Document K6z65qQMkE8MXb5ORaOkm0a1Q

FILE NAME: General Electric (GE) DATE: 1935 DOC#: GE023 DOCUMENT DESCRIPTION: Transactions of the National Safety Council 1935 TRANSACTIONS N ational Safety C o u n cil Incorporated TWENTY-FOURTH ANNUAL SAFETY CONGRESS Louisville, Kentucky October 14 to October 18, 1935 Tbc Brown, Kentucky andjScelbach Hotels Copyright, 1936, National Safety Council, Inc. Foreword ' H E TR A N SA C T IO N S of the Twenty-Fourth Annual Safety Congress, National Safety Council, 1935, are published in two volumes. This volume, d 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 Highway Traffic Section, the Child Education "Tj tion and Home Safety. All industrial members of the Council automatically receive the large volume, e smaller is sent to members believed to be chiefly interested in the sessions tovers. It may, however, also be secured by other Council members upon uest. Many members have found it worth while to distribute copies of these msactions to supervisors, foremen and others in an administrative or super- ory position who may make practical use of them for reference purposes, r the benefit of those who desire extra copies the following quantity prices arc y> ated: One to ten copies of the large volume, $1.50 each; eleven copies and tr, 51.25 each; copies of the smaller volume, 50c each. 'i ACCORDANCE 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 matand to abbreviate the less essential portions because of space limitations. In er words, the material herein presented is not a verbatim report of all the cches presented at the Congress, but rather an abridged version, made as -.pact as possible, yet without any injury to the technical aspects of any Iress. The original manuscripts are on file in the library of the National :cty Council, where they are available for additional reference. In several cs, where illustrations were sent by the speakers 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 are ltrary to Council policies, but it cannot accept responsibility for the views :>ressed either in the papers presented or in the discussions based upon the -,crs. N A TIO N A L SAFETY COUNCIL, INC. 20 North Wacker Drive, Chicago 1l : r'f \ ill c< Council Officers and Directors Council Purposes and Policies Annual Meeting of Members. . Annual Banquet......................... Subject Sessions-- Finding and Correcting Accii Fire Prevention in Industry. First Aid and Health Service Heat Exhaustion................... Industrial Nursing................. Industrial Safety Lectures-- Public Speaking in Safety Selling Safety in Foreman Industry and Its Motor Veh Maintaining Interest in Safe Occupational Diseases.......... Safety Equipment.................. Safety in the Small P la n t... Safety Training..................... Accident Prevention Equipmer Aeronautical Section............... A.S.S.E.--Engineering Section Automotive and Machine Shop Cement Section......................... Chemical Section....................... Construction Section............... Food Section.............................. Marine Section.......................... Meat Packing, Tanning and Li Metals Sectioh.......................... Mining S e c tio n .....'................ Paper and Pulp Section............ Petroleum Section................... Power Press Section................ Public Utilities Section............ Quarry Section......................... Refrigeration Section............... Rubber Section......................... Safety Section, A.A.R.--Steam Textile Section........................... Transit Section......................... Vehicle Fleet Section.............. Wood Products Section........ Index .......................................... National Safety Council Incorporated HONORARY MEMBERS A ssociation or I ron and S teel E lectrical E muveers R obert W . C ampbell A rthur W illiams OFFICERS (1935-1936) D r. C. H. W atson, President. I). D. F ennell. Vice-President for Public Rcbitions. Dr. H art E. F istif.r, Vice-President for Health. J ohn II. G idson, Vice-President for Community Safety Councils. H on. H arold G. H offman. Vice-President for Public Safety. A i.rf.rt S. R egui.a, Vice-President for Engineering. A. V. Ron wedek, Vice-President for Industrial Safety, R. T. S oi.f.nstkn, Vice-President for Membership. A lbert \V. W iiitn ev, Vice-I'residcnt lor Education. W. E. W orth, Vice-President for Finance and Treasurer. W. IJ. Camf.ron. Secretary and Managing Director. E X EC U TIV E COM M ITTEE (1935-1936) A. E. A rmstrong, Chemical Section. C. B. A uel, Past President. J. I. Banash. Past President. C. W. B ercquist, Past President. H arold S. Buttknhf.i m , The American City Magazine. W. If. C ameron, National Safety Council. Robert W. C amitell, Past President. konniT I. Catli.n , Aetna Casualty & Surety Company. Lewis A. D eBlois, Past President. C. W. D empksv, Food Section. NTarcus A. Dow, Past President. D. D. F ennell, Consulting Engineer. Donald A. F i x kleiner, Toledo Safely Council. D r. I I art E. F isiif.r, Chicago Rapid Transit Company. E. W. F iske, Jh., Marine Section. R. B. F oktuix, Lehigh Valley Safety Council. : J oh n B. G ibson, Western Electric Company. E. E. G rant, Paper & Pulp Section. H arry G uilbert, The Pullman Company. H on. H arold G. H offman, Governor of New Jersey. E dwin A. K ayser, St. Louis Safety Council. W alter G. K ing, Past President. 4 I W illiam C. K noelk, St ; C. F. L arson, Associano J ohn E. L ong. Past Prc: , T iios. II. M acD onald, L j E. J. M eiirf.n, Portland ( I I. W. M illard, Industrial 1 A rthur T. M orf.y, Past ! V Lf.w K. P almer, Past Pi ! C. E. P etti bone, Past Prc .! . J A. P urdy, Wood Prodi ] A lbert S. R gula, Indust I Lt. Col. H enry A. R eni j A. V. Roiiweukr, Duluth. I George E. S anford, Cenci Rorert L. S chmitt, Loui: G f.n. J ohn II. S iif.riiurn Charles B. S cott, Past I C. W . S m ith, Standard O W alter D ent S m it h , D c R. T. SiI.ENsten, Elliott J ames M. S trike, St. Jo* J j C. P. T oi.m an, Past Presi Dr, C. II. W ats.on, A m c r A. W . W iiitney, National C. T . W inecar, Automoti W. E. W'ortii, Internation: Arthur H. Y oung, Past 1 J. W. A lt, Mining Section N elson R. A ndf.rson, S c: F rederick A rcher, Child A. L. A rmstrong, Chemie: J. I. Ranash, Consulting 1 E rnest W. Bf.ck, United : C. W. B ercquist, Westen P ercy D". Betterly, Wore D avid S. B eyer, Liberty It Clifford M. Bishop, Broo E. F. B lank, Jones & Lae C. F. Borkeniiaoen, Kenc S. D. Boyd, York County W . A. Brown, Transit Sec S. W. B urciiiel, Automot H arold S. B u t tenh eim , 1 P reston D. C allum, Balt W. H . C ameron, National Tzvcnly-fointh Annual S afe ty Congress-- National Safety Council . Carney, Chicago Safety Council. 1ut I. C atux, Aetna Casualty 5; Surety Company. . Cody, Evanston Safety Council. 1?. Coleman, Cement Section. H ekrert Corson, Safety Dept., Nashville Chamber of Commerce. nk E mery Cox, Berkeley Traffic Safety Commission. CuLLtxr.v, Bethlehem Steel Company. W. Dark, Metals Section. a i m ! G. Deaner. Rochester Safety Council. u s A. D eBlois, Consulting Engineer. E. Df.cker, Mason City Safety Council. W. D empesv, Food Section. M. D iet/. Rubber Section. mes B. D ouglas, The Philadelphia Gas W orks Co. . Louis I. D ublin, Metropolitan Life Insurance Co. I). F enneli.. Consulting Engineer. XAi.n A. F inkbf.ini r, Toledo Safety Council. . H art E. F isher, Chicago Rapid Transit Co. W. F iskf., J r., Marine Section. ms. F itzgerald, W estern Pennsylvania Safety Council. ward 13. F onda, Burroughs, Wellcome & Co. (U . S. A .), Inc. B. Foktuin, Lehigh Valley Safety Council. F oster, J r., Q uarry Section. iin R. GirtsoN, W estern E lectric Company. v M. Godwin, Public Utilities Section. E. Grant, Taper & Pulp Section. miry G uilp.ert, T he Pullm an Company. ma11 I I ale, The Atchison, Topeko & Santa Fc Ry. Co. s j o k Bolling II. H andy', Richmond Safety Council. . T. H arrington. U . S. Bureau of Mines. C. I I avkn, Vehicle Fleet Section. 1. \V. H eiss, Textile Section. . T. I I ellmutii, Chicago, N orth Shore & Milwaukee R. R. Co. iJARi.r.s E. H ill, New Y ork Central Lines. on. H arold G. H offman, Governor of New Jersey. laude J. H olding, Albany Safety Council. nwtN A. K ayser, St. Louis Safety Council. iiomas P. K earns, Industrial Commission of Ohio. . T. K eller. Detroit Industrial Safely Council. i.\ V . K eener, Pennsylvania Salt Mtg. Co. Vii.i.iam C. K noelk, Street & Highway Trallic Section. '. L. La Kountainf, Great N orthern Railway Co. '. F. L arson, Missouri Pacific Railroad Company. mon L azarus, Safety Council of Columbus ( 0 .) Chamber of Commerce. E. Long, The Delaware & Hudson Railroad Corp. V .R . I.oyd, Safety Div. Birmingham Chamber of Commerce, nos. II. MacDonald, U. S. Department of Agriculture. .. T .McArthur, Peoria Safety Council. 1C. J. M cCann, M eat Packing, Tanning & Leather Industries Section. Offi M iller M cC lintock, Harvard U T. It. McKf. nnf.y, Carncgic-Illinc A. D. McW horter, Safety Div., 1 If. T. Martin, Fisk Rubber Comp; F. W. Matson, Minnesota Safety J ames R. M ays, Elizabeth Safety E. J. M eiiren, Portland Cement L I. W. Millard, Industrial Gloves j J ames K. M iller, Grand Rapids J L eslie W. Miller, Superior Safe H arold L. M iner, E. I. du Pont L awrence M. Moore, Eastbay Si R. B. Mokley, Industrial Accidcn George C. A. Opp, The Detroit ! George O ppenheimer, Kansas Cii Lew R. P almer, Equitable Life l D avid A. P atton, Newark Safety C harles W. P endock, Safety Di C. E. P etti bone, American Mutu; Gf.n. George B. P iu .sdury, Unit A rthur P ottf.uton, Hudson Cm W. D. P rice, Employees' Publica ; J. A. P urdy, Wood Products Sect Aliiekt S. R gula, Industrial Re Lt. Col. H enry A. R eninger, Li Marin u s R iter, Paterson Safety R. B. Roaper, Petroleum Section A. V. Rohwedf.r, Duluth, Missal George E. S anford, General Elec H kniiy G. Sciiaffner, Erie Safe Robert L. Schmitt, Louisville 5 K arl G. S ciioeffler, Rahway Si H arry A. S chultz, United State E arl S. S iiartzf.r, Utica Safety R ay H. S heets, Madison Count ' Gen. J ohn II. Sherburne, Mas: D r. L. A. S iioudy, Bethlehem Si E rnest L. S imonds, New Havci J udge Lee E. S kef.l, Cleveland .' C. W. Sm ith, Standard Oil Con: E dwin C. Sm ith, Blackstone V: W alter D ent S m ith, Dclawan W. A. S now, Construction Sccti R. T. Solensten, Elliott Servie E. C. Spring, Lansdalc, Penna. George R. Stephens, Safety Bu J ames M. Strike, St. Joseph Sr Arthur M. T ode, Consulting M H arold M. T oomds. Refrigeratic 8 -Twent y-f our th Animal Safely Congress-- National Saf et y Council W. W. T rench, Schenectady Safety Council. j \V. D. T urukville, San Antonio Safety Council. j E. J. W a u .man, Power Press Section. i D r. C. II. W atson, American Telephone & Telegraph Co. I H arry M. W ebber, Illinois Bell Telephone Co. A lbert C. W hite, J r., Springfield Safety Council. S. E. W hiting, Liberty Mutual Insurance Company. T he A. W. W hitney, National Bureau of Casualty & Surety Underwriters. j Nath T. A. W illson, Accident Prevention Equipment Manufacturers' Section. the first W. H. W inans, Union Carbide & Carbon Corp. j Industria C. T. W inegar. Automotive & Machine Shop Section. the sessi H arry W ise, Sr., Chattanooga Safety Council. J Section : J. M. W oltz, The Youngstown Sheet & Tube Co. W. E, W orth, International Harvester Company. i All: E. J. Zauft, Safety Bureau, Duluth Chamber of Commerce. i The sm; E arl W. Z immerman, Safety Div., Syracuse Chamber of Commerce. j it cover request. i I Ma Transai visory For th quoted I over, S l TN a *" yea o the divisio ter an other speed comp addre Safet cases are o cuss cont expi papi i I to the eroup to .?> took it d a year maintain Itorature, 'ins. sheets of reived a . to save mg lucky depart i days idditional Lcularly : trolley reduction 'ire of a a coal ers, but solely .rhaps I .1 be re- .iployee npaign 'ist give displays inittee- Occupational Diseases FRIDAY MORNING SESSION October 18, 1935 The session was called to order by Mr. \V. Dean Keefer, director. Industrial Division. National Safety Council. Dr. C. H. Watson, newly-elected President of The National Safety Council and Medical Director, American Telephone and Tele graph Company, New York City, presided. Present and Prospective Occupational Disease Legislation By F. ROBERTSON JONES General Manager, Association of Casualty and Surety Executives New York, N. Y. Since the prevention of diseases is, to some degree, a community problem, the state might to do its part toward the prevention of occupational diseases, along with all others. The. public health authorities should study the causes of such dis eases, their prevalence, virulence and the means for their prevention. They should advise as to such means of control, and. as a last resort, appeal to legislatures for power to order compliance with their rules. Statutory regulations for prevention, emanating from other sources, such as arc common in "labor" or "factory" laws, have too scrious drawbacks to he efficient. They arc apt to lie indexible and quickly become "out of date"; and they are too apt to he perverted for the establishment of fictitious bases for wasteful and demoralizing damage-suit litigation. Scientific bureaus of occupational hygiene, under direction of public health authorities, are the best public instrumentality. Efficient bureaus of that character are now to be found in several states; hut, generally, such public health organizations are inadequately manned and equipped. Therefore the primary need in occupational disease legislation is for measures to improve our public health services. Emphasis should he placed on'prevention, not merely because "an ounce of pre vention is worth a pound of cure," hut because public measures for the assurance of relief to victims arc perilously susceptible of being so perverted that those affected 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 of employers' liability for "damages" for occupational injuries--by disease as well as by accident--based upon negligence. That remedy is too uncertain in operation, litigious, demoralizing and wasteful: it furnishes relief to too 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. Losses from ill-health among workmen arc primarily subjects for self-providence or for "social insurance"--for "sickness insurance" to hcln out during brief finesses, ami for "invalidity." "old age" and "widows' and orphans' '' insurance where illnesses or infirmities result in long or permanent disability nr untimely dcaltli. The cost of these insurances against the common misfortunes of life cannot rightly or expediently be imposed wholly upon industry, but needs to be distributed somewhat in proportion 1IS T 'v cnt y-f our th Annual Saf et y Congress-- National Saf et y Council to responsibility. And benefits, at a high scale of maximum earnings, as in workmen's rniiipriis:ition. simply cannot be provided for all such workmen's misfortunes. In invalidity, old-age and life insurance, at least, the benefits must be graded, more or less, in proportion to the individual workmen's contributions to the requisite reserves; and the right to benefit must be conditioned upon some minimum number of contribu tions. It is only for some relatively small proportion of the injuries and physical ills to which workmen arc subject that it is reasonable and practicable to impose the full responsibility on industry. From its beginnings, the workmen's compensation law has covered all injuries to health resulting from occupational accidents. Further it has now, in this country 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 lias been extended indefinitely further to cover "all inclusively'' all injuries to health "arising out of and in the course of the employment" or all "occupational diseases," undefined, "arising nut of the employment." In this country there is strong political pressure in favor of this "all inclusive" mverage 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 terms and conditions. Tin's contention is fallacious. The fundamental principles of the compensation law are that industry shall he held responsible and liable to compensate for the losses from those injuries only which are caused by "trade risks'', resulting from employment and which the employer can control; and that the liability for such risks shall lie suffi ciently well defined as to he insurable at practicable and equitable rates, fixed in advance. The standard compensation laws have been framed to carry out those prin ciples in application to injuries by accident. Tint the 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 a sudden event, happening at a definite time and place. Generally the oansil relation between the employment and the accident and between the accident and the resulting injury can lie traced with reasonable certainly. Generally the employer is autoniaticallv identified. And there is a clrar-cut event from the date of wliirli time-limits on notices, claims, etc., can lie measured. In contrast, many diseases attrilmtahle to occupational risks are of slow contraction, and may be of equally slow progress to harmful results. In silicosis there may be an interval of as much as twenty or thirty years between the first exposure and disability or death. In the meantime, many causes for disablement or death, other than the occupational disease may have operated. Often it is a matter of extreme difficulty to determine whether disability or death really has resulted from an occupational disease or from other eauscs. Medical diagnosis of the mere existence of a particular disease is often uncertain ; yet for the proper operation of compensation for occupational diseases it is essential to obtain true medical diagnoses, not merely of the existence of the disease, lint also of its causes and ronseipirnees. A further difficulty is that, where the disease is of slow contraction, il may he contracted bv n workman under several different employers or insurance carriers. In surh eases it is essential for the protection of the workman that some one existent employer or insurance carrier shall lie directly liable for the entire compensation. That is a higlicly vicarious and harsh liability to impose upon an employer or insurer --whi ther or not accompanied by a right to claim contribution from earlier employers and in-nn rs- - and. ill all fairness, should be subject to strict limitations. Moreover there is a difficulty incidental to the provision of new insurance for rompt nsation for such diseases of slow <onlraction as silicosis, tinder sileti comfitions, tin; liability imposed upon tile employer includes a liability for disability or death in the iut nrr: in other words, a liability, not merely for fill tire risks lint also for the cost of a volume of physical impairments already incurred though 1lie liability therefor is not yet matured. In insurance parlance, these are termed "accrued liabilities." Such accrued liabilities, under a law newly imposing a liability to compensate for silicosis, would, it is estimated, in a slate such as New York, aggregate many millions of dollars. This rust is additional to losses from cut rent risks; and how In meet it and how to fix reasonable charges for insuring it is a complex financial problem. C The situation, then, in my gardless of fault, may well be characteristic of and peculiar to which a person is engaged. T would be applicable only to tli industrial processes and occupr separate and distinct from the | dental injuries, and these distim of formulating such provisions i diseases set forth in the older reliably diagnosnblc, of quick o respect to such progressive disc now generally regarded as licii are promising models for our whereas experience under imlef cliusctts, Wisconsin and Cali fori In my opinion, a law for tie provisions to the following effee 1. Diseases to be made "c in a "schedule" or otherwise, f to bg found in the state, which. : in individual cases, to origins i created by special practices or j 2. There should be a spec! in occupational disease cases. 3. There should be definit right to compensation for varii order to be compensable, disabil and eases resulting from expos coverage, or in industries wlioll 4. Prompt notice either of --the time of such event to be required; and every presumptio as promptly as practicable. 5. In case an occupations disability or death due primar infirmity or, above all, to old a lionatc to the degree to which t accelerates death. 6. The employer, as of tli hazards of the disease, and the the entire compensation--with o and insurers. Put all such 1ial triliutinn to the compensation limitations. 7. In incurable diseases, cs he specially limited in time and 8. In silicosis and other provisions for limited conipcns; with file alternative, under snnu men for aggravations resultin' occupation. 9. A law newly imposing of slow contraction should le.v date of its enactment and that diseases should be specially n appropriate until the "accrued 10. Compensation for occt compensation for accidents; an pensation for surh diseases as ; ancc carriers need to lie radical i 1 ;ivj;.*v- f ourt h . I m n i a l S a f r t y Coiii/rrss-- Nnlional S a f e l y Council Hit: above program is sound and would be highly conducive to occupational asc prevention. But I am not so confident that it would lie safe. The pressure is ns for "liberality" in compensation laws. Merely a few among a large number rohahlc slight diversions from what ! suggest would convert compensation for ipational diseases into indefinite health, old-age and life insurance for work-men in .v industries. The cost might ruin the industries, and, at least, would be so .deniable as to make the risks "uninsurablc," except on the unlimited assessment ni, with all its financial perils and uncertainties. Ill regard to prevention, there arc still some practices to be decided upon in Vrting a regime of compensation for occupational diseases about which llicre ins much doubt. For example: Such a regime will practically compel employers, .-iving. employment, to discriminate against all the ailing or aging--against all pt the most healthy and robust. That seems to he desirable in occupations when occupational disease hazards are great. But is it desirable otherwise? Again, an ideal common to those of us who emphasize prevention is to rcrpiire 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. I Tow . should such cases be defined and treated and how should the law be framed to .t 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 snb who have sincerely at heart the welfare of workers could be delegated the aitily to devise a solution, some progress might he made. But when political 1 Uganda is injected into the situation there is little chance for an adjustment : nctory to all concerned. The greatest need today is the divorcement of occupaud disease legislation from politics or political considerations. Some Practical Considerations in Dust Control By J. J. BLOOM FIELD a-jitary Engineer, United States Public Health Service, Washington, D. C. The prevention of occupational diseases due to the inhalation of industrial dust rimarilv an engineering problem. Lhitil recently, however, little attention had devoted to the control of dust, accounting for the paucity of fundamental data v;bicct. The consequences of the neglect to furnish adequate protection from hazards arc now being felt, and the cost is becoming a serious drain on industry, now well established that exposure to certain kinds of dust, such as (hose ennng considcrnhle amounts of quartz, has increased the morbidity and mortality - from respiratory diseases: while metallic dusts, such as lead and Is compounds, been associated with general systemic poisoning of workers. It is obvious, ore, that any serious nttrmpl to control the dust hazard should. iiFlimc, result nly in Ihc improvement of the health of workers, Imt also he of definite economic rit In industry. The hem-fits of a preventive program in the field of accidents are well known, try is fast realizing the need of a similar preventive program with respect to .itional diseases. Evaluation of the Dust Hazard The first step in the evaluation of the dust hazard is the determination of the national exposure to the dust in question. A typical example of such a study serve to clarify the methodology involved. Table 1 shows the various occupations in a granite quarry and the number of ers employed in each occupation. Drillers arc the only persons using pneu: tools, known to. produce considerable quantities of dust. In other words, 38 .ent of the quarry personnel are shown to he exposed to a potentially dangerous r,azard, The occupational analysis at once indicates that the dust investigation Ocat Table 1--Occupational Occupation Drillers: Lcyner .......................... Plug and jack hammer. Utlier quarry employees: Superintendent ........... Foremen ...................... Compressor engineer .. Hoisting engineers Locomotive engineer .. Locomotive fireman .. . Steam-shovel man . .. . Crane' operator ........... Derrick men ............... Muckers ...................... Blacksmiths ................ Tool boys .................... Water boys ................. Machinists .................. Air-line repairers ....... Pipe fitters .................. T o t a l ........................ Table 2--Occupational Occupation l cyner drillers ................................. Plug and jack-hammer drillers (qu Plug drillers (yard)........................ All other workers............................. should especially concern itself wii determination of tin* occupational di a study. It is apparent in this table that lions, especially the I.cyner and ja From a further analysis of the occ (o determine which activities are re lias taught us that the various ac nrrupntinus are usually associated i it is essential to estimate the among pation and to determine the dust c: such a study in the case of a I.eync It will be seen that a Lcyner di ential analysis, as presented in Tal enables one to obtain a true average pation of Leyncr drilling. (In this with 213.4 million particles per cu Second, it enables one to determine i \ 22 Ttecut y-f ourt h An u un l Saf et y Congress-- National S a f el y Council \ h Table 3--Summary of Dust Exposure of Leyner Drillers in a Granite Quarry Average dust exposure Particle-hours in millions of N um ber <of in millions particles per cubic liniirs spent in per cubic Vtivity lout nf air f a ) m ill activity fb) finit (a X l>) iHiny ......................... .............. 215.4 4 853.6 ' aimin' IrilK ................ ............... 9.8 1 9.8 itching drills ................... .............. fill 2 16.0 "aching ........................... ................ wing off h o le s ............ ............... 6.0 1.0,85.0 Va 4.5 Ya 271.3 Total........................................ 1,155.2 155.2 particle-hours in millions per cubic foot S Ilnurs 14-1.4 million particles per cubic foot :-t hazard. It^is eviilent that tile practice of blowing; off boles by means of inserting compressed air line into each bole is attended with a great amount of dust; and "tigh this activity lasts but 15 minutes of the 8-hour working day, it is responsible r 25 per cent of the total ilnst exposure. It is eviilent that 23 per rent of the l.eyncr sillers dust exposure may be at once eliminated by prohibiting this practice. And .-tly. surli an analysis indicates the necessity for devoting all erne's efforts to the moral of dust during the drilling process, since this activity accounts for 74 per cent the total dust exposure, although a l.eyncr driller spends hut one-half of the eking day at his drill. So far we hare dealt with an industry in which the workers, as a rule, do not bangc iheir occupation. Often workers have had several occupations, either in the me industry or in several different kinds of establishments. If the worker has been nployod in various occupations in the industry, it is a simple matter to determine 's total dust exposure in that industry. This is important from the viewpoint of rrclating a worker's dust exposure and his clinical condition. A typical example is wn in Table 4. Table 4--Total Occupational Dust Exposure of an Anthracite Coal Worker Occupation Number of years in each occupation ate picker ............... .... lieber '.............................. ? *ilc driver ....................... ................. 3 mcr's laborer ................. ................. 3 ; n e r .................................. ................. 15 ctioii foreman ............... ................. 5 Dust concentra tion in millions of particles per cubic font 380 71 71 480 480 7 Millions of particleyears per ruhic font 700 142 213 1.440 7.200 35 Total 30 9.790 790 millions of particle-years per cubic foot I 30 years 326 millions of particles per cubic foot In table 1 the worker's occupations are arranged in the order of employment, e lasr one being bis present occupation, ft is obvious that had one considered this ! ' upafion only', the dust exposure would not have yielded a true state of affairs, Oc nor would it have been possible ti picture. Ill the above technic, cc in each occupation and the dust analysis is it possible to arrive ; his proper designation. Such an with this tcclmic yield excellent i conducted on anthracite coal min It is thus apparent that there of dust samp!es-nnd their analysis is rapidly being adopted in indust taut factors in such investigation not a difficult, procedure, the coll interpretation should be done by Just given show the value of tbit 'control of the industrial dust hnz; Genera The selection of any method effectiveness in reducing a given reduction in dust does not neeess; the reduction lias actually been s and does not interfere with the i four methods of dust control: (1 stances; (2) isolation of the du (4) local exhaust ventilation, respiratory protection. The first method lias a limi silica parting compound for a i foundry molds. Table 5 shows particular study, only necessitate a moldcr's work day (If) per ceil1 5S per cent of the moldcr's total parting compound, which is not a the dust hazard in this instance Table 5 - Aclivity Use of Tarting Compound......... Remaining tasks in molding....... Touring ...................................... Dumping molds ("shake-out") .. T otal.................................... 5958 million particle-minutes i: 540 minutes In the case of abrasive cleat of the substitution of a suhstan use of a material not as toxic a: this type of substitution. Not on of 969 to 155 million particles pc is diminished from 42-99 to 3 pi : ? Twe n ty -f o ur t h An n ua l S a f e t y Congress-- National S a f et y Council Me 6--Showing Reduction in Concentration and Quartz Content of Dust in Sandblast Rooms With the Substitution of Steel for Sand Abrasive pc nf ravive Average dust concentration in millions of particles Percentage lier cubic foot of Quartz. ni......................................... ....................................... %<> , i ......................................... ....................................... 155 42-98 3 The second method of dust control, isolating the dusty process, possesses many l ihilitics, hut unfortunately is not widely used. The theory underlying isolation ; to concentrate the dust sources to one locality or to a single closed space. In this I v. a minimum number of employees are exposed. At present, many foundries, dur- shakc-out expose workers who normally are engaged in occupations with low t concentrations. Thus, molders in a foundry nitty he exposed to a dust conceit- ! tion of 3 million particles per cubic foot under normal occupational conditions, hut j cn shake-out operations are carried on close by, their exposure may be increased more than 50 million. The same condition exists when annealing flasks containing ! und slag are emptied in malleable iron foundries, exposing grinders and tumbling ; cl attendants at work close by. Perhaps the best example of isolation of a dusty process is the abrasive cleaning in. This completely encloses a hazardous process and exposes only the blaster who 1 ei-nerally equipped with a protective helmet. The room is also exhausted, which tber reduces the dust concentration. Processes which arc isolated reeptire good j nidation. Other examples of isolation are the automatic turntable for abrasive j ailing, tumbling barrels, and hatch-mixing rooms found in sonic pottery establish- uts. The third method, perhaps the oldest known, is the practice of wetting the dust us source. In Table 7 an example is depicted in connection with the drilling and ding of rock in anthracite coal mine operations.1 Tt is apparent that a tremendous uction in dust lias been effected by this method. However, as already pointed out. ess a particular method is attendant with a reduction of the dust to a safe limit, eannot be considered successful. In the present instance, the workers engaged in ling arc still exposed to unsafe concentrations of a highly dangerous dust*and more positive method of controlling the dust in drilling operations by dust traps dd be indicated. For drilling and loading operations involving an exposure to dusts toxic than those containing high amounts of free silica, as in the case of coal nr min tales, the reduction shown by the use of wet methods may be considered live. ble 7--Contrasting "W et" and "Dry" Methods of Rock Drilling and Loading esses Ho. of Samples Average dust count in millions of particles per cubic foot "Dry" "Wet" ling ............................................ 23 568 33 ding ............................................ 10 636 32 The fourth method--exhaust ventilation--is perhaps the most effective, and one the widest application. Wc cannot discuss here the details of the theory and gn of local exhaust systems, except to point out there is a real need for more konctilal studies of the tym- conducted by D,'iliaValle with reference In the design :'>enl exhaust hoods, wdtich he has presented in Public Health Bulletin 217. Tli" -k of Hatch and his colleagues" on the control of the silicosis hazard in the hard industries is another example of a scientific approach to the dust elimination blcm. Orel/, Table 8--Summary of Results Co Under Controlled and Operation Dust Cuncenlrati millions of pa: per cubic foot < Controlled Uncoil hiring charge ............. 40 834 Loading coal or rock.. 32 63C Loading coal ............... 4-26 201-1 Drilling......................... 33 56! Hauling coal in mines. 1.2 L Preparation of coal. . . 24 381 lower res ult is associate! wiii i.s based mi the h an d of dr> et It is apparent that there are no from the industrial dust hazard. S determine the type of protection to sized the importance of approacliiiu tional exposure. Studies in repre various methods which may lie emp ing two examples indicate the vnh Table 8 indicates the various anthracite coal mines investigated ii mine practiced all of the control i study in several representative mil known and practiced for the climin. Another example is indicated in lion with merctirialism among wor shows the exposure to mercury dust Table 9--Exposure of Hatters' F Controlled a Occupation Blowers ......................................... Shippers ....................................... Cutlers . . . ' . ................................. Sorters ......................................... Bvushers ....................................... Drummers ................................... Clip p e r s ....................................... . i __> i .. c;:ry-[o:irHi .-iunmil Saf et y Coiujrrss-- Xntioiial S a f et y Council under controlled and uncontrolled working conditions. It is apparent that where sonic measure of control is practiced hy such methods as segregation or local exhaust ventilation, a material reduction in the exposure to mercury has been effected. It Is our helief that in the ease of the Mowers' exposure, a reduction may he effected hy mechanical enclosure and local exhaust ventilation, and that the shippers' exposure to mercury vapor may he lessened hy a general system of ventilation sufficient to change the air in the store room freijiieiilly enough to bring the mercury concentratralion to a hover level. Unfortunately, in the present investigation, it has been im possible to find a plant in which an attempt has been made to reduce the exposure for these two occupations. fn some dusty occupations the methods of controlling dust have not been devel oped. In fact, operations such as removing the cures from very large foundry castings, sand-blasting, handling of used storage battery plates, paint chipping, and cadmium oxide manufacture appear to offer no practical means of adeqnalcly 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 dusts present. These devices consist of various types of respirators, masks, and helmets. It is important to hold in mind the limited use of personal protection devices. Because a worker cannot with comfort wear a mask or helmet continuously, such devices must be employed intermittently. Their use is generally extended to those operations where all other methods have failed or supplementary to them, as in storage batten repair where the exposure lo small amounts of lead breathed is known to he detrimental to health. It should he pointed out that the U. S. Bureau of Mines is equipped to conduct approval tests of respirators used for protection against various dusts and fumes (Schedule 21). These tests arc conducted against the dust for which the device is to he used and arc rated, not on an efficiency basis, hut on the quantity of dust which actually passes the respirator. The results of a study of masks or helmets of the positive pressure type, made during the sandblast investigation conducted several years ago by the Public Health Service in cooperation with the National Safety Coniiv.il. showed that the only practical safeguard lo the worker inside the sand blast room was to provide him with a mask or helmet of the positive pressure type. In studying the efficiency of such devices it tvns found that a relationship existed between the amount of air supplied to the helmet and the concentration of dust inside the helmet during blasting. To 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 same time maintaining the dust conemrntion in the sandblast room (outside the helmet) constant. The positive supply of ft cu. ft. of dnst-frcc air per minute will protect a worker under the operating conditions now in practice in sand-Uast rooms. The ultimate criterion of protection, however, is the result of dust determinations of the air within the helmet, that is, the. air actually breathed hy the worker and not the volume of air supplied. Too much emphasis cannot he stressed on the necessity of maintaining in good order the personal respiratory devices for the protection of the worker against various toxic dusts. Maintenance of exhaust ventilation systems, and other types of protec tive equipment, should he a rule in industry rather than an exception, Too often the term "pood housekeeping" has been interpreted as signifying only the periodic removal of dust collected on doors, rafters, etc. Although surli practice conlrihnles to the general state of cleanliness of a workroom ami should always he in force, the time has surely come when serious attention should he given to the installation and rigid uaiiitc-nance of all types of dust nmlml devices. Ill every plant there should be some responsible individual charged with the periodic inspection of nil workrooms at In sanitation, ventilation, and maintenance of all dust removal ami other protective devices. : I 'erhaps the best criterion of the effectiveness of these devices is the periodic delcriiMiinlion of the dust coulrul of the air at the workers' breathing zone. Inly hy constant vigilance and an approach lo the problem as outlined ill this paper may one hope to make progress in the control of the dust hazard in industry. flfliit the bim-fit.s of even a most extrusive program of dust eoulrol are not muneilialels veali/ed. This is especially true in dealing with fibrosis producing dusts m plants where some of the workmen have already inhaled snllicieut quantities to ' t1 ! I i ) i ( cau*e disability. However, in d compounds, control measures : period. It is di/Ticult, because economic benefits resulting froi estimated by Dean K. Brundajrc. in savings to employer and emp and of the time lost on account demonstrated as attainable, is ?2' is for plants whose accident ra arc no occupational health hnz {lie savings should be far in cxc that in this country there are ap iacturing, mechanical, and minei the problem has not been ovcrc 3. Bloomfield, T. J. amt Drecsse Reports, Vol. *19. No. 23, J u n e 8, 19. 2. Amlir.neo-Silicosis nmoiiff hnr< 3. Bloom field, J . J ., and Greunb industrial health hazard. Jour, huh I. H a tc h . Theodore, Drin ke r, Phil the hard-rock industries. I. A. Intx with pneumatic nrnnite c utting tool J latch, Theodore, Kelley, George the hard-ruck industries, il. An in rock drill of the " J ac k- Jia tnincr" t Hatch, Theodore, Warren, Henry the hard-rock industries. JII. Dcs luuunnalic rock drills in open eNcav Silicosis ; Medical Problems oi By E A hidden element of the Cm rebelled a singe beyond the corns is conservation of man power Disease preventive measures are saving. Incidence. In llic United I 51)0,01) to a 1.000,000 people emp In Xrw York Uilv there ire aim of granite workers in Massaclmsi and silicosis complicated with to the cause of death in over mie-th incidence for males of 20 years ; in Massachusetts, silicosis was h ill degree than in granite worket with pncniiHinoconinsis hits avcr;q silicosis in an industry such as j is nearly as great as that repot figures are much lower than thus whom the mortality from tnbcrciil rates for all nun-tuberculous inf in siliceous lusts than in the ge in silica succumbs more often to the chronic tibrosin. st Twent y-f ourt h An n ua l S a f e t y Congress-- National S a f et y Council Silicosis is defined as a pathologic condition of the limps due to the inhalation -ilica, whether free or combined in such a state ns to lie capable of setting up its acteristic pathogenic effects. The principal factors that determine the incidence f ilicosis are (1) the percentage of free silica in the inhaled dust; (2) the conration of silica particles less than 10 micra in diameter in the atmosphere; (3) 1 duration of exposure to the dust, and (-4) the susceptibility of the individual y >oced as modified by ape, complicating infections, etc. The occupational disease > \ ulting from such inhalation has been defined as "morbid results of occupational t \ ity traceable to specific causes or labor conditions and followed bv more or i extended incapacity for work." I Metabolism of Silica. Significant amounts of silica arc present in all body ,ies and fluids. It enters the body through the digestive tract and the lungs, -t of that entering the stomach is eliminated in (lie stools, but a fairly large tint is absorbed into the blood as shown by the constant excretion of silica in urine. All vegetable foods contain silicon especially the hulls of grains, hay and w. 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 urine of animals be influenced at will by diet. The body possesses a very efficient mechanism the disposal of silica because of the low kidney llircshhold. Silica entering lungs in particulate form is expectorated in part with its enveloping cells, but =t of it is carried into the pulmonary lymph channels. Many such particles reach lymph nodes and even the spleen by way of the blood. The finest particles ever, may be dissolved in alkaline body fluids and carried away in solution, to excreted 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 tinder the microscope. Attempts to influence the absorption of silica from the lungs by administration alkali have been inconclusive. Kliminntion of silica by way of the sputum from nts having deposits ol silica in their lungs appears to lie higher than those mg no history of exposure to dust. Only small amounts of silica arc in the 1 and this le\cl is little different in normals than in silicotics. I'alhnlnay. This disease is essentially a fibrosis of the lungs developing espe"v in such industries as hard-rock metal mining, granite cutting, metal grinding sand-blasting. The pathological changes arc believed to result from two causes, ''.eking of the lung lymphatics by mononuclear evils laden with dust in addition die action of colloidal silica, the exact nature of which is in doubt. The small iclcs under 10 micra are the only ones capable of penetrating the lung tissue. Although silica plays the dominant role in the production of silicosis, the adture of other dusts tends to modify the pathological changes in the lungs so : these resemble then those of other forms of dust inhalation, and the modification 's some relation to the percentage of free silica in the mixture. Silicates, as in stos. produce a definite change in the lung, as well as other dusts such as -hie, coal| etc. Such changes are represented by a fibrosis brought about because ttivcly insoluble minute particles of minerals in sufficient concentration have u 'brought by the activity of phagocytic cells into intimate contact with the mcmary connedivc tissue. This fibrosis is a diffuse cellular one that occurs in walls of the smaller bronchi and of all their finer divisions and extends to dve 1hc supporting connective tissue of the ndjarenl blood vessels and to some nt also the walls of adjacent air spaces. However, when the great majority of inhaled particles arc composed of or contain silica, there develops, in addition, a ific and localized type of fibrosis called the silicotic nodule--an orderly whorlcd .iiigcnicnt of cells and fibres, and with sharp definition from the adjacent pareu nia. Many dusts create a generalized fibrosis hut only one, namely one combined th silicon dioxide produces the special fibrosis of silicosis. Scricitc, known as te mica, which is a hydrated silicate of aluminum and potassium, has not produced ,j ..:iimal experiments the silicotic nodule, hut instead generalized fibrosis resulted. Dusts must he differentiated into those which are chemically active and those h are inert when inhaled into the respiratory tract. Silica is a chemically active : which must necessarily he soluble to a degree in the body fluids and its activity nds oil its solubility. This activity which is manifested in the areas where dust .cles .are carried along the lymph stream by phagocytes, causes lesions of two 1 Occup types, "toxic" and "sclerotic" both . Toxic lesions depend upon local nec growth of tubercle bacilli; the scler inert (lusts arc insoluble in body fluk tissue, but if they accumulate to a I may lead to a certain amount of dif dusts, itch as carbon, may have pin and it has been suggested that on th active clinical tuberculosis in silico-ai Other dusts may even protect, aluminum oxide. Pure pncuinonocor pulmonary fibrosis of workers in dr action of dust and infection, whether In silicosis it is not the mineral record the cause of disease, but t to work, efficiency and health may of finely divided particles even ol a c a lymph stasis which is known to foil leads to retention and accumulation get what is called "miner's asthma' patients arc very liable to have a hi physical changes due to retention of a n( silicosis, with or without tubcrcul Tuberculosis. Most apical tuber silicosis at the age of 30 makes a pn with tuberculosis going into the mil the age ol d5. The silicotic dcvclu in life and the children who arc c little clinical tuberculosis. It is iinpr itself upon the silicotic or vice vc that spreads downward, while olhc lower lobes. It has been found that The diagnosis of silicosis is mai of occupational exposure to siliceous the pulmonary X-ray. The physic; of less value. There are other diagi of silica particles in the sputum, qi at post mortem, chemical analyses examination, roentgen-ray spectrum tissue. We must at times rely on distribution of fibrosis due to silica on the hiiporlanrc of this fibrosis a I.ting fibrosis may be present lung tissue or the pulmonary lyni| divided siliceous particles from lur cannot he distinguished from barn not donhlv refractive cannot he pathological section the presence o lie specifically identified with the sil: the micidincineration method of Irw microscopic examination of any luiif Diagnostic difficulties in clinical first the occupational history. Quar exposure may develop silicosis in a in other occupations it may take 2 in the same room, experience differ the dust-filtering capacity ol the no mined by constitutional chnracteris loidal structure of the particles of : ilica, will influence the rate of di that ire larger than 10 micra arc 30 Tivcnty-fourth Annual Safety Congress-- National Safet y Council -lory of exposure must lie established :uul in general hospitals where patients are eratory, font Iitions mule r which they worked arc very vaguely described and re are not available data on dust counts and silica concentration, so that the history often misleading. As to symptoms, patients ran perform strenuous labor despite extensive disease nd the symptoms of dyspnea anil couch arc common to many diseases. Fever is 'sent unless infection occurs, hut most important is the great disproportion between patient's complaints and what is seen on the X-ray, the latter showing extensive norma! shadows in comparison with the symptoms. On physical examination, extensive disease may he present and few abnormal hysical signs. The physical signs are. merely those of a general pulmonary fibrosis ;lh emphysema, such as restriction of costal and clisphragmatic movement, diniinu- n of or intensified breath sounds and a hyperresonant note. Rales are usually sent unless infection is present. As to the X-ray, there are 3 essential types of shadows described, linear strands, -.mil discrete shadows, and homogeneous shadows of varying sizes; these 'oi re- und to the fibrous strands, silicotic nodules, and the conglomerate masses i fibrosis. The nodular shadows are usually characteristically around the him, or conglomerate nodular shadows of hat-wing appearance extend into both per lung fields, or nodular shadows may be distributed in the upper two-third* the lung fields, perhaps more pronounced on the right side, with the lower third pt clear by emphysema. With infection present, the shadows are less sharp or e linear strands interconnect or fuse. Large conglomerate shadows appearing it from the hilum leaving the periphery of the lung clear throughout because of nphysema. The distribution of some of these lesions may be determined hv the 'lure assumed by the workers, ami infection nay likewise determine an ultimate 'epical distribution. Many variations from these patterns tire seen in the X-ray. pecially under excessive exposure or when other dusts arc inhaled, or in the i cnee of infection. Tt is probable that the main source of the diagnostic dilii- dties is caused by the emphysema which muffles the physical signs and is respon- :'th emphysema, such as restriction of costal and diaphragmatic movement, diminu!'le in great part fur the absence of symptoms. It may blot out, even on X-ray, e silicotic lesions of fine size. Examples of such difficulties in diagnosis as cncoun- t rvd by us are the following: Case I--.1/r. T. A forty-five year old man entered the New York hospital mpl.nning of mild cough and expectoration of four months' duration. He appeared ulely ill. his fever was 103 degrees and respiration 28. Rales were elicited over upper half of both sides ol the chest. Examination of his eye grounds revealed literal retinal tubercles: his sputum contained numerous acid-fast organisms. he X-ray revealed fine mottled shadows distributed throughout both lung fields d a small cavity at the left apex. A diagnosis of miliary tuberculosis was made. I >\vcvcr. after one weeks' stay in the hospital, his temperature and pulse returned 1 nsot rnmoawl abnedcamduericnognftihneedfotlolotwhienglemft oanpthex.he Ignainveiedw18ofpohuisndus.nusTuahle psrioggnrsesisn thhies I* agnosis of miliary tuberculosis was doubled. 11is occupational history revealed at up until three years before entrance to the hospital he had worked for 2(1 ars polishing leather on a sandpaper wheel. There were numerous machines in e work room and no precautions were observed to clear the very dusty air. s sputum was examined through the kindness of Dr. llurke of Mat brook, N. Y. ho found it laden with numerous doubly rcfractile silica particles, lie expressed c opinion that this, was consistent with silicosis for he had found such numerous rticles only in cases of silicosis. The patient suhseipienlly died of a tuberculous ningitis. Retinal tubercles were demonstrated on microscopic section. The thologist's report was miliary tuberculosis. Ashing of the lung showed increased ica content, consistent with undue exposure to dust (more than 2 mgm. silica per un dried tissue). ^ Case II--Mr. R., aged 54, entered the New York hospital complaining of ' mop:;, ses. dyspnea and chest pain. On physical examination there were rales I dullness over the upper third of ihe right chest anteriorly. lie ran a low ole fever but was robust and felt quite well. The chest X-ray disclosed enlarged um shadows, particularly on the right, and diffuse mottled discrete shadows Oecu throughout both lung fields with a gave a history of having worked asbestos-containing paper box boa of dust. Examination of the dust re we felt, was to be explained on the know whether we were dealing wit silicosis or asbestosis. A small noi showed carcinoma. We arc inelinia process, as the man is still alive and say that there is no silicosis. Case III--,1/r. C. A disli-was of cough and expectoration, associal rales at the right base posteriorly, at the right base. His sputum ci revealed no abnormalities. P.roncbo right main bronchus. Symptoms ai years. Discrete mottled shadows li the shadow at the right base dear normal shadows were present throm Diagnosis of chronic pemtmonia of a diagnosis of silicosis entertained, no history of exposure. I-'tirthc-ri alypically having the lesion confincc and then spreading to the left hmg associated with a small degree of how much more extensive the silicc stenosis of the right middle lobe hru infection in the hmg field probably ease illustrates how necessary it is I it here we arc unable to even sugges Case IV--Mr. C., aged 45. com| toration and gave a history of bavin talc powder. It was difficult to o silica exposure except that the roon present at both apices and a few Discrete and stringy shadows were know from the positive sputum tl however, been well fur a period of together with the numerous discrete sistent with silicosis, makes this pa is this tuberculosis with silicosis? working. Canclusion. Cases such as these he borne in mind. If occupational laboratory studies prove misleading However, a comprehensive study of with reasonable certainty. ADi ..... .......S a f e t y Ilijiilf'iiieiit Safety Equipment W EDNESDAY AFTERNOON SESSION October 16, 1935 The session was called to order by Chairman, Irwin \V. Millard, president, y Industrial Gloves Corporation, Danville, 111. Chairman .Millard mentioned some ot the problems of providing adequate safety equipment for industry. Respiratory Protective Devices (An interpretation of the U. S. Bureau of Mines, Schedule 21) By CARLTON E. BROWN, Chemist, and WILLIAM P. YANT, Supervising Chemist Gas Section, Pittsburgh Experiment Station, Pittsburgh, Pa. The respiratory protective devices of industrial hygienic importance arc those designed to protect against the inhalation of harmful solid, gaseous, or liquid atmos pheric contaminants, or the inhalation of air dcficicut in oxygen. The devices in common use arc the mechanical filter respirator (commonly re ferred to as respirator) lor protection against the inhalation of dusts, smokes, fumes, and mists or what may he referred to collectively as atmospheric particulate matter; gas masks for protection against the inhalation of gases and vapors; oxygen breath ing apparatus, hose masks, and air-line respirators for protection against the inhalation of any atmosphere provided it does-not contain harmful constituent which can he absorbed readily through the skin: and the abrasive blasting helmet or hood for pro pteacrttiiocnulaatgeaimnsatttethregeinnhearlaatteidoninofsaannddbltahsetinimg poarctabarnadsivaebrbaslaiostningirowmiththseteaetlmsohsopt.heric 1 These devices are designed to furnish protection cither by making the wearer's inspired air safe to breathe or hv supplying the wearer with sale air from a supply which he carries or from outside the contaminated /.one. The wearer of the first or air-puriiymg type, on inspiration draws air from his uimsumaleldyiabtey cshuermroiucnaldionrgsmethchroaungichal thfieltrdaetivoinc,e owr hciocnhveerittsheirt irnetmooavehsartmhelescsonstuabmstiannacnet,. > This type, of course, offers no protection against atmospheres deficient in oxygent as it does not add oxygen to the air. There arc two types of respiratory protective devices of the second type designed to supply the wearer with safe air. In one. the wearer receives his air supply from a cylinder of compressed oxygen. liquid oxygen, liquid air, or from a chemical which yields oxygen upon decomposition. This air supply is part of the self-contained unit, all of which is carried by the wearer. In the other type a hose, attached to a face piece, is connected to a compressor or blower whose intake is located in safe air. Air is forced through the hose to the wearer. .'JIM!.!'-USg ilOFUC?TMme*S2*'-. jo-i J I 'rn ty -ju u i llt A n n u a l S a fe ty Congress-- N ational S a f e t y Coiiuri/ a- S> There is some confusion in lie use of the term "respirator," to designate devices *i for protection against the inhalation of atmospheric particulate matter. Such devices were the hrst and for a long time were the only respiratory protective devices. They f were logically called respirators, and as long as they were the only devices of this vi hind there was no confusion. The development of other devices of industrial hygienic importance and the development of devices for maintaining artificial respiration over lone periods and for enabling men trapped in submerged submarines to reach the sur face safely, all called respirators, was responsible for the confusion. The Bureau of adwmtagcs in flic use of devices found by examination :nul test to Mines gives the manufacturer n deuce of the qunlity of his prodi which clearly distinguishes then proved find the limil.'itions undei sumcr, the Bureau of .Mines per the requirements. Mines suggests that the term "respirator'' he retained for all of these devices, hut that respiratory protective devices of industrial hygienic importance he called indus trial respirators and that the different kinds of industrial respirators he assigned a name which will indicate their operating principle or field of use or both. Satisfac tory names in common use should he retained. On this basis, the lfureau of Mines suggests the following classification for respiratory protective devices of industrial hygienic importance: Tire submission of cquipmen hirer. On imiking application f turned into the misvclkmcons rec the money accrues to the Bttrent tircly by the desire of the mnmif: interest of the Bureau of Mines i the demand of the consumer for : Industrial Respirators 1. Snpplied-Air Respirators a. Self-contained type (1) Oxygen breathing apparatus" b. Hose type ( I ) Hose mask (21 Air-liue respirator" (31 Abrasive blasting respirator" 2. Air-Purifying Respirators a. Chemical filter respirator11 f l ) Acid gas or type A" chemical filter respirator (21 Organic vapor or type IT chemical filter respirator (3) Ammonia or type C' chemical filter respirator Approval schedules have bee filter respirators or gas masks,3 1 schedule covering hose masks is 1 nir respirators, namely, air-line ai is completed, the Bureau of Mi respirators now in common use. slide for the development of fund: lion of confusion in their selectioi The general plan of the vari divided into 3 parts: (1) Bre-lest requirements, i before examination and test of respirator must he in a fully ilcvc chase if approval is granted. A! maintain control of the essential c the approval of this Bureau. H I Carbim monoxide or type D' chemical filter respirator h. Mechanical filter respirator^ (11 Dust or type A ' mechanical filter respirator (21 Fume or type TT mechanical filter respirator (31 Mist or type C' mechanical filler respirator c. Chemical and mechanical filter respirator* I S Testing and Approving of Industrial Respirators by the U. S. Bureau of Mines (2) Material, construction, . must meet by examination and tes (3) Post-test requirements, after the device is approved. Fro of these concern labeling and ma: iwc of the device, and maintenance the approval. As a check on the device oil the open market and si the appropriate schedule. The Bt Since its organization the U. S. Bureau of Mines has been interested in industrial any device for cause. respirators as a means of protecting workers in the mineral industry against harmful atmospheric contaminants. To this end the Bureau has developed an approval system, Interpretation of U. S. Bureau I he purposes of which are: (1) To encourage and aid manufacturers in the develop ment and marketing of safe ami suitable c<|uiptncnl: and (2) to encourage the con- mner to use such eipiipmcnt, to aid him in obtaining it and to instruct him in its r? .-age. Those purposes arc accomplished by establishing a schedule of the material and erformancc requirements that a safe and suitable device should meet; by making .pproval tests for conformance to such a schedule; and hv informing the public of the c Sometimes called mine rescue brr;i thing apiMinttis. b Sometimes called paint-spray respirator or positive pressure respirator. Testing Filter-Type Dust, B Among the reasons for the < l'iltcr-Type Dust, Fume, am! Mis hv the Bureau of Mines and other respirators to protect workers agn lions where better methods (if con available or practical, the meffici S o m etim es called sam l-blast helm et or hood. * C om m only called gas m ask. * L e t t e r s assigned to c a n iste rs of chemical filter respirato rs . See U, S. Ih ireau of Mines A p p r o v a l Sc hcd. 141), P r o ce d u re for T e s t i n g (Ins M as ks for P e rm iss ib il it y , 17 pp., 1W5. t Commonly called respirator. Sometimes referred to as dust respirator or mechanical Iter-type respirator. 1 IJurcnii of M ines, P rocedure for Itre a d iin g A p p a ra tu s ; l :ees, Cli.rr.ic lt llre a tliiiig A p p a ra liis will lie T e ste d : 5 llu r en u ot Mines, Procedure lor 9. ]M .\ 17 pp. 9 L e t t e r s assigned to mechanical filler respirator filters. See U. S. Thireau #of Mines '- o p ro v a l Sc he d. 21, P r o c e d u re l o r T e s t i n g T u h e r- T y p e D u s t , F u m e , and M is t R e s p i r a t o r s lor 3 Vltircatt of Mines, Procedure for 2., 1927, 8 pp. > r m is .s ib i) it y , M pp., 19.14. 4 b u r e a u ol M in es , Pr oce dure foi * T h e de vices now referred to a s T y p e N or All Serv ice G as M a s k a nd the chem ical for P e r m i s s i b i l i l y : Seller], 21, A u g u s t irt i idge' respirator (all under this heading. l n'cnty-fourth Animal Sa fe ly Contjrcss-- National Safety Council ~ts from manufacturers and consumers that this bureau test and approve such 'ihcdulc 21 follows the general plan of the other bureau approval schedules for ial respiratorsj the pre-test and post-test requirements arc quite similar, and neral principles of the test requirements are the same. The primary purpose of aper is to explain the reasons for the various test requirements. Pre-Test Requirements I lie pre-test requirements of Schedule 21 require that the manufacturer submit nation, drawings, and samples of- the device to he tested. The device must he . Ivtelv developed and ready for release to the public, and the device when tested e manufacturer or his agent must have passed tests of the nature described ihcdulc 21. The reasons for the third requirement are: (1) To assure the iu that the manufacturer is prepared to control the filtering characteristics of espirator; (2) to eliminate any question of competition with private consulting vies in developing respirators: (3) to furnish evidence that the respirator really adv for release to public market: and (4) to save the manufacturer's and the -in's time. After the manufacturer has complied with all the above pre-test avinents he must submit a fee for the examination and test of his device. fee is turned into the miscellaneous funds of the U. S. treasury and none of money reverts to the Bureau of Mines. Test Requirements In developing the tests for mechanical filter respirators consideration was given : to the general requirements for a safe and suitable device. These requirements similar for all types of industrial respirators. The respirator must (1) give mate protection. (2) be reasonably comfortable and physically convenient to r. and (3) provide an acceptable service life. Adequate protection implies that the mechanical filter respirator when properly "dauied and worn must prevent the wearer from breathing enough particulate ier to cause a harmful physiological response under the conditions of occupational sure for which it is designed to be used. Comfort and physical convenience factors arc equal in importance to adequate a ction, liven though aware of the ultimate serious effect which will be produced r prolonged daily exposure, workmen arc inclined to be diffident and unwilling ilier much daily inconvenience and discomfort from the respirator. Kncunihrancc and discomfort also increase fatigue, cause distraction, and in -al handicap the wearer's ability to take care of himself, thus increasing the bility of accident. Important specific items include the weight of the respirator, arriagelon the face or heed, effect on vision, heating of the area of the skin -r the facepiece, inability to expectorate, difficulty in talking, and resistance to ..thing. The importance of comfort and physical convenience cannot be over . .ited. 'I he service life involves elements of practicability in the wearing and maintenance 'be device, and indirectly the safety. This type of respirator is primarily not an rgeiicy device, but a part of the workman's equipment for doing his regular job iy. If the service life is short, the bother of changing of filter elements will reflected in the workman's attitude toward good maintenance and use. UI mechanical filter respirators arc subjected to certain inspections and tests they must fulfill certain requirements. The general design and construction, 'icularly as to facial fit, freedom from irritating facial contacts, weight, effect vision and the wearing of goggles, and ease of changing filter elements, anif nhied. The materials arc examined to determine if they tire obviously suited the purpose for which they arc designed. Rubber parts which come in contact h the skin must not contain any skin-irritating constituent. , Resistance to Air Flow Requirements The requirements for resistance to air flow are the same for all approved mcnical fitter respirators. At no time during or after the filter efficacy testing period 't the resistance to air being drawn through the device at the rate of 83 liters > i t i t l t i Safer (3 cubic feel) per minute exceed 5( height or the resistance to air being of flow exceed 25 millimeters of wal per minute is approximately equivalent work. The amount of particulate r efficacy tests is roughly equivalent to by a worker wearing the mechanical suspension of the particulate matter ill flow of an approved mechanical filter n for an 8-hour period in most suspc countered in industry. The manufactu or changing the filter elements when Direct Leal All mechanical filter respirators r to determine facial fit, whether there obtain information on the comfort o respirators arc worn for 30 minutes atmosphere containing a heavy suspci the period the respirators arc remnv facepiece is examined for evidence of a a millimeter thick were wedged und'et A and C to cause the leaks. The lot arc shown by the black streaks on th: facepieces. The nasal passages and s| and after the tests. Filterin In the development of the fillcrir to the physical properties, especially ; phene particulate matter encountcrc materials had shown that, in general, particle size. It was decided that most of the particulate matter could be classified with method of generation, physical s 1. Mechanically generated dusts such as the dust clouds produced in i tunneling and the grinding, crushim This type of atmospheric particulate particulate matter and mechanical fi against these suspensions arc referre 2. Fumes, ol various metals (n: carbonates) such as lead, mercury (< aluminum, antimony, arsenic, copper, from sublimation or the condensation between their vapor and gases. Thii (erred to as Type B atmospheric pari designed to furnish protection agains mechanical filter respirators. 3. Mists as produced by spray-n acid mist as produced in chromium liquid vehicle docs not produce barm particulate matter is referred to as mechanical filter respirators designed arc referred to as Type C mechanics The mechanically generated dust mists consist of liquid or liquid-co; chanically generated dusts extends o\ visible to the naked eye probably i particle size of fumes is much smallc . 3S Ti 'c u t y - f oiirth A nn u a l Saf el y Contjrcss-- National S a f et y Council up.- (about 0.5 micron), while the lower limit probably approaches molecular iicnsions. 1 he particles of some fumes, particularly zinc and magnesium. readily it and form Iatee ilncklikc dusters. The effect is least pronounced in the case lead. Mist particles are spherical ami probably more uniform in particle size than .sc of dusts and fumes. Suspensions of each of the types of industrially-generated atmospheric particle alter were selected for use in the filtering-efficacy tests. These suspensions were iioscn on the basis of their industrial hygienic significance and their physical roperties. such ns particle-size distribution and tendency to aggregate, which have appreciable effect on filtration. It was desired to test the mechanical filter pirators against the most common or widespread harmful suspensions of each ,.e: the test suspensions In have physical properties, such as particle size and jregation tendency, which would render them as difficult to remove by filtration any other suspension of the same type, 'flic test suspensions selected arc: (a) l o r testing Type A mechanical filter respirators or those designed to "nish protection against mechanically generated dusts a suspension generated from ry fine (W-j- per cent through 525 standard mesh sieve) silica dust consisting of -T per cent free silica (SiOn) is used. The suspension is generated in such a way int all particles larger than about 3 microns tire removed before the suspension uers the test chamber. The particle-size distribution of the test suspension must t exceed a geometric mean of 0.0 micron and a standard geometric deviation of ''0. 'I he particle-size determination is made by collecting samples of 1he suspension "1 the Owens jet dust counter and determining the particle size distribution hv a icroprcijcctinn method developed by the Bureau of Mines." (h) For testing Type B mechanical filter respirators or those designed to uriiish protection against fumes, a lead oxide fume generated by the combustion of atural gas containing lead tetraethyl vapor is used, file particles of this fume arc xtremely small and have about the least tendency to aggregate of any fume, hence ay are very difficult to remove from the air by mechanical filtration. A suspension magnesium oxide is also used to determine the effect of a fume, whose particles ; a oily aggregate in large clusters, on the resistance to air flow of the filter of the vice. fc) For testing Type C mechanical filter respirators or those designed to :mish protection against mists, three different suspensions are used. Chromic id mist generated by electrolyzing an aipieous solution of chromic acid, as is done industrial chromium plating; lead paint mist generated by sprav-eoating with lead int; and a water mist carrying silica dust generated by spraying a 2 per cent uvnus suspension of silica dust arc used. The water-mist carrying silica dust is d to simulate the mists generated in spray-coating with vitreous enamels. ' Tjlie concentration of the particulate matter in the test suspensions was chosen represent more or less the higher concentrations found in industry. Since the nceutratioii of mechanically generated dust found in industry varies over such 'dc limits it was decided to test Type A mechaniral filter respirators against two nceiitraliiiiis; one to represent the more or less average dusty industrial condi11s. and the oilier to represent very dusty conditions. The complete mechanical filler respirator is tested on a mechanical testing . paratus. The test suspension is pulled through the device at the rate'of 32 liters 1.13 cubic feet) per miniilc. continuous flow. The volume of air pulled through mechanical filter respirator is 10 cubic meters in all cases except in sumo !' against particular kinds of suspensions as mechanically generated lead dusts 1 in the high-silica dust-concentration test and the magnesium oxide test whose .-unary object is to determine the increase in resistance to air flow of the filler ith the amount of particulate matter retained. Ten cubic meters is approximately luivalent to the volume of air breathed by a worker in 8 hours. I lie samples of iriieulntc matter for concentration determinations arc precipitated electrically '>m the air of the test suspension both before and after it has passed through mechanical filter respirator. The samples arc collected in containers which 1 lie weighed readily on an analytieal balance. For reasons of convenience, speed, * l i i m r n . ( ' 1\. mill Y m i l , W . 1*. Tl ic M irr npi.,1-1-1, >r fur O c l e n n i t i u i g 1'arl ir lr S iz e o i l m l ' . i i s unit \ u n i l i o r I'niicctitnitiuM nf Alniu'.i'tii-rir Hu m s . ft. S. Ilinc.'iii nt M i n e s firinnt I n v e s t i g a t i o n s .I2K9, 19J5. i and accuracy the samples of sil count. .Samples of the other pa The requirements as to the filter respirators must remove ire available information on the con breathe. These requirements are edge on the physiological cITcct: matter. In other words, the filtc the wearer of such a device must particular percentage filtering effi Mechanical filter respirators than the particulate matter in t Tims Type A respirator? arc m free silica (SiOn) dust. Howcvc mechanical filter respirators agai particulate matter. For examp! approved for protection against constituents arc metals or their ci tors have been submitted and i mechanical generated lead dusts. Table 1 summarizes the det; chanical filter respirators which h Pos The manufacturer of an np mark his device with the name of the type is designated for trade : device by the Bureau of Mines; a number and with the type or ki is approved. The mechanical filter respira with substantial and durable cont; manufacturer by the Bureau of approval label gives the approva' slates what the device is and is n the manufacturer's instructions fc The following is a sample ol facturer. These instructions arc respirators. Instructions for U 1. Respirators will not prot they arc worn. Carelessness in better fit is obtained if the mask 2. To fit the respirator to tl downward, by the metal screw cc with the other hand. Tlacc the while pulling the hcadstrap over facepiece until a firm snug fit is the respirator is in place by liohlii of rinc hand and pulling on the 3. To instruct the wearer position of the respirator on the disc unscrew the filter hag, plat connection on the felt hag. assemb not he able to breathe through under the edges of the facepiece. The presence or absence of d facepiece after wearing the respir; whether a proper fit was obtaintn 4. The recommended proced the nozzle ot a liigh-prcssure aii 140,7 veenty-fonrth Annual Safety Congress-- National Safety Council TABLE 1. DETAILS OF FILTERING EFFICACY TESTS AND LIST *1 Kind of icchanica! li t e r t> pe e>pn .iU/r Industrially generated atmospheric particu late m atter against which the device is designed to furnish protection Test suspensions used J'ype A Mechanically generated dusts resulting p iim ip a lly from th e ilis liuic gra tiou oi a such as the dust clouds produced in milling, quarrying and tunneling, ami the i tu h t- u ia 1. operations of g rinding, c i u s h i n g , and p r e c e d i n g of m in e ra ls Air-suspended ground llint, which consists o( 99-f- perc en t free silica (SUr). O ve r 99 pe rc ent of the d u s t pa ss e s thro ugh 325mesh standard sieve OF APPROVED MECHANICAL F. Concentration oi test suspension, milligi ains* per cubic^ m e te rb of air Vo lume of test suspension pulled through the device, cubic meters* Maximurr matte tin Milligrr (a) 50 10*1 2.88 4 mg. for m 3 devices, a ve r a g e of for each of devices flO 5 _-fc 2d 9.98 12 mg. for of 3 device an avvi age mg. fur ca (he 3 I-times <f vjiiiuiis m e ta ls (us ua lly the ir chemical, compounds, as oxides or carbonale s) such as lead, tu c rc u ty (except m e r cury vapor), manganese, copper, chromium, iron, cadmium, zinc, magnesium, a lu m i num. antimony, and arsenic resulting from sublimation or condensation of their vapor, or irnm chemical reactions between their \ap->r ami gar-es Mists as produced by spray coating with paint ami viticou-. cuaimd*, chromic acid mist as pioduced in c h io m im u placing, ami other m is ts of m ate rials wlio^c liquid v e hicle does not produce harmful gases or vapors (a) I,cad oxide fume produced by (he dccomposition and co mbustion oi lead tetraethyl (b) Magnesium oxide funic, freshly pro* duced hy burning magnesium riblxrn (a) Chromic acid mist produced by electro lyz ing an aqueous solution (200*500 g r a m s of c h nunic acid p e r liter) ot chromic acid (h) l.ead^ paint mist prnduccrl by spraying a paint Imvinp the following composi j ti o n : w hite tear! (p a s te h a v in g appro xi m a te ly 91 percent white lead and 9 perc en t linseed oil hv w eight), 100 g r a m s ', linseed oil, 50 cubic c e n t im e t e r s : and Mcatn-diMillcd tur penti ne, 25 cubic centimeters (c) Mist produced hy spraying a 2 percent aijueons suspension of ground flint, airMoated (99-h pci cent i htough 325 s t a n d ard me sh sieve). The ground Mint rm- *-ist s of 9'M- pcicent fu-e silic a (SiOj). .ally ed lead Mechanically generateli d u - l s \vhn-i> m a m h.'iiuiful constituent is Icari. Mich a* Icari lusts generated in m anufacturing storage hall Mies; i-n.imrling : putivi y m a k in g : mb- M i u u i c used in m a k in g negat iv e pla tes of leal s to ra g e lia tte nes. Con ta ins 72 p'irciit liiliargc, J 'h O ; 25 percent red lead, f ; :m*l 3 pe rc ent lampblack her compounding ; sandp.if'ci iug and chip ping pamlcd surfaces; pninimaking ; pie- pari ug liilio-trail s i n s ; an) m in ing, milling and processing lead ores O n e m i l l i g r a m :_z 0.015-1 giaiii. ' O ne cubic m e te r = 35,315 cubic fret. *' b a t e oi s a m t d i n g n r 32 liters (1.15 c u b i c feet) iut m i n u t e . ,l Out- n i i l l i g r a m of t h i s silica d u s t c o n t a i n s a p p r o x i m a t e l y 300 ed b v t h e i m p i n g c r mctho<l a s d e s c r i b e d hy t h e IJ. S. I 'u h li c g r a m p e r cu b ic m e te r of this d u M ts a p p r o x i m a t e ly e q u i v a l e n t <iibic foot. previous listing of company for complete address. million particles as detcrHealth Service, lienee, 1 t o N.5 m i ll i o n s of p a i t i d e s 1 1 c I 15 5 f lead 100 25 15 + 5 of chromic acid .un-Mni.fic.iii V Id of m Ik : .lust 19 5 of l e n i 9.98 1.5 2 -- 9.98 1 9.9R i.s 9.9S s 2.RS 0. I.1