Document 3edLL2JyKmnbx4jqDYMd3bO00

FILE NAME: National Safety Council (NSC) DATE: 1940 Oct DOC#: NSC243 DOCUMENT DESCRIPTION: Excerpt - Transactions of the NSC - 29th National Safety Congress - Pulmonary Diseases in the Mining Industry TRANSACTIONS " 29th NATIONAL SAFETY CONGRESS GENERAL AND INDUSTRIAL SESSIONS C H IC A G O OCTOBER 711, 1940 NATIONAL SAFETY COUNCIL INC. . Transactions o f the 29th Netaonil Safety C ongress I and Exposhioa o f the N a ^ m l Safety Council, October 7-11,1940, are published in two volumes. Volume I contains the General Sessions and die meetings o f the various In dustrial Sections o f the Council. Volume II contains the Street and Highway Traffic, the Commercial Vehicle, the Transit, the Child Education and the Home Safety Sessions. Volume I is distributed automatically to all industrial mem bers of the Council. Volume II is sent to members who are believed to be interested chiefly in the sessions it contains. However, other members of the Council may obtain Volume II upon request. Many Council members have found it advantageous to dis tribute copies of the Transactions Volumes to the individual executives, foremen and supervisors of their organizations, who make use of the practical safety information the vol umes contain to organize accident prevention programs. The volumes contain a vast amount of standard reference ma terial. Extra copies of the Transactions may be obtained as follows: Volume I, one to 10 copies at $2 each; 11 or more copies $1.75 each. Extra copies of Volume II may he had at 75 cents each. TH E Transactions are a condensed record of the proceed ings of the Congress. The papers and addresses and many of the discussions have been edited to delete ext ram-onmatter, abbrevia the less important portions, and empha size those parts of particular usefulness in promoting effec tive safety organization and other accident prevention meas ures. The volumes are, therefore, a somewhat abridged v e r sion, compact, practical, and of particular value to the m u dent, the supervisor and the executive in achieving m ore thorough accident prevention success. The original manu scripts are available for additional reference, if desired, ui the files of the National Safety Council. TH E National Safety Council, at its Congresses, seeks to eliminate from discussion matters which are not pertinent to the aims of the Congress or which may be contrary to the Council's policies. However, it cannot accept responsibility for all the views expressed either in the papers presented or in the discussions based upon these papers. HONORARY MEMBERS Association or Imon and S i m . E m u m s Robert W. C u m u Lew R. Pa u o * OFFICERS (1 9 4 0 -1 9 4 1 ) Co l John S ru -w tu , President Ned H. D earborn, Vice-President lo r Education I. W. Millard, Vice-President for Fnxmee andT re u a rc r G. T. H ellmuth, A sst Vice-President for Finance and A sst Treasurer W alter S. P aine, Vice-President for Industrial Safety Lew R. P alme*, Vice-President for Cowwinaity Cornells aad Public Relations A. V. Rohweder, Vice-President for Home Safety R. T. Solensten, Vice-President for Membership Leslie J. Sorenson, Vice-President for Pnblic Safety W. H. Cameron, Managing Director and Secretary EXECU TIVE COM M ITTEE (1 9 4 0 -1 9 4 1 ) H. J. Aldrich. Spencer Kellogg & Sons, lac. J. I. Banask, Past President H. K. Bennett, Safety Dept., Automobile Club of Rhode Island C. W. Bercquist. Past President H. VV. Boggess, Sinclair Prairie Oil Company H. E. Bolt, South Bend Civic Safety Council Chas. S. Bowden, Public Utilities Section F. VV. Brai n, ASSE-Engineering Section VV. H. Cameron, National Safety Council, Inc. L. C. Campbell The Koppers Coal Company Robert W. Campbell, Past President D. B. Chant, Ontario Pulp & Paper M akers' Safety Association N ed H. D earborn, New York University L ewis A. DeBlois, Past President Marcus A. Dow, Past President H arold F. E nlows, The American National Red Cross Cadwalladeb E vans, J r., Mining Section D. D. Fennell, Past President H. J. Griffith, Jones & Laugh!in Steel Corp. E. E Grover, Columbus & Southern Ohio Electric Company C E. P n n o a t Past Pieaidcut G. H . P lB r, General Efecttfe Company A u n t& R H n M , In te rn 1 Relations Coonaelors. Inc. R. J. RncB unv, Construction Section L t. Cot. H nttV A. Rnocucaa, P u t President A. V. Roaw n n , Duluth, Mtssabe ft Iron Range Railway Company O m m R. Scott. Pant President F a a m T . S a u ra. Portland Cement Association Ca*l L. S tem , Greater Cleveland Safety Council G R. S a n a , American Air Lines, Inc R. T. S o u m ra r, Effiott Service Company Lxsuz J. Soanoou, T rafic Engineer, Chicago Col. Jo an SnLWKu, Consolidated Edison Company of New York, Inc. Johh If. SvLveuea, Lehigh Valley Safety Council J. R. T urner. Steam Railroad Section C. P. T ourna, P u t President Gcoacc G T eaveb, Greater Chicago Safety Council V. I. T a o raa , Automotive ft Machine Shop Section Da. G R W tn o a , Past President A W. W anner, National Conservation Bureau R. V. W atcnr. Railway Age Magaaine Aaxntnt H. Yotiao, Past President DIRECTORS (1 9 40*1941) H. J. Aumkk, Spencer Kellogg ft Sons, Inc. Fkam lLA iiBS, Marine Section A. G Aa n m enc, Rochester, N. Y. V a n W . A w n , Safety Div., Syracuse Chamber of Commerce J. L Babasr, Past President D. A Balaam . Caraeaie-Illmots Sted Corporation OFHCBS AND OKECIOK, Canfcw! H. K, Bnm m , Safety D e ft, A etoew lie -Ctafc i to o * 1* ^ C W. BaoautsT. Fart PteaWMt E-F.BLAJoe.Jooe f t LaagMfr Steel Cusporntion a w. Bocqbm. Sinclair Prairie OB C ampaay O. C Bmleau, Wood Predacts Section a a Bolt, Sooth Bead Civic Safety Coaacif C a Bouun. Wisconsin P alfic Sem e* Corporation VrwiAS* 0 OwmEH%JrHRMKwVINS MHCHBto F. W. Bcauml A SSE 'E w aefldnc Scctkn Icvnr A. BaonniAJt, Metals Soctioa Joseph A. Bsophy, Elisabeth Safety Cotmd! F. S. Baowx, Standard Accident lasarancr Company W. awwpCameron^p. wNTMoa^t^iwonosaslmS^^BsUf^n^aRj^r ^Gat^NoPNai^^a^^runinLBa^sm L. C Camvbx, The Kopppew Coal Compasp Robert W. Campbell, Past Pm idtw t Raymond A. Carey, Evanstoa Safety Coaacil Ray Carney, Kenosha Safety CooacB Robert I. Catuw, Aetna Carnally ft'S an ty Company D. B. Chant, Paper ft Palp Sectioa Dean If. Clark, Food Sectioa Wr. M. Clark, S t Joseph Safety Coaacil Edward L. Cook, Rochester Safety Coaacil J. E. Cullimey, Bethk h a n Steel Company Ned H. Dearborn, New York University Lew A. DeBlok, Past President C. W. Dempesy, The Liquid Carbonic Corporation R. A. DrmtAR, Cement ft Quarry Section IfiLiOM W. Dobbzeksky, East Bay Safety Coaacil C. R. Dooley, Soconv Vacoam Oil Company, Inc. James B. Douglas, The Philadelphia Gas W orks Company Marcus A. Dow, Past President Ralph W. Elus, Jr., Springfield Safety Council ft Haatyden County Safety Council Harold F. Eklows, The American National Red Cros* CADWALLADEa Evans, Jr., Moling Section D. D. Fennell, Past President Da. Hart E. Fisher, Chicago Rapid Transit Company Edmund Fitzgerald, Safety D iv, Milwaukee Association of Com- merce Victor B. Fitzpatrick, Richmond Safety Council Howard B. Fonda, BTroughs Wellcome ft Co. (TJ.S.A.) Inc. Arthur C. Frty, W orcester Safety Council Lyle H. Gift, Peoria Association of Commerce Safety Council Randolph L. Gilman, Rahway Safety Council Henry J. Gorman, Bladcstane Valle)' Safety Council W. A. Grippin, American Tdephone ft Telegraph Compart) H. J. Griftith, Jones f t Laughlin Sled Corporation " " ^ ------ /~-i-- a fim tlim i Ohio Electric Company W it, & iC inm m , D ettuit industrial Safety Cn-- rtt C L. LAFbtnrrAME, G n at Northern Railway Company Rov L i t Cmtrm Cotta County Safety Coanefl A n n a Laaaennr, Grand fttpiift Safety ^ 1 Joan E. Lane. P u t President I. W. f iwwi Commercial Vehicle Section T ina. H . H ttO w tu y U. & Public Roads Admfcristiatiou Hom. A n n u a W. Magee, Commissioner of Motor Vehicles, New Jersey Rov S- Makshau, Seattle Traffic ft Safety Coontil R. A. lfc A m a a , Public Service Coordinated Transport H. N. McClellan, Berkeley Traffic Safety Commission, Ltd. Da. M o-ua McCuntock, Yale University David L. H u a i , S t Louis Safety Council L W. Mir.i Atn, indnstrial Gloves Company Cmas. A. M tu in , Petroleum Section Hauqld L. Mike*. E. I. du Pont de Nemours f t Company R. R. Moaucv, Indnstrial Accident Prevention Associations C L. MuaaAY, Mason Gty-Cerro Gordo Comity Safety Council G tat Dm b l Needham, Massachusetts Safety Council M. C Nelson. Des Moines Safety Council How. Euot N tss, Director of Public Safety. Oeveland F lu u a & Newell. Toledo Safety Council E. J. (ypM tii. J a , Louisville Safety Council Games C A. Ora. The Detroit Edison Company Walts* & Paine, Aetna Life ft Affiliated Companies Law R. Pauses. Past President David A. Patton, Newark Safety Council V. CLPendleton, Power Press Section C. EL P u tn a m ; Past President G. H. P r a t, General Electric Company Judge R aOT H. P o m * . Street ft Highway Traffic Section OfflC&S AND DIRECTOR, ConUMitd Auwrr S. Rccula, h M U be R .J. Rncauum, Conatnietimi Section Lt. Col, Humv A. Scm ook Fn* P ratil A, V. Ronwcna, UWtaA M in k * Iran H tn v G. S a w n , licnt Railway Company f t Leather Industrie* Section Charles R. Scott, Past P m id en t Earl S. Shari . Utica Safety Coondl Fkamk T. Shots, Portland Cement Association John R- Sherwooo, Baltimore Safety Coondl Dr. L. A. Shoudy, Bethlehem Steel Company Ernest L. SntoNoa, New Haven Safety Coondl Adolph Skinner, Safety D ept, Nashville Chamber o f Commerce Carl L. Smith, Greater Cleveland Safety Council C. R. Smith, American Air Lines, Inc. Arthur V. Snell, Chattanooga Safety Council R. T. Solemsten, Elliott Service Company Leslie J. Sorenson, Traffic Engineer, Chicago John B. Spence, Kansas City Safety Council E. C. Spring, Philadelphia, Pa. Cou John Stilwell, Consolidated Edison Company of N. Y.. Inc. E dmund C. S tone, Western Pennsylvania Safety Coondl J ohn M. Sylvester, Lehigh Valley Safety Council J. R. T enney, Steam Railroad Section A rthur M. T ode, Consulting Engineer C. P. T olman, Past President George G. T raver. Greater Chicago Safety Council V. 1. T rotter, Automotive & Machine Shop Section W ilfred E. V ogler, Albany Safety Council Dr. B. L. V osburgh, General Electric Company J. C. W ard, Superior & Douglas County Safety Council S tanley W arzala, Chemical Section Dr. C. H. W atson, Past President W. B. W eaver, T extile Section T. A nglin W hite, Safety- Div.. Birmingham Chamber o f Commerce S. E. W hiting, Liberty Mutual Insurance Company A. VV. W hitxev, National Conservation Bureau R. V. W right, Railway Age Magazine Arthur H. Young, Past President E .1 Z auft, Safety Bureau, Duluth Chamber of Commerce M il SM ii'S tesi? te s __ ,, , ,... t e c _tw. ft. o( a f k in c mix- tans. ShouM te s be caattbed to u i me* 10 f t I o f A c entry waadd be f i l i Bk: Methane which will percentages of located in re now available ' M r r atr and f r o n d One type n | be ----- -----------------, in the hMt breakthrough and along haulage road: T h b can be aid- Jasted to give a warning by a signal fiffht or other means at any predetermined meth> ane concentration. For example, at t per cent o r any specified percentage between 3 per cent and 3 per cent, it will operate special electrical circuits through suitable relays to cut off the power in a section or part o f die for eon* caied in |M :'. phwes. There between the v o ta to of methane: given off in * ! tee^a* the dhcmkal conipoeition o f the can i both bituminous and anthracite m in p ro te c t methane, and methane has been m etal. ,w^ 1a t th teath carhonaoeone shah* The occurrence and cxglowhflity o f methane arc re # n ib k for numerane nane disasters and every precaution shmdd be taken to keep it within safe liants. This can best be done by the use and guidance of methane detec tors. Pulmonary Diseases in the Mining Industry By DR. R. R. 8AYER8 D irector, U nited S tates Bureau of M ines, W ashington, D. C. Although the attention of those interested in diseases peculiar to mining has been focused recently on one dust disease--sili cosis--other respiratory diseases may cause more suffering and economic loss. The in creased incidence of these diseases usually is attributed to exposure to abnormal air conditions underground, such as sudden changes from high to low temperatures, ex cessive dust, and noxious gases. The prin cipal respiratory diseases to which the miner is subject arc bronchitis, influenza and pneu monia, pulmonary tuberculosis, anthracosiiicosis, and silicosis. Although the mor tality statistics in some of the tables in cluded in this paper are old they have been corroborated by later, less complete data. B ronchitis Bronchitis is an inflammation of the bronchial tubes due, among other causes, to the inhalation of irritants such as dusts {organic and inorganic). Occupations that entail exposure to atmospheres polluted by mmn Aarrv wnth fKjlll til# ritlr rtf During middle life bronchitis causes much recurrent invalidity and incapacity Mortal ity records compiled by Collis8 indicate that it is of a chronic traumatic origin asso ciated with irritating atmospheric condi tions, rather than of an infectious origin. Statistics for bronchitis for the general population and for workers exposed to dusts in Great Britain* for 1921-23 show the role played by dusts in the increased incidence of the disease in certain industries. The comparative mortality per thousand (ages 26 to 63) for those in occupations exposed to siliceous dust was 214, for those exposed to nonsiliceous dust 59.5, and for the gen eral population 49.6. (See Table 1.) In this connection it is interesting to note the mortality statistics per thousand (ages 26 to 65) for coal miners of counties o f Wales (in which most of the coal mined is anthracite) compared with those for two other groups in England and Wales.* The figures for coal tuners are 112 for all un derground workers and 139 for hewers and chtris two la t W rite costs amont chitis. Tabi urea Goal All H Male A lio R ats tei ti Tut ity *** A!  awch Mortalttxboair p n tn ) to d u t t the rale Coal miners1................................... Bronchitis All underground workers.......... 112 Hewers and g etters.................. 139 Males in same racial d arn ............ 46 AN occupied and retired males. SO Ratio of rate Cor hewers and get ters to rate for same social d u r . J02 T able 3.--I nftnon r t -Pncum ocia M ortal ity am ong B itum inous Coal M iners-- O ctober to D ecem ber 1918 Age IVriod All Ages* 15-25 Annua! Death Rate per 1,000 Bituminous Coal Miners 50.1 All Industrial White Males 22.3 793 17 3 w th filr for 4,700 or CoapMiy' ____ 1918 during cpMtaofc <4 o f these miners o r fO M m a . This is to an enneiel death rate of 50 per ljOOQ. Among aB occupied males aped 15 years and over, the rale from influema- pnrmnouio iu the same 3 mooths was 22 per 1/100 o r leas than half as high. In the age period 45 to 65 years the rate among bitu minous coal miners was about four times as high as among all occupied males in the same age group. (See Table 3.) Influenza and pneumonia, as reported, were responsible, in the years under study, for 31 per cent of the mortality in the group of bituminous coal miners at ages 16 to 70 in Indian* Missouri, and Wyoming com pared with 19 per cent among both farmers and "all other'm ales" at these ages in the same counties. (See Table 4.) In 1918, the year of the great epidemic, influenza and pneumonia deaths constituted 55 per cent of total mortality exclusive of accidents among the bituminous miners in contrast with 27 per cent among the farmers and 34 per cent among all other males. These percentages were not as high as the figures for Wilkes-Barre. The fact that the soft-coal counties under consideration are largely rural areas may have made some difference. In die epidemic year 1920, the proportion Male G*mqm ITader 16-79 16-30 31-40 41-50 51-60 61-70 Bitunnaom c n d a n m ___ Farmcre-- ........ ........... All other inrfw ...................... 31.1 69.4 44,7 : 25.1 19.7 10.4 18.7 38.4 32.4 19.7 12.4 10.8 18.6 30.0 29.0 16.0 1U i I0 J ' 1^? ********ft-coel wtecre wcrebuiac4 fna IS cnemit* *f M m , IW f ______ __ot&rr waka" w u oh u iacd from the ricatfctcniitfc<rf Wypmfae. W M 1. portion of deaths from this cause compared with "all other males" than in 1918. The percentages in 1920 were 29 for the softcoal miners and 16 for "all other males." In this epidemic the bituminous miners at ages 40 to 60 suffered heavy excess mor tality from influenza-pneumonia, but the differential mortality was not quite so great as at age- lf> to 30. Among hewers ami getters of soft coal in England and Wales, the death rate from in fluenza and pneumonia, 1921-23, was about 12 per cent greater than among males of v<imparahfe social status (social class 3). The difference was found to he 5.8 times the probable error of the difference which is certainly a significant variation. Thus, an abnormal mortality from influenza and pneumonia is consistently indicated among miner- i.t coal--both anthracite- and h'tummuti-...it; England a- well as in America. The pneumonia mortality figures in 192123 tor occupations in Great Britain exposed to -sliceou- and non-iliceou- dust compared with tho-c for the general population were given by Collis' as 134.3, 76.0, and 85.3, re-''ctively: similar figures for influenza were 47.1. 49 6. and 36.5. respectively. (See Table 5.) According to Brundage,* an outstanding feature of the statistics of death for hard- coal miners in the I'nited States is their extraordinary mortality from influenza and pneumonia not only during influenza epi demics but at other times a- well. In a studv bv the Public Health Service at will-- u -- ,, d, 1QK-M amt 1906-25* gaged in pursuits other than coal mining in Wilkes-Barre and vicinity. The percentage of deaths from influenza and pneumonia for these two groups by ages for the years mentioned was 19J for anthracite miners compared with 13-3 for males in other in dustries. (See Table 6.) Tuberculosis In 1925 Collis* said that for coal miners generally the tuberculosis rate apparently is low although miners at the coal face suffer from the disease more than other coal min ers underground and workers above ground. Results of more recent investigations seem to contradict the assumption that tubercu losis does not occur among coal miners. An inve-tigation by the Welsh School of Med icine, reported in 1937,* indicate- that thss supposed exemption of coal miners from tuberculosis may be due to a mis- <.r partial diagnosis. This investigation revealed a high incidence of tuberculosis (35 per cent if the 'probable" cases are included) among the pnrumnconiotics of the South Wales coal fields and supports the theory that coal dust modifies the tuberculosis, leading to failure to recognize the disease or to the mistaken diagnosis of "bronchitis." Studie- by the I'nited States Public Health Service" revealed that 6 per cent of hard-coal miners examined had clinical pulmonary tuberculosis. The average prev alence in the adult male population of the United States is about 2 per cent. The prev alence of pulmonary tuberculosis among hard-coal mining employees at ages below a. ~ am t for * _years her m- ready is re sniffer aal min ground tubercuners. An nf Med hat this rs from r partial d a high (it if the ong the J o coal -oat dost > failure nistakrn Public cent of clinical te prevt of the he prevamong TMMa M m talit/ u^,,, i i1a,.... j, to to Ages a t Death Comparative M ortality Figure 120- 25- & 45- 55- 20-65 3.3 14.4 30.6 47.2 38.7 .,, . . 4 I J J 28.7 23.9 4.3 11.5 19.4 24.2 25.7 134.3 76.0 85.3 Influenza 1.1 7.7 11.3 8.7 18.3 47.1 5.4 4.8 13.7 10.6 14.9 46.6 2.0 5.2 7.7 9.7 12.0 36.5 about twice, at ages 45 to 54 about $ times, and for ages above 55 it was about 10 times the rate found in the general population. The highest prevalence of clinical pulmonary tuberculosis occurred among the rock work ers (men who had been employed in rock loading or rode extraction for more than 2 or 3 years). A fter 20 years' service, of which more than 2 or 3 years were in rock work, 37 per cent presented evidence of pulmonary tuberculosis. In a group of 135 completely disabled former anthracite work ers, which did not include any known cases of tuberculosis, 10 per cent proved positive for pulmonary tuberculosis. These findings would appear to corroborate those of the Welsh National School of Medicine that in dicate that the supposed exemption from tuberculosis of coal miners is erroneous due to incorrect diagnosis. There is evidence that the above increased incidence of tu berculosis is associated with exposure to silica dust. The incidence of tuberculosis is much higher in metal mines than in coal mines, due no doubt to exposure to dust containing a higher concentration of silica. An investi gation in 1914 by the Bureau of Mines in cooperation with the Public Health Service of pulmonary disease among the zinc minerof the Joplin, Mo., district, revealed a high death rate from pulmonary tuberculosis. The mortality rate for tuberculosis tor Jas per County was 200.8 per 100.000 for i9U and 1912 and 2297 for 1913, according to statistics of the State Board of Health." On the other hand, according to the Jasper County Antituberculosis Society, during the calendar year 1912 there were 720 deaths among miners who had worked 2 years or more underground in Jasper County. Not all T abie 6.--P ercentage of D eaths from Influenza and Pneum onia among A nthracite M iners and am ong M ales in O ccupations O ther Than M ining in W ilkes-B arre and V icinity Ages i- 20- Occupations exposed to dint 25.6 Nousiliceoas dust................ . . . IJ.6 20.6 a t Dwtli 25- 3S- 45 55- 20-65 63.4 141.0 211.6 150.6 592.2 26.3 46.1 56.4 29.9 172.4 37.6 43.6 JO 22.7 163.5 of d m t 720 deaths oocnm d in that county but they had contracted the dhcue there and some o f them had moved away. O f 99 miners in the Joplin District examined by L a n a in 1914" 64 showed definite symp toms of pulmonary disease and 39 of the 64 had the classical symptoms of pulmonary tuberculosis. In a study by the Bureau of Mine and the Public Health Service" in Butte, M ont, luring 1916 to 1920 the death records of the State Board of Health were examined. The^e showed that during 1915, 122, during 1916, 126, and during 1917, 169 Butte miners died of tuberculosis. The significance of the death from tuberculosis of 169 miners in 1917 is indicated by comparison with the rec ords of other regions. In 1917 approxi mately 14,000 men were employed under ground in Butte mines; with 169 deaths from tuberculosis for the year, the rate per 100.000 was 1.207. The tuberculosis death rate of Michigan for the 10-year period 1910 to 1920 was 97.4 per 100,000; hence the tuberculosis death rate of Butte miners was nearly 13 times as great as that of Mich igan. The jart played by dust, especially dust containing silica, in the production of pul monary tuberculosis is shown clearly by figures for Great Britain for 1921-23.' The death rate per 1,000 for ages 20 to 65 was ;92.2 for those exposed to siliceous dust, 172.4 for those exposed to nonsiltceous dust, and 163.5 for the general population; tor ages 35 to 44 the figures were 141.0, 46.1, and 43.6, respectively; for ages 45-54 the figures were 211.6, 56.4. and 39.0, respec tively ; and for ages 55 and over the figures high w ny th o t f gppffd in affica f ia t bat the m adcncc of them Bscaacs b not always the f--we under n*hte such a* exposure to other dusts, hart and fumes, or working indoors. (See Table &) Anthracoailicotis From 1991 to 1937, 87 per cent of the total deaths in Great Britain due to silicosis occurred among the coal miners of Sooth W ales; two-thirds of die deaths and dis ease occurred in the Swansea Division; and 89 per cent of the medical certificates granted in the Swansea Division related to anthracite collieries." In the United States the chronic disease among miners due to breathing air contain ing dost generated in the various processes involved in the mining and preparation of anthracite is called anthracosilicori. This is a descriptive title for the form of pneumo coniosis commonly called miners* asthma The disease was found in about 23 per cem of 2,711 employees of three anthracite min ing companies studied by the I'nited StatePublic Health Service in 1933. About 63 per cent of those hav'ng anthracosilicosi* showed evidence of disability, compared with less than 10 per cent in the control group. Moderate and marked degrees of disability handicapped aproximately 21 per cent of those with anthracosilicosis compared with les than 2 per cent of the men serving a* control- Wide differences were found in the ex tent of physical impairment in the several occupational groups. The highest rate of disability from all causes combined wa- o f the n of South ho M l t e to of Th H of y t 23 ' cent -vmsbv n D Abo 6 inm H oiii- I with of teobihtjr per cart of with 0 I io t e exi the several he*t te e of ' "['H-.r'l:. IT11 ';vj i Im ' -, 5 g h "* 'pBysicd cndfilm Ifiw tS 'S l iIk cqsI Cm ^ ruock wvonsrusk^we*urtoto. un^^^^d^ss oaancowau wuh^nso--ulnwi^^ia uftml^awut riifilr expomne to harm ful te a ts io of : than was foond in the control |ro e p JUM SOa Qm O V R Q i m w u i from aq r am sc was found in 1.7 per cat of the control group, in 9.9 per cent o f the regular anen, and among 12.6 per cent of the rode workers. There was a marked t endency toward in crease fmthe proportion having physical im pairments with increase io the number of years o f employment m anthracite. This tendency is manifested whether one eonside disability of any kind, disability in which pulnumsiji infection was contributory, or te a b te y te e largely to tuberculosis. In each case the occupational groups arrayed themselves according to extent of physical impairment as follows: (1) Rock workers; (2) regular am en; (3) all others exposed to more than 100 aiou d o t particles per cubic foot o f a ir; and (4) men in haatageways except rock orarleers. The pathology of anthraoosilkosb as ob served in these cases is risrntitlly a deposi tion o f coal te s t in the fangs, accompanied by an extensive fibrosis, both diffuse and r, with associated functional and de(siiieosis modified by coaldnst). for ages 16 to t f in Wale.* it w u found that respiratory dis eases acemmted for S3 per cent of the flWMPi ox A B anaix m q v cowipircfl wns Hlt2 per ecat *m--g nudes m the same *""** dois- The proportion among hewers and getters of anthracite therefore was 1,4 times that of men of the same social states. SOicouis There are various definitions of silicosis but all agree that the cause of the disease is the inhalation of silica or quartz d u st" Silicosis is a well-recognized clinical and pathological entity at least as characteristic as that of any came of death known to epidemiologistsJ* The definition of silicosis, adopted at the International Silicosis Con ference in 19% and reaffirmed at the 1939 Conference and generally accepted is: "Stltemis is a the lungs doe to ide. It can be condition of of silicon dmx- cxprimstally in The first investigation of silicosis in the mining industry in the United States was made in 1914-15 by the Federal Bureau of Mines in cooperation with the United States Public Health Service in the Joplin (Mo.) te ln e t" As only a few men were -J - i *--* :* w u derided to rulity from C ertain R espiratory Oiaeaaea of Thoae Exposed to Siliceous Dust, to Nonsiliceous D ust, ad tte Genera] Population--by Age Groups' life III .rww " 3 ** 5 11 te) ozro i dS S g * t ' ** f t a J i ^ "S O 5 * TM:" 4 **" V !I 2 $ 5 ti 33^ .....3 f t n ft . ' a 2 ft tej 1 2te N-C 9A6 Isa s 4 N te f| 11 te <te Si ) i .A - o r - tei 3? 2 (AN te C tes te oi IN OA ft fSl' IT, NX A i *e rsaAj. ri <* -- ^ tei te te ; j *n 1 x te <** N C 1^ X* s tr n n M A tw h* X <N *itAe K r A --; te C 1 w- A ite 1 tr. C- tei C te C*' 5 fte te te j iw ac x , i 1 *r-A. l1 ri m -p *xn ,i o x n . -* f wj. -- v- 5 *rU 1j reAs ""* lr i NIT, f' te l A te A C r- i ~ 1 2? ! t e 1-C -2 H ii iirn f-" - d S J per * ta d h e ro * * ." A M ar report (1W > ^ ta Lm m abI' Q riM i" ndMied ite l a d p o f i t e d m d e file d X -tay etodle o f eBoeis ode in I te tin te d States. luvtsfigarinnt o mining condition* Ijjr Harrington aad te m i* in Botte, M oot, in M it, reveakd that 4Z4 per cent o 1 1 auatrs examined st e wed definite sign* of ItHif.^autans 4oa ta From July I. 17. lo Jone 90, 1932, th Metropolitan Life Jnanronee Co., t t e TriState Zinc A Lead Oro Prodnccrs Associa tion, and tte Federal Batean o f Mines op erated a cooperative dim e at Pieter, OUa.,* to demonstrate to industry a workable method for diagnosis of silicosis, to educate workers in preventive measures, and to serve as a model to industries presenting a dust hazard. O f 27,553 individuals exam ined during this period 5,366 had silicosis. 742 silicosis plus tuberculosis, and 320 un complicated tuberculosis. The chief cause of disability in silicosis is tubercle infection. The silicotic lung appears to be a more favorable medium for the growth of the tubercle bacillus than the normal lung, not because it is fibrotk, nor because its lymphatic drainage is interfered with, but because it contains silica." Ap parently silica dust possesses this character istic of increasing the liability to pulmonary tuberculosis. That this is true i< indicated by the statistics quoted in this paper which indicate also that silica dust increases the liability to other respiratory diseases (See Table 9.) The results of virtually all studies are in agreement regarding the high mortality rates from tuberculosis for industries in which Urge numbers of men are exposed to a silica hazard. These rates are so high that they leave no room for doubt of the causeand-effect reUtionship between the hazard and the high mortality* Joint studies made by the Actuarial So- te r calm tapad tte tap ' a twf : .iri| a lead am Aa a Sam oa of SJ h aU rio r dost A tuberas of read of utia a app* first sia second third st Preve The as the mortali moni i dust as silicosi prevent far ac centrai the wo prope rt parity compos atmosp part k it Altb. breath rated 1 a high non mhi eral pc that, ir proper quartz, the fin enough mal de T ri- i * tot , and to rwntiag a al c u m 1 >ilirridi, d 320 nn- 1 appears i for the than the tratic, nor utter irred tea." Apcharacterpuhnanary . indicated p er which rauca the M . (Se* lies are in tality rates in which osed to a hitch that the causehe hazard uarial Soiriitinai nf xmm snsc.-- ->--------- to the of of s Che h i this group were found <Mefourth o f those with . owe half o f thoae in the 65 per cent o f those in the Prtwoution o f Dost P iaeaae la Mining The data given in this paper point to dust as the greatest contributor to the excessive mortality from pulmonary diseases experi enced a die awning industry and to silica dust as the immediate cause of the disease silicosis. Therefore, the principal method of preventing these diseases is to eliminate as far as possible or reduce to harmless con centration the dust m the breathing zone of the workers. Experience has shown that the properties of a dust that determine its ca pacity to produce injurious effects are its composition, the quantity suspended in the atmosphere breathed by die worker, and its particle size. Although any dust may be harmful to breads under certain conditions, as indi cated by the data presented here that show a higher incidence o f pulmonary diseases in nonsilkcons dusty industries than in the gen eral population, physiological studies reveal that, in mining die harmfulness of a dust is proportional to its content o f free silica or quartz, in particles small enough to enter the finer spaces of the lungs, and in high enough concentration to overcome the nor mal defenses o f the respiratory system. the Und. m M n d i i n o f the dm t pres ent. The phyririan'and the engineer can w w t ric the fcshto o f dieir investigations to determine allowable concentrations o f dust. txj em c to which is an t B a h to cause LnawHeMviiil ppywowiginy mcooD- TtoLe cw*_ gineer is th a t in a position to devise measures for tie redaction of the dust to a harndess concentration. The aim, of course, should he to eliminate toe dust entirely or to reduce the dust to a concentration that will not cause disability during the working lifetime. Allowable Concentrations of Dust in M ining Investigations conducted over a period of years show that exposure to certain concen trations of harmful dusts for a certain time causes varying degrees of respiratory dis ability but that below these concentrations disabling pulmonary diseases do not occur within a working lifetime. The classical ex ample of this is the experience in South Africa with the reduction in mortality from silicosis that has followed the reduction in air dustiness in the mines of that country. The reduction in the incidence of silicosis in the South African mines attests the ef fectiveness of the control measures em ployed and the practicability of using a defi nite dust concentration as a guide in setting allowable limits of air dustiness in the pre vention of pneumoconiosis in dusty indus tries. The production rate of silicosis in the scheduled mines of South Africa" in 193235 was 9.59 per 1,000 compared with 21.95 in 1917-18. (See Table 10.) The incidence rates for silicosis uncomnlw-atMl hv active tuberculosis among South t ' ! ,1M^1; f.-. :i 'r '1i1t-n-o-o* '' 1917-20 1920-23 1923-26 143>70 12423 per 1.000 21.95 19.16 33.28 119I7-I8 Period ' g fa jo " ffiS i Examined Annually 14,624 i6.m 20.139 Production Rateof per 1,000 21.11 13.87 949 per cent than it was in 1920-23. A m the "new Rand miners" who catered die adttry by way o f initial e r animation since 1916 and who have been exposed solely to the progressively impitrriag occupation comfitkms that have obtained since that date, the liability to contract silicosis eras less fay 87 per cent than the similar lability among alt miners working for an equal period in 192023. These "new Rand miners" constitttted 77 per cent of all working miners examined. The group of pre-1916 miners, who in 193536 constituted less than 17 per cent of the total number of working miners contributed nearly 78 per cent o f the new cases of sili cosis. In the study by the Public Health Serv ice1* of anthracosilicosis among hard coal miners silicosis was not found in a control group of mining employees whose dust ex posure averaged less than 5 million particles per cubic foot of air. The prevalence of anthracosilicosis among the entire group of employees was found to be about 23 per cent. Among all except rock workers, less than 2 per cent of the men developed anthraco silicosis when the duration o f employment was less than 15 years, regardless of the amount of dust in the air. Among men exposed 15 to 24 years to dust ccmtaming less than 5 per cent free silica, 14 per cent of those who had worked where the average dust count was 100 to 199 million particles per cubic foot, 29 per _ - far more timu 3S yean in dast ceutainiag leas than S per caul ww mWMuifr.n c proportion o r persons uwbimi isiHcocu tmdsr different con* i. o f dost was as follows: 5 to 99 n d f a pnrtidcs, 7 per cent; 100 to 199 mil lion particles, 54 per cent; 200 to 299 milHcn parfkfefc.71 per cent; 300 or more million particles per cubic foot, 89 per cent W ith the exception o f miners, their help ers, and rock workers, about 25 per cent o f aB the men employed underground devel oped anthracosilicosis after a working period of more than 25 years. This group was ex posed to dust having a quartz content of about 13 per cent The prevalence of anthracosilicosis among persons who had been exposed for more than 2 o r 3 years to dust of which about 35 per cent eras free silica, varied from 10 per cent among those who had worked in concentra tions of less than 200 minion particles per cubic foot for less than 15 years, to 92 per cent among those who had been employed for more than 2S years m dust concentra tions exceeding 300 million particles per cubic foot, more than 2 or 3 years of which time was spent in rock work. Age per se appeared to play a minor role in the development of anthracosilkosis. Analysis o f the data for the purpose of determining safe limits of dust exposure in dicated that employment in an atmosphere containing less than 50 million dust particles per cubic foot would produce a negligible 1 * j v 1 ' - : c than 25 Spereof 5 lo fV m to 199 m* 9 to 299 mxIKoe * a m t m ink R COM. urn, tb d r help25 per cent o rgroimd dewi- period was ts irtx content of mbcosts among d for more than * boot 55 per rom M per cent so concentra- pviKK&i per re m , to 9* per le w employed dust conccntrai particle per i of which ijr a Minor role Ktwilicpaia. the pwpose of wt exposure in* an atmosphere dost particles ace a negligible .. ....iw^i;mmiia<Iwparii; v>*, t' L-. " ; ; ; ; > l:. "; .. : : ' i-i--t"f< tS-H .9 a n d Over % and ow ; Number of] Number of ' WvBBC m^HS ] particle per cubic fo o t The limit o f tol eration for rock workers was set tentatively at 5 to 10 million particles per cubic foot of air. Similar results were obtained by the Public Health Service in an investigation of paeomoconiosts among mica and permatite workers. (See Table 11.) The relation of the average dost concen tration and duration of exposure to the per centage of workers found to l a w pneumo coniosis was as follows: O f those who had racked m an average concentration of 50 million particles of dost per cubic foot of air, 9 per cent had pneumoconiosis in 5 years, 20 per cent in 10 years, 50 per cent in 15 years, and 04 per cent in 20 years. O f those who worked in an average concentra tion o f 25 miltion particles 10 per cent had pneumoconiosis m 10 years, 27 per cent in 15 pears, and 33 per cent in 20 years. O f those who had worked in an average con centration of 10 milhon particles o f dust, 7 per cent had pneumoconiosis in 15 years and 17 per cent in 20 years. (See Fig. 1.) The data obtained m other studies of dusty - *.- !_! . . 1 . . . . . value below which no cases were found and the magnitude o f the trends between per cent affected and both time and intensity of ex posure varies m different sets of data, de pending, to a large extent, on the chemical nature of the dust to which workers were exposed and possibly on the regularity of employment. It is tempting to seek to summarize the data of table 12 and figure 1 into a simple mathematical relation such as the follow ing: W ith each twofold increase in average dust concentration above 10 million particles per cubic foot, the probability of finding cases o f silicosis (in men exponed for com parable lengths of time) is approximately doubled. Application of the standard meth ods of curve fitting would yield more re fined descriptions of these data. Neverthe less, it does not seem to be advisable to set up any mathematical treatment because, of all the men who entered the industry, only the survivors have been studied. There is no adequate way of finding ont whether or not men who dropped out of the industry * m i hm nr wnrr state of health as F igure 1.--R elation of average dust concentration and duration o f dust exposure to the percentage o f w orkers found to have pneum oconiosis. Based on data pre sented in Table II. treatment. It seems to be preferable to pre sent the facts as simply as possible, to gether with the precautions to be kept in mind in studying them, and to emphasize that the principal use of these data is to how the degree of improvement in health to be expected in the future if dust forma tion and dust dispersal are brought under control in these and in simitar industries. M ethods of D ust C ontrol After the physician and engineer have learned by observation and experimentation what kinds of dust are harmful and in what concentrations, it is the function of the en gineer to evaluate the hazard in a particular industry, plant, or mine and devise measures for its elimination. The first step is to be come thoroughly familiar with the industry being studied to determine the dusty occu pations, the number of persons in each, and the various activities and time devoted to each activity in any one occupation." The amount of harmful dust created by various activities can be determined by tak ing samples of the atmosphere in their vicin ity and counting and identifying the dust lunger, however, is the instrument used most frequently in the United States. The Bureau of Mines and the Public Health Service have issued publications describing the method of sampling dust by the impinger (as well as by other methods) and pro cedures for counting and identifying the particles." -" Dust sampling is complicated by the fact that air dustiness fluctuates rapidly from moment to moment. A single dust count rep resents only the amount of dust in the a t mosphere at the time and place of sampling and gives no indication of the average ex posure of the worker over a period of sears, especially if he has not worked continuously at one job. The ultimate lung injurs that he may suffer will depend upon the inte grated effect of the dust over a long period." A proper measure of dust exposure re quires a picture of the variations in dusti ness. The best procedure is to determine the dustiness during different stages of an operation and, with the aid of a time studs-, break down the worker's day according to the time spent in each step; from these data the average dust exposure of the worker can p- neat used most *- The Bureau {Mi Service describing the f the ia p n g rr od<) and proidentifying the ted by the fact tapifiy- from dust count rrp dust in the attce of n o ip h ig he average experiod o f year, ed continuously out injury tint upon the intea long period." exposure rei tn m In dustii to determine it stages of an if a time study, ly according to from these data the worker can i, ^jggggBfgS^ .. fif':-' it*, vfc! 541 Job MifMaiiuiin (drillers). Average Number Number of of Years Men :kwmMll been inspected, the difference con sisting entirely of dust too fine to I t de tected by the older methods. The importance of contMl of drBfing dnst as a measure of the prevention o f atMcosis is demonstrated by die fact that the incidence of silicosis has remained consistently and considerably higher among machine drillers than among those who have never worked machines, and the excess incidence among machine drillers has been in direct propon ion to the amount o f time spent upon rock drilling. I'ntil relatively recently drilling of holes for Masting was a negligible producer of dost or air dustiness in coal mines especially other than anthracite mines. The handoperated auger drill produces very little fine dust, hat with the extension of mechanized mining power drills are becoming more and more essential and some of them are heavy producers of finely divided d u st; this iespecially true of reciprocating drills of tin jackhammer type drilling dry and using compressed air in the clearing of holes either in coal or in roof or Boor material. Blasting---The exceptionally heavy inci dence of silicosis among rock drill miner- in the early period o f the gold-mining industryin South Africa* was doe to the exposure of the rock-drill miner not only to drilling dust but to high concentrations of dust from Masting, and frequently to the inhalation of varying amounts of the irritant fumes pro duced by blasting, owing to the methods of Masting then in use. Blasting produces large quantities of very fine dust, the finest frac tions of which tend to remain suspended in silicosis because o f frequent change o f oc cupation. AH examined were divided into two groups- those exposed to large amounts o f dust (those employed at the face) and those exposed to relatively small amounts (those away from the face). In the order of exposure to the dost hazard, the men at the face included shovelers' helpers, shovelers, drill helpers, machinetnen, trackmen, roof trimmers, powdermen, shovel bosses, and ground bosses. According to analysis of the occupations of face workers the hazard was greater for shoveters' helpers and shovelers than for macliinemen if length of time re quired to produce first-stage silicosis is a criterion. It is noted from table 13 that the average number of years worked by shovelers' helpers and shovelers was 6.8 and 8-4 years, respectively, while that for machinemen was 11.4 years. lx<ading and Hauling.--Voder some con ditions hand loading of coal throw's into the air of the working place considerable quan tities of dust, but the amount is about onetenth that caused by some types of mechan ical loading. The greatly increased occur rence of dust from mechanical loading is due not only to the stirring of the dust into the air by the loading machines themselves but also to the greater rapidity of breaking down and taking coal from the face regions which increases other dust-producing proc esses, especially blasting, cutting, and haul- tng. Poorly constructed or poorly maintained pit cars or over-topping of coal in cars al- -! i* ---------* ____ L at* the ' ....... toMPtop., a*e mthl h a working for a o f the n a to perform at ti* s a n e tim% aad the air speed at the faces to higher.* These if not controlled tend to tocnase the A n t exposure to the face washers. Metckme c o d cwttmg.--When coal-cuttm toto the picture early to the present centnry to supersede to fauge part both hand cutting aad Masting off the solid, the really heavy producer o f coal dost tin t the worker has bod to endure was at hand, and this was especially true of the chain machines operated by electricity. Top a n ting is the worst offender to so far as im pregnating the air with dost to concerned, shearing occupies an intermediate position, and undercutting is the least offensive to this respect However, undercutting ma chines under some conditions (such as cut ting dry in friable coal with dull bite in a confined place with little or no circulating air) may produce air dustiness so dense as to reduce visibility almost to zero with available types of mine lighting and to cause between 100,000,000 and 500,000,000 (or even more) dust particles to be carried per cubic foot o f air of the face region.* M ethods o f C ontrol The principal measures for controlling dust in mining operations are ventilation, wet methods, proper Masting practice, the use of persona] respiratory protection, and physical examination. Ventilation.--The more or less generally accepted conclusion that coal miners suffer less from miners' consumption than metal miners, who either die early in life or are incapacitated in middle age, is due almost entirely to the superior working conditions in coal mines as a result chiefly of ventila- Ventih tion prohaMy to the moat effective dust-control measure Ait8iO0|fa sodci* conditions it rank second to wet methods. Where ventilation am be applied effectively, dust can be removed from the air or its con centration can be so dilated as to render it almost harmless.* Wet methods.--As dry drilling is the dustiest operation to muting, wet drilling will keep air dustiness within safe limits if used with care and judgment to collaring wet. using plenty of clean, dirt-free water, and keeping the drills in good repair with ade quate regulation of the proportion of water and compressed air flowing through the drill steel* In tests by the Bureau of Mines* the dust concentration to the air during actual drill ing decreased as the water flow through the drill increased. The water flows for stopers was 0 to 3 gallons per minute, and that for drifters from 0 to 1.02 gallons per minute. The rate of decrease for stoper drills was greater for water flows from 0 to 1.3 gal lons per minute than for higher water flows. The rate of decrease for drifter drills was similar to that for stoper drills at cor responding water flows and rather constant for water flows of 0 to 102 gallons per minute. The results of this study shows that as water flow through the drills was increased the dust concentrations in the air decreased, but they do not show whether the decrease o f safety e moat effective gh o aff^^^ff ^MPSPtfMEfniB2uwamvH!l(wJar^ it a ir o r 1 on* as to render it is the wet drilling will fe tw ts if used i rolhring wet. free water, and with adeo f water ihlQQ^I the drill Mines* the du>t ing actoal drilllow through the lows for N tttr t ite. and that for km* per m inute toper drills was w 0 to U galh er w ater tow s, rifter drills was drills at corrather constant 1.02 gallons per r shows that as Js was increased ne aw aecreasea her the decrease ' water ills ' r.:i'felSp'lilifeiS; JL* 1 >' he maintained Uw the m \ fcgabtions on tie taw of soch M h rin a d i is also doing am di work aJong tins Boev and recent reports state that sneh drills are practical and pro duce about one-fourth the d t concentra tion of corresponding drills w ittont the "dustless-head" features* The results of this study show that op erators can reduce dust concentrations re sulting from drilling by increasing the water flow through the drill steel, either by increasing water pressure or by die m e of water tubes of huger inside diameter. Tests also have been conducted by the Bureau of Mines* on the effectiveness of spraying water along the outside of die drill steel compared with that of standard wetdrilling practice. The tests show that spray ing water along the outside of the drill steel should not take the place o f regular wet drilling. However, if a method is developed by which the device may be used on holes of any inclination, it might prove to be a valuable accessory to regular wet drilling in collaring and drilling the first 2 feet of a hole. Tests show that the greatest amount of dust is thrown into the air of a working place in drilling the first 2 feet of a hole.* Wet drilling standards have been adopted in New York State for driOmg in various classes of rock. The requirements for drill ing in Class 11 rock (rock containing more 10 per cent free silica) in confined i the !that it has r, dosed and L > months after date of ~wc* drifit rial) be quipped Mr throttle end rower dm* (he required rate the drffl atael will he gftr tfnwltic is in the half Jpeed as well as 3. *Tha water dhafl be dean and bacteria freenad ahaVbe delivered to the drills uader premnre from an td tp n it source o f supply. Portable water tanks for mdiridual drills I net be uatd unless approved by the inaisvifti ixunmnnoner. "W et drilling in Clam II rode in confined arm s slat! he used with mechanical ventila tion, or m confined areas under decking by natural ventilation, if approved by the Indus trial Commissiouer and subject to the fol lowing provisions: 1. "The rock surfaces for a distance of 30 feet from the beading or other drilling area shall be maintained in a damp condi tion. 2. "Hand-held drills (maximum piston bom, 3") minimum rate of water flow through drill steel, 0.75 gallon per m inute; maximum rate of air flow through drill steel at full speed, 2.0 cubic feet per min ute; maximum rate of air flow through the drill steel at half-speed operation, 1.0 cubic foot per minute; minimum rate of general ventilation in the drilling area. 500 cubic fed per minute per drill and shall be in creased if found upon tests by the Industrial Commissioner that the dost concentration is not in accordance with the requirements of the Code. 3. "Drifter-mounted and wagon-mounted drills (maximum piston bore, 4 ') minimum rate of general ventilation per drill in the drilling area, as shown in the table `Limita tions in Air and W ater Flow Through wesaL?' ;TMP,P l!,* ` ht . o t f i a t A t * --- 5. fm m opat o f . bcatfa o f the iulafae p$pc or sndi aa to nam e the tm oval of air hom the entire drilling factory to An; Iadtotrial 6. "The required ventilation may be ofctained by means o f a rerirrulatinf air-eicunmg apparatus provided the dost coacrotratioo m the a ir a t the breathing tome o f the drift operator is maintained a t alew d below that required in Kale 3 3 4 J aad the appnratu is otherwise acceptable to the ladnstrial Commissioner. 7. "The above rates of ventilation shall he increased whenever necessary to redace dust concentration to the amount permitted hv Rule 33-2.3." Proper blasting practice.--Methods of controlling dost and fames in mines by proper blasting practice have been deter mined by members of the Bureau of Mines staff by observation and experiment.*** If at all feasible, blasting should be done at the end of the working shift or on an off shift, and the dust- and gas-laden air should he removed or thoroughly diluted before the men return to work. Ventilation is an es sential agency in cleansing the air where blasting has been done. Results of investi gations by the Bureau of Mines" show settling rate of dust after blasting under the following conditions: 1. The atmosphere was bratticed off for 3 hour- while the dust samples were being taken. In this period, under these condition', the dust concentration dropped from ap proximately 5.000 million particles per cubic foot to 50 million particles per cubic foot. 2. The atmosphere was bratticed off until 36 minutes after blasting when the brattice was raised and natural ventilation (which was virtually negligible except for eddy currents was allowed to dilute the dust laden air. It required 2 hours and 20 min utes after blasting for the dust concentra tion to drop from approximately 5,000 mii- fa r a d iato the after Mtstfc _________ bo drop to 50 __ pier ie io** * 30 *" ** 15 ariffion particles per M e The aceonpaqpm f table shows tira ***. io tnasassst q u ire a io r m e misi a s a r i ' den to drap Cram 82S sniffi partk h a per cubic font to SOa ts and io iS.millM n particles per M e foot under die three dif ferent condition: Time, in minutes, to drop from 825,000,000 Ventilating particles per cubic foot Condition \ o ventilation........... to-- 121 181 Natural-ventilation.. 105 135 Mechanical ventilation 20 24 In addition, the place (walls, floor, roof or top, and timbers) should be wetted thoroughly before blasting is done, and a water Mast should be used during and after the blasting. The region should be wetted thoroughly when the men return to the face region after blasting, and the mock pile should be kept well wetted at all time' while it is loaded out, as the water not only lays the dust but also either absorbs or otherwise aids in diluting or eliminating harmful or poisonous gases that follow blasting and that usually cling to the blasted material. Tests* on the effectivene.' of a spray of water mist in reducing the concentration of dust in the air after blasting and during mucking of the blasted material were con ducted in three headings in medium hard to hard rock. The use of the spray apparently made it possible to reduce the concentration of dust generated and thrown into the air during blasting more than 99 per cent from the amount present when the spray was not used. Dust dissemination during mucking of material sprayed several hours before mucking was begun was much less than tar k*a m dry. la raw pkMtve ose will be imj and the g poiMWMlS P:UVqMn the o f gases at nection it jffprinf 0 now avail the explorf and rodwer and also r gas prorfoc knee of th dust and di air. H woe to investijp known to harmful g them; also, fuse and tl would aid i *>us gases have been base been -ion' as tc likely to i harmful g lienee, utm storing of not held t> Personal method of isfartorv < temporary dust respi against du tially no p taring gas* uncomfort; The Bu schedule mechanical for protect integrator About 30 under this ^mm jm^Mora* i s w cns* * * m b t fawM flat the OK o f r f ' '^mmr VS n ' i tv he quantify o f explosive * * iAh> fedw e the a n o in t o f gw produced m 4 pnoM y reduce A c via- k m o f the Um and it> dust and dhscm afte It i m the : air. It v n d d be well for w e n o f explosives to iavestiaMe types of explosives that are known to give off minimum quantities of faam fnt gases on detonation and to use th a n ; also, the discontinuance of the w e of fuse and the substitution o f electric Masting would aid in reducing the amount of poison ous gases from Masting Explosives that have been held in storage too long or that have been stored under unfavorable condi tions as to moisture, temperature, etc, are likely to give off maximum quantities of Harmful gases, if they detonate at a il; lienee, utmost care should be taken in the storing of explosives to see that they are not held ton king before being used. Personal rrjptroior protection. -- This method of control of air dustiness is unsat isfactory in underground mining except for temporary use in emergencies. Although dust respirators give adequate protection against dust, they afford the wearer essen tially' no protection against toxic or asphyx iating gases, and are too cumbersome and uncomfortable for constant wear. The Bureau of Mines has established a schedule of minimum requirements for mechanical respirators, one type of which is for protection against dust generated by dis integration as in drilling and Masting. About JO respirators have been approved -- i-- u.:. ,, k ^ .1. Me we mpsramry organs ' every A m o th s to aO cases o f simple silicosis, tubemi!Mja with niHfftth. wit* simple tuberculosis that may have developed. In this way com parable records can be obtained for measur ing Ate degree of pneumoconiosis and the o f impairmml o f workiug capacity . employees from pear to year. Com parable records will not be obtained unless periodic examinations are conducted in a standardised way, preferably by a permanent medical board composed of physicians spe cially trained and having adequate experi ence m the diagnosis of pulmonary disease. Sum m ary 1. The principal pulmonary diseases to which the miner is subject are bronchitis, influenza and pneumonia, pulmonary tuber culosis, anthracosilkosis, and silicosis. 2. Statistics indicate that much higher morbidity and death rates from pulmonary' diseases are experienced in dusty than in nondusty industries, especially where silica dust is used or produced. 3. investigations by the Public Health Service reveal that hard-coal miners suffer a high mortality rate from influenza and pneumonia not only' during influenza epi demics bat at other times as well. In 191523 and 1906-25 influenza and pneumonia were responsible for 40 per cent of the total deaths among hard-coal miners compared with 25 per cent among males at ages 15 to 65 who were engaged m pursuits other than coal mining. Six per cent of hard-coal miners had pulmonary tuberculosis com pared with 2 per cent in the adult male population of the United States. The rate for metal miners is still higher. nu actv III all oAma ctmoaad ts-aM n 'iliH 100 mSSm f ia t particles per cubic foot of *r. --4 (4) mm a haotagmngrs except rock a e riu n . 6. The principal pulmonary diaca it in MnfiffkSmamduunmmm MtfSl&Mnh^uMoSat w inn^c^Lat_et- menace 1HHOW * OMCIB WIWMi . i l f p I M f **lc 0m l alone increases the liability to puhnooary tuberculosis. Joint studies made by the Actuarial So ciety o f America and the Association o f Life Insurance Medical Directors" revealed that there were 65 deaths where 6 were expected (about II times the expected number) from tuberculosis in 1925*1936 among a group of underground miners, most of whom were employed in metal mines. Tuberculosis deaths were fourteen times the expected among copper miners, nine times the ex pected among gold and silver miners, and eight and a half times the expected among iron miners. In an earlier study* covering the years 1915-1926. there were 18 times as many deaths as expected among lead and zinc miners. 7. As dust is the greatest contributor to the excessive mortality from pulmonary diseases in the mining industry, the prin cipal method of presenting these diseases is to eliminate as far as possible or reduce to harmless concentrations the dust in the breathing zone o f the worker. 8. The aim should be to eliminate the dust entirely from the air breathed. Where this is not always feasible it may be possible to reduce the dust to a concentration that will not cause disability during a working life time. 9. Analysis of data collected by the Pub lic Health Service to determine safe limits of dust exposure indicate that employment II . The im pu^tr the durt-sampfat* intruamat used m eet fn q aam y m me which States. 12. The dastieat o p e n tm a in m iring are dry d r if a g hhating o f <fcy rock o r ore. shovefing or marking; loafing and hanhtgr. and machine coal cutting. 13. The principal measures for controllbig the ill effects o f dust in mining operations are ventilation, wet methods, proper blast ing practice, the use of personal respiratory protection, and physical examination of workers. 14. The efficiency of these measures in the reduction of the incidence of dust diseases is attested by the experience in the mines of South Africa where among the whole body of miners the liability to contract silicosis in 1936-37 was less by 65 per cent than it wa rn 1928-33. Among the "new Rand miners" who entered the industry by way of initial examination since 1916 and who have keen exposed solely to the progressively improv ing occupational conditions that have ob tained since that date, the liability to con tract silicosis was less by 87 per cent than tlw similar liability among alt miners work ing for an equal period in 1920-23. Thes."new Rand miners** constituted 77 per cent of all working miners examined. Conclusion TIk- mortality and morbidly from pul monary diseases are excessive in the mining industry as a result of exposure to targe amounts of dust in the air breathed. There fore, centred of the dust hazard i* necessary to prevent these diseases. No single measure of control is attolicable to all dustv onera- I !?r}ik r. V, ra- m m mUnittd iar MtrollinK tag <H n tiom p n ftr bbttI re*firalor> a i m m ih dmH dhm*** a A t n o n of t t th o lt body act bcosi* in M than tt wa Raad minrr>" w jf of initial rfco have hern nrefy impon that h aw ohabvlky to coo per cent than auatn work- Then ed 77 per cent ed it > front pul in the mining; enure to larpe eathed. Tbeterd aectttar) treason- The ttH.1 i I M i IS. ik , MaMhy ef Ctel m l 2 * mi, i*** r. v . , t * e Jure 58, I : t*U. N . Tech. MS. I. The Mortality t t I Cal lU: Jour. Hygtcra. vuL I. 1919.2. p. tU . I. CoUi, E fp r L. The Coal Mincr: Hit Health. ENaeaeeo. aad General W dfare: fonr. Iixfnii. Hygvcue. eel* 7, 1925. pp. 221-245. 9. Sen, Prafulla Rumor. Pin n on ronintit ta South Wale Cen M inen aad Ita Rdatiou te rubrrcolow: Jour. Initnrt- Hreten*. I. 19, 1957, i* . 225-257. 19. (M kt nf Industrial Hyaicne and Saatatiou. Anthracw-Silicorii Antena Hard Ceni M inen: l'attcd State* Pahe Heakh Bodl. 221. 1955. 114 1*9 II. tanca. A. }.. and Higgn*. Cdona. Puln aanr Drieaor Amona M inen in the f o f a Dutrtct. M in tari and I Rdatiou n P ed O w m the Mine*. P aitan of Mine* Tech. Paper 105, 1915, 4* pp. 12. Han i atar. O., and Lana. A. J. M inen' m n e n in itn in the Mine* of Pune. Montana: Parean of Mine* Tech. Paper 260, 1921, 19 pp. 15. I il e it t , John. Silicosis: A Review i* tir e n of Soase Recrt Rcsearrhet on the Cante of the Divrase CoUiery Guardian, oL 147. 1950, pt* 290-292. 14. la m a . A J. *Editor). Silcoait and As besto*: Oaford l-'nirerwty Preto. 195*. 459 pp. 15. CeUi*. E4p> I- The StatisticaJ Chararterisrics o f Dant Phthisis (Pahaonary Sihcoei l : J o . ladral. Hratenc, rol. 8, 1926, pp. 457-465. 16. H igatni. Lana, A. J.. la n ey , F. B.. and Rice. G. S. Siceoui D an in Retaran to Pula ta m r D nraw A nona M inen in the Joplin Dutrict. M im a n : Parean o f Mine* Poli. IJ2. 1917. IM pp. 17. Latuo. A. |. . and Child*. S on ad P. I. ,*W . > A- * vf ^ * aud * TU bnc** . * * * W- <l*'45* NMLW.41M. t t V'iaim at We* oT*g ' M Three Yes' . M hi Met* Thhii't- ed. , AMea. the St |ty. : h h riaser. Pretera. 1 A.. t t Ther SfHlfc JMbmK Ijlfe tmdUmm if tk live I Iw t a if S hu the 191*. p. 717. A Mattarical e aad Initi VL 49. 24. P loiw A ilt. } . J.. aad DallaValle. J M. The Determination Control o f Industrial Dust: VaMed State* FuMic Health PolL 217, 1955. 167 35. Broun. Carlton E .. and Schrenk. H. H. A Tcchmqoe for Use of the Utpinfer Method: Bu rcaa o f Mine Inf. Circ. 7026, 195S, 20 pp. Schrenk. H. H., and Fetcht, Florence L. Bu rcaa of Mine* H iffr t Irapinser: Pnnan of Mine, In t Circ. 7076. 1959. 7 pp. Foster. Wilder D ., and Schrenk, H. H. Petro graphic Indeotihcatioa o f Atmospheric Dart Partid es: Bureau o f Mines Rept. o f Investigation 556*. 195, 10 pp. 26. Drinker. Philip, rad Hatch. Theodore: In ilottrial Dost, 1936. 516 pp. 27. South African Mining and Engineering Jour nal. Miners' Phthiris and Working Condition,: Vol. 49. 195, pp. 521-525. 28. S.A .M .E Journal. Future of the Miner-' PtahiMt Prohit a : Vet. 49, 1938, p. 13. t 1. Harringtoo, D. Formatitm, CoUeetion, an.l Tream ent o( Coal Dust in Mines: Bureau of Mine* Inf. Cue. 7089, 1959, 11 pp. 50. Davies, A. L. Airborne Cool Dust: Abate ment of the Nuisance in Intensive Conveyor Min ing: Coll. Gaaed., vol. 153, 1936, pp. 755-7S8. 31. Harrington, D. Mine Ventilation: Bureau of Mine* Inf. Cue. 7047. 1939, 16 pp. 32. Brown, Carlton ., and Schrenk. H. H. Relation of Dust Dissemination to Water Flow Through Rock Drill*: Bureau of Mines Rept. nf ItirrstlRItions 3393, 193, 6 pp. 33. JohaMo, John A., and Agnew. Wing G. Dust Produced by Drilling When Water is Sprayed on the Outside of the Drill Steel: Bureau of Mines Rept. of Investigation* 3478, 1939, 6 pp. a d jo u r n m e n t v ,!; 1 : : III ffil IfpVi.S 'Vi: wynzii .teHf 'f e Cfc. c i w w . Ill- _ _ .., ^ C , CUOM^'flL '" II:' k jB * * * * * * ft 0 " ^ y '3:' ': ^ITM?'1': ' 3Pffp;J: -". ' I t T fa n m ( r M r w ^ . W w t e w J t o y * ^ t o l ^ Ck>.. H agers- ; , \ .. , , ......... U * Rwlroad Co., F. A- IMmb^ CMm m B**k M iitf f t F h d fc Railway C o, Chicago, HL S iM lc ^ M M ijM v ^ ^ R C uaow (C h dm m t.T bt P a n o h n a t Railroad. Philadelphia. " F. R, B to u ra a i B aton f t F r ia r Railroad. Beaton, Mass. O. G. Pm i m , W ih ili Railway Co., $*. Lows,, Mo. Corniest C ommittee C L. LaFocwtawe f f l a 'n w s l. Great Northern Railway Co., St. Paaj, Mnm. L. R. Palm (Secretary), Equitable Life Assurance Society of U. S , New York City. T. H. Cakbow, The Pennsylvania Railroad, Philadelphia, Pa. A. V. R o m ren a; Doloth, Muaabe & Iron Range Railway Co., Duluth, Minn. Roacar S co n , Atlantic Coast Line Railroad C o , Wilmington, N. C. P atter Committee--L. J. Bdisox (Chairman), Chicago, Milwaukee, St. Paul & Pacific Railroad C a , Chicago, UL G H. B u n n o t t , Norfolk & Western Railway Co., Roanoke, V a W. F. Lorvam , Chicago. St. Paul. Minneapolis & Omaha Railway Co.. St. Paul. Minn. Safe Practices Pamphlet Committee--T. K. Gagt (Chairman), Chicago, Burlington & Quincy Railroad C o , Chicago, 111. W. ) . Flaioogak, Northern Pacific Raiway C o, St. Paul, Minn. F. A. B o o n ; Chicago, Rode Island & Pacific Railway Co., Chicago, 111. .Vamma/iomt ami Elections Committee--W. C. Shelve (Chairman), Union Pacific Rail road C o.. Omaha, Nehr. M. T. Fultow, Kansas City Southern Railway Co., Kansas City, Mo. H. A. Daakz, Erie Railroad C o, Cleveland. Ohio. Health Committee--Da. I. S. Cattek (Chairman), Chicago & North Western Railway Co, Chicago, IIL Da. H arvcy Baktlx, The Pennsylvania Railroad, Philadelphia, Pa. Da. A. W. W aue . Southern Pacific Railway C o, San Francisco, Calif Office 1940-1941 General Chairman J. R. T ekkey, Western Maryland Railway C o, Hagerstown, Md. Vke-Ckmrmtm O. F. Gkaoosczb. Elgin, Joliet & Eastern Railway C o, Joliet,'HI sVrrrtary and News Letter Editor--J. E. Lone, The Delaware & Hudson Railroad Corp, M hny, N. Y. F R uckle (Chairman). Chicago. Burlington & Quincy R. R. Co, ! 1 I * C H. W. i t Loraum, Chicago, S t Putt, Safe Practices Pamphlet Commtee~T. K. Gaea Quincy R. R. C o,C hkago, VL W. J. G. C. Jirrzns, Atchison, Topeka A Son* Fe RajBwsy Syt--n. Namimtims ami. Elections Committee--H. A Daakx (Ckahrmm). Erie land. Ohio. M. T. Fuuok, Karnes City Soothers Railway C a, Kansas City, Ho. E. L. Hekrv, Chicago f t North Western Railway Co* Chicago, Q . Health Committee--Dr. L S. Ournta (Chairman), Chicago ft North Co . Chicago, IB. ! > Harvey Barite, The Pennsylvania Railroad, Philadelphia. P*. Chicago, IB. R. R Co., Cleve Western Railway TUESDAY AFTERNOON SESSION October 8,1940 The opening session of the Steam Railroa<l Section was called to order by the Chairman, E. L. Henry, Superintendent of Safety. Chicago & North Western Railway Company. Chicago, who presided. He outlined briefly some of the activities of iIn Section during the past year, and took the opportunity to mention the work of many Standing Committees. He then intro duced J. R. Tenney, Supervisor of Safety, Western Maryland Railway Company, Ha gerstown, Md., Chairman of the Program Committee, who assumed the Chair. Mr. Tenney introduced the speakers. The Effectiveness of Grade Crossing Protective Devices from the Viewpoint of State Authorities By WARREN HENRY Assistant Chief Fngiasrr, Illinois Commirce Co--ui--ion, Springfield, IIL The art o f grade crossing protection has this field seemed, to some of us at least the