Document DD2MEdD8z3Q8pv0kO88dZrLdO

FILE NAME: General Motors (GM) DATE: 1935 DOC#: GM003 DOCUMENT DESCRIPTION: National Safety Council Transactions Foreword ' H E T R A N S A C T I O N S of the T w e n ty -F o u rth Annual Safety Congress, Nat ional Safety Council. 1935, are publ ished in t wo vol ume s. T h i s volume, first, contains the general sessions, the special subject sessions, and the ustrial Section sessions. It is supplemented by a smaller volume containing sessions of the Street and H i g h w a y Traffic Section, the Child Education non and Home Safety. All industrial members of the Council automatically receive the large volume, o smaller is sent to members believed to be chiefly interested in the sessions rovers. It may, however, also be secured by other Council members upon ucst. Many members have found it wortli while to distribute copies of these m.sactions to supervisors, foremen and others in an administrative or superory position who may make practical use of them for reference purposes, r the benefit of those who desire extra copies the following quantity prices are ated: One to ten copies of the large volume, $1.50 each; eleven copies and tr, SI.25 each; copies of the s ma l l er vol ume, 50c each. x A C C O R D A N C E with the plan of publication followed for the past several years the Transactions are published again this year as a condensed record the proceedings at the National Congress. The papers of each session or ision of the Congress have been edited carefully to eliminate extraneous mutand to abbreviate the less essential portions because of space limitations. In er words, the material herein pr esent ed is not a ve rba ti m r e por t of all the echos presented at the Congress, but rather an abridged version, made as npact as possible, yet without any injury to the technical aspects of any iress. T he original man us cr ipt s arc on file in the l ibrary of the Nat ional iety Council, where they arc available for additional reference. In several es, wher e illustrations were sent by t he speaker s to the Council, these also on file. The National Safety Council at its Congresses seeks to eliminate from dis.sion matters which are not pertinent to the aim of the Congress or which arc nr ary to Council policies, but it cannot accept responsibility for the views ressed eitlier in the papers presented or in the discussions based upon the .crs. NATIONAL SAFETY COUNCIL, INC. 20 North Wacker Drive, Chicago CONTENTS Page Counci l Of f i cer s a n d D i r e c t o r s .................................................................................................. 4 Counci l P u r p o s e s a n d Po l i ci e s ................................................................................................ 9 An n u a l M e e t i n g of M e m b e r s ........................................................................................................ 11 A n n u a l B a n q u e t .................................................................................................................................. 27 Subject Sessions-- F i n d i n g a n d C o r r e c t i n g A c c i d e n t C a u s e s .............. 29 F i r e P r e v e n t i o n in I n d u s t r y ...................................................................................................... 33 F i r s t Ai d a n d H e a l t h S e r v i c e i n I n d u s t r y ....................................................................... 51 H e a t E x h a u s t i o n ............................................................................................................................. 61 I n d u s t r i a l N u r s i n g .......................................................................................................................... 73 Industrial Safety Lectures-- P u b l i c S p e a k i n g i n S a f e t y W o r k ..................................................................................... 79 Sel l i ng S a f e t y i n F o r e m a n s h i p .......................................................................................... 89 I n d u s t r y a n d I t s M o t o r Ve h i cl e P r o b l e m ....................................................................... 103 Ma i n t a i n i n g I n t e r e s t in S a f e t y ............................................................................................... H I O c c u p a t i o n a l D i s e a s e s ................................................................................................................. 117 Sa f e t y E q u i p m e n t ........................................................................................................................... 133 - Sa f e t y in t h e S m a l l P l a n t .......................................................................................................... 145 S a f e t y T r a i n i n g ............................................................................................................................... 147 A c c i d e n t P r e v e n t i o n E q u i p m e n t M a n u f a c t u r e r s ' Se c t i on ........................................ 153 -- A e r o n a u t i c a l S e c t i o n ......................................................................................................................... 159 A. S. S. E. -- E n g i n e e r i n g S e c t i o n ................................................................................................... 107 A u t o m o t i v e a n d M a c h i n e S h o p S e c t i o n ................................................................................ 109 C e m e n t S e c t i o n ........................................................ ........................................................................... 177 Ch e mi c a l S e c t i o n ....................................................!............................................................................. 103 C o n s t r u c t i o n S e c t i o n ............................................ 209 F o o d S e c t i o n ........................................................................................................................................... 223 Ma r i n e S e c t i o n ...................................................................................................................................... 237 M e a t P a c k i n g , T a n n i n g a n d L e a t h e r I n d u s t r i e s S e c t i o n ............................................. 265 Me t a l s S e c t i o n .......................................................................................................................................... 2s3 M i n i n g S e c t i o n ......................................................................................................................................... 301 P a p e r a n d P u l p S e c t i o n .................................................................................................................... 321 P e t r o l e u m S e c t i o n ............................................................................................................................... 345 P o w e r P r e s s S e c t i o n ......................................................................................................................... 373 P u b l i c Ut i l i t i es S e c t i o n .................................................................................................................... 391 Q u a r r y S e c t i o n ..................................................................................................................................... 411 R e f r i g e r at i o n S e c t i o n ........................................................................................................ 423 R u b b e r S e c t i o n ............................................... ................................ . ............ 4 ~'J Sa f e t y Secti on, A . A . R . -- S t e a m R a i l r o a d S e c t i o n , N . S . C ...............................................4 a 9 T e x t i l e S e c t i o n ...................................................................................................................................... 485 T r a n s i t S e c t i o n .............................................................................................................................. 495 Ve h i c l e F l e e t S e c t i o n ......................................................................................................................... 513 W o o d P r o d u c t s S e c t i o n ................................................................................................................. 529 I n d e x ......................................................................................................................................................... 537 National Safety Council Incorporated HONORARY MEMBERS A ssociation o r I r o n a m i S teel I'a.urrRH a i . E m a x u r s R oukrt W. C aMITIELI. A r t hur W i i .li ams O F F I C E R S (1935-1936) Du. C. H. W atson, President. D. D. F e n n f.i. i.. \ 'icc-Presirlcnt for Public Relations. D r. H art E. F i sher. Vi ce- Presi dent for Heal t h. J o h n 1!. Gtnsox, \ ice-President for Comnnmi t y Safetx Councils. H on. H aroui G. l i o n ma x . \ ' i c e - P r e s i de nt for Public Safety. A n i r u r S. R i.gui V ice-President for Hnainrcrhiy. .\. V. P o i n t uh.k. Vice-President for Industrial Safct.i, K. T . Sol.r x s i i n , V i c e - I 're-ident for M em bership. Ai.iutur W. W hi tney, Vi ce-Presi dent for Education. W. K. W'oRrn, Vice-President for Finance and Tr easur er . W. II. Camf.rox. Secretary and Mauuei nu Direetor. EXECUTIVE COMMITTEE (1935-1936) A. I.. A rmsironc, Clirmical Section. C. B. Aura., Past Prcsidctit. J. I. IIa n a s h . Past President. C. W. IlF.RCQUisr, Past President. H \koi.i) S. l l um. x i i Et M, The Ame r i c an City Ma z a r i n e W. H. C ameron, National Safety Council. KonutT W. C ami 'Iu.u ., Past President. Roitim I. C. \ u i n , Aetna Casualty S; Su r c t i Company, l.i wi s A. Dr.Pi.ois. Past President. C. W. br.Mi'i'.sY, Foud Section. M arcus Dow, Past President. 1). 1J. F ennell, Consn' tin" Engineer. Doxaui A. F i n k l ; i m '.r. T o l e d o Sa i et t t.'unneil. D r. I I arr E. 1' I<11fk, Chicago P a p a l Tran>it Cn mp ai n . !'. W. F iski:, J h , Marine Section. R. P>. I' oriuin', I.ehit;h Valley Safety Council. J o n s ' li. Gntsox, Western Mleetrtc Company. E E. G rant, Paper & Pulp Section. H arry Guit.nr.Rt, The Pullman Company. llo.x. H aroiji G. H uffman. G o t c r n o r of Ne w Jersey. E dwin A. K ayskr, St. Louis Safety Council W alter G. K ing, Past President. Officers a7id Directors W illiam C. K.xoelk, St r e e t & H i g h w a y Traffic Section. C. F. L arson, Associat ion of A m e r i c a n Railways. J o i t x E. Long. Past Presi dent . Tit os. If. M acD oxald, U. S. De pa r t m e n t of Agriculture. F. J. M kiiken, Portland Cement Association. I. \V. M illard, I ndust r i al Gloves Cor por at i on. A rti!fH T. M orey, Pa st President. L f.w R. P almer, P a s t Pr e s i de nt . C. E. P ettibonf, Pa s t Pr e s i de nt . J A. P urdy, Wo od Pr oduct s Section. A lbert S. Rr.ni:la, I ndust r i al Rel at i ons Counselor.-, Inc. I.T. Cot.. H enry A. R exi noe k, P a s t P r e s i de nt . A. V. R ohvvedfr, Dul ut h. Mi ss al ' & N o r t h e r n Railway Co. Gf.orge F.. S a n roun, Gener al F.lectric Company. R obert D. S c h m i t t , Louisvil l e Safet y Council. G f.x . J o n x If. StinutURNF., Ma s s a c h u s e t t s Safety Council. C iiahi.es B. S cott, P a s t Pr esi dent . C. W. S m i t h , St a n d a r d O d Co mp a n y ( I n d . ) . W alter D ent S m i t h . De l aw a r e Safety Council R. T. Soi.kn- h ' n , Klliott Service Co mp an y . J ames M. S trike, St. J os eph Sa f e t y Conne d. C. P. T o l m \ n . Pa s t Pr esi dent. D r. C. II W. v i s n x , A m e r i c a n Tel ephot t c X' Tel egr aph Co. A. W. Wmr N EY, Nat ional Bu r e au of Ca s u a l t y tv Sur et y Unde r wr i t e C. T. W ixegar, Au t o mo t i v e & Ma c hi ne S hop Section. W . F.. W orth, I nt er na t i ona l H a r v e s t e r Company. A rthur II. Young, Past President. DIRECTORS (1935-1936) J. W. A lt, Mi ni ng Section. N ei s ox R. A xdersox, Seatt l e Traffic & Sa f e t y Council. F rederick A rcher, Chi l d Ed u c a t i o n Secti on. A. L. A rmstrong, Chemi cal Section. J. L Ha x a s h , Consulting Engineer. Ernest W. Beck, United States Ruhher Products, Iuc. C. W. B f.rcquiST, W e s t e r n Elect ri c Company. P ercy D. B f.tti.ri.y, W o r c e s t e r Saf el y Council. D avid S. r,EYEK. Libert y Mu t u a l I n s u r a n c e Co Cliiford M. B ishop, Br ookl yn Safet y Council . F. F. B lank, Jones & I.aughlin Steel Corp. C. F. B okkeniiacf.x , K e n o s h a Sa f e t y Council . S. D. B oyd, Y o r k Co u n t y Saf et y Council. W. A. B rown, Tr ans it Section. S. W . B urciiiki., Aut omobi l e Cl uh of R h o d e Island. H arold S. B uttexiikim, T h e A m e r i c a n Ci t y Magazi ne. P reston D. Cai.l u m , Ba l t i mor e Sa f e t y Conne d. W. H. C ameron, National Safety Council. National Safety Council Incorporated HONORARY MEMBERS A ssociation' or Iron a \ h S i km. F.i.r.cntu'Ar. FxiaxiXKS Ruukrt W . C amitskli. A rthur W i m.iams OF FIC ER S (1935-1936) U r. C. H. W atson, President. IJ. D. FtxNr.i.i.. Vice-President for Public Relations. Du. H art E. F isher. Vice-President for Health. J ohn 1!. Gibson', Vice-President for Community Safetj Councils. I Ion H aroi.ii G. H oi : man. \ icc-l'rcsidcnt fur Public Safety. Ai liner S. R i.gui.a. Vice-President fur Knyinccriny. A. V. Rom tun.n. Vice-President for Industrial Saict>. I\. T. Snia'Nsai N, Vice-Pre-ident fur Membership A i.iikri W. WniTNl'.V, \ 'icc-President lor Kdiiealiun. \V. K. W orth, Vice-President fur Finance and Treasurer. W . II Camkron. Secretary and Manaeiii" Direetur. EXECUTIVE COMMITTEE (1935-1936) A. I.. A rmsikonc, Cbnnical Section. C. P Aur.i., Past President. J. I. Ra n a s II. Past President. C. W. l'-KneioutST, Past President. H \kui.n S. Pu rri'.NiiKi.M, The American City Magazine. W. H C a m - run, National Safety Council. Koii/ rt W. Camituxi.. Past President. Ruin.:;,' I. C.m i i n , Aetna Casualty 5: Suret> Cump.my. I. im is A. D kT i.ois, Past President. C. W. Ut'.Mt'KSY, Food Section. M arius A. Dow, Past President. D. 1J. Fr.NXKi.i., Consulting Engineer. D onauii A. FtNKUiNt.il, Toledo Safely Council D p. 11ai<r F. l'tstmi, Chicago Ra|ml 1 ran-it ( u m p .u u . I". W. I'lSKt:. J r , Marine Section. I\. P>. I-'oriuiv, Lehigh Valley Safety Council. Ions' 1!. GirsON, Western Flcctric Compain. F IC. Grant, Paper & Pulp Section. H arry G uii.rkkt, The Pullman Company. H on. H aroi.ii G. H oit.v i n , Governor of Xew Jersey. F iiwin A. K aysi.r, St. J.onis Safet> Council. W ai.ti.r G. King, Past President. 4 Officers and Directors W i lli am C. K xoelk, St reet X- H i g h w a y Traffic Secti on. C. F. I.arson', Association of A m e r i c a n Railways. Joh n H. L ong, Pa s t Presi dent . T i ios. II. MAcPu.VAi.tt, U. S. D e p a r t m e n t of Agr i cul t ur e. E. J. M eiiken, Portland Cement Association. I. W. M illard, Industrial Gloves Cor por a t i on. A rthur T . Murky, Pa s t President. L ew R. P almf.r. Past Presi dent . C. F. Pr.TTinovK, Past Pr esi dent. J A. P uhuy, Wo od Product s Section. A lbert S. R egui.a, Indust ri al Re l a t i ons Counselors, Inc. Lt. Col. H enry A. R enixgf.r, Pa s t Pr e s i d e n t . A. V. R o n utiikr, Pulutli. Missal' it N o r t h e r n Ra i l wa y Co. George E. S aviokii, General El ect ri c Co mp a n y . R orfrt 1.. S chmitt, Louisville Saf et y Council . G f.v . Jon. v II. Snr.RiiURNF., Ma s s a c h u s e t t s Safety Council. C harles D. S coi t, Pa s t Pr esi dent . C. \V. S m ith. St andar d Oil Cot npanv ( I n d . ) . W alh-r D ent S mith, Delaware Safety Council. R. T. S oi.i.n s i i nt Elliott S c r \ ice Compa ny. J ames M. S trike, St. Jos eph Sa f e t y Council . C. T. T oi.m a v . Pa s t President. D r. C. If W . m son, Amer i can T e l e p h o n e it Tel egr a ph Co. A. W. W hitney, National Bureau of Casualty ,t Surety Utidcrw rlters C. T. W inegar, Aut omot i ve it Ma c h i n e Shop Section. tV. E. W orth, International H a r \ e s t e r Company. A rthur H. Young, Past President. DIRECTORS (1935-1936) J. W. A i.t, Mi ni ng Section. N'ei son R. A nderson, Seatt l e Traffie it Sa f e t y Council. F rederick A rcher, Chi ld Ed u c a t i o n Secti on. A. L. A rmstrong, Chemi cal Section. J. f. Ha n a s i i , Consulting Engineer . E rnest W. B eck, United States Ruhher Products, Inc. C. W . B f.rcquist, We s t e r n Electric Company. P i.rcv D. BF.rrr.RLV, Wo r c e s t e r Saf ety Council . D avid S. B eyer. Liberty Mut ua l I n s u r a n c e Co. Clii lord M. B ishot, Br ookl yn Safety Council . E. E. B lank, Jones & Laughlln Steel Corp. C. E. B orkeniiagen, Ke nos ha Sa f e t y Council. S. D. IIoyd, Yor k Count y Safety Council. W. A. Brown, Transit Section. S. W . B urciuel, Aut omobil e Cl ub nf R h o d e Island. H arold S. B uttexiikim, T h e Ame r i c a n Ci t y Magazi ne. P reston R. Cali.u m , Ba l t i mor e Sa f e t y Council . W. H. Cameron, Rational Safety Council. Twenty-foinih Annual Safety Congress-- National Saf et y Council C arney, Chicago Safety Coinin'!. =ur I. Ca t m x , Aet na Casualty & Surety Company. . Conv, KnahsU'ii Safety Council. Coi.r.Man', Cement Section. Ifr.iuirtiT C orson, Safety Dept., Nasi ni ll e Chamber of Commer ce, x k E mery Cox, Berkeley Traffic Safety Commission. '. Ctu.t.i nt.y, Bethlehem Steel Company. W. D ark, Metals Section. .m a m G. D eaxer. Rochester Safety Council. is A. De B lois, Consulting Engineer. ' E. D ecker, Mason City Safety Council. \V. D empesy, Food Section. M. D iet?. Rubber Section. trs TL D o u g l a s , T h e Philadelphia Gas W o r k s Co. I.nt' is I. D ublin'. Metropolitan Life Insurance Co. D FENXEt.i.. Consulting Engineer. x.u.n A. Fts'Kr.rtNi r, Toledo Safety Council. H art E. F i she r. Chicago Rapid Trans it Co. W. I'iske, J r , Marine Section. ms. I ' itzci kai.p, W'e-lcvn Pe nu- yKa ni a Safety Council. 'Ward U. F o n d a , Burroughs. Wel l come & Co. t U. S. A. ) , Inc. B. FoKruiN, I.chigli Valley Safety Council. Ftis-iru, J r . Q u a r r y Section, u x B. Gms o x , Wes t e r n Electric Company. v M. Godwin, Public Utilities Section. F. G rant, Taper & l'ulp Section. very G u n . pert, T h e Pul l man Company. maji Il.u. r. T h e Atchison, Topcko & Santa I'e Ry. Cu. \ j or Bo u .ing II. H andy, Ri chmond Safety Council. . T. H arrington, U. S. Pur e a u of Mines. C. H aven, Vehicle Fleet Section. !. W. I l n s s , Text i le Section. T. 11i.i.t.Mis 1n, Chicago, No r t h Shore & Milwaukee R. R. Co. ;j Mu.rs E. H i m., Mew Yo: k Centra! Lines. on. I I auoi.ii G. I I o i t m a n , G o \ e r n o r of New Jersey. ,. M'DE J. H olding, Albany Safety Council. ;m i n A. K aysek, St. Louis Safety Council. monm s P. K enrns, Industrial Commission of Ohio. T. K i.u .i r . Detroit Industrial Safely Council. \ V. K i j 'Neh, I 'ennsyUani a Salt Mig. Co. Vm i .iam C. K xoei.k , Street S; Hi ghwa y Traih.c Section. ).. 1. \ F o u n t u n r, Great Noi t hei n Railway Co. F. L arson, Missouri Pacific Railroad Company. \ro.v L azarus, Safety Council of Columbus ( O. ) Ch a mb e r of Commerce. E. L ong, T h e Del awar e &- IIiuKon Railroad f.orp. 1?. L oyd, Safely Div. Bi rmi ngham Chamber of Connneicc. nos. H. M acDonald, U. S. Department of Agriculture. . "J'. M cA rthur, Peori a Safety Council, h. J. M cCa n n , Meat Packing, Tanning X Leather Industries Section. Officers and Directors 7 M jj././.h M l C u k t o c k , H a r v a r d Uni versi ty. 'I'. H. McKr.N'Nr.Y, Car negie-Illinois Steel Corp. A. D. M cW horter, Saf ety Div., Me mp h i s C h a mb e r nf Commer ce. H. T . Marti.x, Fi s k Rubber Company F. \V. M atson, Minnesot a Safety Council. James R. M ays, Elizabeth Safety Council. E. J. M e h r e n , Po r t l a n d Cement Association. I. \Y. M h.eard. I ndust r i al Gloves Corporati on. J ames K. M iller, Gr a n d Rapids Safety Council. L eslie. W . M iller, Super i or Safet y Council. H arold L. M ixer, E. I. du Po n t de N e m o u r s & Co. L awrence M. M oore, Eas t bay Safety Council. R. C. Mokley, I ndust r i al Accident Prevent i on A 'sn s. G eorge C. A. O r r , T h e Detroit Edison Company, George O ppenheimer , Ka n s a s City Saf et y Council. L ew R. P almer, Equitable Lite As s ur ance Society. D avid A. P atton, N e w a r k Safet y Council. C harles \V. I'endock, Safety Div., Mi l wa u k e e . V- o . of Comme r c e . C. E. I 'r.iricONT:, Ame r i c a n Mut ual Liability I n s u r a n c e Co. Gen . G educe B. I'lLi.sr.uuY, Uni t ed St.ates E n g i n e e r Office. A rthur P otti rton, Hu ds on Count y Safet y Council. \Y. D. P rice, F.mployecs' Publication Section. J. A. P urdy, Wo o d Pr oduc t s Section. Ai.iu.KT S. R ecula, Industrial Relations Counselors, Inc. ..T. C ol. H enry A. R exinger, I.cbigh P o r t l a n d Cement Co. Marines K iter, Pat ers on Safety Council. R. B. Roarer, Pet r ol eum Section. A. V. R o n v. EiiF.R, Duluth, Missahe & N o r t h e r n Ry. Co. G eokce E. S anford, General Electric Company. H enry G. S c iia if ne r , Er i e Safety Council. Roiuinr L. S chmitt, Louisville Safety Council. K arl G. S ciioeitler, R a h w a y Safety Council. H arry A. S ciiuetz, Uni t ed St ates Steel Corp. E arl S. S haktzer, Ut i ca Sai d}- Council. R ay H. S heets, Madison County Safety Council. Gen. John I L S iierdurne, Massachusetts Safety Council. D r. L. A. S iioudy, Bethlehem Steel Company. E rnest L. S imonds, New Haven Safety Council. J udge L ee E. S kcf.e, Cl evel and Safety Council. C. \V. S m i t h , St a n d a r d Oil Company ( I n d . ) . E dwin C. S m it h , Blackstone Valley Safety Council. W alter D ent S mith, Del aware Safety Council. W. A. S now, Construction Section R. T . S olen si e n , Elliott Service Company. E. C. S pring, Lansdalc, Penna. Ci orge R. S teph ens, Safety Bureau, Buffalo C h a mb e r ol Comme r c e. J ames M. S trike, St. Joseph Safety Council. A rthur M. T ode, Consul t ing Ma r i ne Engi ne e r . H aroi.d M. T oomiis. Re fri gerat i on Section. T he Natit the first, Industria the sessi Section ; A 11: Th e sm; it cover request, Ma Transat visory F o r tht quoted over, S T NA yea of the divisio ter an other speed comp addre Safet cases are o cuss cont expi 8 Twenty-fourth stnniwl Safely Congress-- National .Safety Council W . \V. T renci i , Schenectady Safety Council. \V. L>. T ukukvillk, Sa n Ant oni o Safety Council. E. J. W a u .m an , Power Press Section. D r. C. II. W atson", Amer i can Tel ephone & Tel eg r a p h Co. H arry M. W hirkr, Illinois Pell Tel ephone Co. Ai.nniir C. W h i t e , Jr., Springfield Safety Council. S. E. W hiting, Liberty Mut ual Insur ance Company. A. W. W iiu 'ney, Hat ional Piircau of Casualty fy Sur e l y Under wr i t er s. T. A. W illson, Accident Prevention Equipment Manufacturers' Section. W . H. W i n a x s , Uni on Carbide & Car bon Corp. C. T. W inegar. Aut omoti ve & Machine Shop Section. H arry W i se, S r., Chatt anooga Safety Council. J. M- Woi.Tit, T h e Youngs t own Sheet & T u b e Co. W. E. W orth. International Harvester Company. E. J. Z altt, Safety Bureau, Duluth Chamber of Commerce. E arl W. Z immerman, Safety Div., Syracuse Cha mbe r of Commerce. icil Ocail'ationd Diseases il to the :i(.)Up to > took it -I a year Occupational Diseases Ma i n t a i n tcraturc, 1:ns. -beets of 'cived a . to save Mg lucky FRIDAY MORNING SESSION Oc to be r 18, 1935 T h e session *vas called to order by Mr. \V. Dean Keefer, dirictor. Industrial Division, National Safety Council. Dr. ('. I. Watson, newly-elected President of The National Safety Council and Medical Director, American Telephone and T e l e graph Company, Ne w York City, presided. depart i days iddltioiial Present and Prospective Occupational Disease Legislation By F. R O B E R T S O N JO N E S General Manager, Association of Casualty and Surety Executives New York, N. Y. cularly trolley . eduction Since the prevention of dir.ca<es i-l t<i ^onie d^tirec. a communi ty problem, the state mmlit to dn it< part t owa r d the prevention of occupational diseases, alomj \ith all f'thvr* 1 ho puMic health authorities simulci mikIv the causes of such di s eases, their pre\a)enee, virulence and the means for their prevention. They should advise as t<> Mich means of control, and. as a last resort. Appeal to l egislatures tor [lower to or der compliance with their rules. St at ut or y regulations for prevention, emanat i ng from ot her sources, such ns are common in "'l abor " or "f act or y" laws, have ;cc of a ton serums drawbacks to he etticient. T h e y are apt to he indexible and (|tiickly become a coal "nut of date"; and they are too apt to he periertcd for the establishment of fictitious ers, but liases tor wasteful and demoraii/.iiu: damaec-sui t litigation. Scientific bureaus of occupational hygiene, under directum of public health authorities, arc the host public solely i nst rumentality hliicirnt bureaus of that charact er arc now to he found in several rhnps 1 , slates: nit. generally, such public health organizations ar e inadeciiatcly manned and 1 be re- cumpped. Thcrcinrc the primary need in occupational disease legislation is for iployce measures to improve our public health services. upnigii , Emphasis should he placed on prevention, not merely because '`an ounce of pr e t^t give vention is worth a pound 01 cure," hut because public measures for the assurance of lisplays relief to victims are perilously susceptible of being 'ii perverted that those affected .inittee- will tend to rely upon and abuse the protection afforded as a substitute for, instead of as a supplement to , means for self-protection. Expert opinion now calls strongly for the entire elimination ni employers' liability for '`damages" for occupational injuries--by disease ns well as by accident--based upon negligence. That remedy is too uncertain in operation, litigious, demoralizing and wast eful : it furnishes relief to ton few of the victims unless it he so liberalized as to be grosslv unjust and financially perilous to employers--and thereby harmful to industry and all dependent upon industry Dosses from ill-health among wor kme n arc primarily subjects for self-providence or for "social insurance"-- lor "sickness insurance" to lieln out during brief illnesses, and for "invalidity." "old age" and "widows' and orphans' " insurance where illnesses or infirmities result in long or permanent disability or untimely dealth. T h e cost of thc'C insurances against the common misiortuncs of life cannot rightly or expediently be imposed wholly upon industry, hut needs to be distributed somewhat in proportion 118 Tn'i'ntx-faurth Annual Saf et y Congress-- National Safety Council to responsibility. And benefits, at a high scale of m a x i mu m e a r n i n g s as in wo r k me n 's compensation. 'imply rnnnol l)c provided for all such w o r k m e n 's misfortunes. In invabditv. old-nee and life insurance. at least, the benefits must he graded, mot e or lec'. in piopoj'ton to the individual wmk i ne n T eontrihutions to the i f <; u i t o reserves; and tiie right to heneht must he conditioned upon some minimum number of mutrihutnai-. It is uidy for some relatively small proportion of the injuries and physical iils m which workmen are subject that it is reasonable and practicable to impose the full tvvj-.m-ihilily on industry. Fr om its beginnings. the wor kmen' s compensation l aw has covered all injuries to health resulting from occupational accidents. Fur ther it has now. in this countrv and abroad. been extended to cover many specified diseases, not resulting from accidents, classified as "occupational" And in a few states in this country and Latin America it has been extended indefinitely further to cover "all inclusively" all injuries to health "arjsine out r?t and in the course of the e mpl oyment " or all "occupational diseases," undefined, "arising out of the employment." In this country there is strong political pressure in favor of this "all inclusive" (overage of injuries by disease based upon the contention that there is no difference in principle between "injuries by accident" and "injuries by disease" ; therefore, indus try ought to be liable for both classes of injuries on the same t erms and conditions. This contention is fallacious T he fundamental principles of the compensation law arc that industry shall lie held responsible and liable to compensate for the losses from those injuries only which me caused bv "t rade risks", resulting from eiuplov ment and which the employer can control : and that the liability for such risks shall he suffi ciently well defined ns to he insurable at practicable and ccpiitablc r a t c c, fixed in advance The standard compensation laws have been framed to carry out those prin ciples in application to injuries by accident. But ttic factual conditions relative to injuries by disease arc so different from those relative to injuries by accident as to necessitate different treatment. The crucial difference between accidents and diseases is the time factor. An accident is n sudden event, happening at a definite time and place. Ocnerallv the carnal relation between the ctnphnmcnl and the accident and between the accident and the resulting injury can he t raced with reasonable certainty, fiiencmlly the e mp h ne r is automaticallv identified And there is a clear-cut event from the date of which time-limits on notice1-, claims, e t c . can he measured. Til contrast, many diseases attributable to occupational risks are of slow contraction, and may he of rquallv slow progress pi harmful results In silicosis there may he an interval of as much as tvwnfv n; thirty voars between the first exposur e and disability or death. In the meantime, ninnv causes for disablement or death, other than the occupational disease may have operated. Often it is a mat t er of ext r eme difficulty to determine whet her disability nr death really has resulted from an occupational disease nr from other causes. Medical diagnosis of the mer e existence of a par ti cul ar disease is often uncertain; yet for the proper operation of compensation for occupational d b c n ccs it is essential to obtain true medical diagnoses, not merely of the existence of the disease, hut also of ijv causes and consequences. A fm llier diflicnltv j- that, vvheie the disease is f slow contraction, it iu.iv he coot 'acted bv a workman under several different employers or i nsurance m i n e r s . In such cases it is essential for the protection of the wo r k ma n that some one existent emphivev or insurance e ar ne r spall he directly liable for the entire compensation. Thai is a highrlv \ (rations and h a n h liability in impose upon an omplover or insurer --wh i t h er or not aeonnp.inied hy a righl to claim contribution front r a i l i n ' emplovcrs and i i i - n n t s ami. in all fairness, should In. s n h i i i l to strict limitations. M i ' i m \ t r dieie is a diflicnltv incidental to tin- pt'ov sion of new iiisni.iure for ( m.)u ie-at ' 11 for such diseases of -.low c<ml i ac t ion as sihiosis. I nidi r mu Ii (onditious. lie- li.delily imposed u p m tin mplov* r incjnd-s a liability for disability m death in the inline. in otbci words, a liahililv, not mrialv for future lisks but also for the cost of n vdi ime <.f pbvsical unpaii imnt - a l n a d v i m u m - d 11>ni<*11 the liahililv t hen for is not Vet lualtiud. In illMliaiHc pai l al ne, these a l e Pt n r e d ".ic'CT1led 1i;t111111II - Snell a e c i md liabilities, under a law newlv imposing a liability to compensate for silicosis, would, it is estimated, in a slate mu li as \ Y w ' n u k . aggi c r a t e main* millions of dollars. '| hi- (o-l is additional to los-i s fi..iu r t i i n n l ri sks; and how to meet it and how to 'fix, reasonable charges for ism nr ; 1 is a complex Imuinial pioldem Occuf'citional Diseases 110 The situation, then, in my opinion, is thi*: T he principle of compensation, r e gardless of fault, ma y well be e xt ended t o cover t hose di sabli ng diseases that a r e characteristic of and peculiar to and have their origin in the occupation or process in winch a person is engaged. This would exclude the diseases of ordinary life, and would he applicable only to the specific h a z a rd s which arise out of and because of industrial processes and occupations. T h e provisions for such coverage should be separate and distinct from the provisions of law applicable to compensation for acci- dcntal injuries, and these distinctions should be constantly emphasized. The problem-' of formulating such provisions is relatively simple with reference to those recognized diseases set forth in the older occupational disease laws, since such diseases are reliably diagnrxablc, of quirk contraction a n d non-progressive. Hup it is difficult in respect to such progressive diseases of slow contraction as silicons and asbe-tosis-- now generally regarded as being truly "occupational." Fortunately, however, there are promising models for our guidance in sonic of the foreign compensation laws, ; whereas experience under indefinite, "all inclusive" coverage in Connecticut, Ma ss a chusetts, Wisconsin and California is helpful with lessons of faults to avoid. In my opinion, a law for the compensation of occupational diseases should contain provisions to the following effect: 1. Diseases to be made "c ompensabl e" should be dist inct ly specified--by listing in a "schedule" or otherwise. Th ey should include all those diseases, hut only those, to h$ found in the state, which, accor di ng t o prevai li ng medi cal opinion, can hr traced, in individual eases, to origins in "t r a d e - r i s k s "-- i. r.. risk, not of or di nar y life, but created by special practices or processes in industrial occupations. 2. T h e r e should be a special r egime f or e xper t adj udi cat i on of medical questions in occupational disease cases. 3. Th e r e should be definite period* o f e xposur e r e q u i r e d as a condition to the right to compensation for various occupational diseases; the time within which, in order to be compensable, disability or death must follow exposure hnnld be limited: and cases resulting from exposures prior to the effective date of the compensation coverage, or in industries wholly outside the particular state, should he excluded. A. P r o mp t notice either of the firM mani f es t at i on of tin- disease nr of disablement --the time of such event to lie de t e r mi ne d as a medical q u e s t i o n --should he strictly required: and every presumption should he against the validity of a claim not made ns promptly as practicable. 5. In case an occupational disease m e r e l y a g g r a v a t e s , prolongs or accelerates disability or death due primarily or proximate!}* to n non-necupational disease or infirmity or, above all. to old age. the c ompensati on should be i educed to lie p r op o r tionate to the degree to which the occupational disease contributes to the disability or accelerates death. () T h e employer, as of the time of t h e w o r k m a n 's last substantial e xposur e to hazards of the disease, and the insurance c a r r i e r then on the risk should he liable for the entire compensati on-- with or wit hout r i g h t to contr i but ion from earlier cw.pb>\erc and insurers. Rut all such liabilities, whet her dircctlv for compensation or for c on tribution to the compensation payable by others, should be subject to brief time limitations. 7. In i ncurable disease, especially silicosis, the obligator} medn al benefits should be specially limited in time and kind. 8. In silicosis and other diseases of sl ow contraction, t h e i r should be special provisions for limited compensation to wor k me n laid off before actual disablement, with the alternative, under some conditions, of waiver of e o mpe nmt ion 1>v such wo r k * men for aggravations resulting from being allowed to continue in the hazardous occupation. 9. A law newly imposing liability in c ompensat e for .m-1 oilie r diseases of slow contraction should leave a substantial inteiv.d for preparaiion between the date of its enactment and that when it shal l take ef ieet ; the* eo-up uwitioii for such diseases should In* specially T*di;id and limited below what w*nld ah.-ru ise be appr opri at e until tin- "a< ei ned liabilities" a n - wo i k c d nff 10. C' ompensat: 0 ) for occupational di seases di ouM he ui mi i . J iIc sr pai . i ti l v from compensation for accidents; and. in ihe initial stage, at haM, of a regime of c o m pensation for such diseases ns silicosis, the* r a t i n g practices now inipo-e<l upon i n s m - mice car r i er s need to lie radicallv modified. .'O T -.rru tx-fou rth A n w t u l S a f ciy Co'u/rcss-- National Safely Council Tin. above pr ogr am is sound ,ind would Ik highly conducive to occupational asc prevention. Hut I a n not so confident that it would lie safe. T h e pressure is me for "liberality" in o riipcnsation laws. Merely a few among a larce number .rohnli'c slight diversions from what I suggest would consort compensation for ipatiuiial diseases into indefinite health, old-nee .and life insurance for waul,men in industries. The cost might ruin the industries, and, at least, would he so .deniable as to make the risks "uninsurahlc." except on the unlimited assessment a. wi t h all its financial perils and uncertainties. In reward to prevcr.tim:, there ar e still some practices to he decided upon in v r t i m r a reep.me of compensation for occupational diseases about which there "n s much doubt. For exrtnpl c: Such a regime will practically compel employers, o', big employment, to discriminate agai nst all the ailing or aging--against all pi tin' most healthy and robust. I hat seems to he desirable in occupations when occupational disease hazards are great. Hut is it desirable otherwise? Again, an ideal common to those of us who emphasize prevention is to require prompt removal from exposure of workmen manifesting the first symptoms of an ipational disease. But for the elderly or skilled workman the loss of his trade-job . he worse, in every respect, than the danger of continuing his exposure. How should such cases be dented and treated and how should the law be framed to .( or induce such treatment? Political impatience is the chief obstacle to a just and equitable settlement of the ipational disease problem. If those thoroughly informed as to this complex snh- wlm have sincerely at heart the welfare of workers could he delegated the auity to devise a solution, some progress might he made. But when political iganda is injected into the situation there is little chance for an adjustment "actors to all concerned. T h e greatest need today is the divorcement of oceupa\d disease legislation from politics or political considerations. Some Practical Considerations in Dust Control By J. J. B L O O M F I E L D S a g i t a r y E n g i n e e r , Un i t e d St a t e s P u b l i c H e a l t h Service, W a s h i n g t o n , D. C. Th e prevention of occupational diseases due to the inhalation of industrial dust r u n a n l y an engineering problem. Luitil recently, however, little attention had devoted to the control oi dust, accounti ng for the paucity of fundamental data e subject. The consequences of the neglect to furnish adequate protection from hazard? arc m v being felt, and the cost is becoming a serious drain on industry, now well established 11mi exposure to ceitain kinds of dust, such as those con: g considerable amounts of quartz, has increased the morbidity and mxst.ility from respiratory diseases; while metallic dusts, such as lead anrl its compounds, h< cn as s or :ater| with general systemic poisoning of wor ker s. It is obvious, '"re. that any serious alt nnpt to eontiol the dust hazar d .should, in time, result idy in tlie i mpr mci ncnl >f the health of workers, hut also he of definite economic ':! to industry. I he benefits Ilf a prevent"vc p r o g r a m in the field of accidents a t e well known, -n v is fast realizing the need of a similar preventive p r o g r am with respect to utional diseases Evaluation of the Dust Hazard I he (li st step in the evaluation of the dust ha za r d is the determi nat i on of (he ..ilii.nal e x po. ui e lo the dust in question. A typical exampl e of such a study st rve to clarify the mclhrdiilopy involved. 1able ] shows the various occupations in a granite quarry and the number of ers employed in eacdi occupation. Drillers arc the only persons using pnen- tools, known to. produce considerable quantities of dust. In other words, .18 tilt of ills- quarry personnel are shown to he exposed lo a potentially dangerous Lizard. I Ik orcupalimini analysis at once indicates that flic dust investigation Occupational Diseases 121 T a b l e 1-- O c c u p a t i o n a l Cl as si f i c a t i on of G r a n i t e Q u a r r i e r s Occupation N u m b e r in Mach ' Occupation Drillers: I.cyncr ......................................................................................... 17 Pl ug and j ac k h a m m e r .......................................................... 37 Ullior quarry employees: Superi ntendent ....................................................................... 1 For e men .................... Compressor engineer 1 Hoisting engineers . 12 I.ocomolivc engineer 1 Locomotive fireman 1 Steam-shovel man . 1 Crant' operator . . . . 1 De r r i c k men ........... 24 Mu c k e r s .................... 24 I'lacksmiths ............. 6 Tool boys .................. 2 W a t e r boys ............. 1 Machinists ............... 3 Air-line repairers . . 1 Pi pe fitters ............... 2 T o t a l ...................................................................................... 142 Table 2-- Occupational Dust Ex p os u re of Granite Q u a r r ie r s Occupation 1 c\ nor drillers ...................................................................... Plug and j a c k - h a mme r drillers ( q u a r r y - h o l e ) __ _ Pl ug drillers ( y a r d ) ........................................... ............... All ot her w o r k e r s .................................................................. Number in each occupat ion 17 37 88 Dust counts in millions of particles per cubic foot of air. Weighted Average 144 4 112 1 3fi 9 5.8 should especially concern itself with these workers. T h e next step involves the di t ermination of the occupational dust exposure. T a b l e 2 s h o w s t he results of su< It a study. It is apparent in this table that the drillers are exposed to high dust conccntra- tiuus. especially the Ley tier and j a c k h a mme r dri ll ers w o r k i ng in the q u a r r y hole. From a further analysis of the occupational dust exposure of drillers it is possible to determine which activities are responsible for the dust. F o r example, expci iencc has taught us that the various activities comprising the processes of most dusty occupations ate usually assoc i.ilr d with dissimilar dust exposures. For this reason it is essential to estimate the amount of time spent in each act i vit y in any one o c c u pation and to determine the dust exposut c for each. T a b l e 3 s hows the results of such a study in the case of a Levitt r driller. It will he seen that a I.cyncr driller has five difTcient dust exposur es. A di ffer ential analysis, as presented in Tab l e 3. yields several valuabl e findings. First, it enables one to obtain a true average dust exposure for workers engaged in the occu pation of Leyncr drilling. ( I n this rase the wei ght ed a v e r a g e is 1-14.1 a- contrasted with 213 4 million particles per cubic foot found dur i ng drilling operations only.) Second, it enables one to determine which activity, or activities, contribute most to the 22 T u ra i v-foiii ih Amami Sa ir ly Comp ass-- National Safety Comici! T a b l e 3-- S u m m a r y of Dus t E x p o s u r e of L c y n e r Dri l lers in a Gr ani t e Q u a r r y \. t i l ity As erase c\])">urc i n 111: 1! i<ir.^ of J.Mt K 'Ic'x jHH Cu1>ic lo.it of ait f a ) M u t n h e r of Im u r hpenl in e .it li a c t !\i! \ f h ) dim:- ................ . .. 213.4 4 Hi1.' i:i" I: i i! ^ . . 0 8 1 . l e h n m ( b i l l s .................... 8 0 2 a d i i m : ............................... ........... 6.0 H \\i11 il: off h o l e ................ . . . . 1.085.0 ' -- Tota' ... . ... 8 Pat lidr-hont in m illio n ]u t c u b i c foot (a A h) 853 r, '18 16 0 4.5 271 3 1,155.2 '55 2 particle-hours in millions per cubic foot - - - ---------------------------------------------------------- s-r 14-1-1 million particles per cubic foot 8 hours ; ' ward. I t "';- e\ dent that the pr.u tire of b b i n i n s "(I holes by means of lU'-ortin;; ; ie-'ial air line up. each hole is attended with a preat amount of (lust; and i wo tins acl i i i l v lasts Ioit 15 minul rs of |la- 8-hnur wo r k i n g (lav, il is responsible r 2s ps r cent of the total dust exposure It is evident that 113 per cent of the Leaner xl l i r ' s (tint exposure may lie at once eliminated In prohibiting this practice. And -;ly. such an analysis indicates the nrcessijv for devotinp all one's efforts to the n o -, a! of dust duri np the drillinp process, since this activity accounts for 74 per rent t r : t-iial dust exposure, althoiieh a I. ej ner driller spends hut one-hali of the o: .. ,;;,y his (Irill. S- far v.c h ar e dealt with an industry in which the workers, as a rule, do not anco their occupation. Often wor ker s ba se had scxcral occupations, either in the alustry or u several diflcrent kinds of estahhshnicnts. If the worker has hern in carious occupations in the industry, it is a simple matter to determine - ('mt exposure in that i ndustry. Th i s is i mpor t ant from the \ iewpnint of Te'atniL' a w o r k e r 's dust exposure and his clinical condition. A Apical example is w: : in Tabl e 4. T a b l e 4-- T o ta l Occupa t iona l D u s t E x p o s u r e of an A n t h r a c i t e Coal W o r k e r 0( up.v.ion Xuml ' Cr of years in cad occupation :t C .d:cr . . . . ............. ............. 2 - ? .1, - \ c r ............................ . . . 3 t I;iI><'*cr . . . . . . 3 'If ' 15 ft ' ................... . . . . 5 Dust contiutialion in million of particles per cubic font 380 71 71 480 4 SO 7 Millions of panicle\e;\r pet cubic font 70:1 X2 213 1.4 ;n 7 3ofi 35 ~ --t.il .......... . . . . 30 9.700 OP - alien; of pnrticlc-\ car per cubic foot -- ..................... ................ ............ -- .... .. ------- 30 j ear - 32f! mi!!iiin of particle per cubic foot : 1aiilr | tllQ \\ ()fl.f-1*4k `Ccii | >11i*ni s ai o ai ! am :cd in the or der of r mpln\ ment, ' - .'He In iup his present oc( upaliiin II is olwions that had one Considered this m i ; ..on only, the dust exposure would not have yielded a true state of affairs, Occupational Diseases 123 nor would il have been possible lo correl at e i l l i d u s t exposur e wi t h the m a n 's clinical picture. In the above technic, correct weight is given to the number of years spent m each occupation and the dust exposure associated with cadi. Only by such an analysis is it possible to a r r i \ e at a lair es t i ma t e of a w o r k e r 's dust e.-.posure and his proper designation. Such an analysis is j imtihed by the fact that results obtained with this technic yield excellent correlation with the climco-ruentgenological studies conducted on anthracite coal miners.* It is thus apparent that there F mor e to engine-, ring dust mu vcy s t han the taki ng of (lust samples-aud their analysis. Owi n g to the fait that the mak i n g of dust studies is rapidly being adopted in industry, it lias wcim d neccssaiy t o e mp h a s h e the i mpor- lant factors in such in\CMigatiun-. Al t h o u g h the maki ng of dust c o u n t s pee sc, is not a difficult., ptocedurc, the collegium of dust samples in industry and their pr oper interpretation should he dune hy a t horoughly t rained i nvestigator. 'I lie exampl es just given show the value of this technic in tlie subsequent steps to be taken in the control of the industrial dint hazard. General Dust Control Methods T h e selection of any method of di nt Mippression will depend pr i mar i l y upon its rfTicti\enc^s in reducing a given hazard and its adaptability. A large percentage of reduction in dust does not ucie^sanly indicate that the method u-cd A etucient. unless the reduction has actually been MjJJicieni to br i n g the exposur e hi low the >.iie limit, and does not interfere with the iinlu<t 1ial ope r at i o n s i m o h e d . In general, t her e are four im thuds of d mt conirul: ( ] ) Mihstituti>*n <u mai duM-producing or h a r ml e s s subsl.mces; ( 2) isolation of the diMy oper at i on ; ( 3) wi t t i n g t he dimt at its -lurcc; ( 4) local exhaust Mutilation. \ lte<e me t h o d s may he suppl ement ed by personal respiratory protection. T h e first iiKtlmd ha< a limited application. One e x a mp l e is the use of a n o n silica parting compound for a silica c o mp o u n d in connection with tIn: m a k i ng of foundry molds. Table 5 di ows that al t h o u g h the ime of p a r t i n g compound, in this pait i cul ar study, only nc-ee^itau d an e x p o s u r e of 54 minut es of the 5-40 mi nut es of a m-lder's work day (10 per cent), actually this activity accounted fur approximately 5S per cent of the molder 's total exposur e It is olwious that the empl oyment of a parting compound, winch is not as harmful ns one composed of free silica, will lessen the dust hazar d in (In's instance to a consi der abl e extent. Activity T a b l e 5-- D u s t E x p o s u r e of M o l d e r s A v e r a g e Du>t Exposure in Milhous Time oi F.xpo- of Part icl es sure in minutes per Cubic Foot (a) (b) Pn Mi c l o Minutes in Million, (aX b) l '>c of Pa r t i n g Co mp o u n d............. 54 Remaining tasks in mo l d i n g ............ 412 Pouring" ................................................ 58 Dumping molds ("shake-out") . . . . 16 <53 8 4.4 3 1 33.5 3 415 1.813 ISO 5. '0 Total 540 5/i58 5958 million particle-niinutcs 540 minutes 11 0 million par ti cl es (per cu. ft.) In the case of abrasive cleaning with Me el in>tead of sand, we have the exampl e of the substitution of a substance i nvolving a leaser du-t exposur e as well ns the use of a material not as toxic as sand. J T a b l e 6 shows the i m p r m <inent efi<rt<d by this type of substitution. Not only is the dust concentration reduced from an average of 969 to 155 million particles per cubic foot, but the potential exp- Mi t e to qua r t z dust is diminished from A2J) ^ to 3 per cent. Ih , liuiiial Safely Conr/rcss-- National Saf el y Council pvJuction in Concentration and Q ua rt z Content of Dust in With the Substitution of Steel (or Sand Abrasive Average dust concentration in mil Iions of pari i des 1Yn i nt agr jut cubic foot of Q u a r t / ...................................................... %<> ........................................................ 155 .IJ.UR 5 ,,,,,1 of tlusl control, isolating the dusty process, possesses many , uiti.itely is nut widely used The t heory underlying isolation ' j u t siiv,vets to one locality or to a single closed space. In this ...........f employees arc exposed At present, many foundries, dttr,, ot he rs who normally are engaged in occupations with low I Inis, moldcrs in a foundry mat be exposed to a dust conccn,, iiclcs per cubic foot under normal occupational conditions, but ,11,.11s are carried on close bv. tb.eir exposure may be increased i,..,, The same condition exists when annealing flasks containing ,, .[ to malleable iron foundries, exposing gri nder s and tumbling ' ..... I. <lose by. 1 . . 11iipic of isolation of a dusty process is the abrasive cleaning l, , e, loses a hazardous process and exposes only the blaster who ' ( ,,nit a protective helmet. The room is also exhausted, which l., i , oiicentratiou. Ptocesses which arc isolated recpiire good ,,,,pies of isolation are the automatic turntable for abrasive ,,.Is. and hatch-mixing rooms found in some pottery cslablish- , ...I baps the oldest known, is tb.r practice of wetting the dimt ' an example is depicted in connection with the drilling and ,, l i e coal mine operations.5 It is apparent that a t remendous ., e effected by this method. However , ns alrcadv pointed out. 1 is attendant with a reduction of the dust to a safe limit. I nee essfnl In the present instance, the wor ke r s engaged in ,.! to unsafe Concentrations of a highly dangerous dux>and .i ,,i controlling Inc dust in drilling operations by dust traps .1, illing and loading cap,orations involving an exposure to dints : lining high amounts of free silica, as in the case of coal or ... ii shown by the use of wet met hods may he considered D r y " Methods of Rock Drilling and Loading Xn. of Samples \ \ c r a g e dust count in millions of particles per cubic foot "Dry" "Wet" 2.1 508 52 10 d.M 32 exhaust \entnalinn --is perhaps the most effective, and nnc ...it We cannot discuss l u r e the details of the theory and . cstems, except to point out there is a real need for more ' tvi'c conducted by 1l.dlaV.dlr with lefereme to the design ,,Inch he has presented in Public Health bulletin 217 T i e , plli agues* on the ront iol of the silicosis hazar d in tin hard ,i example of a scientific approach to the dust elimination Occupational Diseases 125 T a b l e 8--- S u m m a r y of R e s u l t s C o n t r a s t i n g t he D u s t E x p o s u r e of M i n e W o r k e r s Under Controlled and Uncontrolled Working Conditions Opel mini! Dust Concentration in mill it ms of part i cl es tier cubic foot of air Controlled Uncontrolled Remarks I-n in- c i n i p e . ............. -in Loading coal or r o c k . . 32 Loading coal . . ............. 4-26 Drilling ............. .............. 33 1bulling coal in mines. 1.2 Preparation of c o a l . . . 24 oCO S3 4 636 291-1138* 568 17 Unl ess at least 15 mi nut es elapsed alt er tiring a i barge, miners found to be exposed to high dust concentrations. B\ vetting the loaded material the dust count is reduced as shown. Mechanical loading decreases the dust e x posure as indicated. W et drilling is effective in reducing the dust concentration. Further reduction would necessitate exhaust ventilation. Wcttine coal and empty cars reduces dust in bauiapenays. Wet breakers reduce dust counts as shown. * I l i o t i m e r i CMjIt i s .i s mh i;itr( t fi c li ai m i'UittTv; <>( u c t c o. i l w l i i l c t h e l ' t k' li cr a v e r a ^ c n b . F w l ntl jliC li.TUtl IfMi li lt p O t l l \ Cti.ll. It is appar ent that tlieic are no ^et rules f or the mechanical pr ot ecti on of wo r k e r s i mui the industrial dust hazard. Specific cumliti-ms in an i ndust r y, or a plant, will (kn-nni ne the l \ p e of protection to he c mp l me d T h e present di*cu*sion has e m p h a sized the ini|K>nance of approaching the prohlcin irmu the s t andpoint of the occupa tional exposure. Studies in representative plants of an industry often reveal the \.:riuus methods which may he emphwed in emiirollinet the dust h azar d. T h e follow ing two e xampl es indicate the value of such i m estimations. Tabic 8 indicates the \ariou control measures wliich wer e found in use in the anthracite coal mine: i m estimated in the stud> r efer r ed to earlier. Al t h o u g h no single mine practiced all of the control measures shown in this table, by an occupational vpjdy in aweral r c p r o e n l a t h e mine* it was povMhlc to -how that met hods ar e not Known and practiced for the elimination of the d m t hazar d in this indiMry. Annther example is indicated in the results of a study now in progress in connrcwith me r cnri ali sm amcaii; wor ke r s in the h a t t e r s ' fur cuttin.c industry. T a b l e 9 dn. ws the exp(M: rc to mer c u r y dust and vapor of some of the w o r k e r s in tin's indust ry Table 9-- E x p o s u r e of H a t t e r s ' F u r W o r k e r s to M e r cu r y D u s t and V a por U nde r Controlled and Uncontrolled Conditions Dirupatimi Total Mercury Exposure in Mi l l i g r a ms per 10 . cubic meters UnemitrulKd Controlled I'dnwers ................................................. AG .. Shippers ............................................... 7.2 Cut ters ................................................. -10 18 Sor t er s ................................................. 3 8 1.7 1ji ushers ............................................... 3 1 12 D r u mme r s .......................................... 2.5 0 6 Clippers .................. *............................ 1.5 0.7 Method of Control None practiced Imeni exhaust \entilali<m ** Sept elation " ]26 Tiacntx-jourth Annual Safety Comjrrss-- National Saf el y Council im(]cr controlled ami uncontrolled wor ki ng conditions. It is appar ent that where <um: ni casmc of is practiced hy Midi methods as segregat ion or local exhaust ventilation, a material induction in the expoMiie to mercury has been effected. It Is our h u i r i that in the ca<e of the Mowers' exposure, a icductiun may he efieeted hy mechanical enclosure a:i<1 local exhaust ventilation, and that the shi pper s' exposure to i m r e u r y \ a p o r i p v he lessened by a gcncial system of ventilation sufficient to di anye the air m the s 'ure in.au fr<<jnei111\ enough to bring the mer c u r y conce nt r a te.unm to a ic\wT Ie\el Unfortunately, in the pieseut in\estimation, it has been im possible to find a plant in which an attempt has been made to reduce the exposure for these t wo occupations. I n S'-mc dusty occupations the methods of timtt<>11ine dust have not been devel oped. In fact, " peraticii' mu.1i as lemovir.g the c u e s from \ e r y l arge foundry castings, and-blaMmg. handling of ued storage battery plate, paint chipping, and cadmi um wide mar.uiacnirc appear to offer no practical means of adequately controlling the dust generated. In such eases, it is therefore necessary to furnish the worker with personal respiratory protection devices to prevent his exposure to the harmful effects of the du>ts present. 7hcc devices consist of various types of respi r at or s, masks, and helmets. It is i mport ant to hold in nnrnl the limited use of personal protection derives. Uccarse a worker cannot with comfort wear a mask or helmet continuously, such devices must be employed intermittently. Their use is generally extended to those operation? where all other methods h a \ c failed or supplementary to them, a? in storage battery repair where the exposure to small amount s of lead br eat hed is known to he detrimental to health. It Mtould be pointed out that the L\ S llureau of Mines is equipped to conduct approval tests of respirators used for protection against various dusts and fumes (Schedule 21). Thcc tests arc conducted against the dust for which the device is to he uced and ar e rated, not on an efficiency basis, hut on the quanti t y of dust which actually passe? the respirator, 7 he results of a study of mas ks or helmets of the positive piesMire type, made during the sandblast investigation conducted several year ago by the Public Heal t h Service in cooperation with the Xal ional Safetv da'wed that the only practical safeguard to the worker inside the sand blast r oom was to provide ham with a mask* or helmet of the positive pr essur e type. In study ing the efficiency of such devices it was found that a relationship existed between the amount of air supplied to tlie helmet and the concentration of dust in-ide the helmet (haring blasting. T o determine the optimum air volume to he sup plied to such protective devices, it was necessary to obtain dust samples from inside the helmet while varying the air volume, at the carne time mai nt ai ni ng the dust conrnirataai in the saudhla't room (nutide the helmet) constant. The positive supply .f 6 cm it. of dust-iron air per minute will protect a wo r k e r under tlie operat ing condition? now in practice in wind-Mast rooms. The ultimate criterion of protection, however, is the result ot dint dctMmitiatiuns of the air within the helmet, that is, the air actually breathed hy the woi kcr and not the volume of air supplied. To o much emphasis cannot he stressed on the necessity of mai nt ai ni ng in good or dt r the personal n pii atnry devics for tin- piotectinn of the wo r k e r against various P>\ic dusts. M amU wince of exhaust Mutilation ^ v h o u y and other types of pr ot ec tive (impni'Ut. should he a ink- in industry l at her than an exception. T o o often the t rim "'o.ul Jinmrhee; mi' " has M m i n t n p i e t r d as sigmfvmg onlv the pei iodic removal of du t eohi i led da ilnnis. i.Jlei'-. <te Mlhmrdi such piaclice Conttihiihs to the geui r.d Man- of <1<anliiK -s of a v.oil umin and Tnii M a l i e n s he in fotce, the time h.;.< s n : d v (i me w l a n si:ioi;-> .iMenthni should he given to the installation and rigid u.-'.ah n.un e nf all t\p<->- of du-.i emtlinl devices. In every plant t here should he mj'iil' re-pomi hl c individual c h a i m d with the peiMdic inspection of all wo r k r o o ms nv to sanUaiioTi. ventdat 1. <:\t and mniut'-naner of all dtwl m n o v a l and ot her protective <!. vices. I k i h a p s the h<M i n l e m n of the eft e ti\encss of these devices is the pfiiof)*. <I( n i nnn.i t . ai nf the d uv| miiioil nl llie air at the u m b e l s ' In a Ibine /one. in ly h y (uvi.uil v i e i l a t u r and an a p p i . u . l i In |lw p in h le tn as o u ilin e d in litis p ap er UI.'IV ' li e 1.. i l l . d o 1 p l M j ' i r v . i l l th e ( n i i t i o l n f l l i e d u s t l l . l / a t d i l l i n d U s l i y . M i f i i i t h e M m M s o f e v e n a n m .i < .iin- i i e p m g i a m o f d u s t c o n t r o l a r c n o t i m u u (1: 11* ! \ l e . d i / ' d . I l i i s i-. r ^ p c i i . i l l y l i n e in di dine, w i t h f 11<i 11-.i . p i , . d i i e i n j * dm-ts in plants w h e ic s,,nie ol llie u n ik n ie ii have a h e.id y inhaled su lh eieu t tjn a iU ilie s to Ocatj'nlional J^iM'iisrs 12 7 caiu-c disability. Ho we v e r , in dealing witli such du-ts ns lead, cad mi u m, a n d mer c u r y compounds, control measures may produce salubrious results in a relatively brief period. It is difficult, because of lack of sufficient reliable data, to indicate here tlic economic benefits resulting from a preventive program of dust control. It lias been estimated by Dean K. Hninda.se. statistician of this offer, that t he minmiuni expectancy in savings to employer and employee from an indicated reduct ion of the accident rate and of the time lost on account of illness ( or an npnvnl cnt r e duct i on in liioi tal it y), demonstrat ed as attainable, is $20,000 per r e a r p< r 1,000 empl oyees. An d this estimate is for plants whose accident rate is considerably below the aver a ge, in which there arc no occupational health hazards. In plants whirr hazards arc known to exist the savings should be far in excess of this r o me rr a ti v c estimate. Wh en one realizes that in this country (here ar e appr oxi mat el y 15 millions of w o r k e r s engage d in m a n u facturing, mechanical, and mineral industries, then it is e vi dent t h a t the ma g n i t u d e of the problem has not been overemphasized. References 1. Bloomfield, T. J. and Drcc*?en, \Y. C.: KiKco-is atimoi; granite cyanic-. Public Health Reports, Yol. -19. No. 23, June 8, 1'*3-5. 2 Anthrnco-Siltco^is am on c h<>'d coal nutter*. Pubhc Iknith Bulletin Xo. 221, 1938 3. Jlk't-infield, T. J. . nud Grcotibut", L o - t u u d : Sand and m e t a l li c a b r n M \ c b ln M iu g a* an industrial health ha7.ird. Jour. hid. 11>k , vnl :m 4. J u h , 1933. 4. H a t c h . Theodore, Hi inker, Philip, ami Clrnatc. Sarah. I'.C on tr ol <f t h e mucovU bn/-,rd in the hard-rock ind ust ri es . I. A. lnb-'-rat<>i \ undy <>i ;!rc d c o e u m d u s t co n t ro l s y s t e m * for ue with p ne um at ic /rtaniie cuttinp' tools. hair. 1ml. H ' C . \ o l 12. no. 3.M . i u h , 1V) Jb iUh , Th eo d or e, Kel le y, Gem S , ami P e l . m l . J. \ \ \ : ('or<\r<M r>i the h.oatd in the li.ml-rork Industrie*. JI. An uixe^turation the Kctbp <!u*t t r a p foi imc w i t h p n e u m a t i c ;**rk flnlU of the "J a ck -b a r, n n c r" i \ p c . J" iu. Im! \- d 14. no. 2, J r l u n a r x , 1,J32. H ; ,u h . T heo do re. W ai icii. H c n r \ , and Kelley. Gc -u u e S : (' n t t o l r,f the - i l i u i s i e h . i / n t d i i i the hard tock ind ust ri es . 111. lU^tun and o p si- iti -H of a h o i e o u t i o l a c m for u - e with por-uinatJC rock di il k in open cse.\ ati>n. Jour. Jt.d 31\ jr , vol. 11, n o . ", be pi rm l - c t , 1932. ^ Silicosis and Silico-Tubcrculosis Medical Problems of an Im portant Industrial Disease By E D G A R M A Y E R , M.D. New York City A hidden clement of the o u t of production is i ndustrial di<eU'C I nd u s t r y Ibis icached a since bc>ond the coiuern only of w-iurs and hours. h m m m e important is const r \ a ! ii>n of man power by p n w o u i v e medicine an! i mpr nxe d c n e i t k e n n " . Disease | r c \ ui t i \ c measur es arc tint a c<M, bn'.. in the h'lit* r u n , a ur eal economic sa\in". Incidence. In the U n i u d Stales it lias been comput e d t hat tin re a r c from 5(1(1.0(10 to a 1.00(1,000 people employed in m citpati--ns wher e a m Iuoms b a / a i d exists. In New Noilv C'it \ t i m e a i c alu-iii (o,0!K) >uch c npl ou- es. In a r* m - n i a t n e p m n p ol inanity u o t h e r s in Massm luisrits silicosis ab-ny w. n p n u - n t m about 15 per cent and silicosis complicated with tuberculosis in almost X per t en t . Tnlu t <ulosis was tlic i.uiM' of dcatli m h u t one-ti nni of the "i.iintc w o t U m wliitli is lour times (lie mud nee for males <*i JO years and (ver in tins co i mi i \ . In l otmdt v n u n studied in Massacbusells. silicosis was less f t c q mn t (ai'oiit 0 p i t m i l ) am! less advanced in dte.rct t b;iii in p r a n i t r worlmrs. I be d n i nl i on .i \ p n - n r r in ioniidiv u o i k r i s with jnicunioiioConio'.is lias a w i . i p c d many note \ i . u s tli.m tb.it iipni<d to po-duce silicosis in an indust ry Mich as puld minim:. I lie lulu r culosis h. t / . n d in found* ie* is nearly as p i ea t as that r c p t n U d for some *( the oilier d t i s | \ ti.ules. but the (mines arc much lower titan those of m i n u s -n mid. -abci . c o p p u and b a d . ainniij; whom the mor t al i t y from l u h e m d o s i s is -S | o IK tunc-. tin p n u . i l i p r i i . i m y . I ba l l i talcs for all non tnbcrrnlnus inflations b a \ e b u n n poi ir d hmhi i anii-ni: u m b e l s in siliceous dusts than in the p c n u a l population !i is snu.u.-^i,-I t bit the \\"i krr in silica Mucnni lx mo t e ofo n to a n i l e iiidtu nun v infri lions i al b*t ib.m s n i \ i \ i n i i the chronic libioti*- 7':arnty~f onrth A n n ml Safely Congrass-- National Saf et y Council Silicosi* is defined as n pathologic condition of th e lungs clue to the inhalation Mica. whether free or combined in such a Mate as to he capable of setting up its .ictcristlc pathogenic effects. The principal factors that determine the incidence lirosi are (1) the percentage of free silica in the inhaled dust ; (2) the conration of silica particles less than 10 miera in diameter in the a t mo s p h e r e ; f 3) duration of exposure to the dust, and (A) the susceptibility of the individual .<rd as modified by ace, complicating infections, etc. T h e occupational disease ailing fiom such inhalation has been defined as "morbid results of occupational it\ traceable to specific causes or labor conditions and followed by more or extended incapacity for work.'' \J,-ft;!-r;isni of Silica. Significant amount s of silica ar e present in all body :es and thuds. H enters the body t hr ough the digestive tract and the lungs, t of that entering the stomach is eliminated in the stools, but a fairly large out is absorbed into the blood ns shown by the constant excretion of silica in urine. All vegetable foods contain silicon especially the hulls of grains, hay and v. The low silica content of the liver, spleen and kidneys indicates the little ition of the absorbed silica in the body. Silica content of the uri ne of animals he influenced at will by diet. T h e body possesses a very cflicicnt mechani sm the disposal of silica because of the low kidney thrcshhold. Silica entering lungs in particulate form is expectorated in part with its enveloping cells, but *. of it is carri ed into the pul monar y lymph channels. Ma ny such particles reach lymph nodes and even the spleen by way of the blood. T he finest particles ever, may he dissolved in alkaline body fluids and carried a way in solution, to Ncretcd in the urine. There may he a constant drainage of silica from the through the inhalation of extremely fine particles of silica in dusty atmospheres, mall that they are not seen under the microscope. Attempts to influence the absorption of silica from the lungs hv ndminiMration ..Ikali have been inconclusive. Kliniinalion of silica hv way of the sputum from ;nts having deposits of silica in their iungs appears to lie higher than those mg no liiMory of exposing to dust Only small amounts of silica are in the ! and t'u.' level is little different in normals than in silicotics. / 'iitliolrny This disease i> essentially a fibrosis of the lungs developing c-pey in such industries as hard-rock metal mining, granite cutting, nn ta 1 grinding sand-blasting The pathological changes are believed to result from two causes, chine of the l ung lymphatics by mononuclear cells laden with dust in addition Me action of colloidal silica, the exact nature of which is in doubt T h e small cles under 10 miera arc the only ones capable of penetrating the l ung tissue. Although Mica plays the dominant rede in the production of silicosis, the ad\src of other dusts tends to modify the pathological changes in the lungs so these resemble th.cn those of other forms of dust inhalation, and the modification 'S some relation to the percentage of free ilica in the mixture. Silicate, as in tos. produce a definite change in the lung, as well as other dusts such as !c. coal, etc. Such changes are represented by a fibrosis brought about hecau.se ::vch insoluble minute particle of minerals in sufficient concentration have br ought by the activity of phagocytic cells into intimate contact with the unary connective tissue. Th i s (ibtosjs ,'s n diffuse cellular one that occurs in '.alls of the smaller bronchi and of all their finer divisions ami extends to Ac the supporting connective tissue of the adjacent Mood vessels and to some at alo the walls of adjacent air spaces. I b r n e u r . when the great maj or i t y of nhalid particles arc couijoscd of or contain silica, there develops, in addition, a lie and l'jcali/ed type of fibrosis called the s d i c t i c nodule--an or derl y whoi l cd menu.nl M cells and fibre;, and with sharp definition from the adjacent p; m nan. Many du.Ms create a L'ener ah/ cd fibrosis hut onlv one, namely one cuinhsmd silicon dioxide produces the special fibrosis of silicosis. Ser i at e, known as `o mica, wlncli is a hydrated silicate of aluminum and potassium, has not produced ' i nn! experi ment s the silicotic noduh*. but instead generalised fibrosis resulted. Musis m i s t lie diflert minted into those which arc <hnni col l y active and those !i ar e inert when inhaled into the r espiratory tract. Silica is a chemically active winch must ncce-sarilv he soluble to a degree in the body fluids and its activity :ds ->n its solubility. This activity which is manifested in the areas wher e dust elcs are 'Carried along tic lymph st r eam by phagocytes, causes lesions cd two I Occupational Diseases i^y tv pcs. "toxi c" am] "sclcr.iuc" belli of which have been reproduced exper i ment al l y. Toxic lesions depend upon local necrosis and slow death and appear to favor the " i o n th of tubercle bacilli; the sclerotic lesions produce the nodul ar fibrosis. The w e ft (lusts are insoluble in body fluids and cannot exert chemical action in the lung tissue. but if they accumulate to a marked extent their effect is mechanical which niav lead to a certain j i n u u n t of diffuse fibrosis around the dust deposits. Cer t ai n (iii-ts. such as carbon, may have plnsic.nl effects, they may adsorb toxic substances and it lias been suggested that on this basis t he r e is a relatively l owe r incidence of active clinical tuberculosis in silco-antbracuiics than in silicotic lungs. Ot her dusts may even protect, as in the case of contain clays, gypsum and aluminum oxide. Pure pneumonoooniosis may be only a lnhorntorv disease, as the pulmonary fibiosis of workers in dusty trades probably results front the combined action of dust and infection, whet her it be tuberculous or not. In silicosis it is not the mineral particles that are b n a t h e d in dur i n g life that record the cause of disease, but the particles that have been dissolved. Risk to work, efficiency and health may be greatly accentuated thr ough the inhalation of finely divided particles even of a chemically inactive dust when t her e h a s oc cur r e d a lymph stasis which is known to follow exposure to silica. This l ymphat ic blockage leads to retention and accumulation of the inert dust. In soft coal miners who get what is called "miner's asthma" we have this accumulation of carbon. Such patients arc very liable to have a high incidence of bronchitis with mechanical and physical changes due to retention of aiitlu acolic dust, Furt her mor e, unequivocal cases of silicosis, wi t h or wit hout tuberculosis, can no longer be doubted. Tuberculosis. Most apical tuberculosis is acquired before the age of 25 and so silicosis at the age of .30 makes a previous tuberculosis tunic set ions. Most w o r k e r s with tuberculosis going into the mines before the age of 30 die of tuberculosis by the age of 55. T h e silicotic develops a s put um that contains tuber cle bacilli late in hie ami the children who arc contacts with tuheieular silicutics develop very little clinical tuberculosis. It is impossible to say definitely that t uberculosis engrafts itself upon the silicotic or vice versa, for we see apical t uberculosis in silicosis teat spreads downward, while other silicotics show only the tuberculosis in the lower lobes. It lias been found tli.it most silicotics die of tuberculosis. The diagnosis of silicosis is made primarily on two findings, the proper history of occupational exposure to siliceous dust and the presence of a bnormal shadows on the pulmonary X-ray. The physical examination and the patient's symptoms arc of less value. There are other diagnostic aids such as the finding of large quantities of silica panicles in the sputum, quantitative determinations of silica in urine, and at p " ' t mortem, chemical analvscs of the lung ash supplemented by pelrogiapliic examination, roentgen-ray spectrum analysis a nd special incinerating qi nlits of lung tis-uc. M e must at times rely on the pathologist to determine the amount and distribution of fibiosis due to silica and trout microscopic studies give an opinion mi the importance of this fibrosis as the ul ti mat e cause of disease and death. I.ling fibrosis may be present without any silica. Silica may be present in lung tissue o r tlu: pul monar y h m p h channels without associ at ed fibrosis. Finely divided siliceous particles from lung tissue' m a y contain innocuous sr11( 1 1e which cannot be di-ti:ieiii'lud from ha rmml silica particles. Hydr at ed silica which is iii l doubly ref: active cannot be d emons t r at ed with prisms. T h e r e f o r e in the patliologaeil section live presence of siliceous fibrosis can be st i' pccicd but cannot In- spe i lie.illy identified with the siliceous mat eri al that it may contain. Ac coi dut gl y the ime I oi nc incra t ion method of Irwin with li_vrlrocbloric arid is now included in the microscopic exami nat ion of any lung as a means tow.uid a sttier diagnosis. I Jiaenostie dillicultics in clinical medicine ma y be more obvi ous if we exami ne fit st the occupational liistorv. Ou a i t e gri nder s wor ki ng under c o n d i t i o n ' oi massive exposing may develop silicosis in acute fnun m e n in a period of months, whereas in o t b t r occupations it may take 25 .wars. W o r k e r s in the s ame indiistrv, indeed in the same room, experience diftcient degrees of exposure dependent upon perhaps the dnst-liltering capacity of the nose and functional condition of the lung as deter mined by constitutional characteristics and antecedni t disease. T h e si/e and col loidal st ructure of the particles of silica, as well as the dns.ige a n d total amount of 'ilic.i. will influence the rate of development of the disease. A p p a i eu t l y p ani cl es that u e l ar ger than 1(1 uucra a i e not pltagocv (used in the lung. So a definite 0 Tieenlx-foiiit '? Annual Safety Conr/rrss-- National Safety Council tor\ of e x p o - mo * wist he established ami in penoral hospitals when' patients are j r.itury. condi t i on: under which they u o i k c d arc very vaguely described and re nrc not avaikdk . daia on dust muni s and silica concentration, so that the history often jm.-dcndimp \< to symptom patients can perform strenuous labor despite extensive disease d the symptoms dyspnea and Cotiqh are cnnuiion to many diseases. Fever is -ent unless mfrelif occur, hut most important is the ".read di sproportion between . Hunt ' s complaint- and vvhal is seen on the X-iay. the latter show ini: e \ t e n s i \ e i-ama! shadows in comparison with llie s\ mptoms On physical exm-uination, extensive disease may he present and few abnormal sical siens. Th e physical sii*ns arc nicrc-1 > those of a general pul monar y fibrosis :li emphysema, sue : as restriction of costal and diaphragmatic movement, dimimi:i of cm i nteusifud breath bounds and a hyperte-nnant note. Kales are usually Lid unless infecti' i is present. As to the X- r a y . `.here are 3 essential types of shadows described. linear strands, all discrete shade- s( and homogeneous shadows of varying sizes; these Sm r e nd to the fibrous strands, silicotic nodules, and the conplomerate masses fibrosis. I he ; alukir shadows are usually characteristically around the 'am., or comeloiuer.v e nodular shadows of hat-wine appearance extend into both a r hm.e fields, or nodular shadows may ho distributed in the upper two-third* the Inner field, per haps more pronounced on the rieht side, with the lower third c h a r by cmphy - a n a. W i t h infection prevent, the shadows are k>s sharp or ; linear strands imcrconnect or luse. Larue rouoloinerate shadows appearine :! from the hihnn Havi ng the periphery of the Inn" clear i hrouehnut because of oh. w.ma. d lie d i - ' ' i b u l i o n of some if these [(mmiu may lie d d e r mi n e d by the mr e assumed by t' c uot l mr s, and inu<tion may likewise determine an ultimate ; pical distribution Many variation- from these patterns are seen in the X-ray, ;.cinl;> under e xem- i ve exposur e or when other lusts are inhaled, or in die nrc of j unct i on. It is probable that the main source of the bin::m>Mie dhhh.Vs A earned by t' c emphvscin.t wliieh mufllcs the physical signs and is u - p o n ::h e mp h y - u n a . sue!: as restriction of co-tal and diaphragmat ic movement, dimmu: *v in ercat pai t for the absence of symptoms. It may blot out. e\ en on X-ray, silicotic Irskins of -: ue si/e. Fx ampl cs of such dillicultics in diagnosisas encuun- d by ns are the fo" ow in" : ( as, / --Mr. T. A forty -H\ c year old man entered the Ne w Voile hospital plaining of mild c> ygli and expectoration of funr mouths* duration. He appeared ely dl. his levcr v as 103 decrees and respiration 28. Kales wctc elicited o \ c r up] or half <n boll: -bdes r>l the chest. F xntnina t x m of his eye grounds revealed :eral retinal tube* cle<: his sprit inti contained numerous acid-fast organf-ms. X- r a y revealed ; no mottled shadows distributed throm.diout h.ith lung fuids a small cavity at the k i t apex. A diagnosis ni miliary tuberculosis was made. - eva r. after one weeks' -fay in the hospital. his tenipciaturc and pulse ri tur ned 'rival and dm mg the follow ins* month he `.mined IS pound-. 1he sums in Ins - n o w became coupucd tn the left apex I" view of his umiMinl pr ogi ess the . :ii>'k of nul iary tuberculosis was d o u b u d 11 is oi eupat mnal history r e v ea k d p up unis! three years before entrance to the hospital lie had worked for 20 . -v p-'ii'-lmi" leather on a sandpaper wheel Tlieie weie nutueious machines in work room and no precautions were observed to clear the very dusty air. - s u n t u n i w a- i w a m m i d t h r o u e h tin* k u id n e s c oj I ) r l h ) r k e of K i v b r o o k , X found U laden with numer ous doubly u t r a e t d e spiea p a n u l c s lie expressed opinion that this was consistent with silicosis for he had found Mich numerous n ude s only in eases ,,f silicosis, '['he patient subsequently bed of a tube! onions mphis. Ketinal tubercles were denmnsti aied on micn.seopic *wctiou. The olopist's report was miliary tuberculosis. Ashing of the h u m showed increased . t content, consistent with undue expost ue to lust ( more than 2 mgm. silica .pci m <h :ed 1i ssue). ("a<v I f -- \ f r /At aeed 5-h e n u r e d the New York hospital complainin'.: of op. - scs, dv spiu a and chest pain. On pin oca! examination tlx re were tales dullness over the upper third of the right (dust anteriorly, l i e ran a low ale f Her hut was robust and felt quite well. The (best X- r a y disclosed enlarged an sjiado.ws, particularly on the right. and diftue mottled discrete shadows Oren['alioiml Diseases 131 throughout both lung fields with a circumscribed density near t he right apex. H e gave a history of having worked for twenty-four tears as a cutter and sizer of asbestos-containing paper box boards. The room; " e r e in a continuous cloud of dust. Exami nat ion of the dust revealed 5 per cent silica content. T h e hemoptysis, u c felt, was to he explained on the basis of infection or neoplasm, hut we did not know whether we were dealing with one of those proee-.es alone or an associated silicosis or ashestnsis. A small nodule in the neck was subsequently r emo v e d and -Imuid carcinoma. W e are inclined to believe that this does nut explain the whole pi "i ess, as the mail is still alive and ecrtuiiily, f i om tin X-ray standpoint , we cannot say that there is no silicosis. G w / / / -- ,1/r. C. A di sh-washer, aged -hi. entered Ilellcvue' hospital because of cough and expectoration, associated with dyspnea. There was some dullness and rales at the right base posteriorly. Chest X - r a y revealed a homogeneous shadow at the right base. His sputum contained no tubercle bacilli a nd lipiodol study revealed no abnormalities. 1' roiiclioscopic e xami nat i on disclosed a bl eedi ng mas s in right main bronchus. Symptoms and disease progressed dur ing the following four years. Discrete mottled shadows first appeared in the upper ri ght lung ficid and the shadow at the right base tlcarcd somewhat. Three years later extensive ab normal shadows were present throughout both lung fields, pa r t i cul a r l y on the right. Diagnosis of chronic penumonia of unknown etiology was made. At no time was a diagnosis of silicosis entertained, because ns far as could he determined he had no history of exposure. Fur t he r mor e if t here w i r e silicosis it behaved very alvpieally having the lesion confined practically to the right base at the beginning and then spreading to the left lung Autopsy however, revealed a typical sdiensis as-.oci.ited with a small degree of tuberculosis. A picture of the lung showed how much mor e extensive the silicotic process was hi the r i g h t lung. T h e r e was stenosis of the right middle lobe luonrhus with bronchiectasis in tins lobe. Chronic nice that in the l ung field probable accounted for the unusual localization. Thi s ease, illustrates how necessary ic is Vo have the hi st ory of dust e x p o s u r e f or without it here vve ar c unable to even suggest a diagnosis G w I V -- Me. C., aged -15. complained of c o u g h and dyspnea wi t h slight expret oiaiion and gave a history of bavin;; worked for mai n years r e p a i r i n g tires, using tale, powder. It was difficult to obtain acc ur at e details as t o the possibility of silica exposure except that the rooms were filled with clouds of dust Rales were present at both apices and a few tubercle bacilli were found in the sputum. Discrete and stringy shadows were disseminated throughout both lung fields. We know from the positive sputum that tuberculosis s present. T h e patient has, however, been well for a period of two years. T h e doubtful history of exposur e together with the numerous discrete nodular shadows in his lung, which are con sistent with silicosis, makes tins patient a problem. Is this tuberculosis alone or is this tuberculosis with silicosis? Th e patient is still living a year later and working. ( t'lu'lu emu. Cases such as these ar e exceptional. hut their c x i s t t u c e must alwavs he borne in mind. If occupational history is made.piate auel X- r a y . conical and l aboratory studies prove misleading, the di agnosis may pr esent great dillieuitv. However, a comprehensive study of all possible data usually clears up the problem with leasonahlc certainty. .W JO V R X M F .X T Safety u[itifuait r*x Safety Equipment WEDNESDAY AFTERNOON SESSION Oc tob er 16, 1935 The session was called tu order hy Chairman, Irwin \V. Millard, president. 11H1ns t r ia I (doves Corporation, D a n u b e , 111. Chai r man Mil lard mcniinncd `'me o the problems of providing adequate safety equipment lor industry. Respiratory Protective Devices (A n interpretation of the U. S. Bureau of Mines, Schedule 21) By C A R L T O N E. B R O W N . Chemist, and W I L L I A M P. Y A N T , Supervising Chemist Gas Section, Pittsburgh Experiment Station, Pittsburgh, Pa. I he respiratory protective devices of industrial Ingieuic importance arc thu^c designed it piolet t ax.mist die inhalation liarmiul ''"lid. gaseous, o r liquid a t m o s pheric contaminants, nr the inhalation <>i air driim-ut m oxygen i he dmirev in CKiiriinii use arc tie: mechanical filter i nspi rat or (cnmmoul y refern d In as r espi rat or) tor protection auamsi the inhalation of dusts, smithes, fumes, and mists nr what may he rcicrred to colleetive.iy as atmospheric particulate m a t t e r : gas masks tor protection against the inhalation of gases and vapors; oxygen b r e a d l ine apparatus. M^e m.uks. and air-lme i CsniratniN tor protection against pie inhalation of any at mosphere provided it d o o - iint contain harmful constituent u ha di can he ai)M,rhed readd^ liirougli the s u n : and the ahr.isixe blasting helmet or imtd or p r o tection against tiie inhalation oi and the impai t and ahruMun from the; ai uu i"phene pai ta ate mat t er eruct at ed in sand lasting or abrasive blasting with steel "hot. I hese dev mes are des i gned to lurm-di p m t c r t um either by making the wearer' s inspired air s.ue to Ir.cathe nr bv supplying tiie wear er with safe air from a supply winch he c ar n e s or m i n outside the contaminated /one. T h e went er oi tiie f;r-i or ai r -pnni v mg type, on inspiration d r a ws air from Ins minicdiate ' i r n i i i Kl n r p through the device winch either removes the n. ntammnnt . U"i;ai]_\ bv eheinaaii or n u a h a n n a l lihraiiou, or converts n into a harml ess substance. Ibis tv pc. oi course, oilers i.u protection against atmospheres dehetent in o w g e n t ns it does not add oxvgcn to the air. d here arc t wo types of respiratory protective devices of the second tvpe designed to >uppiy the wearer with cam a:r. In one. the wear er receives his air supply from ;\ o l i n d c r oi c o m p l e t e d o x y g m . liquid oxygon, liquid air. or from a chemical which yields on\ gen upon decomposition This air supply is part of the soil-contained unit, nil of winch is carried hy the wearer. In the other l>pc a hose, attached to a face piece. is connected to a compressor or Mower wdtosc intake is located in safe air. Ai r is forced through the hose to the wearer. N'ntc. Published by pctiuissuu oi tlircem r. Ik S. Uni can oi Mines. ( X o t subject tu con right.) 133 T w c u i y - f o n r t h A n n u a l S a f c t y C o n g r c s s -- Abtf loim/ S a f e t y Ccnnu'H here is some confusion in the use of the t erm "respi rat or, M to designate devices otertion acainst the inhalation of atmospheric particulate matter. Such devices ho first and for a lout; time u c t e the only respi r at or y protective devices. They Mgically called respirators, and as long as they wer e the only dev ices of tins here was no confusion. 'The development of ot her devices of indnMna! hvgmnic '.wee and the development of devices fur mai nt ai ni ng artificial respiration o u r n ods and for enabling men trapped in submerged submarines to react) the surfely, all called respirators, was responsible for the confusion. T h e b u r e a u of `nggests that the term "r e s p i r a t o r '' he retained for all of these devices, hut S'i? alory protective devices of i ndustrial h\ gienic import ance he called mdus' c u r a t o r - and that the different hinds of industrial respirators lie assigned a Inch will indicate their operating principle or field of use or both. Satisfacicks in common aw should he retained. On this basis, the b u r e a u nf Mines ? the following classification for r espi r at or y protective devices of industrial c importance: Industrial Respirators died-Air Respirators 'Cii-contained t>j>c M) O x y g e n breathing apparatus" lose type ' 1) I lose mask .?i Air-line respirator' 1 .'' Abrasive blasting respirator'' burifv ing Respirators kemical filter respirator'1 i Acid gas or Ivpc A ' chemical filter respi rat or Organic vapor or type H' chemical fi ler respirator Ammoni a or Ivpc C ' chemical filter r espi r at or ` Carhi-:i moiKi.xiile or t>pc D ' chemical filter respi rat or '' chnnical filter rcspiratorr * Dust or type A 0 mechanical fi ler respirator ' Fu me or t \ p e Bff mechanical filler r espi r at or Mist or tvpe C# mechanical f i l e r respi r at or mieal and mechanical f i l e r respirator* :md A p p r o v i n g of I n d u s t i i a l R e s p i r a t o r s b y t he U. S. B u r e a u of Mi ne s :ts organization the U. S b u r e a u of Mines has been interested in i ndmt t i al as a means of protecting wor ke r s in the mineral i ndustry aeuinM harmfiTl c contaminants. T o this end the b u r e a u has developed an approval svstem. m n f winch a r e: (1) To encourage am! aid man uf act ur er s in the de\c)<>pma r k e p n g of safe and Mutable c p h p n x n t ; and ( 2) to encourage the o m:<e si kh cejmpment. to aid him in obtaining it ;nul to instruct him in its . `se purposes are acc' unplMu d by i Mabli'dnng n schedule of the material and '.e requirements that a safe and suitable di vice should meet ; hy making '' -t s for conformance to such a schedule; and hy i nforming the public of the VM'.es r m in e n m i c in--.I ihinjr .i If'.!: :ii tj :::'CS . .ll'.fi! paint 'p o o le u - i t a l- T -r '-i11\ r p tc '-s m c replii alcr. ::iics Cailed '-.Hid -hl.iiM helmet nr 1m...1 only <;dUd IMS Hl.i-k. ;ix-n- iii.-it iI-. i. m n : ci ^ of c hcinn al 'her ?. - ;m . tints. See If S. Ttuicau f'i Mines :c l . m i . V mCcrlli: C i'*r T e n i m : C:n *: M;o k. - 1"i P c rn ns s iln li t v, 17 t . p , PU5. 'nly c. Uled re-'inr.it ut S 'lu ift m ie ' i rfei t cd 11> a s duM i cs|)ir.itoi or i m r liann at 'I'Mat" r. lUM) mrd Jn me. 1:;ni ii'.il filler ir*- 'ii .Our idle Si-r U. fs 1'm e a u of M i::rs cd. 21, pjr>im l m r (. r PUu-. V\pc t >u u , 1' nine, and Mist Pc '.pi i a tm s lor . H pp . yd t > %K`C'- i f fen t d 1" as \ ) , c \ ct All S o \ k c Gas M a <k and the <"1m u r a l . j.ii.iu.i fall under this he.ulitiK. / Safety lufififluent 135 adv.ullages in the me of devices hearing B u r e au of Mines approval. If the device is found by examination and test to meet the require im-nt* of the schedule the Bureau of Mines gives the manufacturer a certificate of approval which he may display as evi dence of the quality of his product. T he a pproved devices a r e marked in a manner which clearly distinguishes them and indicates the purpose for which they arc app! r \c d and the limitations under which they may he used. As an aid to the con sumer, the Ihircau of Mines periodically issues a list of the devices which have met the requirements. The submission of equipment is entirely voluntary on the part of the manufac turer. On making application for tests, t he manuf act ur er d e p o r t s a fee which is turned into the miscellaneous receipts of the treasury of the United States; none of the money accrues to the Bur e au of Mines. T h e approval system is motivated e n tirely by the desire of the ma n u f a c t u r e r s to p r o d u c e and ma r k e t pood equipment, the interest of the b u r e a u of Mi nes in havi ng sa f e equipment available commercially, and the demand of the consumer for such e q u ip m e n t. Approval schedules have been issued for oxygen breadline apparatus.' chemical filter respi rat ors or pas masks,* hose masks'* a n d mechanical filter r espi r at or s. 1 T h e schedule covering hose masks is being revised to include the other kinds of suppliedair respirators, namely, air-line and abrasive-blasting respirators. W h e n this revision is completed, the Bureau of Mines will h a ve approval schedules fur all types of respirators now in common use. T he approval system undoubtedly is largely respon sible for the development of fundamentally safe and suitable devices, and the elimina tion of confusion in their selection and use. T h e general plan of the var i ous schedules is similar. T h e r equi r ement s may he di\ sued into 3 p a r t s : f l ) P r e - t o t requirements, or those with winch the manufact urer must comply lu. h u e exami nat ion and test of a device will he under taken. F o r example, t ho respirator must he in a fully developed form ready for market and available tor pur chase tf approval is granted. AUo. the ma nuf a c t ur e r must he prepared to test and maintain control of the essential characteristics of his device by a method which meets the approval of this Bureau. (2) Material, construction, and performance requirements which the equipment must meet by examination and test. (3) Post-test requirements, or those wi th which the manufacturer nnM comply after the device is approved. Fr om the viewjmint of the consumer the most important of these concern labeling anti marking, provision of adequate instructions for proper use of the device, and mai nt enance of design a n d quality of the product mar ket ed under the approval. As a check on the latter, the Bureau nf Mines obtains samples nf the device on the open market and subjects t hem to the various inspections and tests of the appropri ate schedule. T h e Bur eau r eser ve s the right to wi t h d r aw its approval of any device for cause. I n t e r p r e t a t i o n of U. S. B u r e a u of Mi n e s A p p r o v a l S c h e d u l e 21, P r o c e d u r e for Testing Filter-Type Dust, Fume, and Mist Respirators for Permissibility Am o n g the reasons for the development of Schedule 21. Pr o c e d u r e for Testing Filter-Type Dust. Funic, and Mist Respirators for Permissibility, was the realization by the Bureau of Mines and others that there was a definite need for mid:anic.il filter respirators to protect workers against harmful atmospheric particulate matter m situa tions where better methods (if control of dust pr oducti on and r emoval wi ne either not available or practical, the mcfucimey of existing mechanical filter n-quralors. and 1 Hinc.in of Mi ne s, Pt .icctlm c f<" l A l i M i - h i n g b ic . t i ln n g Appat a t u s ; F e e s Chamclci nf T e x t s U u .t i lt in g A p p u a i n s will lc Teste!: Sehrd. 1 V \, " P. ii ic. ui <( M i n e s , P r o c c l u r c foj T e s t i n g T . t x '). TU>. 17 pp. A f.r-t P c rn n - ^ i| ,|c Sri i ( . >n l .i:urI O w g c t l anti (*onhtnni Tinier which Mine H o m e l a n n . i r \ 21, 1'UO. 1? pn M . t x k x f-r P r r m i s s i l n l n \ S>1k <! 111), M.*tv 1 burc.iu nf Mines, P u x r - h ir c fir T e s t i n g l h i e M.o-kx Tr Pei nnxxj|il,t\ St h o i 1. A p n l 2<\ T'27, 8 pp * P u r c . n i of Mi ne- - , P i o c e i l m c P t T e s t i n g F i l t e r - T \ p e D u - a , F u m e , ;nul M i s t K e xpi t . Hot s i nr P e i m i s i i b i l i f > Sc l i c d. 21. A u g u s t 20. 19.11, 14 p p . l'7eenly-f oinih Annual Safely Congress-- National Safely Council -1. Irmn r n m i f a c t u r c r s and cohsu ii-a t s t hat this lutrc.ni lost and appr ove such C -Module -1 follows the general plan oi the other bureau npp n u n i schedules for al i e s p i r a t o r s : the pre-test and post-test requirements arc tjnitc similar, and i`cra! principles oi the test requirements ar c the same. T h e pr i mar y purpose of nper is to explain the reasons for the \nrku;s lest requirements. Pre-Test Requirements Tjie pre-test requirements of Schedule 21 require that the manuf act ur er submit .ation, drawings. ;n:d samples of the <!c\ icc to he tested T h e de\ ice must be . ktelv de\eloped and ready for release to the public, and the device when tested .c manuf act ur er or his ncent nm-4 h a \ e parsed tests of the nat ur e described Module 21. T h e reasons for the third r equirement a r c : ( 1) T o assure the w that the manuf act ur er is prepared to control the filterin'; charact eri sti cs of rsjnrator; (2) to eliminate any question of competition with pr i\a lc consulting cics m de\ d o p i n g respi rat ors; f 3) to turmoil evidence that the r espi r at or really ad> fur release to public ma r k e t : and ( 4) to save the manuf act ur er ' s and the . nub time. Af t e r the manuf act ur er lias complied with all the a h n \ e pre-test ..I'lucnts he must submit a tec for the examination and test of his device. ice is t urned into the miscellaneous funds of the IM S. t reasury and none of m^ney r c \ e r t s to the Bur eau of Mines. Test Requirements Jti developing the tests for UKchanical Inter respirators consideration wa< e h e n . I-' the general requirement- for a safe and suitable device. These i equiremonts similar for all typ.es of industrial icspis ators. T h e respi rat or must ( 1) g i \ c quale protection, (2) be reasonably comfortable and physically convenient to r. ?.ud ( 3 'i p r esi de an acceptable ser \ i cc life. Adequate protect}* 11 implies that the mechanical filter r espirator when properl y tamed and worn m ml prevent the wearer from breadline enough particulate n.r to cause a harmful p k y s h .1eieal response under the conditions of occupational "'.ire for which it is designed to he med. Comfort and physical convenience factors arc equal in importance to adequate I'Ction. If von t houeh a war e of the ultimate serious effect which will be produced r prolonged daily exposure., workmen are inclined to lie diffident and unwilling :frr much daily inconvenience and di-comfort from the respirator. ! ucumhrancc and di-ccunnrt also increase fatiene. cause distraction, and in al handicap the wear e r 's abilit\ to take r ar e of himself. (bn< increasin'.: the lulity of accident P u p ' r i a n t specific iu-ms include the weight of the respirator, ; .irria.ee on die face or herd, effect on \ i-i nn. heating of the area of the shin r the facepiece, ir.abil:ty to expectorate, difficulty in talking, and resistance to ..M;::g. Th e importance of comfort ami phvsical convenience cannot he over 't'd. T lie s u \ k c life involve* elements of pract `.'ability in the weari ng and mai nt enance he de\ice. and indirectb die safely. Tin's type of i nspirator k p r nnnn'ty not an icciuw d'.vkc. but a pait of the w o r k m a n 's equipment for dome his regular job \ If 111- ser\ ice life A short, tlu- bother of changing of filtei elements will : *fleeted in die wo r k ma n 's attitude towar d good maintenance and use. \1: mechanical filter r< -pi mp i ' are subjected to n r ! : i i n ni>pcM" ns and U- K ;!h \ n r . ' t fulfill lerl.iin req-.nrma nts '1he .".eiieral dv-deu and con^ti notion, ui tdarl v ns to facial fit. i iccdom irmn i n bating facial contacts. weight. effect \ ni"ii and th.c weari ng of goggh-s. and ca-e of changing filter el enunt s, and enu-d The materials rue examined to d< lerinmc if they are olwiously suited the pm pose f,.r which r a w arc dr dgned. Rubber parts width come in contact b the skm must not contain any skin-irritating constituent. .Resistance to Air Flow' Requirements The requirements for rcsiMam.e to air fhw are the same for all appr oved meucal filter respirators. At no time duri ng 01 after the filter c-iVicai y testing period -t tlio''sistance to air being dr a wn t hrough the device at the rate of 85 liters Safely Equipment 13/ (3 cubic feel) per minute exceed 50 millimeters (1.97 inches) of wat er column height or the resislancc to a i r being bl own t hr o u g h the device a t the sa me rate* ni {low exceed 35 millimeters of wat er col umn height. A n air flow of S5 liters per minute is approximately equivalent to the respiratory rate of a man doing heavy work. The a mount of particulate mat t er pulled to the device du r in g the filter efficacy tests is roughly equivalent to tlie amount that would he pulled to the idler In a worker wearing the mechanical filter respirator in a moderately concentrated suspension of the particulate ma t t e r during an R-honr period. T h u s resi st ance lu air flow* oi an a ppr oved mechanical filter respi rat or should not become excessi ve w hen wor n )'<>r an 8-lumr period in most suspumi . i m of atui"-q>hene p a r t i cu l a t e m a t t e r cn- o mu f cr u l in industry. The manufacturer m reuu-*td tv give instriicfitnis on cleaning or changing the filter elements when the icdstUK .:> ilow noticeably increases. Direct Leakage and Man Test All mechanical filter r espi r at or s ar c subjected t> a direct l e a k a g e and ma n test to determi ne facial fit. whe t her t here is any direct knk.iec of unfi lt cred air. and to obtain i nformat ion on the comf or t of the device. Thr ee of t he mechani cal filter respirators arc worn for 30 minutes by 3 men with different facial feaiurc> in an a t mos phe r e cont a i ni ng a he avy suspension of bit uin:iMus-C"al dust . At t he . nd of the period the respirators arc removed and that part of the face covered by thd facepiece is examined for evidence of any leak under the edge of the facepiece. Sticks a millimeter thick were wedged under the edges of the facepieces worn bv subjects A and C to cause the leaks. T he location and approximate magni tude of the leaks are shown by the black st r eaks on that part <,f the face e n u r e d by the edges of the facepieces. T h e nasal passages and sputum of the -ubjecN are also exami ned before and after the tests. Filtering-Efficacy Tests In the development of the filtering-efficacy tests. particular attention was given to the physical properties, especially particle size, oi the significant kinds of at mos pheric particulate matter encountered in industry. Previous studies of filtering materials liar! shown that, in general, filtering efficacy <Ucreases wi t h a decrease in parlii le size. It was decided that most of the significant industrially generated atmospheric particulate matter could he classified into the fnllov ing three groups in accordance with met hod of generation, physical Male, and particle size: 1. Mechanic ally (generated dusts resulting from the di s i n t e g r a t i o n of a solid, -null as the duM clouds pr oduced in the vai i vus processes of mini ng, q u a r r y i n g and tunneling and the grinding, crushing, and general processing of solid materials. This typo of atmospheric particulate mat t er is referred to as T y p e A atmospheric particulate matter and mechanical filter respirators designed to furnish protection against these suspensions ar c referred to as T y p e A mechani cal filter respi rat ors. 2. F u m e s of various metals ( usual ly t hei r chemical comp o u n d s , ns oxide** or catbouates) such as lend, mercury (except mer cur y \ a p o r ) manganese, magnesium, aluminum, antimony, arsenic, copper, chromium, iron, cadmium, and zinc resulting from sublimation or the condensation nf their vapor, or from the chemical reactions between their vapor and gases. Tin type of atmospheric particulate matter is re ferred to as T y p e 13 atmospheri c particulate ma t t e r and mechani cal filter r e spi r at or s designed to furnish protection against these suspensions arc r e f e r r e d to as T y p e 13 media ideal filter respirators. 3. Mi st s as produced by spray-coat ing wi t h paint and vi t r eous cnr nml s chr omi c acid mist as produced in chromium plating, and other mists of materials whose liquid vehicle does not produce harmful gases or vapors. This tvpc of nltm 'spheric particulate mat ter is referred to as Type C atmo.\p!uric particulate mat ter ami mechanical filter respirators designed to furnish prelection against these suspensems are referred to as Type C mechanical filter respirators. The mechanically generated dusts and fumes consist of solid particles while the mists consist of liquid o r liquid-coated solid p a r t i J e s T h e par t i cl e s h e of me* chanically generated dusts extends over a wide ranee, in some cases, from p a i t w h s visible to the naked eye probably down to molecular dimensions. The range in jM'ticle size of fumes is much smaller. T h e upper limit is in the l ower microscopic 3S T'lacnfy-fanyth Annua! Safely Congress-- A'ational Safety Council ngc (about 0.5 micron'), while the lower limit probably approaches molecular nrnsmr.s 1 lie p:trtirIt ^ of ^iiiic (imics |;ii tit 111a11v /m e and magnesium. t <.at 111\* a ami foiin knee flockhke dii'-li-rv 1 In- clicct is hast pronounced in the case had. Misj pa: tides are spherical and probably more uniform in particle si/c than sc of (lasts and fames. Stispuisjons of each (l> the types of indust rial ly-generat ed atmospheric particle Tier were selected lor use in the Idle ring-Chiracs tests. These suspensions were nosen on the basis of their industrial hygienic significance and their physical ->.in rtic' . such as partiele-si/c d:stn!mti(' n and t endency to aggregate. which have appreciable eiteet on filtration. It was desired to test the mechanical filter pnntor.s ngnuM the mod common or w idrspread lurmful suspensions of each e: the test suspensinns to l a n e ph\sic:d properties, such as partielc si/.e and vrey.ation tendency, which would u n d e r them as difficult to remove hy filtration any other suspension of the same type. T h e test suspensions selected a r c: ( a ) b o r testing \ ype A mc(hauica1 filter respi rat ors or those designed to' u n s h protect ion against mechanically generated dusts a suspension geneinted from :y hue per cent thr ough 325 st andar d mesh sieve) silica chut consisting of t per cent free silica (Si O. ) is used. T he suspension is generated in such a way at all panicl es larger than about 3 microns a r c removed before the suspension ters the test chamber. The partirle-si/e distribution of the test suspension must ! exceed a geometric moan of 0.6 micron and a st andard geometric deviation of n The parlicle-sizc determination is made by collecting samples of the suspension tin* Owens jet diut counter and determining the particle size distribution bv a crr'pi oj iction method developed by the I ' ur eau of Mi ne s .6 b) Fo r testing Type I) mechanical filter r espi r at or s or those designed to rmsh protection against fumes, a lead oxide fume generated hy the combustion of .viral gas containing lead tetraethyl vapor is used. T h e particles of this fume are xt remel y small and have about the least tendency to aggr ega t e of any fume, hence vy ar e very difficult to remove from the air by mechanical filtration. A suspension magnesi um oxide is also used to determine the effect of a fume, whose particles hi; aggregate in large clusters, on the resistance to air flow of the filter of (he ice. (c) For te.-ting Type C mechanical fdter respirators or those designed to msh protection against mists. three different suspensions arc u-cd. Chromic . : mist generated hy electrcdy ?ing an apm-ngs solution of chromi c acid, as is done industrial chr omi um plating: lead paint mist generated hy spray-coaling with h a d it; and a water mist c ar r yi ng silica dust generated by spraying a 2 per cent '.rigs s 5sp(11sji,> of silica dust are used, d be wat er-mist carryi ng silica dust is d to simulate the mists generated in spi ay-coating with vitreous enamels. ' T h e concentration of the particulate mat t er in the test suspensions was chosen 'epresgut mor e or less the higher concentrations found in industry. Since the* enlrati'-n of mechanically generated dust found in industry varies over such T e litnMs it was decided to tost Type A mechanical filter respirators against two iCeutv.itions : o ik . to 1epresgut the mote or less aver age dusty industrial rondiv. ami the other to represent very dimly conditions 1 lie complete mechanical filter respirator is Usp-d on a mechanical testing arat us. *1 he test suspension is pulled t hr ough the device at the rate of 32 liters : 13 cubic feet) per minute, continuous flow. Th e volume of air pulled t hrough mechanical filler respirator is 10 cubic met eis m all cases except in inmc > against particular kinds of suspensions as ni eduni cal i y generated lead dusts 1 in the high-siben dtml-cnm u. t r at i on test and the magnesi um oxide test v.hove miry object is to determine the increase in icxixtance to air flow of the idler ill the amount of panicul at e matter retained. Te n cubic meters is appi oxun.tlely valent to the volume of aii b n a t l u d by a wo r k e r in 8 hours. The samples of ni' ulate mat t er for concentration determi nati ons a i c precipitated eh c ti i<.111v :n the air of the test xuspuisinn both before and after it has p.iss( d t hrough mechanical fi le r respit.itor. d he samples are collected in containers u h u h be wejglicd readily on an analytical balance, f o r reasons of convenience, speed, i r IJ. ( ' I ri'l V . l II | , \\ . I * T h e M l> 1 ri| .1 . i j . . 11 .t (*! I >Ct M Ml i UIII}' 1' .I I 1il I f S ' /<* ' : 11111f-'I .mil NllillliCl (`r`IHC'lt r.1tH>11 <if A I inc |11CtH I )11' Is. I \ S. Il'llC.III ' ( \llllfv Kr|iri|| i \r si '* .iti >>ii + .L'sy, JfU r). Safely Equipment 139 \ ;nnl a ccur acy the s.'itupic* of silica <1nst an- <p:antit:itc<l by we i g h t r a t h e r t han hy ronnt. Samples of the other particulate m at t er are fpiantitatetl chemically. The requirements as to the amount of particulate matter that the mechanical filter respirators must remove from the air ptillc'l through them is based on the best axaibdde information on the concentration of the paniculate matter that is safe to breathe. These requirements are subject to chance with the accumulation of knowl edge on the physiological clTccts of i ndust r ial ly generated a t mo s p h e r i c pa r t i c u l a t e matter. In other words, the fillcring-cflKacy requirement is that the air inhaled by the wearer of such a dcticc must he safe to breathe, and not that the device h a t e a n y par ti cul ar percentage filterin',' efficiency. Mechanical filter respirators arc not n p p r o t e d for any substance more harmful than the particulate matter in the test suspension against which they are tested. Thus T y p e A respirators are not approved for any substance more har mf ul than free silica ( S i O . ) dust. H o t t e t e r . Schedule 21 prot idcs for t esting and appr oving' mechanical filter respirators against any kind of industrially generated atmospheric particulate matter. For example. Type A mechanical filter respirators are not approved for protection against poisoning hy breathing dusts whose main harmful constituents arc metals or their compounds. However, two mechanical filter respira tors have been submitted and approx ed for protection against the inhalation of mechanical generated lead dusts. Table 1 summarizes the details of the filtering-efficacy tests and lists the me chanical filter respirators which have been a ppr ove d to date. ( P a g e s 1-10-141.) Post-Test Requirements T he manufacturer of an approx ed mechanical filter respi rat or is required to marl; his device with the name of his company, the name letter, or number hy which the lx pe is designated for t r ade purposes, a n d the approx al n u m b e r assi gned to the device hy t he Bur eau of Mi nes; and the filter uni t must he m a r k e d with the approx al number and with the txpe or kind of a tmospheric particulate m at t er for which it is approx cd. The mechanical filter respirator and replaceinent Idler units must he prnxidid with substantial and durable containers, (.'"pi cs oi the a ppr oxal labels issued to the manuf a ct ur e r by the Bureau of Mines must Ik- attached to t hese contai ners. T h e approval label gives the approval number, shows to whom the approval is issued, states what the device is and is not appr oved for. and cautions the w e a r e r t " iolloxx the manuf a ct ur e r s instructions for the use a n d care of the device The following is a sample of the re qui r e d instructions furni shed by the m a n u facturer. These instructions arc similar for all of the a ppr ove d mechani cal filter respirators. Instructions for Use of Mechanical Filter Respirator 1. Re-spit ators will not protect unless pl aced on the face pr operl y each time tins arc worn. Carelessness in face-fit means dangerous leakage. In general, a better fit ;s obtained if the mash is wor n not ton liigh on the nose. 2 'I o fit the respirator to the face hold the respi rat or, ex h au s t xalxe pointing downwart:. In the metal screw connection \x itli cither hand, and hold the hc a d s t r a p with the other hand Fb.ce the facepiece a gai nst the face and hold it in place x'.lnle p u l ' mg the hcadstrap over the head a n d below the car s. T h e n a d j u s t the facepiece until a firm snug lit is obtained. T h e hcadstrap may he adjusted while > the respirator is in place In bidding the metal slide between the t h u mb and forefinger of one hand and Hilling on the pr ope r s t r a p with the ot her hand. .1. ' Jo instruct the \xcarer in the p r o p e r adj ust ment of the ln-adstraps and position of the respirator on the face a c ar db o a r d disc is enclosed. T o m e this disc unsc r ew the filter hag. place the disc a g ai n s t the felt xv.ashc r in tlm metal Connecticut on the felt hag. assemble the r e s p i r at o r , and put it cm. T h e xxeater should not he able to breathe t hr ough the r e s p i r a t o r or feel any i n wa r d leal.age- cd nir under the edges of the facepiece. Th e presence or absence of dust st r eaks o n the (arc- inside the line- of lit of the facepiece af ter wear i ng the respirator in a d u s t y atmospher e can also he user 1 to tell whether a pi opcr fit was obtained. 4. T h e recommended procedure for cleaning the Idler hag is to mart loosely the no/.zlc of a hi gh-pressure air hose into t he hag opening and to Minx several