust and fibrosis of the the lungs would have been by the absence of a tuberculous infection strengthened An close early survey of the industry in 1910-11 by the Department Department did dis- any evideneviden of the existence of a serious health hazard in the not but some experiments experiments of Sheffield on animals conducted in 1912 by Professor Professor J. industry M. Beattie University for the Department showed that the inhalation of dust will cause a mild degree of fibrosis asbestos industrial and When therefore infective investigation of Seiler's Case showed that other definitely causes of fibrosis could be excludedexcluded the deciding whether the supervention of this disease in an asbestos accessity of exceptional occurrence or evidence of a grave health risk in worker was an apparent and the investigation referred to was undertaken the industry was EFFECTS OF IRRITANT DUST UPON THE LUNGS The include most important local effects which may follow the inhalation - pulmonary and lungs and bronchial catarrh asthma bronchitis of dust fibrosis of These changes in stheecolnudnagrys cwhhiachncghanges es such as emphysema emphysema local or diffuse the the living tissues to repel or inmcaayrcebreatleootkheed upon as a measure of the efforts of cause interference with the irritant particles of dust necessarily general efficiency of the lungs capacity may be slight or The impairment of pending on the variety of of dust and length of dust severe and temporary or permanent dieand on other factors such as concentration exposure lungs inhalation Morcuver individuals individuals whose inhalation of have been affected inhalation of respiratory infections susceptibility of some increased dusts show an increased such as tuberculosis or pl~ as suceptiblity susceptibility to timonia . the the result of the supervention affected Fibrosis of the lungs is recognised to be the most important by the inhalation inhalation of dust and the of important lesion caused with with pror mess workers with a dust fibrosis of the increased pulmonary tuberculosis has been shown to be thte he main tu tious suurtality rate from the latter latter disease in certain cause . certain dusty cecu a- irs] 43 reaco",ter wen "2a * ee (4 ON g > of ay wary~an em tek e ren.te te oe oe ye wm 4 oO ated emda 0 owrentidebony heb LS we Ts em om ee meee t Memot Erwean e bi CG Vi \ . } yilnaers Beatrnre Ee LUST ve ar. rar Vow 6 + This from exposure to dust fibrosis of the lungs and high mortality rate and pulmonary tuberculosis important industries and in found to be common to a number of large crystalline silica SiO all of them the dust incriminated was free These features were while while there was not observed however in other industries in - which exposure to siliceous combined form dust the silica was found to exist in the a as silicate and not in the free condition Thus shortly production industrial of industrial free silica came to be regarded as the eminent fibrosis of the lungs and as a notable cause of the excess mortality rate from pulmonary tuberculosfiasctionr cterhtaein industries Whilst the pulmonary fibrosis produced by free silica and is being minutely investigated the potentialities Silicosis as fibrosis has been of dust other than free silica have not been producers certain that some other inorganic inorganic dusts fully explored although it appears under the conditions met with can and some cannot produce fibrosis in industry silica That a serious even fatal degree of fibrosis can be of these other dusts has not been produced by some a thoughtful paper has drawn generally attention appreciated although Badham in silipcualmonary fibrosis caused by dust of atno otrhtihsopcloaisnet biansarletpocrotnitnaginainfgattaol cfarseee . The Nature of Asbestos fibrous minerals " asbestos fall into the latter group the silica commercially being combined with known as mainly magnesium or iron and to a less extent metallic basos The term is a collective calcium sodium or aluminiuci differ from each other name applied in chemical to a variety of silicate minerals which reserable one another in their composition and physical properties but depends on the facility with finely which fibrous nature and flexibility Their value fibres for spinning and weaving they can be split on their resistance up into long and fexible their insulating properties with respect to heat to and heat and acids and on asbestos possess these characteristics in differing degreeelectricity Varieties of Practically either fibrous speaking all that goes under the name asbestos in commerce is the most serpentine important are or a fibrous mineral of the bornblende group of which crocidolite amosite and tremolite Serpentine asbestos iorroncharynsdotiplreactisiceaslsleyntnioalclyalacihuymdrated silicate of magnesium containing little nesium and usually more calcium The hornblende aluminium varieties contain less mag- being mainy silicates of iron and crocidolite and amosi~ e ; SCOPE OF THE INVESTIGATION essential of Asbestos is very different largely used in industry being an important prodi ts The diversity of industries constituent . essential that some restriction of the field of concerned made it -- -- -- investigation should I decided . in The manufacturing processes affected fall more or less . groups 1 those in which there is sharply into two with a very small percentage of exposure cotton to pure asbestos or asbestos mixed or in which there is exposure to a mixture of other vegetable fibre and 2 those The former dusts of which asbestos is but one a branch group comprises the main the textile branch of the manufacturing insulating materials from industry and some prelim aury processes in other branches practically pure asbestos examination The latter group includes a number of of asheshin it the dust evolved processes in which the proportion Since i is impossible ranges to evaluate from a negligible quantity upwards upwards which adestos dust is the effect on the lungs of mixed dusts of was deterniined the eoxnalmyionnaeticoonmpoofnewnortkemirrstilfotrhe tahcetion of asbestos dust itself was restricted to workers employed in purpose processes included in of this annuiry words to workers as nearly as possibile group 1 in atten dust Furthermore the effects of exposed to the influence of pure asbestos ruch as thint of free silien had be perxevcilnuidsedexposure to other irritant ditata , we - Gee mae + 7 The Population at Risk gross uuniber of workers who may be exposed to the inhalation of asbestos dust to any extent is unknown and owing to the great variety of processes concerned there are insuperable difficulties ascertaining this figure 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 works to the influence of pure or almost pure asbestos dust Some information on this point is very desirable to check the adequacy of the sample of workers examined and to envisage the problem confronting the industry in this While only a rough approximation 2,200 is the present number of persons work to the inhalation of asbestos dust is possible it is believed that about count exposed in their daily either pure or admixed with a small proportion of cotton It should not be overlooked that this figure does not include the considerable number of workers exposed to the influence of mixed dusts of which asbestos is but one and commouly not more than 20 per cent of the mixtura Of these 2,200 the sample examined numbered 363 excluding 11 for reasons referred to later or 18.5 per cent . Selection of Workers for Examination selection of workers for examination was not left entirely to chance since it was early evident that the proportion of those employed 10 years and upwards in the industry was very . amall 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 scale so as to obtain information as to the length of exposure to dust necessary before e^-ectsare manifested and also to the particular process on which the worker was engaged in as By balancing the component groups of the sample this way the enquiry proceeded it was felt that the maximum information would be obtained in the shortest time in It follows therefore that 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 clear Table 1 shows the distribution according to length of employment not necessarily in one factory of 775 workers the total number engaged on those processes in several factories Table 2 shows the _ sample of 363 workers distributed in the same way TABLE 1 TABLE 2 Years employed Number Parcentage of Total ae - $ad sce vos 10-14 ITE 15-10 ves 20 and over Totals wee Smet 48 3 200 $ 24 17 775 62.3 23 39 e-6 a-4 } 3-2 { 100 Years employed | t 0-4 =e 10-14 vos soe | woe 15-19 wet 20 and over : Tatala ote | Number Number | Percentage |. of Total a9 41 84 23 er | 84.5 38.6 | 23.2 . 7-7 5-3 383 | 100 The enormous preponderance numerically of workers employed under five years is striking as also is the very low percentage of workers employed 10 years or longer : Comparison of the two tables shows that the effect of the method of selec tion of workers for examination is that the number examined in each site site five years employment group is a progressively greater proportion of the total mmmber which could have been examined in each partientar group ; group 6748 at me rnn m te ce Rh . ey A ee ee a me oeae ee eSamtn em 8 ee es tee . ee Oe 7 rr a, t ;. in 4 oe bi, I (-~- . i iN - |; 4 b It th If i ki ). meee wae wedumetema eo ee . ne Se as. ee e te Ae . - sn as - ~- : y aan i 8 With a solitary exception all those examined were at work on the day of , + examination The Clinical Examination and Standards adopted nature and purpose of the inquiry were explained to each worker whom it was proposed to examine individually and his or her operation obtained Each in- dividual's previous industrial history absequent to leaving school was noted in detail This essential in order to exclude especially the effect of pre- vious work in any of the numerous processes involving exposure to free silica . dust and to a less 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 some of - which like asthma and bronchitis are cominon enough amongst the general population yet are also specific signs of irritation caused by the inhalation of dust whilst others like influenza and pneumonia are occasionally followed by a degree of pulmonary fibrosis War service if any was gone into especially as to whether there was any history of the worker liaving been a gas casualty at any time The family and personal history in respect of pulmonary tuber- culosis was enquired into and also as to any close association with known cases * leading of this disease in friends or relatives In approaching the pertinent subject _ of symptoms grent care was taken to avoid questions especially in eliciting information as to the existence of any undue shortness of breath " The actual details of the physical examination do not call for comment inasmuch as they followed the usual lines of a detailed examination of the chest with observations of the general health and of the condition of the upper . air passages SO Reference must be made however to the standard of normality adopted in assessing assessing the state of the lungs The appraisement of any departure from the normal necessarily supposes the existence of such a standard Every , clinician has attained as the result of experience his own clear conception of the normal chest but it is not often that he finds it nessary to denne this state in so many words in fact it seems scarcely possible to do so and this for several reasons the heart and lungs function efficiently within wide limits of applied strain and although vestiges of past disease may be present and they apparent on examination will be unimportant if they will never tax the organism beyond these limits are progressive and do not predispose to other disease Age itself has recognisable effects but for this reason alone the chest cannot be considered abnormal ; . : There is obvious disparity between the standard of physical fitness required for an air pilot and that required for life insurance at ordinary rates in- " dividuals reaching either standard can be classed as normal yet many attain- ing the latter standard have never approached the formuer Thus within limits various gradations of cormality may be distinguished and corresponding 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 as been that evinced in any large group of persons living under similar environmental conditions apart from work in dusty occupations as those of the group being considered This is neither a high standard nor a very low standard but the average standard of normality displayed amongst the industrial population of this country Reiliographic Exumination of the Lammys In addition a careful radio- graphic examination of the chest was made in many 133 cases the necessity necessity for which in investigations into the effects of dust upon the lungs has beei emphasised repeatedly by various ; athorities It was not of course Tensium to obtain technically suflicient radierams of all the workers examined derivcideriavcia as they were from factories scattere + over the country some in districts remote from a radiological centre The m of sekrtion was dietated by the neers of the situation with the object of widating material points germane to the . investigation ... the elucidation w complimiting affections tr mensuring the (< . . which progress extent and of the lesions and locating the point at the earliest prraedsieongtreadphbiyc thsiegenxsamaipnpeerabrimasnedlf finally as a check upon the human factor , . RESULTS OF THE INQUIRY : To anticipate examination of the data collected in this investigation leads in the conclusion results the that the inhalation of asbestos dust over a period of years in development of a serious type type of fibrosis of the lungs visualise Asbestosis Pulmonary Fibrosis of Asbestos Workers is helpful to visualise fibrosis of of fibrous the lungs as it occurs in asbestos workers as the slow growth tissue scar tissue between the air cells of the lung wherever the in- haled dust comes rest While new fibrous tissue is being laid down like a spider's web that deposited earlier gradually contracts This fibrous tissue cells is not only useless as a substitute for the air but with continued inhalation causativo of the dust by its invasion of new territory and consolidation of that already occupied it gradually and literally strangles the essential tissues of In common with other essential organs of the body the lungs have a large reserve of tissue for use in emergencies and to permit of a diminution of functional capacity due to advancing age or disease For this and because fibrosis of the lungs is essentially a local disease it is reason only when the brosis progresses to the extent of obliterating this reserve that undue short- ness of breath on any extra efort draws the worker's attention to the fact that his health is not what it should be The other symptoms of the disease such as cough are equally unassuming and are readily ascribed to some common and trivial cause . . From this point the progress of the disease is more rapid since it is now encroaching on the remaining sound tissue of the lungs already only just sumcient to maintain him in his ordinary daily activities Ultimately if no acute respiratory infection has precipitated a fatal termination a stage is reached when the lungs can do little more than maintain life and the shortness of breath becomes extreme In its main clinical features therefore the disense resembles silicosis as . might be expected It differs from silicosis however in the mode of distri bution of the fibrous tissue in the lungs in its more rapid development in its radiological features and there is some reason for believing in a lessened . wsuhsiccehptidbiisleiatsye tios stohedefsiunpietrelvyenatnioanddoefd phualzmaorndariyn stiulbiecrocsuilsosis the liability to The Asbestos Bodies the lungs of those exposed to asbestos dust angular particles derived from asbestos and spicules of asbestos are found on microscopical examination and also numbers of peculiar bodies described by Cooke and Hill and Stuart McDonald They are yellowish brow in colour of elongated bead form often with bulbous ends Cooke and Roodhouse Gloyne independently demonstrated a mineral core in these bodies evidently derive from the asbestos fibre Stewart and Haddow have also demonstrated their presence in the sputum of asbestos workers These bodies have not been found to occur in any other human affection They have been found in the sputum within a comparatively short time after exposure to asbestos dust and in the absence of clinical or radiological evidence of pulmonary fibrosis their be presence cannot taken at present as indicating anything more than previous inhalation of asbestos dust Lo Workert The Incidence of Pulmonary Fibrosis in Asberto the risk to health associated with exposure to asbestos dust trial conditions may now be considered in detail The extent of under present indus- Of the 374 workers of both sexes examined 105 were found to have a difuse fibrosis of the lungs attributable to the inhalation of dust Ten of these and one other in which there were earlier signs of the same rondition have been excluded from further ennsideration inasmuch that it was felt that work in other dusty occupations such as quar ying and coal previous been the prime or contributory factor in the development mining of the may have lesions found . pulmonary , coe . aa e a oe er . re ho. edee ePey ed rePean eSbards OT Cer OBS Boe eead ae --- --- D0 ae ae Oe Oto ermew ee mk Baw neae eatrepny A meer No 00 f m mee e ut ese el ws war Tea wee as8 = es oe pret me ne 8 ae me e be 10 _ Thus 95 of 363 workers or 20.2 per cent showed a vite fibrosis due to * asbestos dust An additional 21 were found with preeurais ins of this disease which but these are given no weight in the general conclusions which are derived sol.ely . from examination of the 95 cases of definita fibrosis Of the 133 radiographed 02 presented radiographical signs of a diffuse fibrosis and in a further 25 there were suggestive radiological changes not definitely diffuse fibrosis In 10 of the former group and 3 of the latter the changes were possibly referable to prior work in other dusty occupations or to other cause and they are therefore excluded leaving 52 cases of fibrosis and N with signs suggestive of early changes the lungs due to sufficient radiological confirmation . .. What inferences should be drawn from these figures 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 5 years and over than obtains in these sections of the industry at the present time Tables 1 and 2 above and is shown in Table 3 below the incidence of fibrosis increases with the length of employment Therefore in order to obtain an approximation of the general incidence rate of fibrosis in these sections of the industry a correction must be applied on this account Applying the rates shown in Table 3 to the figures in Table 1 it appears that the general incidence rate of fibrosis of the lungs amongst those employed in these sections of the industry is rather less than 1 in 8 or excluding those employed under 5 years rather less than , in 3 . Further corrections would have been necessary if the sample had included an undue proportion of workers from the more dusty processes but this was found not to be the case Also no correction is required on account of difering age distribution since as will be seen later the incidence of fibrosis is unaffected . - thereby Sex bas no efect These general incidence rates are convenient merely as affording a rough indication of inherent risk associated with exposure to asbestos dust at the present time They have no permanent value either as an index of the general risk of fibrosis in the industry from year to year or as a measure of the risk in any particular factory or group of employees This must be so since not only will the distribution of workers in the industry according to process and length of employment vary from year to year in accordance with trade developments but the increasing application of methods for the suppression of dust will have a cumulative effect in reducing the fibrosis incidence rate in future Effects of Age and Length of Employment 3 shows the distribution of the workers examined according to length of employment and Table + their distribution distribution according to age together with the incidence rates of fibrosis in - each case Table Incidence of Fihrosis relative to Length of Employment Years Employed Number Examined | : Casas of Fibrosia [- Number Group Incidence per rent Average ag~-in years : | Of Group leas 03343 of Fibrosis Of set of Fibrosis Ont ... 500 ee 10-14 soe 15-17 oe 20 and Grap ... Toda ce | iT) : 80 0 | 141 84 30 . 27 | .. 18 21 17 | 363 115 ' - 25.3 , 12 i { 37.6 AQ , 29-2 ; T4-2 30-3 414 41.9 34 10.1 - 06.0 101 101 - 3-2 ieee 106 weg ws we Bere e we ane wer ine ce we me ot we 8 eae tome 11 . . . , Age Group Tax dm Incidence of Fibrosis relative to dine . Number Examined , . Cases Fibrozis Fibrozis of Fibrozis - + Number Group | Incidence per , cent length years AverageAverage length of cingl^,ymeat cingl^,ymeat oo Of Groop less { Fibrosia of Fibrosia Fibrosia Fibrosia Of of Fibros Fibros Fibros - Up 20-23 ove 30-30 ,., 40-40 ** eae .80-30 .80-30 GO and over cos *** Totals 4.1 i 33 . 130 100 47 29 14 ' 303 0 14 30 31 11 9 95 - o-3 20.0 43-9 37.5 64.3 86.2 a-t 82 0.1 11-3 8-7 16.0 7.5 . H 3.7 1.. ... 14-7 16.9 > 13.5 These tables and hence indicate the outstanding importance of length of employment length of exposure to dust and the negligible effects of on the production of fibrosis age Thus age groups 30/39 and 30/59 Table 4 have incidence rates of 30 cinecnltudaenwdor3k7e.r9s pienrvacreinotusrespectively not a wide difference since the grouppes Moreover the processes exposed to different concentrations of dust cases of fibrosaivserisagaelmleonsgtthiodfenetmipclaolyibnuetntcoinnstihdeesreabtlwyo legsrsoutphsanextchleuding the . length for all the cases of fibrosis 13.5 years average It appears also from the same Table that no special susceptibility to: the dtheeveflioguprmeenotf 8o.f7fyiberaorsiss tihseshown by young persons unless it is considered that in average length of employment of the cases of fibrosis of 20.ageAsgrohuopwe2v0e/r29thheaasvbeereangesahogretoefnetdhibsygirnocurpeaastedcassuesscoefpftiibbroisliistiys 2a6g.e7s under years and also because retirement from the establishment of fibrosis does not necessitate immediate work this is largely discounted Column 4 of Table 4 also shows a general irregularity which in itself points strongly to the negligible effects of age in the production of abrosis Turning seen Table to the effects of length of employment a very diferent picture is 3 shows that after 5 years exposure the incidence mie rapidly and after 10 years increases almost in geometrical mounts Effect of Work in different Processes progression in ascertaining trustworthy figures of the precise are insuperable incidence difficulties workers in particular asbestos processes This is the of fibrosis amongst " practices in transferring the industry of housing many processes in result of the common transferring from one process to another These one room and of workers workers dust from neighbouring and prior worktwo factors the influence of processes operate to obscure the effects due to prior work in other asbestos processes in any one process according By distributing the workers however to the has been longest employed and grouping similar process in which er h to draw certain broad conclusions as to the processes together relative it is possible In this effect of work in processes diferent , way groups were obtained as follows : " 1 Crushing opening disintegrating and mixing mixing 2 Carding tristing ; Spinning Miscellaneous doubling The The incide incide incide se compared rate fibrosis termed with amongst * further grams a tions of iinn ai is ai bins 3 tristing plaiting etc. 4 Insulating mattress making 5 Weaving and associated processes . 6 processes and remaining unclassified workers outstanding point brought out in this way is the relatively of * in grup very low each of the other groups Spinners There for convenience convenience as spinners the disease takes longer to is some indication also that , reveals further indications indications develop Study of the radio- dust content of the consumatary of this Moreover Moreover air in the neighoneboon of ching estimas chers in the various various groups show that the processes and fatively low Talde 5 evolution ^'dust group - group . ws 12 te In fact the history and the medical and radiological features of the cases me of fibrosis together with the results of comparison of the dust counts all con tribute in some degree to the view that with comparatively low concentration of er dust in the neighbourhood of a process the resulting cases of fibrosis amongst we ed the workers in that process are longer in developing and remain longer in accumulation milder stage It follows therefore that in such cases the rate of of dust in the lung has not greatly exceeded the rate of elimination and a mee further point of great practical importance emerges namely that in order to prevent the full development of the disease amongst asbestos workers within the - space of an average working lifetime it is necessary to reduce the concentra- tion of dust in the air of the workrooms to a figure below that pertaining to sem spinning at the time over which these cases were exposed . Not only does group 3 show the lowest incidence of fibrosis but it it forms the , largest individual group in these sections of the industry one third + Relative Dustiness of Various Asbestos Processes some referencs these differences cece here to the varying amount of dust evolved by the different processes is necessary ew: the causation of and methods of suppression of dust are dis- cussed in Part II of this Report - e e Different asbestos processes do cause the evolution of different amounts of ee dust into the air of the workrooms and under present conditions the diference " b' etween the least dusty and the most dusty processes is very pronounced In some processes the production of asbestos dust is insigni^-cantin a second group dust is continuously evolved but in relatively low concentration as in spioning in a third group the evolution of dust is continuous and in high con- centration as in dry cloth weaving and in a fourth group much dust is dissi- pated in bursts of short duration as in emptying the fibre from settling chambers by hand into bags . Some additional data were obtained by means of a limited number of determinations of the dust content of the air at the breathing level of opera- tives engaged in various processes with the aid of the Owens Jet Apparatus The figures in Table 5 which were calculated from soine 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 dist in some of them The counts in other processes are expressed proportionately to the spinning plaiting and braiding group taken unity It will be seen from this Table that the dustiest old fashioned teasers sieving with no local exhaust pvreoncteislsaestiaorne aonpdensihnogvewlliitnhg or otherwise handling asbestos fibre with a comparative figure of 2.34 The heaviest counts of all were found in this group in sack filling by hand in a settling chamber The comparative figure here was 6.S4 but the record dense with much clumping together of the dust particles with the result was that the total dust count arrived at was undoubtedly too low that Next in order is dry cloth weaving without the application of localised exhaust ventilation with a figure of 1.05 This is undoubtedly a dusty and of although local exhaust ventilation reduces the count at the process breathing level the weaver much dust still escapes into the workrcom Weaving cloth wet not merely damp reduces the dust count to a remarkable degres Colum , Table Relative Dustiness of various Processes and Ej rts of Localised Exhaust Ventilation and Damp Methods in suppressing DuDsutst C C ( Spinning Residing Carding Carding Carding Plaiting without Wal Incal exIhnacaul st ventil | erhaust Tentil30100 ation ay Tearing ~ tte eee Tearing ee steel Cloth | Band -_- . Drg Without Without onict rentil rentil atinn 173 With With Imal ghest Trill BLIOA oo Dr. with | | Wee | Inert ot | exhaust | | Ventila : Wish Wish I | , 7 ... = Mattress MMaakkiinngg Ope ing re Withoul Withoul Withoul 10671 | are ... ... : | Athairst Athairst tralitralie e ethoxast ...'t.1 16100 i ALION | m banching Koro D without ...Sill Inst ...... venti ation ... ...... retest... ! ventil ation ... jj 1911 ' Note * Note munt munt 1.19 1.19 1.75 | a re eee that heed the exhaust exhaust betalis ah khan watch watch 1.0 ; | {cas . ventilas . manquoral barmi les les | ,Weed . ' |,.40 - manquoral manquoral griersi griergsrieirsi pertiislam n^ th"pn | "a3 0.34 actress may~-noArn - may~-n e re oe Se oa we CO o- : oT eo ce wee aries sem - 13 7 for band i.c. narrow weaving wet is not accurate since the figure has been raised by dust from a neighbouring dry cloth looms Mattress making without any precautions such as exhaust ventilation or damping floors tables and cloth follows next with a figure of 1.83 Sec footnote Table ) the Application of exhaust ventilation and damping reduces figure considerably but it may be that the figures in columns 9 and 10 are too low and since counts for some subsidiary processes such as buttoning sewing cutting out are not available the It will be observed that carding although essentially a very dusty process produced a comparative figure of only 1.17 This is due in part to partialpartial enclosure of the working parts of the carding machine but is mostly the result of the application of local exhaust ventilation Moreover the figure does not take into account extremely dusty operation of stripping Relative to the comparative numbers for the other different processes the figure of 1 for spinning plaiting and braiding is probably rather too high owing to contamination by dust from neighbouring and more dusty processes pertiesSamples of asbestos vary much in chemical constitution and physical proand of the three main varieties chrysotile crecidolite and dinosite the latter two in the opinion of experienced workers usually give rise to more dust than chrysotile in the textile manufacturing processes No evidence 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 longitudiually and apparently this process can go on indefinitely since there is no ultimate fibre comparable to a vegetable fibre such as cotton . Concentration of Dust and Length of Exposure Necessary to Produce Fibrosis the data so far examined it seems clear that ^bresis of the Jun is a definite occupational risk amongst asbestos workers as a class Furthermore it appears that the risk falls most heavily on those longest employed and on those engaged in the more dusty processes Some further consideration of these two important factors length of em ployment and concentration of dust is desirable Obviously to some extent they are interdependent since assuming that a specific quantity of asbestos dust inust be inhaled to produce a generalised fibrosis the fibrosis will result from exposure for a period of time varying with the concentration of dust in the air breathed . Siuson reports the case of an asbestos mill worker in South Africa exposed for 12 months to a very dusty atmosphere who died from 2 rapid tuberculosis sections of the lungs showed apart from the changes due to tuber- culosis & moderately marked Ebrosis Burton Wood and Page report the case of an asbestos spinner employed 15 months who died from a tuberculosis 3 months after ceasing work was generally to be seen surrounding the generalised In this case a little brous tissue asbestes fibres found in tissue but there was no fibrosis It the lung further research is gross that seems probable therefore although of the dust very necessary required for the producti . not only is a certain minimal of a generalised fibrosis but quantity tion of the dust in high concentration results in the production of that ichald of fibrosis in a shorter time than when the a more marked degree concentration is low Investigation of this important concentration of dust and length of exposure necessary to produce fibrosis the clinical side is difficulties one of the most confusing being that the existence of beset with recognisabia dif~rse fibrosis is quite quite compatible with a clinically continued work in industry and therefore the car of fibrosis discovered in he as this are in various stages of the disease with the such an investigation which they first became recognisable clinically cannot breesausltcerthtaatinethde ppoint oint at Despite this some confirmation posmie tu ashestos dust nevessary to cmmerntration of the dust in the vir be obtained of the hypothesis that produce theosis varies the length of inviseiv with exthe within certain and high limits may 6:48 (~ io wee on . ise . . e ye o o . . . , . lps . ios : 1 to? | fi : ry 4 ca wer rm +0 Z . cary 2. . e ore : i fa 1 i t : g Bes 3 ser j . so . , . : ; coe : Be . . ren fe e : .. t tem } re 0 Table fibrosis 6 shows the average age and length of employment of the of in the groups of processes previously dealt with p 11 cases a . : . Tad~-z G. * - a . . Process . ; . ; - 1. Crushing opening disintegrating mixing 100 2. Carding ... tee sae ... ... and . 1. Spinning doubling plaiting Le 4. Mattress making +4 ooo see one 5. Wearing associated processes * ave .... 6. Miacallan processes and clami^-aw,,orkers . remaining - vo Caseosf Fibrosis 7 Average Agt 43 30.0 370Q 38-1 . 43-5 . 42 Average Length of Employment rs Ineg . 13 15-7 13.0 19-7 13.6 Totala , eae : | 13.5 be The much longer average period of employment of the cases of in group least 3 as compared with the other groups will noted fibrosis There is also exposure to dust in group 3. It seems therefore that in this longer period rapidly elapsed before the fibrosis developed or that it group a progressed less This is the more apparent if the incidence rates of Ebrosis employed in the processes in group 3 are compared amongst workers for workers employed in the more with the corresponding rates dusty processes comprised in groups 1 2 4 5 taken together These rates are set out in Table 7 ; . ~ TABLE . 7. Comparison , between the Incidence Rates of Fibrosis employed in Group 3 less dusty processes and amongst Workers the Incidence daumsotnygpsrtocWeosrskeesrs employed in Groups 1 2 4 5 taken together mRaotrees we _ . : Group ... Groups 4 taken together Young ExpLOTED 04 50 10-14 15-12 ee ome {1 and over 2 Zi f] a{ Rato sh 2) 2fo) 2) over g1S3) #S1y5)3s]5]&Rato 2E/S 31S2, Ss3" ]|} 2|_3/ 23] EISS] E=|] =] 4] Z]sSi . es ed(2|"A/|E8= !2 | sls8]3 pete 3 |Nu . SIGS [etic [2 [24s |e 1g [2 Nu 3 Per Per | crat cent 30 Of 60 2] 5.0 30 Per cent 8.7 Per cent 4 3G <6 8 Per cent 4 66 | 47 of 1 92 31 33.7 43 it ry 43.9 Ty 8:ST'1 13 11 84-0 the higher from amongst employed thatGroun 3 @ Spinning twisting doubling plaiting ste Groups 2 , 5 ^ Crushing etc carding state sa making and rearing and associated process muchIt will be seen thtahtoseafter 5 years employment the rates are consistently rate is high about 5 in the incre dusty precesses and whereas not until abrit the years onwards in the 15th year of employment is reachedmoinrethdeusletsys dpursotcyesses it is the rate for t latter becomes high about 5 years empiryment in the more and approximates processes approximates to that resched after dusty processes the Exposure to different concentrations of dust together with recognition of the cases of different the effect of fibrosis afford an explanation of the in different stages of the disease also dividual cases of fibrosis widely whieh differing lengtas of cumployment of in- definite ease of fibrosis ranged froin 5 years to over 30 While with less than 5 chuirly due to asiestos list was found no years exposary the possedulity of such amongst workers cutes cocuring cocuring writh 15 exposure to high concentrations of dust cannot be ruled out found with B 3 and 4 years work in asbestos respectively was previous exposure to other dusts see p 10 Three but in cases were each there Support for this view is provided by I Professor Beattie's experiments previously mentioned which demonstrated that the lungs of guinca ex- posed for 43 and 67 hours to asbestos dust slowed delinite cellular pro- liferation though not very extensive and this is certainly a preliminary stage in the production of fibrosis " 2 Simson's case mentioned above and his report in the same paper on the lungs of a guinea exposed by Mavrogerdats to asbestos dust for 100 hours during a period of 50 days On the death of the animal from causes other than asbestosis some 32 months later sections of the lungs showed a slight generalised fibrosis In commenting on the amount of fibrosis found he states that a comparison between the hum^ocases and the Sre y experimental auiiual showed that the fibrosis was more rapid and extensive in the human cases than in the experimental animal and again the amount of fibrosis in two of the human cases was quite rapid and if due to the presence of asbestos dust the initial rate of production was rapid when compared with present day infective silicosis on the Rand " 3 data from this investigation in which 21 of the 363 workers showed signs suggestive of commencing fibrosis p 10 Of these 12 had been employed for less than 7 years and G. for between 4 and 5 years al To sum up therefore it appears probable that concentration of dust and length of exposure as factors in the production of fibrosis are interdependent within certain l^...taits While itseems necessary for the production of generalised fibrosis of the lungs that a definite minimal quantity of dust must be innaled the lower the concentration of dust in the air breathed the longer the lapse . of time before the fibrosis is fully developed and within a certain limis the developed higher the concentration of dust the sooner the fibrosis becomes fully developed and the more intense Use involvement of the lung tissue | If this hypothesis is correct and the evidence points to it the practical >' infercuces are of very great importance since it follows that the application of measures resulting in the reduction of the concentration of dust in the air in the neighbourhood of dusty asbestos processes will cause firstly a great increase in the length of time before workers develop a disabling Ebrosis and secondly the almost total disappearance of the disease as the measures for the suppression of dust are perfected Disablement produced by the Asbestos Regarding the amount of disablement produced by the development of pulmonary fibrosis in asbestos . workers a number of years this is surprisingly slight even more so than ca. is generally the case in silicosis This is partly due to the character of the a discase and partly to the nature of the work which in the majority of these processes does not involve much p'ysical p'ysical exertion The afected person may wre and often does contique at work with occasional intermissions latterly due to exacerbations of bronchitis until the condition is need although he suffers < increasing inconveniences from shortness of breath on exertion Some- times a terminal pneumonia or other acute infection commences while still at work and there is no long period of invalidisin . a There is no doubt but that fibrosis of the type produced by asbestos itself lead to complete disablement and to a fatal termination and this absence of a superadded tuberculous infection can of 8 in the g been Particulars have an advanced degree of collected up to the end of 1020 of 10 cases in which the asbestos Ebros without tuberculosis was the primary cause us death 1. 9 the cause of death was verified by post mortem examination and in the f repeated clinical radiological and sputum ex- aminations confirmed the diagnosis In an 11th case post mortem examination showed that a lobar pneumora had sunervened union langs already the sent of a moderate degree of the asbestos fibrosis With one exception all these deaths occurred in the years 1927.29 The length of exposure to asbestos dist in thiete esses varied between 9 and 24 years 675 4 (< on oleas oe e one ome ' 1 ey wy - on ee aed rt os Oe be rhefe Uaete & o. . eg con ae ee a OTee sem hee ArT + oesOr er meee - ree * ote eer OG: rary we OA eoy e te ee me 0WO6. Oe whe e we ow a) ets ehie erry wert ee enn ee Lentrmpw 6 a awe Ok 8 em oo Ome we eee Oe el! me) Oe Oe Ser emo. me te e 16 . has It is not suggested that these few fatalities in which the cause of death verifed been verified by strict enquiry are any criterion of the true effect of the disease on the mortality rates of asbestus workers Others are known to * occurred in which the existence of the asbestos fibrosis has been determinehdaivne life but no post mortem examination has been possible Duration . Discase Progress Discase of and Duration of the ^' rate of progress and duration duration of the disease varies within wide limits With continued concentrations of dust the fibrosis may be fully developed in exposure bys froiu 7 to 9 high anpdermioady cauo setdh eae thrafter about 13 years exposure exceptionally items years items items items diminution the concentration histories andustan There are definite indications derived from the industrial histories and ex amination of workers that a in y air breathed either by change of employment from a highly dusty the ton one less dusty or the effect of methods taken for the suppression of process dust of this period of of the mia prolongation maturation refolis While this so lite stages of the fibrosis disease the existence in the cognisable degree of the asbestos fibrosis in a clinically re- of ! adverse factor in the prospects of recovery farnoym ianndyiviadcuuatle iisna fnecatdidointiotnhael lungs such as pneumonia or pueumonia Association of the Asbestos Fibrosis with Pulmonary Tuberculosis previously mentioned p 6 silicosis the fibrosis of the lungs due to the inhalation of free silica dust tuberculosis in that has an unhappy association with pulmonary there is a much increased liability to the supervention of the latter disease amongst silicotics It is of importance therefore both from the point of view of the individual worker and in its bearing upon the of the preventive measure required to enquire whether there is a scope similar liability attached to the asbestos fibrosis It will be remembered that in this investigation the examination of workers was restricted to those at work at the time of the examination and therefore nurcher of advanced cases of fibrosis and a number of cases of tuberculosis or without an asbestos fibrosis in pulmonary either given up work or who were off work addition had missed temporarily will have been Moreover the supervention of a tuberculous infection the subject of fibrosis produces an increase in on a lung already or disregarded and i+ duces the worker to seeskymmpetdoimcuasl pardevviicoeuslyHeunnisotitcheedn appropriately advised to give up his dusty employment migrates from the in- dustry and may or may not accept sanatorium treatment . periodical Thus there tends to be a drift of such cases from the Ebrosis industry In fact during the course of the investigation producing information obtained of a mumber of persons previously employed in asbestos who was either at home or in sanatoria suffering from chest complaints were Precise information as to the incidence of pulmonary tuberculosis asbestos workers cannot be obtained therefore in the absence of amongst - medical examinations search of the in the industry without prolonged enquiry involving the records of local sanatoria tracing workers known to have work in asbestos and examination of death certificates and of the ceased records of firms where these are kept sickness . did Nevertheless with these reservations the data obtained results did ner disclose any entstanding susceptibility guli amongst asbestes workers as a class or amongst the cases Ebrosis . Summary of a defuite The outcome of this investigation is to establish the existence a distinct occupational risk in the asbestos industry . of This takes the form of type fibrosis of the lungs resembling silicosis in its main aspects but differing from that disease in the mude of clinical distribution abrous tissue in the lungs in its radiological teatures in the enhanced of the the development muder average conditions conditions in this rate er goes in lower country and far as the evidence susceptibility to the supervention of pulmonary tuberculosis eth provinThaerastbesteosThcearaussbeesstos concentration truncheons truntcrunh cheoens otrunchn eonstrunches ons truncheons The being causes provinate ee eee concentration medical and radiological concentration concentration of dust the aft concentration eee -- err ee aft aft stata ubtashori i bitta inteligating inteligianteligatting iintelnigatging will breathal and lengthlength - ee length be purbilenud purbilenud olaywhere olaywhere ry . 17 those the hendenes hendenes ratoris highest dusty la padangoskopi the hendenes hendens ratoris highest nem momsostt in the dusty pro cases anwingst those Age and sex and employed have no apparent influence of the production of the discase . Factors Determining the PRESENT RECOGnition of the Ascestos FIBROSIS It is of in est to consider why it is that this disease has only recentl . attracted noticed noticed become a problem in the industry although asbestes was- - known to and worked the ancients ; . Many factors contribute to this position some dependent the usture of . the disease some on the phenomenal expansion of the industry others on the 1 advance of medical science : cd e . While asbestos has been known and spasmodically worked for hundreds of yers yers it is only in the past 40 years or so that it has been commercially exploited to any extent Not only that but it is less than 30 years since the great expas sion of the industry commenced Even after a number of years 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 symptoms of the disease in its earlier course its covert advance by imperceptible stages its points of resemblance latterly to fibroid tuberculosis with which infection it is sometimes associated and the migration of those a^-ectedfrom the industry have all com- bined to delay its recognition as an entity and to coscure the causal agent Knowledge of the eccts of specific dusts upon the lungs has been greatly _ extended in the past 20 years but research has been mainly concerned with the more important and widespread risk associated with the dusts containing free silica and enquiry into the e^-ectsof other dusts had to wait upon those investi- gations . . PREVENTIve Measures 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 and secondly measures directed towards those employed in the industry " These latter include the control of the disease by periodical medical examing " tion of the workers by which these unfitted by health reasons are prevented from entering the industry and cases of fibrosis and pulmonary tuberculosis are reliable test detected at the earliest possible moment The ultimate and only of the effectiveness of the preventive measures adopted in the industry will be found in the statistics derived from the records of periodical medical examina * tion of the workers . include the They also education of the individual as in other dangerous ' yw /\ trades to a sane appreciation of the risk and to his personal responsibility in the \ prevention and suppression of dust responsibility prevention The protection acorded by respirators is only partial and there is a real danger that the use of them may give a sense of false security dust Asbestos Asbestos dust dust dust dust . | floating in the air contains a majority of particles of the order Qu and under under Q. , many being only 0.5... rinch rinch in size Q. <> of constant wear and difficulty in speech > In practice the discomfort discomfort discomfort etc. ronder workers very very very very Q. ,) unwilling to use this form of protection for any length of time Since \ . however a high class respirator will trap a proportion of the large ticles which can enter the lung they cannot be said to be valueless Eut cs \__ only be recommended as a second line of defence And not in substitution for other preventive measures specifically directed to the contral of dust as near possible to its point of origin Under very exceptional circumstances there may scope for the use of the efficient type of breathing apparatus comprising 3 mask or helmet with a long tube enabling the womer to breathe pure mir ira a distance THE OUTLOOK industry HOLD HOLD HOLD rehvijra tfuarethrats felt that tas for HOLD gooKrondgside KrongsTide hat rehvirfurers rehvirfurers the nature theproses | and other Krongside rehvirfurers nature of in the rehvirfurers it felt antlisic industry prevntive industry is antlisic preventive measures 15 in the space of a decade or reabouts the cllect o 4729 4729 is ae, oy, 18 ORO ' measures ecergetic HD applicationof presente presente measures shoulbde apparent greatreduc in apparent te in mn idenceof farasisw measures great due reduc Ps SEE Animmediate temporary rise in the incidence rate is probable due to the steady EY ", accumulated damage partly legacy of the war years butwith the passing of EGE the peak a fall should cusuc during Much generous assistance has been received from many sources the OED elsewhere gratefully course of this investigation these are gratefully acknowledged however Manchester Re . SRY Special thanks are due to Dr. E. W. Twining Twining of N. Tattersall of Leeds for their indispensable expert assistance in the and Dr. elucidation ar of the radiological features to Dr. W. E. Cooke Professor M. J. Stewart Ren and | Dr. Roodhouse Glovne whose researches in the same field are well known po to Dr. I. M. Grieve for information from an unpublished study a of of asbestos group G86 workers . . . mo, 2c rte ee ey eT ee ee ae eee. tebe & reime ae ee e a 2, REFERENCES 1. Seiler H. E. Brit Med Jal 1928 II 982 et 2. Departmental Committee on Compensation for Industrial Diseases Diseases a Minutes of Evidence Appendices and Indes 1907. Cd 3490 127 Le res Report 6 1007. Cd 3495 p 14 3. Cooke W. E. Brit Med Jul 1921 II 147 4. Cooke W. Brit Med Jul 1927 II 1024 E. A. McDonald Stuart Ibid p 1025 Dob. ot Lotte a ae SLs Hygiene Report 6. Badham C. Studiesin IndustriaHlygiene No. 13 General of Public Health New South Wales 1927 of the Director- Soe Tee otet 7. Cooke W. and Hill C. F. Jnl Roval MicrosSScccc Med 8. Cooke W E. Brit Jal 1929 II 573 Roodhouse 9. Glovne S. " Tubercle 1929 X 404 1927 232 Sa 1 1 1 Haddow Bact XXXXI 10. Stewart M. and A. C. Jnl Path and 172 11. Simson F. W. Brit Med Jnl 1923 I 5 . 1929 : age att drew Burton Page D. XI 12. Wood W. and " D. S. Tubercl"e . 1930 . EET ee . let ee ob stattes - 6 8 Cee ets ew ott ee Te : 2. oes Eee PART II rete seee OO oe et ngefetft ee hee . DUST PROCESSES GIVING RISE TO AND METHODS FOR ITS SCPPRESSION SCPPRESSION ow ? Des INTRODUCTION me Get 4 . 7 The asbestos industry has developed greatly in recent years and continue to expand rapidly mainly because of the demands of the motor electrical paic etongtihneeeirnisnuglatainodn boufilsdtienagm ipnldaunsttritoespraonmdotoef ftuheel ienccorenaosmiyng attentica now grouApssbe: stos products may for convenience be divided into sev. en main TextileTsexa tilesYarn and cloth Textiles ing ing other build b Millboard paper asbestos sheets tiles and materials sheet material material of ruliber or bituminous mixtures build contam asbestos e Insulation inaterials and articles d Br 2 nd glutch lings c Packing and jointings . covereil f Asli wiring electric electrodes wiring but for electric machinery cabins 2012 Some filerized " filerized filerized ) Mellaneous including moule electrical and other ponds etc factories make both textile and tion textile goods calle ** calle asbestos i.e. opened my broken up material material in a ^fins Rock lila : ops me ome + ems emy ew em oo 7 me, ees etm:te 6 e ee ow e me oe 10 is condition manipulated unmixed with other materials in large quantities in the factories incluiled in groups b and c and to much sinuller extent in some of the other facturies and workshops a Asbestos yarn is woven into cloth for insulation mattress coverings insulating wrappings filtering material Gre curtains smothering blankets and resisting clothing Narrower woven material is produced for beiting for conveyors brake livings and insulating tape Some asbestos cloth is p' roofed for use in the manufacture of steam packings and joint Besides its main use for weaving weaving asbestos yarn is braided and plaited for use as packing and also for insulating material Spools of yarn are supplied to factories in which electric cable or electrodes are made and polished thread for the completion of incandescout mantles . b Asbestos millboard and paper are manufactured from pulp containing short fibre asbestos by a wet method like ordinary millboard and paper Asbestos sheets tiles gutters pipes etc. for building and similar pur- poses are made froin wet mixtures of Portland cement and short fibre asbestos panelling A synthetic composition sheet is made from a rubber mixing for use as Bituminous mixings containing asbestos are made for switchboard and other mixings for ficorings c Insulation materials include fiberized fiberized asbestos " magnesia " magnesia jointing called ~ containing abo 15 per cent of fiberized asbestos and 85 per cent of magnesia and other finely divided mixtures composed partly of ^...berizedasbestos used as insulating cements or plasters fiberized asbestos stiffened into thick sheets sheets sheets sheets like mats for lining bulkheads of ships shaped sections and slabs moulded from fiberized fiberized asbestos or mixtures containing it or built up of corrugated asbestos so as to enclose air cells mattresses inad of asbestos cloth and filled with fiberized asbestos magnesia or other filling d Brake and clutch linings are chiedy prepared from impregnated and treated asbestos cloth but also from moulded asbestos material Plaited and braided asbestos yarn proofed asbestos cloth and coin- asbestos 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 Some electric cable and wiring required to withstand heat are plaited with yarn eldcoils for electric machinery may be wrapped with asbestos tape ; partial y products composed Miscellaneous manufactured articles or partially partial y of asbestos include in addition to moulded electrical asbestos putty and powder rubber hose plaited with asbestos others wholly wholly or and other goods yarn and many to Apart from manufacture certain work is carried on in premises subject to the Factory and Workshops Acts as well as in other premises which involves use or manipulation of asbestos or products containing it The insulating of boilers pipes engines and parts of ships is the most important Much of this work is done on board ship by contractors who employ a considerable of this cusdcor staff - a Yv PREMISES The factories and workshops included in a to g number at least 160 of which 18 are textile factories This total is based on lists supplied by the District Inspectors It does not include the large number of works where there is incidental use of asbestos packing and jointing asbestos electric cable . or other finished goods required for completing other manufactures There is only one works in which the employees exceed 500. There are many small premises in which some cases only one or two are employed A smail is found in number of important fict^'ries concerned with asbestos but a few employees in but " asbestos department Textile departmer's are usually well housed in modern buildings A few of the older textile factories have been improved recently by the addition of modern buildings In one case a badly housed small removal to newly constructed premises concern is in process of process cement sheet The fictories are modern lofty and in the remises of large floor area spacious main single storey buildings The cable and electrode factories are also modern and generally stitibi~ electrode electrode (* te mmm +80 emw. oes ml 1s rome! ty roe . . ot > . ee bem U ee We 8 re se, ewre come em ren rey Os 28 s e me 20 Some small works more particularly those engaged in making boiler com- pusitions are unsatisfactory are difficult to keep clean A few are mere sided sheds , Such premises + Some works are congested with plant and stocks of material This may result from inadequate accommodation or a temporary falling in the demand but the effect e cleanliness is bad The dust evolved in manufacturing pro- cesses is tuore diffient to control if the premises are unsuitable particularly if crowded with plant or material dust is more concentrated Cleaning is not easily accomplished and the . Ventilation arrangements provided for ventilating asbestos works vary as in other industries Dus removal systems where used effect a measure of general ventilation A number of workrooms in textile factories are ventilated by plenum systems the air supply being warmed in winter Overhead extracting propeller fans are but little used now and would be unsuitable In one mattress making room extraction fans connected to large overhand hoods are used Extraction by downward displacement the air being drawn through openings in the floor or acar floor level has not been uiet with but has been considered for some weaving rooms This system if designed of a capacity sufficient to effect a high standard of general ventilation would tend to reduce | the dust in the general atmosphere at breathing level and with other safeguards be a possible alternative to localised exhaust ventilation It could not be -uccess- ful without eficient heating owing to the rapid change of air entailed Separation of Processes In many works several processes are carried on in the same rcom In the absence of effective means of preventing escape of dust into the air many workers are subjected to a risit from which they would otherwise be immune or to a greater risk than that arising from their own work In a few textile factories crushing and opening plants are placed close to spinning and carding machines Spinning frames are installed close to looms and wet and dry weaving are carried on close together In textile premises there is , more effective separation of dusty work and processes from dusty . DESCRIPTION OF PROCESSES AND PREVENTIVE MEASURES - A complete account of manufacturing methods is not attempted Attention is mainly directed to the producing processes a description of which in broad outline has been deemed necessary to make clear the circumstances under which exposure to dust arises and the character and object of the remcdial measures already in use or here recommended Somewhat important changes are on foot which it is confidently hoped will greatly reduce exposure to dust in certain hitherto dusty processes On - the other land certain developments e.g. speeding up of textile machinery and the increased use of asbestes in various industries may intensify the dus prprooblem blem , if adequate adequate measures to deal with the dust are not taken TEXTILES a Yarn and Cloth ; The manufacture of asbestos yarn and cloth proceeds on the whole like that of other textiles but there are some important differences Fiberized and other asbestos material is freely handled in various operations in gathering waste and in cleaning Exposure in sonie degree to asbestos dust is common throughout all the factories but steps have been taken extending over many years to deal with dust produced at various ponies though the necessary degree of efficiency bans generally speaking not been reached Exhaust ventil~fl tion plants used in the equipped asbestos factories for removing dust appear to be as efficient as those used in other textile industries and to have been applied over a wider field As regards other safeguards against diet eg milestitution milestitution of mechanical methods for handwork for feeding the machines machines in greliminary greliminagrelrimiynary operations efficient enclosure of inclines and vacuum methosis of cleaning littl development has been made Opening Asbestos suitalde for yarn luis usually too far These ani all ' eases opened These tory processes prevale ing ta romasp ** Siberized ** before is ready sue mardanes le machinery are effested effested machinery iru and grading or but ondack anne sk teanediee f sieving failow crusing but prevale prepara art operang oe? ' : oe ag . . 5 * 1 . C = ~~ - . . . Oe . e *. * a ad . e - : owe eee " 21 . : = } . . . . : . . 1 hI . o ; Material for yarn is not usually treated in disintegrators but in most factories these machines are used for fiberizing waste asbestos yarn etc. Crushing flattens out and breaks up the mineral without damaging the fibres It is accom- ' plished either in a large edge runner or in small pau mill of the mortar mixing type The material is emptied upon the floor close to the machine the contents " of several sacks sometimes being spread on the floor to obtain a rough mning The crushed material is aither taken from the muschine by hand or discharged discharged through a bottom delivery slide usually filled into sacks or skips and if neassary weighed on a portable weighing machine edge A few discharge unua runners discharge discharge . short inclined lattices and the material falls automatically into tho sacit or si~ i Edge runners give rise to dust of considerable amount where short fibre " is crushed some are enclosed and have exhaust applied This is always acces- sary Pan mills are not enclosed and also give rise to dust though less in amount . Handwork c.g. sack emptying and filling mixing shovelling and feeding machine paus or lattice feeds gives rise to dust sometimes of considerable amount and is done without exhaust Application of exhaust crangut would be facilitated feeding were done from a higher level so that sacks might be _ emptied under enclosed conditions i.c. in sack emptying apparatus Autcinatic delivery and reversible bagging lattices eliminate dust produced in hand ^/lling of sacks but require to be efficiently enclosed with exhaust draught applied An open travelling band passing round an magnet is separating separating loose iron the asbestos being delivered to an elevator apparatus should be adopted used for Encicsedi Enclosed rotary sieves rotaries or long oscillating frame sieves are used for roughly grading crushed material Rotaries should be mechanically fed and the asbestos collected under enclosed conditious not always done and exhaust applied to the machine enclosures otherwise unnecessary dust is created Some oscillat- ing sieves are very open the material being allowed to fall on the floor and being filled into sacks by hand Very dusty conditions are then inevitable cient enciosure with exhaust draught applied and to avoid band filling automatic delivery and bagging lattices also enclosed and exhausted as used in some cases . are generally practicable . Crighton openers enclosed centrifugal machines are used for opening crushed asbestos preparatory carding Careful mixing or blending of crushed material is effected by spreading it evenly in layers on the door over a considerable cotton may be added at this stage if required when feeding taking . vertical cut through the mass Admixture with a small proportion of lattice also be achieved by delivered upon a blowing it into the feed opening The opened material is and collected either in a large container or or or feeding sacks sacks sacks sacks sacks sacks under automatic bagging lattices being used in some cases Mechanical feeding feeding fe ding feeding under under under under emp other enclosed conditions with exhaust draught applied to feeding lattices or other conveyors should be adopted Hand feeding gives rise to dust from sack emp : other + hindrants . ing shovelling and particularly mixing on the door Mixing is great hindrants hindrants den to elimination of hand work is asserted that poor yarn results if it is not te and that machine mixing has been tried and gave less satisfactory results results large retained it should be done at a higher level than the opener under under under a large exhausted canopy and the mixture fed at a series of chutes large large should be well enclosaendd exhaust applied as now done in some cases latices latices dust is evolved Opened material not required at once may be stored in open bins in workroom involving emptying and filling sacks or skips which necesartiy cause dust This storage in bulk should be avoided alternative arrangents might be adopted which avoid dust Some material ... long fibre waste from Later processes is openin openin cnclosed lattice teasers or willeys not infrequently of primitive design wert out and emitting much of the machine These Dust may he emitted at dust note ithstanding ithstanding tthhaatt a tam is an integral part old machines should not be mact for asustes opening feed points of mcuera chimes particularly when the irregular feed is Exhaust necessary feeding itself is also because feeding feeding itself causes dust causes the feed lattice for this reason and and The materul either discharged materul either discharged upon upon suggested f^r Crighton lattice immediate collection chamber a glopted . for f^r Crighton or blown into a machines should machines should let glopted glopted let The shandavas shandavas shandavas tes o oe : we bum rm ere wr ' e wae 2 bas om hee re eee + 22 22 Hopper lattice feeds are largely used with opening machines the lapper lips are about 3 feet 6 inchies above floor level Much must is produced in shovel- feeding as it is difficult to avoid scattering at the lip An enclosed lattice fed or just below floor level with localised exhaust applied to the enclosure is more , intisfactory ~ more . Siugle disintegrators or two or three machines in series are used for break- ing up textile or other asbestos waste more rarely for opening crushed asbestos Present arrangements for preliminary haud sorting of waste are unsatisfactory . it should be accomplished at a covered bench suitably exhausted Whereas in some cases the indraught the disintegrator feed openings caused by the rapid rotation of the rotor is not sufficicut to remove dust and because at rate as soon as it is stappert escape of dust may result from reversed any air exhaust should be applied here also currents _ Disintegrated material is blown into chambers a blower fan being in some cases 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 escape a " relief balloon " connected or exhaust applied Chambers connected with disintegrating and teasing machines vary in size some are little more than a large box others are more roomy Some but not all are separated from the workroom They are entered for emptying the material being filled into sacks or sitips by hand after the machine is stopped or the flow of material diverted to another chamber Work in chambers is dusty and its elimination is most desirable See page 26. very Considerable developments have taken place in recent years One or two important new cardrooms have been started Many new machines including some of foreign construction have been installed The machines of large overall dituensions are of the roller and clearer type Modern cards are of high class construction and fitted with two do~ es cylinders supported on a carriage which can be racked into or out of position For fine yarns a breaker and a unisher constituting a set is used connected by Lattices lap sliver from the former being automatically fed to the fuisher card In cases where the sliver is collected in cans a Derby doubler is used for prepar- ing laps for fuisher cards os . equipped - Single machines and breaker cards are equipped with hopper lattice feeds supplied from skips or sacks handfuls being dropped in and shaken as fed or the sack emptied into the hopper The asbestos falls apart a creeper feed which conveys it to the " intermittently upon licker feed rollers between which point and the doffer the material is under enclosed conditions 44 The material is combed from the open do^-ers of Enisher cards as a me or sheet " the sheets from the two do^-ersusually being combined at a con- denser and the resulting sliver yarn wound into spools Occasionally combed web is collected without being condensed the condenser carriage being with drain In other carding the sliver may be obtained as a lap . being Admixture with cotton is usually accomplished by carding the two materials together a cotton lap being mounted above the creeper feed and the cotton fed through the feed rolfers with the asbestos . The evolution of dust at cards is inevitable and a fine dust cloud may be observed in most cardrooms Suppression of dust cannot be realised unless machines are maintained clean and in satisfactory repair and there is effective enclosure of various parts Above all localised exhaust must be vdiedfedineWiddepsoiWidens tascionfg doufstmaecmhiisnseisonisaanldsoidmepsriorvaebdlestripping arrangeampepnltisedproa-t at The upper parts of modern machines are usually provided with well made wooden covers and the lower parts are enclosed below in metal The frames are well enclosed the sides A hinged metal cover fitted in some vents escrpe of dust produced by movements of the feed lattice cases preA curtain of fabric is less satisfactory In older types particularly the wonder envers may not fit satisfactorily the cylinders may not be truly aligned with the frame and other d feets may account for side escape of dust not enntrafiable by exhaust Such defects should he remedied Creeper veds da^-ers and condensers and connecting lattices between breaker and fasher cards in evolved at duerroniles and at creeper fields are not enclosed Dust i we - Localised exhaust ventilation was first applied to carding machines many years ago Methods and apparatus have since been and gradually more powerful.exhaust powerful.exhaust draughts are now used One large firm ihamvperoavcehdieved much success by standardising their practice as regards points of application of exhaust draught design of air guides size of branch ducts to air guides and duct relocity roller Exhaust is applied at a the presser at the creeper feed b feed at licker c top of cylinder d each doffer air guides or noods being fitted at these points with connecting branch ducts Muil couplings used ou branch pipes facilitate easy disinantling Branch pipe sizes and duct velocities are liberal of the The improvement realised by applying powerful exhaust at ench points mentioned at all of which evolution of dust that this practice should be followed generally and givesispoiimnptorittmpoaorntttanhte s stows v ti oe ww s expressed by some occupiers that carding can be carried on practically dust - Apart from the above case exhaust is applied in nearly all cases to the cylinders top in a moderate proportion to the creeper feed in a few to one doffer and in one or two only the bottom doller But apart from 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 are not possible unless the exhaust draught is applied as closely as possible the producing points Transverse air gud~gud~s swith branch ducts connected at ench end are apparently more efficient than with hoods of the usual type pyramidal Ducts of adequate diameter and high aust veiccities are essential thrown The usual air guide for the cylinder provided to effect removal of dust both during carding and stripping and grinding though proved inadecuate for stripping is placed a little above an opening in the crown of the inadecuate inadecuate inadecuait nadeecuate branch ducts as above and in addition a larger central branch cover inadecuate during stripping are connected to it The shallow cucu sstt for use the air guide is closed up during carding space below by a wooden hinged the the back of back for stripping the dust produced at the cylinder is escaping by inflow of air from the room at the front The prevented from withdrawn at the side ducts In stripping inflow of air laden air is stripping dust takes place from below the lifted carrying some of the cylinder branch duct kept closed by a blast cover the central to provide a greater ir volume gate during carding is then fully opened opened continuously condensers In one factor a circular doffer cleaning brush runs above the do^-er .mb A pyramidal exhaust hood is provided but much dust escapes unless fully efficient exhaust is devised provided provided but cleaning if really necessary should be found The an alternative alternative alternative to this election of combed web previously referred to is done without exhaust and dust is produced might be effected by exhaust draught as applied for Collection removing side waste at Notwithstanding the use of covers for card lattice feeds dusty conditions conditions produced and exhaust draught shou be applied at this point also are Stripping and Grinding " stripping " or cleaning is done a machine is opened out for grinding which follows cleaning and takes when when the the place atat each machine about once a week but shorter and longer intervals place place place place obtain In one important factory the two processes are combined in also obtain obtain obtain obtain . and clearer cards must be opened out i.e the lattice me operation feed Roller Roller Roler Roller Roller and denser and defier carriages are drawn back the and breast and the various small rollers which cylinder covers are raised cancan can a and and and ; removed The cylinder is first are cleaned and ground at special machine cleaned with the doffer carriage drawn back the carriage is then replaced and the do^-ers min cleaned turn Cleaning takes at greatly increased speed hours hut in about ten minutes and icumally done in working case at least after hand brushes about The men press their " strickles '* or lat 12 inches long covered with card clothing against the wire- covered surfaces erolved in dense Much of the debris is heavy and falls to the floor Dust is one case floor cloud some being removed at the cylinder exhaust hood openings beneath the machine the connected In as Present exhaust arrangements are altogether inadequate to the exhaust particularly so regards the bottom doffer Much dust is thomore atmosphere of the The carried into the genral In a few room cases more cleaners cleaners pear perimtore or 44 helmets effective machine is almost entirely enclosed mensupse are are taken mw with high enverori the opened serpine In the ae dh 2.1 ES ULAR ore GbE cone MOLIAL ore Ss wie clair are AIA re ee covered works where cleaning takes place after working hours system with a hood for the bottom do~eris brought into usaen auxiliary exhan Grinding which takes several hours is an abrasive rollers driven by the automatic machine The process effected ' produced is chiefly of a metallic character smail aimount of de to In the factory where grinding and cleaning are combined the dofter arrangements are first connected exhau Much less dust is evolved and be dealt with more effectively This firm consider that hand strickling appea grinding should not be allowed Their methods strickling befo paipepclesicoafbdl^e'bA rislittle strickling may may be necessary mafatyer hgorwinedvienrg ntoot rbeemogveeneurnaal The trade recognise that present conditions are not satisfactory and eg ments are being made with the object of developing improved appliances exper In Ore casa a revolving brush is being tried with independent exhaust by flexible or draught applic connections it is said to give promise of success The brush : narrower than In the hand strickle and less dust is evolved at a particular moment Cee another case a vacuum fitting is under consideration Previous use of vacuui OE stripping was given up because of rapid erosion of the metal pipe bends and othe parts Unless effective other than dust suppression is realised for stripping all workers ee strippers should be excluded while it is in progress and for afterwards and the room well ventilated some tim ee Se eee Ee ahes phat erie sroes Sere ore Pay ee to The machine for cleaning and grinding the smailer roilers which gives ris much dust should be fitted with efficient exhaust forward matter arrangements straight d^'brisprecautions as completely which enclosed as practicable to collect the heavie in the are not always taken The machine is either installer carding room or in a room adjoining Independent machines should be provided to deal with rollers of different lengths otherwise inconvenient inents liable to be neglected have to be made adjust- . : Card Side Waste Treatment irregular separated the " " seivedge of carded fibre at two sides of the finishing card being unsuitable for sliver perforated is removed by suction draught to a it side machine which prepares it yarn for further use The material is blown upon perforated cylinders the air adtustthe side and the material being discharged on the floor escaping The process produces particularly when the between the feeding is irregular the air then having a free path cylinders The material should be delivered under section and under pressure a '* pressure '* machine being unsuitable not . Spinning and Doubling is spun at flyer or ring frames which carry up to 80 pindles 40 on each side Much may comparative wenioness of the fibre A fine metalpietchirnegadisisrequired owing to the for brake linings and certain other purposes Mule spinningspisunnowtith asbestos this country A large amount of doubling is carried on practised in . * Peco fibre to breaks carding oe proproduceddSucpeidnnbiyngthm eo" rebaplalrotoinciunlgar" ly oruitngofsptihecuing gives rise to dust continuously the spindles which may run at speeds of owing the rapid rotation of 1,700 revolutions intermittently when the yarn per minute and Doubling is less dusty than While the amount bears no comparisen with that produced in spinning $250 than that from dry weaving the workers are continuously add is leis others doubtless than ST more in some factories in exposed to some dust due to differences in materials methods or Exhaust drugs drugs for its removal has not working been ere hitherto but experiments in one factory have been so far successful that applied the doubling are prepared to equip all spinning and frames with exhaust firm plant embodying ( exhaust ducts perallel with the frames above the ventilation tin with shaped hrs at intervals each to deal with a small group of rollers beneath spindles lioiwefrorpamro tsreofeftfheectifvreamcoenscentration osfpinthealdersougcahptabplaeneolflibneigng for the cuds aanndd when Such salt spinales require pata spinales somewhat being easily removed neessary ventilation special unless general pr^culed ventilation ventilation is require pr^culed pr^culedpr^culed somewhat somewhat wide application Warping the frame creeling frames and Wabr eams are roparsi the usual way from cynlution a small cynlution at dust ccoomm ee the and frames machine localised exhaust ventilation ventilation cores the fms be med beaming beaming beaming ectiven A machine machine mechanically , off space mechanically vent slot es. a with extraction partitior extraction at low level v inspirovement effect 25 Winding Many winding machines are used varying from makeshift types of primitive construction at which the practice may obtain of holding the yarn " in the hand to modern universal winders for winding cheeses Dust may be evolved to some extent particularly in connection with the above practice which could be eliminated Application exhaust draught will then probably . not be necessary except in particular cases . Plaiting and Braiding Plaiting and braiding also carried on in engine packing and electric cable factories and done machines of normal design cause some evolution of dust except where the yarn is impregnated with grease While the amount of dust is sometimes less than in spinning the difference is not material But tliere is perhaps less exposure of the operative under ordinary working conditions and precautionary measures other than * localised exhaust ventilation may suffice Weaving vary greatly in size and general arrangement As many as 140 loomis inay be found in a single room but this is exceptional The cic space between machines may not exceed 18 inches Some looms are independently driven by electric motors Cotton warp or weft is sometimes used This cloth for mattress covers filters clothing etc. is woren from a single warp beam at simple type of loom Belting looms for thick beiting and brake lining inaterial are complicated several warp beams arranged in tandem under the loom or in some other convenient way being required These looms are narrow but often very long Tape looms are also narrowr unless several tapes are woven together when several shuttles in line working in unison are used Cloth is beamed at the front in the usual way but belting may be led under the iccm ' and coiled high above it at the badd . Most weaving is dry but some weaving is done wet either warp or weft and occasionally both being wetted Wet wearing is accomplished more casily and a closer weave obtained but rusting of heald fittings and the subse- quent drying entailed and the less 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 account " Considerable evolution of fine dust occurs in dry weaving as a result of LE a the forward movement of the slay in beating up this source being close contacts to the operative b the repeated of the rising and falling warp threads with their neighbours this source being the most important from a quantitative standpoint c the disturbance of " dust or Bud " on machine parts especially those in motion A fine dust cloud may be observed behind the lealds above the warp threads Much less dust is produced in wet wearing " Some dry looms are now fitted with localised exhaust usually applied applied - to deal with dust evolved by both a and b in some cases c only dat c A dat dat t horizontal hood is fitted in front of the operative just above the cloth the the the -b opening facing towards the bealds b either an upright pyramidal heed placed placed placedplaced transversely or horizontal Ent hoods one on each side facing each other are are are appears fitted close behind the healds The second arrangement is the more effeecffteictviveeeffectiveefective * for narrow looms as the * " scissors action of the warp threads to displace most of the dust to the sides The exhaust draught has efected at some improvement but all the dust is not removed especially that preduced by . b It may be impracticablteo apply the draught to all producing points behind the healds particularly long looms but greater success would have been achieved with more powerful draught and larger air displacements as is Dow being recognised : for The methods described for dealing with " the dust create by 0 must be less successful at cloth Inoms of ordinary width A for such looms in one factory have recently been equipped with large bonnet hoods fitted transverseiv close down over the machine covering the slay reed and healds The hoods air of hemispherical section with extensions over the shuttle lox~ s An internal electric light fitting and hingel sections facilitate working A powerful ee draught suitably applied should prevent escape of dust generated within ey operative placed In another ense experiment is said to have shown that a inclineri hoed facing the just below the warn near the front of the leani can le more effective for reducing dust concentracont centratioi n ocon ncentration so the air breathed than present arrangements and the new desiga te l^ be substitutal , Oe 26 Application difficult difficult of efficient dust removal arrangements to machines The in expedient of installing individual individual machines weaving is c machines in suitably ventilated small rooms or small grou " e " Warping does not appear to have been or cubicles as tried but might suggested be i incalised a single lainreraonfgenients are not sufficiently effective consider Long uarrow sheds 8 looms ventilated as suggested might be a possible alteru ee Cloth Picking Ezamining Measuring ew out the rulls of cloth and tend to produce a small operatious operatious involve rus done so that very little dust is is created other amount of dust If care ee precautions may be unnecessa + TEXTILES . Fiberized asbestos is not used in some of the exposure factories to asbestos dust may be slight or even textile factories negligible Dust is or departments where such material material is evolve or for sale and also in departiments where prepared fiberized for subsequent ere containing it are manipulated in preliminary material manufacturing or dry muxt finishing of processes involving abrading or cutting at high processes Ag speed be such dust but dust may contain only a small may so percentage of asbestas e application of exhaust draught where suggested percentage following te + under nceen in Fiberizing or OpeningFiberizing is almost exclusively confined to groups b and c in Much of the work is done less we textile factories and unsatisfactory machinery is more supervision t ete teasers devils " are used in several common Prima work is also an making works and cham unsatisfactory feature see p 22 Oet In some asbestos sect factories crushed material from falls into worm conveyors below which transfer it edge ruzzi on In one large the works the process is being automatically to disintegrate entirely enclosed the material fr edge raised runners which are lattice will be discharged upon a + by an elevator to large overhead storage hoppers fitted conveyor = with bagging lattices automa termoe Localised exhaust delivery points where dust might escadpraeught will b;e applied at feeding = dented ... ... : oe me wre feeding The Chambers have been eliminated in some large works with beneficial resul to a hmoaptpeerriaflittaefdtweirthbebiongttodmisintegrated or opened is handled and blo The material is bagged at rotary delivery Direct lattices valves the air being circulat aunther improvement now being tried Such a manufacturing point practicable in many cases Localised exhaust preumatic conveyance should of these systems is necessary at and discharge poiz practicable filling sacks may also . ; by If chambers are retained providing chambers the recessity for entering them might be avoide at which sack of small front to back dimensions fitted with low over the filling doors would be done localised exhaust ventilation being door applic b Mimboard Paper Sheets and Tiles The wet mixtures for millboard paper and asbestos prepared in a beater as used in paper mills cement products a Dry fiberized into the beater trough the sacks being shaken to asbestos is emptie ke dust occurs before the material becomes mixed with soice the extent Evolution c sionally a sack is emptied before the water is circulating water Cont e required for a charge and the turned on Several sacks ar Precautions are not taken at process is repeated a number of times daily present a mechanical feeding under en dosed but the dust might be avoided ee foreign works b applying exhaust conditions as appears to be done in som draught c and in such a way that the material feeding in small quantitie is wetted at ones Om Finishing processes of asbestos sheets include include gating pressing and drilling carried on swing to size corru so minist as to prevent dust and this it some factories with the materia practice should be adopted generally samie ye . 27 . Otherwise much dust is produced in sawing owing to the rapid cutting speed und localised exlinust is necessary though not applial Similarly turning filing and smoothing of dry asbestos pipes at lathes may require exhaust to remove the dust produced Synthetic composition sheeting sometimes male in a rubber department is produced from dough consisting of fiberized asbestos and rubber mixed with solvent in kneading machines Dust is produced in feeding the mixer with asbestos doue in a>open manner by hand from sacks or skips the sacks being shaken out or from an open lattice feed Subsequent processes are dust Exhaust should be applied at the feeding point , , c Insulation Materials and Articles Compositions Magnesia the most important insulating composition is produced on a large scale by the principal manufacturers by enclosed inethods with pucumatic conveyance of the mixture to automatic sack Ellers Weighing and feeding the fiberized asbestos gives rise to dust for which exhaust is ; necessary Fiberized asbestos or " magnesia is a component of many insulating cont- positions which may also contain clay kieselguhr fossil meal fax |: emp or jute waste and other materials The proportion of asbestos in the final product varies widely In many smail works the materials are mixed dry by hand in an open manner involving sacks emptying and filling shovelling and weigh- ing Enclosed rotary mixers could apparently be used for such work with exhaust applied at feeding points and the material discharged and bagged bagged under enclosed conditions If hand work is retained exhaust should be appucd sprayed Consolidated Large sheets resembling thick mats built up of layers of fiberized asbestos are consolidated with silicate of soda on in manu- facture The sheets niay be backed on one face with millboard or supplied without a backing being faced when fixed with millboard or asbestos sheets The sheets are produced of the required size and shape at work benches or built up on the table of machine capable of slow reciprocating movement and fed from a hopper above In the former case the fiberized material is taken in handfuls from ships and spread out in the forms the surplus being serped away and falling about at the sides of the work benches and on the Acors a considerable quantity being scattered Dust produced in manipulating the dry fibre before treatment with the silicate of soda is largely avoided at the machine Efficient localised exhaust should be applied to the hand process with improved bench arrangements to prevent scattering ; Band sawing of piled sheets causes evolution of much dust owing to the considerable depth of cut Localised exhaust alone not yet applied may prove insufficient may Sections and Moulded insulation is made chiefly in two forms , seccylindrical and moulded hollow to suit various pipe sizes slabs which are rectangular and solid These products are usually moulded wet either by hand or machinery from a paste or cream prepared in a mixing machine or tank Feeding of dry material involves evolution of dust which which might he avoided by one of the methods suggested for feeding beaters in millboard making Sections are made at one factory by a dry process at a machine indiferently enclosed Feet hoppers filled from skips deliver the asbestos to internal lattices which in turn supply a travelling hand at which the section is rolled by hand Revolving brushes which clear the lattice and spread the material evenly on the hund give rise to much dust and dust is produced at the hoppers and in rolling and brushing away superikoas materiai Exhaust dranglit not witherio applied is to be provided at the exposed brush and die nuudline nuudline is to be more 64 effectively enclosed An enclosed feed is also becaMSADY The mytions ami slabs are trinpoed to size with onular or band saws Much dust is produced and exhaust exhaust draught is commode appued but is in some enses inellicient in one operation 1 Circular saws used in some cases in pairs can be fitted with exitust lemnes above and for trimming studs below the ciches oe + oe eed me anon N68e! meee kinhiad ret c00 oe me wer to e ee ee ee e. me e me m es str 23 and band saws can be enclosed below the tables exhaust draught being applied as for woodworking and inverted hoods fitted ments should be readily practicable for all sawing swaowodiwnogrkiwng omrakchhienrees Ellicient arra . Mattresses MattressesMattresses are produce manufactured insulation requisites requisites though only by practically all firms v large contracts are made made in the occasionally contractors by some Mattresses necessary measurements measurements and premises their outdoor staff tak to be mida on site preparing rough plans A mattress has someti Mattress making associated involves broadly speaking the sequence of with the making of domestic mattresses sequence The work work proces hand work Lengths of asbestos clot for is aliuast entir and sewn up by treadle or driven covers are cut out on a wide fr the method of filling power Large mattresses machines to an extent depending sides may be scamed and may be sewn along one side only or be filling turned inside out done from both ends Before filling covers : Supplies of filling material which usually but contain fiberized asbestos are brought in sacks or skips may n from open bins in the skips from chambers or tak of material room kept supplied from the chambers or from supplied by outside firms and quantities be sac Filling is done by hand scoop or shor may weighed referred to above necessitates The end filling of long seamed mattress the workmen mounting on the bench to i material from skips into the openings to make After filling the mattress is empty levelled beaten being used the Elling lie evenly within the hand or a flat wooden best Finishing fixing on hooks etc. processes include final serving stubbing or buttonin Some dust is produced at the cutting out bench in cloth and at the sewing machine but far more in opening out the roll- roll- dsuacskts tihne weighing Elling and levelling taking material from bins ( Beating of the cloth amount of which is largely increased if the produces asbest The work is All benches largely done without regard to the filling Decessity for contains ascesto are entirely open Localised exhaust suppressing dus One firm have improved conditions conditions draught is not applied cautions - considerably by the following pr fillinbga Keeping Hose floors and benches damp and spraying covers befc b connections and spray fittings are provided provided division of department into several Exclusion during filing of all independent workroom workers excluded workers proceeding to another section not so employed th - ing d Mechanical ventilation of each room plenum supply by cross ventilationembody warized when necessary at one side and low leve teixmtreasctpieorn haotutrhe opposite side the air being changed between and a e Enforcement of use by fillers respirators of respirators These precautions do not include -, without which mattress filling and application of lecalised exhaust beating ventilation . of dust For small mattresses a beating must involve wide double some risk of inhalation draught applied at gratings along the centre canopied bench with exhaus line material being supplied within the canopy Such a mbiegnhcth be used the filling practicable for the making of large mattresses but the may not perhaps be explored adopted Otherwise at l;east the precautions referred ptoossiabbiolvitey sshhoouulldd bbee d Brake and Clutch Linings Hefro being be caleneered impreguated the dry asbestos cloth known them at squaring rolls and in all cases the quils as 650y separate a little so ensuring operations rough treatment by the are eased out to separate produced in i se operations but insuflicient liquid special little dust is Beistles Itin essary Other to retuler special precautionar preparatory of special linings preparatory work on Lengths of cloth grey arises in the maki templates are then eat with chisel or shears lightly hired hired to rig shape winn stitching machine as used in and the radial oiliges sewn togethe book insting stitching A canopied Twinchi Arteid waalebowaleni bowaleni eDxuhsatusotccurs in hammer provides and the mischite pinceil unier exhaust GRAUINE artanigenichts GRAUINE 29 Dry impregnated material is shaped and finished mainly by driven machines c.g. knives circular and guillotine cutting presses hydraulic squeezing presses and band saws Catting and sawing expose ends of wire and leave rough edges trimming and smoothing done on grinding wheels and linishers are necessary to obtain exact size and finish All the operations except squeezim produce waste and ilust is created in sonic The dust is heavy and sticky and less likely to fly about than dry asbestos dust The amount is considerable at zawing and grinding machines and localised exhaust draught to remove it has been applied some cases with much success is always necessary Inverted hoods are fitted at band saws just below the tables the dust being drawn through the small openings in the table guides A powerful draught is .essential ; Grinding and finishing wheels include in addition to ordinary singie machines dise and vertical spindle segmental grinders used for flat unings 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 baille plate to prevent dust being carried past the hood by the high linear speed of the band is a necessary addition Special linings and friction bushes are moulded from disintegrated impregnated waste Some dust is created in the filling of mouids and efficient localised exhaust draught may be necessary The articles are snaped and finished as just described Bushes are turned and bored in lathes with production ci waste and dust but exhaust draught is not at present applied thougu possibly necessary e Packing and Jointings " " Engine packing is either a cloth packing built up from cloth usually rubber proofed on both sides handling of which does not cause dust and " * B rope packing made from yarn at braiding and plaiting machinery as used in textile factories a Negligible amounts of dust may arise at the spreading machine from the unproofed cloth and in building up from material ' J prooted on one side only b Cheeses of yarn are first rewound on bobbins for the braiding and plaiting machines Simph winding mechanisms are used Some little dust is produced special preventive measures will usually not be necessary " Flat packing known as gruminet is made on a small scale from asbestos yarn threaded on a needle and wound in and out by land as balls of wool are wound This apparently insignificant process causes sufficient dust to cover in a . short time the hair and clothing of the workers and should be doue at canocpiaednopiecandopied bench provided with localised exhaust arrangements I Asbestos Electric Conductors > Electrodes are either wrapped with yarn the usual method or passed through paste containing asbestos fibre yara being wrapped upon this high coating . machine travelling axially through travelling consolidating The former method is usually achieved by a small carrying spools fitted with a flier axially axially the the or bobbins flier with flier Treatment with speed stranding of yarn consolidating consolidating the liquid wire liquid liquid straightening and cutting to length follow all done at the stranding machine Alternatively single electrodes may be wrapped by a simple winding mechanism operated or driven covered electrodes are also made singly at small extruding machines a flier for feeding the yarn being Atted behind the extruder After drying a short length of the envering at one end is ground away leaving the bare metal necessary for making electrical contact in the holder when use Smail abrasive whel almost entirely encln are used Small amounts of dust are projected from iliers though insuficient prob ably to require the adoption of special precautions Much dust is pronneed pronneed in grinding ends and efficient exhaust ventilation is essential present afisarztus afisarztus where provided is capable of impencement The poress would be unrevessary unrevessary if bared ends were left manufacture rud experiments directed directed to this destrande end are being made and give promise of success women vemeee we ee ee ee me a ee Gk me ; , . re ~ - oll Preparatory processes in paste making inclufe ( dry grinding of fiberized - asbestos by small vertical disc grinding wheds fed at the centre from a hupper periphery above and dis harged from the into a box below and ii hand mixing of the ground materials at a bench involving emptying emptying mut of dry material into " paus Dust produced the amount being considerable in grinding Little precaution is taken The processes might be accomplished under almost entirely enclosed conditions elicient exhaust draught being applied at points where dry material is exposed c.g. in feeding , . . Rewinding of yarn is sometimes necessary and primitive arrangements may . used the practice referred to on page 24 being followed and as a considerable mount of dust is produced the practice should be given up - Cable and Wiring Asbestos cable and wiring constitute a small percentage of the output of the cable factories The yarn is braided and plaited on the conductors at machines not reserved for ' ** asbestos products similar to those previously described Rewinding of " cheeses as receive from asbestos textile factories is done at universal winding machines The amount of dust evolved is small and special precautionary measures are apparently not required Field Wrapping coils for electrical machinery are wound with asbestos tape by hand at ordinary work benches The process does not give rise to appreciable quantities of dust et Moulded Goods g Miscellaneous electrical insulating fittings are moulded from impregnated ^...berized asbestos prepared after thorough drying in a es mixer and grouod in an edge runner Alternatively impregnated scrap ground e in a rumbler may be used The preparatory processes on dry or practically dry material are intermittent and involve sack emptying shovelling weighing filling and emptying shallow trays They are curied on in an open mapper . without special precautions except that as regards grinding hanging curtains may be used at the edge runner and the scrap ruiculer is enclosed Dust is evolved in the processes mentioned and localised exhaust ventilation should be applied to effect its removal with in addition effective enclosure of some hand ome: 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 bats handle for turning them over Localised exhaust may be necessary for Anal Aha trimming if done at abrading wheels we Moulded articles made in other trades may contain but a small proportion aes of asbestos although a large quantity may be used In one case the asbestos is sieved after drying both operations being done in enclosed machines and ee in addition dry mixing done in rotary machines and paste mixing on ope rolls as in ruliber works are also required Processes carried on with some risk of exposure to dust include emptying of sacks into bins filling of trays + for drying feeding at the sieve elevator hoppers the dry mixer and the rolls Localised exhaust is applied at a the elevator hopper b the storage chamber . above an intermediate bagging point c the dry mixer and d the roils More efficient arrangements appear to be desirable for a and e the 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 Localisel exhaust is necessary at storage bins Final trimming of rough edges is done under eficient exhaust draught Other processes of comparatively minor importance c.g. asbestos putty mixing in which there is handing and feeding of dry material in preparatory processes will call for precautions as previously described for similar work 4. SACKS In few cases sacks of sailcloth or other closely woven material are used inside the factories Such sacks are much to be preferred to those made of the ordinary material which is lenky and gives rise to dust in handtag CLEANING or Wonkh MACHINERY AND Sxey Some factories are kept in a RECORTAN Comix date than others but higher standards and improved unetheids are desirable generala Weekde eleaning by dry methods is general in testrie testrie ~ acheries int os amens elativeis elativeis cone in some {- .- - a ery Pe 8 rm twet ee ce 31 cases than in others Casual cleaning may also be done during the week The from dust which gathers in a week renders cleaning a very dusty operation Young workers may be.seen on carding machines brushing dust into the air from the covers etc. in considerable amount near other workers Some firms have instituted more frequent regular cleanings and more satisfactory thethods by damping before sweeping Vacuum cleaning incthods have not been adopted and such methods seum to be regarded as impracticable but this can hardly be nerepted Portable vacuum sets are constantly used with great advantage in other classes of works c.g. electric cable factories by adult cleaners who keep the machines plant service pipes etc. thoroughly clean . If vacuum methods are not adopted well organised daily cleaning by adults using damp methods for floor cleaning should be the rule in textile factories A water supply with suitable hose and spray connections should be provided D^'brisproduced asbestos sheet works under moist conditions may become dry and cause general dusty conditions Cleaning should be so frequently done as to prevent this : The cleaning under machines such as looms and cardis entails enilecting wasta of considerable value donc at present by hand Vacuum collection should be possible in principle it is already used for removing side waste at finishing cards The sound principle of collecting card waste through door openings has been adopted in one new factory and might be followed in others with automatic collecting arrangements Sack cleaning is done in a few large works in enciased machines involving some risk of exposure to dust in filling and emptying notwithstanding the " provision of localised exhaust ventilation A type of exhausted nashine which does not involve such work is to be preferred SummanY AND RECOMMENDATIONS Asbestos factories and workshops cover a great variety of processes The premises difer widely in structural features and are congested in many cases with machinery or material Processes are largely carried on in close association Dust is product at many kind of machines in hand process works and in simple incidental operations particularly in emptying settling chambers and in " *' all handling of fiberized asbestos * P. In textile factories pure asbestos dust is continuously produced in differing amounts at all the is usually effected principal machines by hand strickles Card stripping a very dusty operation Hand mixing of different grades and varieties incidental to opening processes is also dusty feding In textile factories pure asbestos dust is produced at opening machines in in feeding machines in making insulating mattresses a dusty hand preces ) and in incidental hand work Dust though rarely pure asbestos is produced in finishing operations e.g. sawing grinding and other abrading of asbestos products ined when the harmful effect of comparatively low concentratinus of asbestos dust are duly appreciated Very dusty processes will not fail to be recognised trades but in processes such as spinning and weaving in which in ether textile special methods for dust contrul are not required due precautions are also neces- neces525 The asbestos manufacturers are clearly confronted with the necessity attaining conditions in their industry which will ensure much less dust ationsphere than can safely be tolerated in many comparable trades not aslestos The principal methods for the control of dust are . a application of exhaust draught at durt producing points b substitution of enclosed mechanical metlinas for hand ennveyance en veyance and for dusty lasil work generelle c effective enclosure of dust producingproducing machines d tilation of wet mechous for dry a machines and plant : ee ety e ee ee . ee . - oot ae a ee ntrere . . the 32 utility tions Each of these has its particular sphere of and the particular indice tions for their adoption are put forward inter alia in the reemmendations below - RECOMMENDATIONS . . 1 Application of Efficient Localised Exhaust Ventilation at producing points This measure of thegreatest importance where manufacturing and locidental processes occasion escape of dust not controlled by enclosure or other measures is necessary for , a producing machines e.g.- : i Crushing disintegrating teasing and other opening + machines sieving machines fibre grinding machines dry mixing - machines rolls fed with dry mixings ' ii Carding machines to suppress dust from cylinder and doffers caused bystripping and grinding in addition to that pro- duced by carding card side waste exhaust machines loomis 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 a other plant feed hoppers at elevators bagging lattices feeding of dry , material at wet mixing machines " c Chambers containers cyclone " hoppers or other enclosed space into which fiberized asbestos or mixtures containing it are delivered or pass + d Work benches e.g. for mattress making waste sorting a Various hand operations e.g. sack emptying and filling ing mixing = weigh- . This is the principal measure hitherto adopted and is probably that most generally applicable It has been applied to some only of the above machines and appliances but not to hand work The methods of applying the exhaust draught and other a ociated factors are becoming more effective but there few are fully satisfactory plants Special difficulties remain to be overcome in some cases e.g. looms mixing mattress making If not surmounted an . alternative viz general ventilation of a high standard applied so as to draw the laden air away from the worker should be provided 2 Substitution of enclosed mechanical methods for hand conveyance and for . : dusty hand work generally . This measure- intermediate a avoids depositing material 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 reuders exhaust draught more effective or in some cases unnecessary . It is already employed to some extent and its further application wherever possible is greatly to be desired 3 Effective enclosure of producing machines and plant a To powvend capes capes af dust not continiled by exhaust draught ar 4 to render its application application more ethicient ethicient na r~ 73 4 Substitution of wet methods for dry e8re To reduce the dust given off in certain processes and work c.g. | te a cousiderable amount of weaving + b inattress making by wetting the covers before filling and by frequent . wetting of floors and benches . taete c final sawing and other machine processes in asbestos sheet and me tile factories before the prepared material has had time to dry romwr * d works cleaning by damping floors and beuches before brushing or . fe sweeping ; This measure might be adopted to a greater extent than at present * ot 5 Elimination of certain producing appliances Certain appliances are used in a few works sometimes with a measure of . precaution but which emit much dust difficult or impossible to control by efficient enclosure or exhaust draught They should not be retained unless effectively . : modi^-ed ; a exposed doffer brush at carding machines . b card side waste exhaust machines delivering under pressure c certain willeys and teasers particularly oid machines 6 Abandonment of Settling Chambers in Manufacturing Processes to the . atmost extent (7} Efectual separation of processes to prevent un cessary exposure to dust New factories should be laid out so as to avoid exposing workers to risk from processes upon which they are not engaged be effectual separation of _ In particular there should a opening carding and weaving from each other and from way other - process doubling . , b spinning doubling plaiting and similar processes fro: m works ; not causing dust . c mattress making from other work . d chambers containing fiberized..bestos fiberized..bestos in bulk and dust settling chambers and apparatus from any workroom . - The separation of mattress making should be adopted in existing works and other separation referred to as far as practicable _ 8 Wide spacing of producing machines in new factories and as far as : practicable in existing works This measure would bring about permanent reduction of dust concentration in the air of the workroom as a whole and provide improved cleaning facilities * 10 9 Use of sacks of close texture material for internal work Efficient Efficient cleaning system with wide use of vacuum methods See also 4 te 11 Storage of asbestos and other goods to be outside workcrooms 12 Exclusion of young persons from specially dusty work ene on preventive Particular medical referred Vote Vote Particular preventive mensures of medical native are referred to in Part 1 where also the limiteri valu of respiraties as safeguard in this industry is briefly discussed 4 st, NOTE ON EXHAUST VENTILATION IN ASHESTON WORKS es ; te +sonte are designal and inefficient others again do not effect removal of dust to a sufficient extent the The draught may not be applied as closely as possible to . producing points or may be too weak The emission of a visible dust . cloud at ^ pot pot where exhaust is applied a clear indication of inadequacy an - meget SP CLD a oy Pr Ne. tebe, OT : Exhaust Extensive alterations of existing plants may produce serious loss of efficiency Esxpheaakuisnt vbiesmiatde fionrdn epeewndmeancthliynerWyhainlde pardovcaenstsaegsesshoreusludltthferroemfodreealgienngerwailtlhy many mducing by a single exhaust plant a number of contained points plants independent faus and settling apparatus is often more effective (9 E 1 ventilation applied on a large scale entails continuous removal of , a consistable volume of air from the room The supply of fresh air must be 7 ample or the efficiency of the exhaust ventilation may be reduced In winter be - the workers are liable to bring about this result by closing windows and doors ae : Plenum ventilation capable "+ of supplying supplying the volume extracted the incoming air being warned m-ay therefore be desirable where extensive exhaust plants installed jf peocas. rm rae Awe STe faces cs " ates . oy be connected with efficient Efficiency of an exhaust ventilation plant may greatly reduced by in- efficient settling methods " Each fan should discharge into an independent settler Settlers adopted in asbestos works include cyctones large chambers cyclones large chambers enclosed with sacking or other filtering material and bag filters Cyclones and chambers are usually well separated from workrooms Bag filters are now being commonly adopted for small instal- lations These filters and balloons are sometimes placed inside workcroams sephaardatepdrafcrtiocmewoTrhkeryooamrse best placed in freely v7 entilat d rooms effectively T ome +. Ore so: ere tote bre . 2 6 . cathogdee es we we exhaust plant . , . t - Filtering fabrics for settling dust gradually become clogged and as this |, effect increases the exhaust plant becomes more and more ineficient the volume of air moved by the fan being reduced Such settlers must therefore be kept : clean The usual practice is to beat the filtering material Arrangements for shaking bags from outside or automatic shaiding apparatus are not provided Asbestos dust does not appear to be so difficult to detach from suitable filtering material as some dusts but much dust is pinduced in beating Efficient shaking arrangements avoiding this exposure should be provided if this method of settling is retained Some firms strongly support the view that it should be given up because of the difficulty of maintaining the at the highest +. efficiency The matter merits careful cousideration particular the - efficicory of the exhaust plant should be kept under constant observation by a responsible person nh _o me to Cyclones should be of adequate dimensions The combination of chamber and cyclone is used extensively the fan discharging the air into the chamber which the cyclone inlet is connected The efficiency of this arrangement should remain practically constant R. A. MEREWETHER CHAS W. PRICE 14eaet remeh 14th March 1030 * . ee TS Ate wer owe Pm fet