Document NGk7we0gzdDQDwGkMYQxJL4QV

WEDNESDAY MORNING SESSION . October 12, 1938 Assembling in , the Grand Ballroom of The Stevens Hotel, this -meeting was called - . to order by Chairman Walter S. Paine, - Manager, Engineering and Inspection De- parfment, Aetna Casualty & Surety Com- pany, Hartford, Conn., and Vice-President for Engineering, National Safety Council, Chairman Paine briefly outlined the session objectives, and then introduced the speakers. Recent Developments in Detecting Hazardous Dusts, Fumes, Gases and Vapors.... By WARREN A. COOK/ Superintendent, Engineering Department, Zurich General. Accident and Liability Insurance Company, Ltd., Chicago "y- In discussing the determination of injuri- ing able to see or otherwise perceive the / ous dusts, fumes, gases and. vapors, I am potentially hazardous condition. very sure that you are not interested so ; Most gases and vapors can no more be much in a meticulous dissertation on such. seen, than the well-known black cat in the . phases' of the subject as whether the loga- caaA-cellar. Some of i them cannot even be ' rithm. of .the reciprocal Of. the. hydrogen ion detected by odor, though odor is itself no * 'shouid .be 9.S or 9.0 for the determination ' reliable criterion as is evidenced by the gas, of lead by the1 dithizone .method, but rather . hydrogen stilfide, which has .a most ob-. in a discussion of this matter along broad noxious odor but has caused many a case . lines, pointing out what types of potentially, of poisoning. injurious materials. should be looked for, whether determination of;them is in order!,. . a brief discussion on sortie of-the more im.. portent and common .methods of determina tion", and interpretation of the results,ob tained. ; How, then, are we to know- whether the .atmosphere in which we. work is safe or injurious? Are we to wait until we see the effects of unhealth ful or irrespirable at mospheres on our men or is if not more intelligent to determine, within the limita - Foolhardy to' "Work in the Dark" : tions of modern methods and practical ap plications, just what sort of atmosphere we , Working in the dark without any means are subjected to? . . . . of illumination where there may be hazard The- importance of. having facts before ous conditions serious, enough to cause loss us is well-illustrated by an atmospheric con of life or severe injury would be considered dition where a life could be snuffed- out in a most foolhardy; yet every day mien conduct- few minutes, even though the more com-.' their operations. in atmospheres containing mon situation is where excessive exposures dusts, gases, and vapors .which may. cause may require weeks, months or years- to death or severe injury to health without be cause their injurious effects. - 45 V f -! -i 46 Silver Jubilee\ Safety Congress. Thirteen years ago this month a powder case of carbon -monoxide - poisoning, was crew was walking down. the .tunnel of a the ready availability of a simple- means of new water supply system of a Connecticut ' determining the . carbon monoxide cbnicen- city. Their ditty was-to inspect, the. roof . trationiontlie job. . and the face, to see that all the shots were Tlie-present tendency, in development of fired. On approaching the' tunnel - heading methods of determination of injurious. ma7 immediately after'the blast, they found that . terials in air is toward such simple, quick- dying rock had broken the compressed air actitig devices. As many of you. know, the .line, which had been left turned on in order Hoolamite carbon, monoxide detector opr to blow the smoke and gas away from the erates merely, by. pressing a rubber bulb ten face, of the tunnel. The crew, consequently, times and comparing a purple color which ran into a heavy blanket of smoke, but- they develops in presence of carbon monoxide were hardened workers, used, to smoke and wjth a standard color scale mounted oil the gas, and a little smoke, even though they instrument--an operation' which, requires knew it contained carbon monoxide,..did not about a minute. Instruments of' this type hold them back. are especially important for gases which They found ;the roof intact. But four of may cause acute poisoning such as carbon the.holes -had not fired. Caps with 3-foot monoxide, hydrogen cyanide,' and hydrogen fuses were inserted in sticks of dynamite, sulphide. . one for eafch of the holes.} The gas condi? Ah instrument-for determination of hy tion by the- time .this- work had- been ac drogen cyanide,, similar -to the Hoblaniite complished was beginning to make these carbon monoxide detector, has recently . men feel-a'blt.groggy.."Following the usual been developed- by the United' States' "Bu practice, the powder foreman sent the rest. . reau of Mine workers, and, together, with of the men back down the funnel before a number of other of these -simple detec-' he lighted the fuses. tors, is now available commercially. De The men walked back through the smoke termination of such materials can accord to the. car, about a quarter of a mile down' - ingly be made much. more.'widely than the tunnel. There they waited for the fore "formerly when laborious chemical labora man. Seconds passed. - -The -time stretched - tory methods were necessary. : to a minute'. Down the tunnel came -. the Potentially- Hazardous. Materials boom, of the blast--but ho .foreman.. The men rushed to the heading and found the- The first step in an organized endeavor foreman stretched -on. the tunnel floor, to avoid environmental conditions- which nearly covered with rode from the blast, may cause injury to health is a listing of all where he had collapsed from the effects of materials, .used' or produced, which may ' the-carbon monoxide. under certain conditions. be deleterious. It was found in a study by the United States , -This is a true story up to a certain point, Public Health Service, of potential hazards but I have omitted a part of the story, and in a typical industrial, area (1)'that a con the ending, I am glad to say; is pure fiction. siderable percentage, nearly 20 per cent, of The part of the story which I omitted was the workers were exposed potentially to that carbon monoxide determinations were carbon monoxide.- The report by no means being taken when-those men got up to the intimated that this percentage of workers heading, and a concentration of ;3 per cent were being poisoned by carbon monoxide,- carbon monoxide, was shown to be. present but rather that if-things went wrong and a* by means of the. Hoolamite carbon monox concentration of the gas built, up,to .in ide detector. With such a .high concentra- jurious proportions these men might be- tion, it was realized by the man making the. come poisoned. ' determinations that it would not take long {of exposed persons to collapse. He. .in formed the crew of the condition and hur ried them back to the car to wait until the smoke and gas .had cleared enough to jfermit them to work safely aind fire the blast. So I suggest .that you go-through your plants and see what operations involve, por tentially injurious materials. .Of the'dusts, those which may produce, silicosis occur.hot only in the well-known industries`.where, major studies of conditions have been con-, The difference between fact and fiction fri ducted but in other industries as . well, this case, between a brief delay and a fatal. . though usually to a lesser extent - In silver--' . Dusts, Fumes, Gases and Vapors 47 'ware manufacturing, for example, one man. tions in air or instituting control measures, may' be' exposed day after day to tripoli you make a thorough survey of the-.condi- dust, in making up a polishing compound tions and . divide the various operations .for use within, the plant A list of indus where these materials are present into tries in which such diist exposures may groups: (1) those which, are obviously exist is given in the report of the National safe; (2) those which ate admittedly caus , Silicosis; Conference!1;. ing injury to health or . are worse! than The toxic dusts and fumes are more, readily'spotted. We recognize and guard against. lead exposure, in storage battery plants, but often-.overlook such an operation good industrial practice dictates; (3) those conditions, .where it is not readily discern ible by general observation whether the ex posure is'withih safe-limits. ' as where red lead is bring mixed with a . Certain conditions we know definitely vehicle by a worker, in one comer, of the - and can say definitely will not cause injury top floor of the plant to color lettering on a to health. I would-not; say. that those are steel part. -It is not so' much whether a to!be forgotten, but at least they need not pound of lead.br a ton. is used in a day, be the subject of initial action. If, for ex but.the extent.to which it contaminates the ample, a gas containing. 30.. or 40 per cent .air .breathed by. the worker* . . carbon monoxide', is used for hot' plates, Carbon monoxide, hydrogen . sulphide, and those hot- plates are connected with . hydrogent cyanide have- been mentioned as rigid conduit rather than with rubber .tub examples1 of. gases. s The first-of these oc ing,, you can feel reasonably safe that the curs where producer; gas or water gas is carbon monoxide ;exposure ; is within safe used. The last named- should be .looked for limitsr and I would not recommend that where fumigating may be done' from time . determinations be made. Where, spray to time. Where dry .ice is used in .quantity painting is being done in a- well ventilated or fermentation processes are conducted, booth in such a . manner- that there. is .no carbon dioxide is..liberated and has caused excessive rebound into'the face of the deaths usually at the bottom of -confined * sprayer, determinations of vapor or pigment . areas such as ships' holds and fermentation need not be made, even though:the odor of >tanks.. the solvent is detectable... From time to Vapors ..are'' present .wherever organic -solvents are used. Death may:result quickly where high concentrations* exist as has- oc curred when .a drum of solvent was dropped time it,may be well for state authorities to ' check some of. these .lesser' exposures'; but there, is a-considerable number of such ex posures which- can.be accepted as safe. on a basement, storage-room floor and split The second group of exposures--that open, and again where carbon tetrachloride where conditions are. admittedly severe--is -was being . used for. fumigating, a flour mill another' where determinations are not es and the fumigator . sprinkled the liquid, in sential. . Institute control measures immedi the basement as his last operation* It was ately. If there are clouds of dust contain . his last! ' . . ing free silica in your plant, go to work on `Injury- from' continued exposure to sol vent vapor at concentrations which. cause them. If excessive lead,absorption is shown by development of symptoms or by high their effect after weeks of exposure, is the more common condition,; The various basophilic aggregation -percentages', reduce the lead exposure.' It rhay.be desirable to solvents differ widely irt' the concentration . make determinations even in. these' cases. of vapor necessary to cause, injury. ' These either, to provide; a before-and-after picture are- divided- into .groups in accordance, with their toxicity in'a-paper delivered before Uie Northwestern University Symposium on = Occupational Diseases , a year ago.*. . of exposures to show what .improvement is .effected or to obtain a dear picture of just ; what part of an operation is/respohsible for the excessive exposure! to. the end that con trol measures can be more spedfically ap . Where Should . Determinations Be '! plied:! This latter: use of-! air analysis data Made? .\ . is of especial - value where the materials After, going over your, plants and learn..ing . where- potentially hazardous materials are present, it is my suggestion that, before are. invisible as is! the case with gases, vapors, and even some of the more toxic dusts such as quartz.and lead,. . - making actual determinations'of concentra-' The prindpal use for -deterinination of .48 Silver Jubilee Safety Congress injurious materials in-air is where general such as to provide the desired information. observation does not give the necessary in* It has been pointed out that- one;set' of formation. Suppose exhaust ventilation conditions-exists today, and quite a -differ-, and partial enclosure have been. installed - ent set of conditions may exist, the next to reduce exposure to a dust high in free day; that if air analyses show-conditions to silica. - You might learn whether control , be satisfactory on the first day, our. eyes measures-are effective by waiting ten or a - may be dosed to the fact that conditions dozen years to see whether silicosis devel 't are much' worse, on the second day. So, ops among those exposed; It is- much more .rather than encouraging the.installation of economical to run a group of dust de * safeguards, `we are setting up obstacles to terminations. A recent series of such -de-, . them. ,, . ' terminations indicated that exhaust ventila . My plea is that methods of determination tion was - adequate.. at an operation where .be'used intelligently and .honestly... If it is. pulverized siiica was being transferred - to desired to sbo'fr exposures under. themoSt the hopper of ah elevator, but the manipu severe .conditions, be sure to set tip these lation was at fault. '. conditions when you make the test; if rep-s Where fumigation .with cyanide has been resentative conditions are desired, see that conducted, it has long been the practice, to they are-truly representative. Whether you depend upon a time period of ventilation yourselves make these tests; in' -your own aid .upon the nose of the fumigator to. plants, whether you bring , consultants in to establish that the premises are safe for make them; whether state .departments, in occupancy^ Now. that a simple hydrogen surance companies,, or some' other agency, cyanide detector is available, .it is in order makes .these. determinations; make a real, . that determinations be made in every case effort to see that conditions are as repre before re-occupancy and, further, ti\ait every sented when these determinations are made. municipality where cyanide fumigation is For. a .. comprehensive . discussion of carried on-enact an ordinance covering such .equjpmenf for conducting determinations of -. fumigation with. the. provision- that deter dusts, fumes, gqses and vapors, may I refer minations be made, especially in any dead you to a paper entitled' "The Industrial air spaces, before the premises are consid-p-." Hygiene Laboratory."4: This paper includes ered safe for occupancy. descriptions-of both; field equipment and Hydrogen sulphide determinations - are . laboratory apparatus, together with a dis today being made routinely in the spinning cussion of. their applications. . 4 -rooms of viscose rayon manufacturing plants. Carbon disulphide determinations involve a more laborious procedure but are regularly made in a number of departments of the larger plants of this same industry'. Operations are regulated so. that any ex posures to these-materials are within safe limits, but the continual checks, permit de tection, of. any excessive exposures before injury -to health, develops. References to the- methods themselves may be obtained in the reports of the Com mittee on Methods of Determination of In jurious Materials in Air" These reports are available on application to the Amer ican Public Health Association. The Preventive Engineering Committee of the. Air Hygiene Foundation' of Ajnepica has recently developed a bulletin on A good general rule to adopt is to make determinations of -concentrations* of injuri ous materials in air wherever there, is any question that these may produce deleterious exposures. Methods of Determination Methods of Determination,* and in that bulletin are included only" those methods which have been satisfactorily used' in this country. The trouble with many papers on methods of determination is that.they are woefully deficient in their/practiCal qual-.1 ities and simply do not work when put to'1 Discussion of methods of determination the test, , will be limited to certain general considers- ' You are.all interested, I believe,. in a. ' tions,. reference to complete descriptions of brief discussion .of the inethods available available, methods, and comments of timely today for dust determination and some of interest on a very few methods. the up-to-date viewpoints on collection and' In the collection of samples, it is of ut determination of dust. It is my. opinion most importance, that these samples are that where it is desirable to know whether Dusts, Fumes,: Gases and Vapors 49 a condition is or is not'safe.in the light .of electrostatic precipitation, method, which is investigations so far. conducted in this coun about .the most efficient method of collec try, it is well--to collect samples by; means tion, is a preferable, instrument for- mate- .- of the impinger method. I will not go into rials o'f sufficiently ~ fine division to be the advantages .or drawbacks of that, method classed .as fumes. This type of. instrument at the present time-beyond bringing atten has long been available, but only, recently tion to the micro-impinger set-up as devel commercially; and I feel,-that where lead oped at the Bureau of, Mines and now avail in the form of - fume is encountered, the able commercially which largely overcomes electrostatic precipitator should be used. the bulkiness of. the original equipment. The facts which we have in the literature ' It is to be emphasized that only--the'im today concerning the production of lead pinger will give, impinger results. Due to fumes in workrooms where high tempera the., different characteristics of other ture-melting pots are-used, are based' on the methods of determination, you cannot get results of impinger samples, and so until we : a duplication under'a variety of -conditions get further data from the electrostatic pre- , by the use of other instruments. However, cipitator, we have a big question mark as other instruments, such as the grab sam . to whether there is-more lead fume in the plers, which take a sample over a period of - air where lead melting pots are present than a second or two, are of very considerable we. had previously anticipated. value for a number of .purposes. If. an . A year ago, the,A.P.H.A. Committee on impinger sample, collected over a period of . Air;Analysis mentioned above obtained .in an hour shows a high dust concentration formation from all -the laboratories in the exists, we may-know, what particular op-- . country: conducting industrial hygiene de eratidns during that hour caused this high terminations concerning what injurious at . concentration. If we. have a Zeiss koni- mospheric.. constituents had been., analyzed,' mete'r,' a Bausch and Lomb dust counter, or .what methods were used and whether these some instrument which will give us the were.'satisfactory. ' ' '. / concentration, at any given instant, we can. obtain precise information on those opera tions which are. contributing most of the ; dust. .. -. Furthermore, after we know whether a condition is safe or not, one of these 'quick Lead was .the .material which was de termined by the largest number of labora tories. The next material of interest was hydrogen sulfide, and the reason being that most rayon manufacturers make routine tests'for this gas. . sampling instruments is extremely valuable as a control measure. Wherever a concern If any of- you believe that a man will not hap a dust condition, determinations may voluntarily Walk into a dangerous hydrogen desirably be taken by some of these quick. sulfide concentration,-.-, let me recount the methods regularly as a control.: Whether . experience of one of the promising young they compare; exactly withthe.impinger or. workers in- industrial toxicology who walked jnpt is pf no great .consequence; the impor-.. into his laboratory one morning, about two tant thing is. whether conditions are holding years ago, found .'that a hydrogen sulfide- .at levels, shown'by the. impinger. to be safe. cylinder .Had tipped over and. the valve If .dustiness is' bn the increase,.a survey of brokefi off. In trying to get the cylinder to dust producing operations should be made an. exhaust- hood, he- collapsed and was and control measures instituted.. found dead in his laboratory by the janitor Collection of .lead dUst and funies is of . timely. interest with the - commercial avail ability :pf ithe portable electrostatic precipi who arrived not long after. Certainly if an intelligent, research worker, thoroughly aware of the toxic action of this, gas, could . tator. Most .of; us who have been sampling so expose - himself,- we must hot assume - lead-in this country have.been.using the . that the odor of hydrogen sulfide! will cause . impinger for. the collection of-these samples.. This instrument is. highly efficient for. the the., plant worker amounts'of it. to avoid' .dangerous ' . collection of. samples where lead dust is the ' Carbon monoxide was next in the list of material of interest Where .lead fumes are injurious materials placed in the order.of. given,off, w6 have evidence that the 'im the number of - laboratories ' making deter pinger collects these fumes .at'appreciably minations of them! In addition to the small' less, than 100 per cent. We feel that the" .Hoolamite detector,- previously mentioned; SO SUver Jubilee Safety Congress several ..types of detectors and continuous ing air'through, a cylinder, turning a dial indicators are available commercially, both and reading the concentration.. Unfortu portable , and stationary. A. home-made, de nately the interferometer is not specific for vice has just been suggested' whereby air any one .vapor, merely measuring differ is drawn past tbe filament of a cigar lighter ences in densities.- The cost of the instru for combustion and'the CO* formed by any ment is high, but it is available through a CO present is determined colorimetrically. number- of investigators and some .of the This ingenious device may solve the prob-' insurance companies, and, , where , many de lem where the. exposure may not justify terminations are to be made, amply jus the expense of the continuous indicator. tifies itself. Mercury was the next in line.. Unfortu Interpretation. nately we do not at the present time have a quick method for mercury. One method In the interpretation of results, there are will give concentrations of vapors within a number of important hems to be taken injurious limits if the sample is of several into consideration. It is appreciated that the hours duration, but. we would like to be results must be referred to some threshold ' able to obtain the desired information with value 'such as 100 parts per million , for a ten or twenty minute sample. carbon monoxide or 2 milligrams per. ten. The list then includes sulphur dioxide, hydrogen cyanide, ammonia and chlorine in that order. cubic meters for mercury. There! are sev eral, collections of such threshold values, that published , by - Bowditch1 being one of the most complete. Of the organic materials, the greatest number of laboratories made determinations of hydrocarbons as such. .In referring results of determinations to these standards, consideration should -be taken of the duration of exposure of the The inflammable vapor indicator, orig worker and also the duration of. the ex inally designed to show whether an at posures used in developing the threshold mosphere was within inflammable limits, is limits. If a worker is exposed to a con of value for hygienic purposes in some centration of 20 milligrams of lead per-.10 cases, but just because an inflammable cubic meters of air for a period of an hour vapor indicator shows negative results is no a week, we need have fitfle apprehension good reason for assuming that the; condi that he will develop lead, poisoning; but if tion is necessarily safe .from- a .hygienic a group of workers is*exposed to this oon- point of view. One of these'indicators has . centration as an average Condition, then we been sensitized so that it'will give as low can anticipate, lead poisoning cases. as 20 darts of a million of benzene vapor, but the' minimum reading on most of these instruments is 1,000 parts per .million. Carbon disulphide has been of much in The conditions under which the .air samples were collected must be carefully considered. In some instances winter con terest ditions may be the more severe; in other cases, summer conditions. If open windows A method has been developed, and is adjacent to a chromium, plating tank cause commercially available, for the determina high concentrations of chromic acid to be tion of chlorinated hydrocarbons, such as blown into the plating room, the results of trichloroethylene, with which we are be determination should be interpreted to .in coming more familiar through its use in dicate the need, not of increasing the local. vapor degreasers. The chemical method ventilation, blit of keeping- adjacent', win will give chlorinated hydrocarbon concen dows Closed. trations in the presence of such other ma terials as gasoline,, with which they are sometimes mixed. Careful note should be made of all opera tions which may contribute to the exposure. The dust concentrations near a group of A rapid physical method for. the deter molders in ah iron foundry may be exces mination of all vapors and gases having a sive, but it is possible that "the cause may density substantially different from air (and be due not to the molding , operations, but this includes most of them--notable excep to an unprotected sand conditioning 'ma- .- tion's being CO, HCN, methanol, and chine in the~ vicinity. - Where conditions ethane) Is the portable interferometer. The change rapidly, samples must be taken fre operation, after calibration, involves draw quently or over a long period in order to. DustSi Fumes, Gases and Vapors . 51 permit proper interpretation. Where con ditions are essentially static, a single brief sample may be adequate. As previously mentioned, it is usually of such value* to have available, two types of collecting devices: one which takes.a con tinuous' sample oyer a-long period of time, the other which gives the concentration at any given instant.. TJie 'former gives valu able information' oh the average, exposure of the worker, and the latter on the par ticular operation causing the major portions of . that. exposure. The results of both methods, used; together, permit in many cases much'more complete and valuable interpretation of existing, conditions. Know the limitations of ; the methods used and-interpret the findings accordingly. We must remember that a screw driver is a very convenient tool and it has its use, but it should not be employed for; making a mortise,and tenon .joint. These determina tions have their definite value, but do not try to read more'into them than they are worth. Determinations can be .used more extensively, to great - advantage. Through determinations, we can learn whether the exposure to dust, fumes, gases and vapors is safe or dangerous even though we can, not see them. Let us not work in the dark, ) but. raither, cast all light possible on these otherwise.invisible hazards. ,. . . References (!) Bloomfield, J. J., Johnson, W; S., and Sayers,. R. R.: The. potential problems of industrial hygiene in a typical indus trial area in the United. States.' U. S. . Public Health Bull. No. 21$ (1934).' (2) Summary reports of the National Sili cosis Conference. U. S. Div. of Labor ' Standards Bull. Nb. 13 (1937). (3) Cook, ,W. A.;. Industrial - solvent""ex posures and their control.' Proceedings Occupational Disease Symposium, Northwestern . University Medical School (1937).. (4) Cook, W. A.: The industrial hygiene ,laboratory. J, Ind. Hygiene arid Tox., . 18 623-636 (Nov. 1936). , (5) Report of Committee on . Methods of ' Air Analysis. 1935 Report available as reprint, 1936 Report available in 193637 A.P.H.A. Year Book. American Public; Health Assn., N.Y.C. (6) Routine sampling for control of atmos pheric impurities. Committee of Pre ventive Engineering. Bulletin in pub- lication.by Air Hygiene Foundation of America, Inc., Pittsburgh, Pa. (7) Make, your own carbon'monoxide test. Safety Engineering (Sept. 1938). (8) Bowditch, M.:. Toxic Limits of Injuri ous Materials. Div. of Occ. Hygiene, 23 Joy St., Boston, Mass. " Discussion Chairman Paine: .This is* a mighty im conclusion has been reached in two' sep portant subject, and I. know there are many arate investigations. '. who .would like to discuss phases of it. Let us make our questions clear and concise. - The collection of iron oxide was made by the electrostatic precipitation method. A. G. Speer (Western Electric thorne) : Are you familiar with connected with arc welding,, like Co., Haw the fumes iron oxide ' Mr, Speer: We had occasion to make such a determination but we-used the im and ozone, and means of detecting them? pinge* method, and we did not find toxic qualities or .properties.. We could not find Mr. Cook:.. A study has been made of any available data on that, particular subject. iron oxide concentrations in connection with .arc welding, with the thought that a large Mr; Cook: A paper was published by amount of. iron oxide being breathed by the Drinker, together with*a number of other, arc welder might injure his health. X-ray ' investigators, in the Journal of Industrial determinations, have been made, and al Hygiene," and the conclusion was that in though the .lungs looked very milch as if- jury, to health was caused by nitrogen ox they .were severely fibrosed, it has. been ides,' with .a possibility-of-ozone entering pretty conclusively shown that iron .oxide into the* picture. does not cause injury, to the lungs.. This R. C. Meldrim (Glens Falls indemnity 52 - Silver JubiUe Safety Congress Co., Glens Falls, N. Y.): Mr. Cook, do you may have, been around 2 of a milligram - believe that an arsine determination should whereas 1.5 milligrams per ten cubic meters .. be made in a metal pickling operation? is definitely safe.. Suppose instead of- 2 of Mr. Cook: Generally, no. I have seen no a milligram'per ten cubic meters, there .are .actual arsine poisoning from metal pickling, two or three times as much present in the even though the literature includes such form of a fume as found by the-electro cases. As far as cases in this country are static precipitator. Even if .6 or .8- milli concerned, it has seemed to me to.be largely gram were present we. would be within safe a literature' condition. In talking with Dr. limits. This is further shown by the fact Cunningham, of .the Ontario Department of that physical examinations of workers `in Health, Division of Industrial Hygiene re? rooms where lead melting pots are present cently, be mentioned a considerable number have demonstrated that there is no great ' of arsine poisoning cases and I suggest you lead absorption. write him for further details. I have not So my conclusion is that the collection of seen any thorough, investigation of the sub samples by means of the electrostatic pre-' ject, and that has been one of the things. cipitator is not going to confuse the issue. that lead me to believe that the condition at all. It is going to give us more accurate isn't sufficiently, severe to cause us great data on some of these exposures where lead ' apprehension. The experience in this coun is present, in the form of fume.: try has hardly indicated the necessity of making such determinations. I have not made any myself. However I should like to see somebody make a series of them at a half-dozen locations where metal pickling is done. F. L. Warner (U.S.S. Lead Refinery, Inc., East Chicago): Do you feel that fur G. W. Daubenspech (Illinois Department of Labor,- Chicago): How would you de termine arsine in air around pickling tanks ? . Mr.. Cook: It would- be necessary to.re sort to a chemical method, and I think that I had better not use the time for .a discus sion of chemical methods. ther investigation with the .precipitator will J, W. Fehnel (Metropolitan Life Insur change the present permissible limit of lead ance Co., New York.City): You mentioned exposure that has been determined by the. the use of the electrostatic .precipitator in impinger method? - lead sampling. I have been doing that work Mr. Cook : The answer to that question is "No," but I. feel that this further thought can be added: We have had many opera myself along with the impinger samples, at various times, to correlate results on lead, both dust and.ftimes, since 1926. tions where lead dust was the prime ex Here is an interesting thing. I know, that posure. Where the lead is in dust form, the Bloomfield a few years ago made some tests V impinger will get- essentially the total iti a large baking plant and found lead. He ] amount of the lead; consequently where we came up to consult with Dr. Wright about .have made physical examinations of. large, it, and It was concluded that the source of numbers of workers in such.-.exposures, the lead was the paint they used. That correlation of the results of physical ex sampling was done with the impipger. aminations of workers and of incidence of About two years .ago I made an extensive, cases of actual lead poisoning with concen-, survey in one of the General Motors plants . trations of lead in air have fixed fairly where there were extensive soldering opera definitely, within workable limits,. just about tions. I took impinger samples, and. I got how much lead can be considered to be safe. a. series of factors that .I presented in the The threshold .limit based on such ex report, and a short time later I was called posure to lead dust would be - the same on. the. carpet and told tl^at my figures did whether the samples were collected with hot agree with their plant chemist's: So I impinger- or electrostatic precipitator. ~- consulted with the. chemist." When he On the other hand in rooms-where lead' sampled with the electrostatic precipitator casting is done, where there are leqd melt and I with the impinger, and we took them ing pots, the impinger probably gives low on identical reading levels,, we got the . same results. The chances are 'that the concen results^ He had consistently gotten iower tration of dead, in-'thbse rooms is greater results--and we proved this later by checked than found by the impinger. But those im sampled--because he had his electrostatic pinger results, those that we have made, precipitator.'tnounted on a .little truck that Dusts, Fumes, Gases'and Vapors S3 lie pushed through the aisles, and the men is a little too. cumbersome. I would say working on. a platform that was about' 12 to that where you have a definite hazard in 18 inches higher than his main aisle, which the lead industry, have your, impinger sys 'meant- that instead of . sampling at the tem a permanent system of the organization breathing zone of the workmen,- he was of your department and keep it there as a sampling at about his waist level. .permanent fixture. Robert. Winters (U. S. Metals Refining Co., Carteret, N. J.): We have overlooked one point, ;Mr. Chairman, and that is ,the metallurgical control, the heat control ;of the kettles. If you have -a problem on hand, or- if you are -pouring lead and you heat your .kettle up to 1,000 degrees Fahren heit,. if you can pour .that same lead at 750 Fahrenheit;-why pour'it at 1,000 Fahren heit, because the nibre heat you have, the more liberation'of oxide?. So we have re duced the hazard to a large extent now. Mr. Cook stated that the impinger system The question came up too, as to the merits of the electrostatic ' precipitator. against the impinger, and I cannot agree with that statement at all because the fumes are made up of minute particles of dust--a fraction of a micron in size--and we found that the impinger system gener. ally is just .as efficient as the electrostatic precipitator, with the exception that ,we do have at least six impinger. bottles in series, because you cannot get efficient sampling with one or two or three bottles. You must take enough bottles to get a reliable result. Men Who Go Down to Their Death in,Tanks--A Demonstration . By S. E. WHITING ' Vice President and Chief Engineer, Libert^ Mutual Insurance Company, Boston The title of . this feature, "Men Who Go do so with our necessarily -crude demon Down to Their Death in Tajiks," should be stration apparatus. taken extremely broadly because, as you know, there are not only stationary tanks (of which we give you a very crude simu lation, in our demonstrations) but there are truck`tanks and there are railroad car tanks, both of which are enclosed spaces. In our city streets we have thousands of manholes for utilities,' pow;er and telephone and sew-, age* that are also enclosed spaces, or "tanks" . There are two hazards in. enclosed spaces that we shall hot dwell'upon at length. In any .enclosed space that has not much venti lation, that collects moisture and is dark, you will have a severe slipping hazard and an accentuated electrocution hazard--but we shall here consider only, the typical aspHyx-. iation and explosion hazards. as we call them.here. You have trenches, Most of those enclosed spaces are nor- excavations, shafts, tunnels, mines. In your mally- just as good, to work in as outside factories, you have tanks again, small base spaces and that, is part of the danger. Men, ment room.s, vaults, cisterns and sumps. have worked in tanks year after year with Even open pits may prove hazardous. On no trouble,' only ' to have something ex- ' board ships you have a very complete set of traordinary come up. to contaminate' the enclosed spaces, compartments and holds. tank, something, that they have not antici Even when you go out into the open-coun pated, to, make that enclosure a hell hole, as try, as we here look at it, you may find we' shall demonstrate in merely reproducing. dangerous enclosures--grain bins, wells and not an' exaggerated situation but only what the bottom of silos. So there are just as has actually taken place. many varieties of enclosed spaces as there How do these spaces get into that condi are pickles, and perhaps more. tion? Merely because there.is no free dr-, Will you please remember that from this dilation of normal atmosphere.. That is of demonstration you are to visualize the po fundamental importance because all animal tential conditions in your own plant where life, especially higher animal life,; must have there may be enclosed spaces--and you will a constant supply of. normal atmosphere to need a very great power of imagination to sustain life. The normal atmosphere is re- 54 . Silver Jubilee Safety Congress markably constant in general and it is con . carbon dioxide. All the .beer we drink has . taminated only locally. It `is in largest part ^carbon dioxide. Even all -the strong, liquor .; aii inert gas, nitrogen, 78 per cent, with we .drink! had some carbon dibxide'in'it fractional percentages of rare gases that during the' fermenting process by 'which it- are equally inert. There i&'a small amount is made. Now. that prohibition, is'over ,you (a few., hundredths of one per cent) of can see how many tanks there are loaded carbon dioxide from which- plants grow. more or -less frequently with carbon, diox The remainder, almost 21 per'cent, is oxy ide. . gen, and we depend very definitely oh oxy gen to sustain life. Of course, we.can hold our breath momentarily, but we cannot con tinue without that normal supply. We are particularly sensitive to it, we higher mam mals. It is this, apparent harmlessness of carbon dioxide that gets us into trouble with' tanks. But a.little of something.may be all right -, whereas too much of it may be all wrong. It is not true that carbon dioxide remains. . non-toxic in high percentages. The best . In these tank situations, where there is authorities are inclined to believe--they lack of oxygen, men get panicky. They haven't quite checked it up but are'still breathe more quickly, they are demanding working on it--that around 20 to 30 per more oxygen, but the. supply is less, and cent of carbon dioxide will produce an im they precipitate' trouble. It is not true that mediate narcosis, will put you out of busi -you do not get into trouble until all the ness immediately and you will go down flat. oxygen is gone, , not by any means.- You begin to get definite weakness and symp Of course, such a reaction is:vitally im toms with perhaps 15 per cent instead of the portant when you get into, any enclosed normal 2!.. If you get down to 10 per scent, space, because then you cannot get up' and --and I am only quoting the rough, figures walk out, and .I do not care whether it is an - of authorities--you get into .a condition open pit or an enclosed tank. Men have where you cannot do anything, you cannot been killed in open pits, only 6: or 8 feet move, you become unconscious, you fall in deep, when they got down to that layer of collapse. If you go into an endosure alone carbon dioxide. It is 50-per cent heavier and get into that condition, you cannot res than air* and it is. likely to be. colder than cue yourself. That is a very characteristic the air---and so, it pockets. And this brings element of this hazard: men going alone us immediately to our first demonstration. into enclosed spaces, not knowing. Whether (The Demonstration Apparatus consisted or not there is oxygen. of a. wooden framework in ike shape of a In addition to. adequate oxygen we have vertical, cylindrical tank,-JO feet in.diameier to consider highly toxic substances, a frac and 9 feet in Height, the. bottom-, end'being tional percentage of which in normal at solid and the top end having a central man mosphere will cause distress that renders us hole opening with a .ladder through it Jo unable to leave the enclosure--like Carbon permit entrance into the tank 'from the monoxide, hydrogen sulfide, etc. Then, too, top. The. cylindrical, vertical sides of,, the there may be small quantities of merely tank were covered with a semi-transparent flammable gases which we can tolerate to clpth to permit the audience to ser the in breathe but if that small mixture with the terior of the tank, A controlled flood light air gets ignited it flames or explodes, cre ing of'the-interior, was provided. Access to ating a hazard so severe that the space be the top of the tank was by an exterior lad comes literally a "hell hole." der at the .rear of the tank. All characters I, mentioned carbon dioxide in normal air - in. the demonstration acted in-pantomine that in very small percentage's is necessary only.) ' to plant life. I'will say further that all of Now, as the curtain swings open, you will us here-in this room are exhaling, carbon see what we call a tank.' Again I must ask dioxide in small percentages, harmlessly. you-to use your power of imagination. Of We have breathed the oxygen in and dis course, we could not set up. a real tank be- ' tributed it to all of our tissues where it cause you do not have eyes that can see combindb with those tissues and is dis through boilerplate. Since-what .goes on charged through our breath as carbon di inside of the tank is just as important as oxide. Again, at every soda fountain if what goes on outside of the tank, we have there is any gas in the drink we take, it is made the frdnt of it partly transparent and Dusts, Fumes, Gases and Vapors 55 in addition for your further assistance I- ", This is the safety man who-is going to have in,my hand a control device that al- look over the job to see. that everything is ' lows me to flood the inside of the tank .; done right--I hope he calls, help when he with light upon occasion. Just keep in mind sees that man in the-tank--yes 1 he sees him/ that this light has nothing to do with, the --he's called help--why---he's going into the action in' the tank- .itself but is merely for tank himself! A safety man ought to know, yourassistance in .seeing the action. We do better than that! He cari't hold his breath not show, the details of piping and valve .long enough--he won't think about holding connections' through . the tank but merely his breath--yes--he's going to get caught-- the-top manhole opening ., with a ladder there he goes! He's overcome too! stuck down through it to enter the tank. Well, there ought to be help, arriving (Summary of Act I: A. tank used for a pretty soon now--ah! Here's the foreman fermenting process and containing a residual With an assistant--he's got a life line too--: layer of carbon dioxide is to be.cleaned out. . but what else has he .got--oh--he's got a . A helper arriving ahead of time drops his canister gas mask--he's getting excited--he pipe into,tank and enters-tank to get it and puts the mask on--that shouldn't be de-. is overcome The safety man looks over, . pended upon for anytank work unless you the job, glances in- 'tank; Signals for help know what the concentration is--there he and hastily enters tank and is quickly over come. The foreman and an assistant hastily arrive with gas mask and a life .belt and goes down--he's got the life belt with him --oh, the canister gas mask isn't any good, it's of no value against carbon dioxide gas- line. Hastily donning gas mask and carry ing life belt, the foreman enters tank, the assistant holding the life line. The foreman is overcome and 1the life belt is'Pulled out of the-tank with no man fastened to it. The assistant puts on the belt, gives the . life line to a fifth man who has arrived but the latter prevents him from entering the tank. Curtain, followed by chopping sound ) backstage.) This is a .cleaning job of a tank that had some , fermenting'process in it but the liquor has all .been drained off. This first man arriving; is a helper and he probably doesn't know what it is all about but anyhow he gets' on . the job ahead of time and I see - why; He thinks he'll have time to light up his pipe. Perhaps he. shouldn't be using matches around tank's but somebody must have toid. him that carbon dioxide is harm less--you can't start a fire with' that--well, he hasn't-gottenthe pipe going yet. These pipe smokers smoke more matches than they, do tobacco--oh, his- shoe is unlaced so . he puts down the pipe--wait a minute! he didn't apparently set it .down in the right place-^oh, he thinks it's fallen in the tank --now,- you shouldn't go into the-tank, you or any other gas ih high concentrations-- he's overcome!.-The other niari is going to . pull him out--ho ! he doesn't pull him out --the belt comes out without any man in' it!-- Here comes the. other, fellow--he has seen such accidents before--of course, the assistant wants to rescue them--he puts the belt on and he gives the rope to the other man--he tries to go--down but the other man won't let him--no use killing any more people--(Curtain closes.) You see there'.the very typical situation . of everybody losing their--fSonnd of chopping backstage.) That chopping of wood reminds me how they got those men out of the tank--no one else dared to go in, so when the Fire Department arrived they cut a hole through the side of the tank and dragged the men out, but it was. too late to save their , lives. Now, these tank accidents are typically multiple death accidents--not only is the first victim lost but the rescuers themselves in their haste are frequently lost also; it is not merely one life,, it . is . two lives, three lives, four lives, .and even five lives.. know.. that is against' the. rules--nobody The spontaneous action of almost every should go in until the boss arrives, that isn't one to rescue, anyone they find in trouble is safe, suppose there's some, gas down there a very, noble attribute but it merely builds r-but he's bound to get his pipe before the up a catastrophe where this latent hazard boss arrives and finds it in the; tank--look of .tank asphyxiation has. not. been antici out I .don't get your head ; down--maybe pated by training men beforehand how to there's some, gas--yes! there is! It's handle such emergencies intelligently. There knocked him out! is too..much sheer indifference to. this haz a 56 Silver Jubilee Safety Congress ard--until it strikes like a bolt from a clear as it absorbs heat. and its vapor' is ' run sky; * through.a tube down to the-bottom of the Now, please do not conclude that this jar, rising in a layer. One candle has died, pantomime of an accident- has been exag two, three, all of them. gerated in its details. 1$ has not, they Thij asphyxiation of candle lights by dry actually occurred. We. cannot predict, what ice is just the-same as the killing of men in men will do in a panic. Even the . sudden a fermenting vat you have just witnessed. collapse , is fact, not -fiction. I was puzzled This ice is only solidified carbon dioxide by this until recently. Because we all.know and you must handle.it with care in . .any. that men. can hold their breath under water enclosed spaces even including open pits. and have no oxygen supply for a minute or Not long ago a steamship hold was being, more with no collapse* An expert in this unloaded of perishable fruit refrigerated technical question, however, recently gave by dry ice. No odor, no color, no warning the explanation of why the breathing of an --and three stevedores, went down and died atmosphere deficient in normal oxygen con as quickly as those candles. tent is quite different from holding your The other two experiments illustrate breath and not breathing at all. principles involved" in our next tank act.' In normal respiration, the flow' of oxygen This , transparent bagof .normal air has only is into the lungs, thence ' into the blood ten drops of flammable liquid evaporated, stream and- thence into the vital tissues that into it, the vapor, and air are- mixed .by .control all of the muscular and nervous and gentle pressure' on the sides of the bag and, mental processes, the. lungs retaining a re ignited with a spark plug. Only ten drops, sidual supply of oxygen even at the end of only-about 2 percent of vapor, but what, a the expiration portion of the.- respiration snappy explosion. cycle! The pulmonary blood . stream con Now imagine an enclosed or:tank space of tinues to feed, on this, residual oxygen and the same shape as this bag but- ten times as . the following inspiration portion of the long with the'same proportion of flammable cycle soon furnishes a new and ample sup vapor--vapor from a leaky pipe connec ply' of oxygen. With a deficiency of oxy tion, from entrained solvent in sludge in gen in the air itself, inhalation adds nothing to the lung supply while exhalation actually discharges the residual lung oxygen and the blood quickly drains its own supply back into the lungs, whence it is exhaled. Thus the bottom, from a. half dried film being scraped from the sides, or from a quick-* drying paint, being applied. Imagine your self in this tank with the ever-present chance of a' spark. You would be in the all vital functions become rapidly paralyzed. vortex.,of .a flanie and a blow one thousand (Summary of Interlude Demonstratiotis: times as great. The answer is ample venti Entirely separate from the tank apparatus, lation to keep below the. 2 per cent of vapor small scale demonstrations arc made: (a) content. Extinguishment of four candles in a tall The last. experiment is simple but'perti-. glass jar by carbon dioxide generated by nent.We ' brush this quick-dicing paint the warming of dry ice; (b) The explosion along a narrow strip of metal and-ignite; it. of a transparent bag into which 10, drops of ` See the. quickly running flame, imagine it flammable; solvent are vaporised, mixed, and surrounding you in; any enclosed space,' ignited; (c) A strip of metal is painted with imagine it even in your home on the kitchen quick-drying paint and flamesjip upon ig floor. Such work should be done only under nition with a match.) full ventilation arid' freedom : from-, all Now we have just a few brief-demonstra sourced of ignition. tions illustrating three principles involved . .(Summary of Act II: A' tank that has in certain tank hazards. These candles bum been emptied and ventilated is about to be brightly since currents of air feed them painted* ..A chemist makes tests of the tank oxygen. Any flame or any fire ('needs a con air in succession with an oxygen deficiency stant supply of atmospheric oxygen to con indicator and a flammable, gas indicator, tinue living. If you reduce the percentage using a' sampling tube, at various levels in. oxygen below normal more and- more, the the tank.. Two painters have arrived and flame gets sickly arid then dies -just as hu the chemist now 0:K.s the tank for their mans do. You see dry ice being vaporized entrance, Painters enter lank and proceed. Dusts, Fumes, Gases and Vapors 57 with, their, work but are gradually overcome too strong and he falls over unconscious! by the fumes from the paint. The. chemist finally notes ,the trouble, signals . for help and hastily] enters the tank and is over come. The foreman and his assistant hastily arrive, the latter carrying a lantern. With life belt 6tt him,"the assistant enters, tank, still carrying lantern, the foreman holding the life line. There are several flashes as the lantern gets lower.in'the-tank and finally the assistant falls overcome as'flames burst out of the manhole. Curtain.) The chemist evidently hears some noise-- he goes to the tank--now he's in great ex citement ! He calls for help from the plant --he shouldn't go into that tank when he sees the others overcome! He should wait until help arrives! No,, in his excitement he thinks he can get in there and help them out! There he goes inside--I hope lie keeps his head up high--the vapors are probably near the floor--he tries to lift a man--he's overcome too--down he goes!! They're all Now, as' the curtains part,-you see an- overcome! I hope.the rescuers hurry up! . other tank and I do. not care what process Here they comer-they've got a life line-- or what contents this particular, tank had but what are they doing with a lantern? been connected with...We know that it has The foreman is . sending the other ; man been emptied but precautions are here being down to get them out arid, he needs a light taken by .'a chemist to test out the air. of to see but he shouldn't use a lantern in the tank before any man enters it for any there--Hold that lantern high 1 Oh, he falls kind of work whatever. He is making two. unconscious-r-the foreman tries to pull him . kinds of test; one for oxygen deficiency by out! The lantern has fallen over!. The gas ; means"of a flame lamp that is. properly pro is ignited--see those flashes! (Explosion tected from being an ignition source by use followed by curtain.) of. metallic gauze surrounding it like^the well-known Davy's Safe^Lamp. He will make, a second , test, howevbr," since a tank that has adequate oxygen in it for sustain ing life may, at the same time, have flam mable gases in it sufficient to cause an ex plosion like1 that we have just.demonstrated with laboratory apparatus. ,, That was .the type of hazard where a tank was found by test to be safe to enter but the kind of operations to be performed in-the.tank: were given no consideration at all. The men have, fouled their own. tank and made their own .atmosphere unsafe. They used a quick-drying paint that had low flash point solvent in it and there was These-other men. we see coming onto the' ho controlled ventilation to minimize those . scene are."'obviously .painters who are going- . contaminating and explosive fumes..- to- protect the inside of "the tank against ' Evidently it is necessary to consider not rusting by suitable waterproof paint. Ap only what has, formerly; been stored in' the parently both tests are O. K. and the chem tank but-also the exact repair operations to ist authorizes the two.painters to go into b done, that may. cont|rfiinate. it. Even-a the tank.and this precaution is. a valuable . tank.; that had never ^contained anything initial step, against unexpected contamina worse than;.water will become hazardous tion of any'`enclosed space. . . . if certain operations are done upon it--such The. men now" are at their job at the bot tom of the .tank .and the chemist has 'fin ished his job but is just standing around because he hasn't anything else to do. Well, look at that man on the right--he has been as. a repainting job with highly volatile paint solvents, a prolonged job`of arc or ; acetylene welding or cutting,'leaks of gas ,from: the surrounding' earth for buried tanks; manholes, etc.; painting, with his nose pretty close to the With so many types, of enclosed spaces paint and it seems to be affecting him 1- That which men have to enter,' we cannot must be a highly volatile' paint--There! prophesy, "what kinds of contamination 'He's getting worse--he's fallen over uncon might occur. There was a small steel com scious !.- I hope the other man sees him-- partment in a steamship that had .been the. chemist doesn't seem to pay any atten kept closed for many years. Nothing what- tion--the other man does see hitn! He gets . ever had been in that enclosure, it had been excited-and begins to breathe faster--he merely sealed. Yet a.man was sent into it goer over, trying to save the other man, and died immediately of oxygen want and ,he finds he's getting too dizzy himself,, he's the answer was that the mere rusting, of [reaching1-for the ladder--but the fumes are the steel plate had robbed the1 atmosphere 58 Silver Jubilee Safety Congress of its normal and vital. 21 per cent of oxy supply of oxygen stronger- than'air to . in gen. ... . "' (Summary of Act . III, Scene I: A man has entered a. tank with a life line on him and two men guarding him. from the top. For some reason Ke has been overcome and the men .promptly bring him out of. the tank, lay him face down and immediately hale; 93 per cent oxygen and 7 per cent of carbon- dioxide, our old acquaintance. When ever the patient has been/asphyxiated by > some poisbn that attacks the blood like carbon monoxide or hydrogen sulphide; you heed both prone pressure and the'inhalant mixture working together. . apply prone-pressure artificial respiration, one man continuing this method steadily while the other, calls for help. Shortly an inhalator is brought to the tank and is ap plied to the patient without interfering with the manual artificial .respiration. Both op erations continue steadily. Curtain.) Now this time we are doing the job right.'* A man has entered a tank, and it was too (Summary of Act III, Scene II: A tank' that is empty has. to be.entered for repair work. A chemist, makes both tests for con dition of. air. in tank. A mechanic sets, up a low-pressure portable blower and-inserts discharge end through manhole into lower Part of tank. Two men place air-hose masks on themselves and a third, man op erates a hand-driven portable blower that' gassy for some reason we need not concern feeds air to the hose masks. The chemist ourselves with, but the important point is . continues making tests, fht Ijvo workmen he did not enter the taftk except with a in turn enter tank taking^ with them non- life belt around him and a life line attached sparking tools and a' vapor-proof standard to the belt and held by two helpers at the extetision' lamp. Alt operations continue manhole. They have just brought him out steadily. Curtain.)- -.'* of the enclosure and will be able to save his life. Again , we see the chemist making his two When a rescued man is not breathing, it is evident that artificial respiration must be given, to him without the slightest delay. Therefore, he is placed immediately on the top of the tank, face down, with his head resting on one arm so as not to block his tests for explosive atmosphere in the. tank and for oxygen want Indeed, nowadays we no longer need a chemist for such tests j any intelligent man can make them, so-much -improved are the test instruments made bythe manufacturers: breathing. Quickly the mouth is opened to This tank job is a big one and needs1 sec that there are no obstructions in it, the every precaution. .-You will note the chem operator straddles the patient with his. ist continues his-tests throughout-the whole knees just below the waist and presses.for procedure. There is a second man now set ward on the small of the back to push the . ting up a portable blower to keep the tank air out, of the lungs. Then the operator itself -constantly ventilated. The two men swings back and takes his hands' entirely* who are to enter the tank first doh hose off the body--note that particularly. The masks that have air pumped to them by a inspiration stroke is done by the body itself hand-operated blower.- The mask air pro in its natural expansion after it Has been tects against asphyxiation, the blower air pressed upon during the down stroke.' protects against explosion. There are other Everyone in any plant (and in - fact in precautions and checks.; your homes and on vacation) should know Now they go down into the tank and are how to apply this simple,, direct/-efficient; tended .from above with life lines fastened prone-pressure method of resuscitation: to them. Life lines that men so.often sneer Note that the. operator is not working too at. Life Hines nevertheless that so .connect rapidly but .slowly; like a person naturally men in..the outside free air with;meo.in.the. breathes. Note he does not put the. pressure enclosed foul air. that, by this: precaution- ' on* with any jerk but steadily and smoothly. - alone, a substantial catastropKe can be. re Now the inhalator is set. up not to pro.-- duced to a negligible momentary -dizziness.. duce artificial respiration but only to supply The job is organized and safe so that men a special atmosphere f<0 breathing that will". who go down to theircwork in tanks can help in the resuscitation work It provides.a come up and go down tomorrow. - . ADJOURNMENT