Document 3JMKKzQOqwORmvBmE5LJan9KJ

FILE NAME: National Safety Council (NSC) DATE: 1929 DOC#: NSC125 DOCUMENT DESCRIPTION: NSC Health Practices Pamphlet - Dust I Health Practices Pamphlet No. 4 Published by National Safety Council 108 East Ohio Street, Chicago This pamphlet is a compilation of experience. It must not be confused with Federal, State or insurance requirements. f General Statement exposed to mineral, metallic, sugar, to lower the social status and self- flour, aniline or other dusts. respect of work people." There is a definite relationship be tween dust and occupational disease.. In industrial processes, dust may be responsible for the occurrence o! va rious types of intoxications (lead pois oning) and infection (anthrax). Numerous studies have been made of the effects of smoke and soot upon the health of workers by anti-smoke commissions. The results show an apparent relationship between the smoke nuisance and diseases of the Effects of D ust Inhalation Zenker has applied the name of pnewmonoconiosis to the various forms of diseases of the lungs caused by the . The chemical composition of dust respiratory organs, especially pneu inhalation of dust. It represents two may be of more importance than the monia. words from the Greek which mean weight and num "1 u n g " a n d ber of individual "dust." The kind particles compos- of dust inhaled i n g it. T h i s determines t h e s e e m s particu type of pulmo- larly t r u e o f n a r y lesions. dust containing However, there poisonous s u b i s o n e patho s t a n c e s and logical process infectious which underlies organisms (lead, all f o r m s o f anthrax, etc.). lung disease ,and Apart from its this consists of a r e l a t i o n to fibrosis or a re respiratory dis placement of the eases, an impor- elastic tissue of tant r o l e is the lungs by that played by dust of an unyielding in the irritation scar tissue. of the eye, ear, Probably the nose and throat; most important this is manifest kind of. disease ed by the undue of the l u n g s prevalence caused by the of chronic in Courtesy Metropolitan Life Ins, Co'. inhalation flammatory con ditions of these Figure 1. Smith-Qreenbury implnger taking sample of air near lead casting operation. of dust is that which has been organs in various industries. It is also Certain injurious effects of dusts named "silicosis.'1 This disease is seen in the frequent occurrence of cannot be questioned. This is further caused by breathing air which contains the ulcerations of the nasal septum in em plfsized by the study of tubercu a relatively large amount of free silica. certain workers. losis in relation to the dusty trades. The chief forms in which free silica Flour and sugar dusts, usually con sidered harmless, may be converted into lactic acid in the mouth and thereby increase the virulence of germs; this is illustrated by the undue prevalence of dental decay and pneu monia in some flour and sugar work ers. Skin irritation is sometimes pro duced by a combination of dust, sweat and heat, particularly among persons It is fortunate, however, that only about 25 per' cent of dust inhaled actually reaches the lungs. According to Lehmann and other investigators, the bulk of dust that may be inhaled is either sneezed or coughed up, or swal lowed. Haldane says that, in addition to the mechanical irritative and poisonous influence of dust, "it inevitably tends is encountered in industrial processes are crystalline silicon, dioxide, granite, quartz and sandstone. There are two tentative standards existing in regard to the dangerous quantity of free silica in atmospheric dust: 1. The South African experience estab lished the upper limit of safety be tween eight and nine million particles per cubic foot of air. Copyright, 1929, National Safety Council. PLAINTIFF'S EXHIBIT 2 HEALTH PRACTICES PAMPHLET NO. 4 Smokes--from 0,1 to 0.001 m-mm. in diameter. ' Although size of 'particles is import ant, the quality of the dust is equally of moment, for there are both non-, irritant and irritant dusts. A physio logic classification of dusts by Dr. C. K. Drinker is apropos here: I. Poisonous (from a chemical stand point (a) Lead,' mercury, arsenic and others. This kind of dust is taken up by the liver after ab sorption through the lungs or gastro-intestinal tract. Courtesy Metropolitan Life Ins. Co. II. Mon-poisonous () Organic--mainly the vege table fibres, such as cotton, jute, hemp, etc. (according to Landis these do not produce lung fibrosis). (b) Inorganic (mineral dusts) 1. Non-silica-containing sub stances, such as coal and lime. (No fibrosis). 2. Combined silica (silicates) .. .... : --no fibrosis. ..Orothosilicates---cly.- - Metasilicates--talc... -. Trisilicates---feldspar. 3. Harmful silica (crystal line silicon dioxide) gran ite, quartz, sandstone. Figure g. Smith-Greenburg impinger with hand-driven punvp for collection of samples where electricity or com pressed air is not available. 2. The United States Public Health Service in its research at Barre, Vt. found that the upper limit was some where between ten arid twenty mil lions of particles per cubic foot. These upper limits of safety are ob viously depen-dent upon the percentages of free silica found in the atmosphere under consideration. Classifications of Dusts The size- of dust particles has much to do with whether or not they will cause trouble in the lungs. The larger particles may be neglected when con sidering this point. The words "large" and "small" are used here in a relative sense, for all of these particles are ex ceedingly small. For instance, the particles that are significant in consid ering the production of a fibrous re action in the lungs range in size from 2 to -0.5 micro-millimeters in diameter (a micro-millimeter is the equivalent of l/25000th of an inch)'. Gibbs has classified dust particles according to size as follows: Dusts--greater than lOm-mm. in diameter. Clouds--from 10 to 0.1 m-mm. in di ameter. The Mechanism of Absorption of Dust Particles The lungs of persons living in large . towns are always, more deeply pig mented than those of persons who live in the country. .O n examination the cause of-the pigmentation is found to .-.be particles of carbon or other kinds ; of dust. The finer particles in the at mosphere a re. responsible, for these changes, th coarser 'particles. usually having been entrapped in the nose or the upper portion of the respiratory tract arid ' usually 'Jater expelled by coughing. It is. likely.-that particles over 2 micro-millimeters in size do not reach the lungs. Normally the structure of the wind pipe and the bronchial tubes is a de fensive barrier. Dust is caught in the mucous secreted by these tubes and is wafted outward by the waving action of the small hairs of the epithelial lin ing of these tubes. It is said that recurrent colds lead to a shedding of the surface lining and an important defense is thus lost to. the lungs. This circumstance is not without effect since chronic catarrh of the upper respira tory passages has been found to'be a frequent precursor of pneumonoconiosis. In the ultimate structure or alveoli of the lungs, the possible fate of par ticles inhaled may be: . 1. .Going out the same route as that by which entrance was gained. J > 2. Removal by the blood stream. 3. Removal by the lymph stream. The stages by which a particle may lie removed from an alveolus are as follow s: 1. By phagocytosis. This process is accomplished by certain kinds of cells which are given off by the blood vessel walls, when, an irritant comes into that neighborhood. These free ceils move into the alveolus or tiny lung space, and surround or engulf the foreign particles. The phago cytic cell then moves through the walls of the alveolus and probably back into the lymphatic circulation. 2. The phagocytic cell may then be carried into the lymphatic circula tion and to the glands at the roots of the lungs. This may happen-within 24 hours at first, but later, collections of lymphoid material may offer ob struction to such migrations. These nodular collections may show' as dense spots in an X -ray film. Later, on they may become fibrous and show as dense strands in a film. 3. The phagocytic cell may migrate back into the blood stream going through the blood vessel wall. Haldane and Mavrogordato have proposed a theory, which simply stated, is as follow s: the question of whether or not a given dust will cause a disease process in the lungs (aside from the particle size and the poisonous chemical character of. the dust) is probably de pendent upon the difficulty of ', absorp tion rather than upon the massive deposition of material. In illustrating this theory, experimental animals were caused to breathe carbon dust. The lungs showed a definite clearing after a A Figure 8. Lung oell (alveolus). Sche matic drawing . showing engulfing cells migrating to- blood and lymph vessels. A, blood vessels; B, lymph vessels.. O. C. 0., cells with engulfed particles. D. I>. Z)., dust particles free in air space. DUST 3 few inonths this- was'-not- tr-ue- when silica was breathed; probably it acted as an irritant. This caused a circulatory disturbance by which the particles be came coated with serum. Because of the lack of absorptive power of silica particles, the consequent circulatory disturbance and production of serum, the particles of silica were not taken up by the white blood cells and removed from the lungs as had been the case with carbon particles. This behavior of different lands of particles was re sponsible for the working out of the theory as stated. Probably the best analysis of present day .opinion with regard to the effects of dusts upon the human body has been made by Dr. E. L. Gollis in the report of the Fourth International Medical Congress on Industrial Accidents and Diseases: 1. Dust particles which have reached the alveoli are there engulfed by . cells originating from the epithe lium lining the alveoli and are car ried within them into .the lymph channels of the lungs. 2. Particles of some kinds of dusts are more readily engulfed than those of others. Organic particles, such as coal, are most readily taken up, and particles of silica least read ily; . but when, certain cells have been, as it were, educated in the function of absorbing dust particles . through the presence of, say, coal dust, they more readily take up par ticles of such substances as emery, carborundum, and silica. 3. Particles of certain dusts, such as carborundum, when engulfed and carried into, the lung tissue, remain inert, and produce no reaction. 4. ' But silica particles slowly dissolve within and react chemically upon the cells containing them, causing cell death and mummification. 5. The dead, mummified cells collect in and block up the lymph passages and glands; here they disintegrate and distribute the' dissolved silica, which reacts with the surrounding tissues. 6. The final result of the reaction is the formation of scar tissue as a solid mass of material which in time replaces the normal alveolar structure of the lungs; the condi tion ' is one of silicosis. 7. Ali_ the various stages through . which silicosis advances can be de tected by X-ray photography. 8. The same results follow whether fine silica dust be artificially placed in the body or soluble silica be in jected, but in the latter case the . disintegrating. changes take place . more rapidly. 9. Dead tissue so caused forms a me dium in which tuberculosis germs readily flourish. Figure-4. Left-. Bmith-Greenburg impinger.. Right! Drinker electric precipitator at Industrial Laboratory, Metropolitan Life Insurance Co. 10. When soluble silica is introduced into the blood stream it reacts with liver cells, causing scar tissue there, and also in kidney cells. 11. Statistical records indicate that Bright's disease as a cause' of death is unusually prevalent among certain occupational groups exposed to sil ica dust. 12. Clinical observations have shown that (a) in many persons who have been exposed to silica dust for a period sufficiently long to enable the dust to gain access to the lungs, the silicotic process continues to ad vance after complete withdrawal from exposure; (b) the silicotic process may-progress to fatal termi nation without the effect of any intercurrent disease; but (c) a sili cotic patient is particularly liable to fall a victim to tuberculous infec tion; (d) tuberculous infection in a lung containing silica particles hur ries the process of silicosis; (e) pulmonary, tuberculosis in silicotic subjects, (depending upon the amount of scar tissue present,) runs an unusually rapid and fatal course; but (f) when silicotic per sons are protected from exposure to tuberculosis infection, the occur rence. of tuberculosis among them is minimized; hence tuberculosis in such persons appears to result from fresh infection-, during adult life; (g) tuberculosis infection from sili cotic persons seems to be less potent than usual for infecting nonsilicotic persons. How Much of the Inhaled Dust Is Retained? Drinker, Thomson and Finn have noted in an article. published in the Journal of Industrial Hygiene for Jan uary, 1928, the following .effects; Suspensions of freshly generated zinc oxide fume (particles of about 0.4 mi cron) of Kadox (a zinc oxide powder with particles about 0.16 micron) and of marble dust (particles about 0.3 to 6 microns) were set up in a 1,600 cubic foot gas cabinet. The subjects, seated outside the cab inet, inhaled the air from within and exhaled, through an electric precipitator into a 125-liter spirometer. The percentage retentions for all three suspensions averaged 55 with a standard deviation of 8.4. The concentrations in haled varied from about 50 to 450 mg. , per cubic meter, the exposures from five to forty minutes, and the rates of breathing from 6 to 18 respirations per minute. Preventive Measures , Kober discusses this important phase of the dust problem under six headings : 1. Prevention of D u st Formation. A number-of important processes in industry can be properly con trolled by the application of oil, sprays of water or jets of steam. This method of protection is espe cially applicable to the metal, lead and pottery industries, rock drill ing, mining, blasting, stone-crush ing, cutting and grinding. Several investigators have em phasized this method of control, be lieving that proper usage and adapta tions -would result in the abolition of some of the. more severe diseases arising from exposure to dust. Another important application of wetting processes -is prevention of disastrous explosions of coal dust in mines. 2. Prevention of Dust and Fume Dif fusion. Protection is accomplished under this head by the enclosure of ma- HEALTH PRACTICESPAMPHLET NO. 4 cKiriery' or ' operations..in ait-tight cases. This method, however, some times gives rise to great difficulty because many processes cannot be wholly enclosed and still be effective. 3. Removal of Dust and Fumes. Much has been accomplished by devising systems of mechanical ex haust ventilation, which remove dust and fumes at the point of origin. Various codes have been invented which lay down specific rules and definite provisions for removal of dust and fumes by the proper con struction of benches, tables, arid other furniture with reference to hoods and other section apparatus. A very important point in the ar rangement of this type of protection is that provision should be made to carry the dust and fumes away from the face of the worker. It is not within the province of this work to give details as to the working out of various exhaust sys tems. (See Safe Practices Pamphlet No. 33, "Exhaust Systems.") i. Collection of Dust and Fumes. Where poisonous fumes and gases exist, methods of collection consist of condensation, absorption by water or chemicals, destructive distillation by heat in a closed vessel, combus tion of gases that can be burned, and finally, by the discharge of gases into the air above the working level. Valuable by-products are also re covered by condensation and ab sorption. An example is the value of blast furnace and coke-oven gases, which are used for fuel, for heat and power, and also sulphuric acid fumes which are collected and made into sulphuric acid. Certain dusts which have no espe cial value can be passed through a tower and precipitated by means of fine water spray. Where the dust is of value, it may be collected in suitable tanks under water for ulti mate recovery of constituents. Large particles of dust are usually collected by a so-called cyclone sepa rator in which the dust is collected by centrifugal force. Mechanical filtrations have been accomplished by the use of mechanical knocking devices, through textile fabric or wires of different meshes. Electrical precipitation as devel oped by Cottrell has been found efficient in precipitating and collect ing certain kinds of dust. 5. Masks and Respirators. It should be borne in mind that masks and respirators are usually uncomfortable to those who wear them. There is an endless number of these devices upon the market. The best respirators so far designed are intended to filter out dusts and fumes by means of sponge, cotton, wool, gauze or other material. Most of these are efficient for a certain period, after which they become clogged and need to be replaced, Masks are more reliable and afford a greater amount of protection under ordinary conditions. (See Safe Prac- .... tices...Pamphlet...No; 64)r... Kober states that working conditions should be so nearly perfect as to obviate the use of respirators. Until this is accomplished, he says their employ ment should be encouraged. 6. The Cleaning of Workshops. It is impossible to set up exact standards which will apply to all Figure B. Microphotograph of talc dust; on scale 1 division equals 1 m -m m . cases and all industries. It is also well to emphasize the fact that no amount of ventilation can do away with the necessity for frequent and systematic cleaning of plants. Shops should be swept daily after work has ceased, using damp sawdust or other material and having windows open widely. Some industries use a vacuum system for cleaning and dusting and this should always be encouraged. Under certain conditions, cement floors made with a considerable in cline for drainage have been useful in facilitating washing. Feather dusters ordinarily do not remove dust, but'merely redistribute it. Moist cloths have been found ef ficacious for removing dust from surfaces of furniture. "Dust oil" has not been found efficient, as us ually it only allays the dust and does h o t remove it. D ust Respirators Through the Bureau of Mines, S. H. Katz, G. W . Smith and E. G. Meiter conducted a study on the construction, and filtering efficiency of dust respira tors. The conclusions reached'were as fo llo w s: 1. The efficiencies of industrial dust respirators in restraining tobacco smoke range from 6 to 33 percent when the air is passed at a rate of 32 liters per minute. A gas-mask canister with two filters of ab sorbent cotton showed 63 percent efficiency. The_ Fogler flat felt filter was most efficient, showing .97 per cent. a. T h e e ffic ie n c ies a g a in s t silica dust floated in air, range from about 9 to 70 percent for dust respirators, or about twice the efficiency against ...... the...tobacco smoke; most--of- the silica particles were X micron in dia meter or four times the diameter of the tobacco-smoke particles. 3. As dust particles m ost injurious to miners, stone workers, and many others engaged in dusty trades are about 1 micron in diameter, res pirators, if worn, can prevent a con siderable amount of dust, but not all of it, from being inhaled. i. Although the laboratory study has shown that most dust respirators are not highly efficient in removing tobacco smoke (very difficult to arrest) from air, a . filter that re moves 50 percent of the tobacco smoke from air flowing at rate of 85 liters per minute is very efficient in restraining the ordinary dusts encountered in industry and also the smokes, (such as those from burn ing wood and other carbonaceous material) that city firemen en counter. Hence, the Bureau of Mines adopted a 50 percent effi ciency test against tobacco smoke as a standard requirement, (in ad dition to others) for the approval of respirators or gas masks designed to afford protection from smoke or dust. 5. Because the laboratory tests of the dust respirators were severe, the low efficiencies given do not indi cate the general effectiveness of these respirators under all industrial conditions. Much of the dust en countered in industry is less difficult to arrest; the overall efficiency of the respirators in actual service may thus be correspondingly higher. The tests therefore show that as a rule the respirators are of much value in removing injurious dust from inspired .air. 6. The discomfort caused by respira tors covering the face--the heat generated, the irritation of the skin in contact with the respirators, and the resistance to the flow of the air breathed--are the most serious dis advantages of respirators. The re sistances of industrial dust respira- ' tors to air flowing at 85 liters per minute were 0.35 to 1.5 inches of water. The Fogler flat felt filter had a resistance of 2.35 inches and the gas-mask canister 3,6 inches. 7. A man wearing a. gas mask can work hard only about half an hour; then the extra effort caused hy the resistance to breathing compels him to stop to rest or greatly reduce his exertion. The resistance of the dust respira tors, although causing some dis comfort, does not seriously inter fere with a man's exertions until the filter becomes clogged with de posited dust and the resistance cor respondingly increased. The filter must then be cleaned or freed of dust, or be replaced by a fresh one. 8. Filters of various fabrics, including cheesecloth, canton flannel, un bleached muslin, closely woven bleached muslin, filter paper, and 1 absorbent cotton, all made for test ..... purposes so as to expose- exactly.. 100 square centimeters, of filter area, were tested against tobacco smoke and against silica dust in air flowing at a rate of 10 liters per minute. Each material was tested in a single layer and in multiple layers. Results showed that each layer of fabric (in effect) removes about the same proportion of smoke or dust that penetrates to it before the filters become cloggedor altered by deposits of an arrested material, . such as silica dust Consequently, when the efficiency of a single ply of a filter is known, the efficiency of any multiple. ply filter of that material may be calculated. 9; Silica dust clogged filters rapidly and increased the resistance to air flow, but some materials were more resistant to clogging than- others. The dense filters of paper or closely woven muslin clogged most rapidly; filters of loose texture like cheese cloth or absorbent cotton clogged the least. 10. The efficiencies of the filters were increased by clogging with dust until eventually many filters gave an efficiency of 100 per cent. 11. Tobacco smoke did not clog filters, and there was no increase in effi ciency as the smoke was deposited. 12. A few tests were made with woolen fabrics, but they proved to be no better as filters than cotton fabrics of similar texture. 13. The efficiency of the filters de creased somewhat with an increase in the rate of air flow. Sometimes a cotton fabric with a nap showed a decrease after humid smoke had wet it and the moisture had caused the fibers of .the nap to adhere to gether. 14. The resistance of the filters to air flow increases in proportion to the number of plies of fabrics after the first ply. The first filter layer shows a somewhat higher resistance than the additional ones. 15. The resistance of fabric1 filters to air flow is very nearly proportional to the rate of air flow. 16. Air filters of high efficiency can be made with a sufficient number of plies of material that has a low efficiency per single ply--cheese cloth, for example. Such filters have less resistance to air flow than equally efficient filters made of fewer plies of the higher-efficiency materials, such as closely woven muslin. 17. The thicker filters of loose-textured material clog less rapidly than equally efficient filters composed of fewer plies of tightly woven ma- . terial.. 18. A new type of dust respirator was designed and constructed accord ing to the principles, brought out in the tests. This respirator consists of a large filter of canton flannel made into a cap or turban for the head. Air filters through the can DUST ton -flannel - to- the interiorp passes through a check valve, and is then conducted through a rubber tube running over the forehead and be tween the eyes to the nose, which is covered with a small rubber nose Ill mining- and in other industries efforts to prevent the formation of dust and its distribution by the air, by the use of hollow drill steel and water, and by sprays on the under cutting machines should be con tinued. The National Safety Council has pre viously called attention in the reports Riven by A. L. W atson, Chairman of the Industrial Poisons Committee (at the Eleventh. Annual Safety Congress in 1932), to desirable qualifications in respirators: 1. Lightness in weight. 2. 'Automatic adjustment to facial lines. 3. Comfortable contact -edges which will not irritate. 4. No obstruction to vision. 5. No interference with wearing gog gles. 6. No serious resistance to breathing. 7. Relief valve that will not clog. 8. No interference with chewing and spitting. 9. Relief valve placed so as not to blow dust in eyes. 10. Headbands curable and easy to fasten. 11. Inflation valves easy to operate if contact is pneumatic. 12. Durability of parts requiring adjust ment. 13. Little attention required. Figure 6. Graph of particle sines in three samples of d/ust, after recordr ing microscopic count. cap. At an air flow of 85 liters per minute the efficiency of this respira tor was 58 per cent against-tobacco smoke and 93 per cent against silica dust. 19. The1 data presented and the prin ciples outlined may aid manufac turers in improving dust respirators. 20. Although the use of respirators should be encouraged among workers in dusty industries, a respirator can not be considered a final.safeguard. More recently Barreto, Drinker, Finn, and Thomson tested the efficiency of dust masks and respirators and em phasized the following points: 1. Masks for protection against dust and fume particles must be provided with effective filters, preferably of a fibrous nature and with large cross-sectional area. The materials used in gas masks for protection against poisonous gases are ineffec tive in removing particles of dust and fumes. 2. The efficiency of masks of large or small area can be very greatly in creased by plugging the surface meshes with 1a freshly -generated, finely divided fume like zinc, mag nesium, or aluminum oxide. If the filtering area is small, plugging quickly increases the resistance to prohibitive figures; but masks with large area (800 to 1,200 sq. cm.) can be plugged to give perfect pro tection against finely divided lead fume and over 97 per cent against tobacco smoke. At the same time, the resistance to air flow can be kept below 30 mm. of water pres sure measured at 85 liters a minute. 6 HEALTH PRACTICES PAMPHLET NO. 4 Other Methods of Protection Dr. R, C. Williams calls attention to the following general measures for pro tection against dusts and fum es: 1. Industrial Law The foundation of industrial hygiene and sanitation rests on in dustrial ' law. The history of the control of industrial hazards is the Courtesy Metropolitan Lite Ins. Co; Figure 7. Irapinger in use for deter mination of fumes from, a lead pot. history of the enactment of indus trial laws. Industrial laws must be scientifically sound. Fundamentally, the law is for the protection of the worker, but, on the other hand, in forming such a law the effect on in dustry and the cost of production must be considered. The elimina tion of all dustiness in the work processes where there is a dust hazard, may be desirable, but there is no scientific reason for such a requirement if the dust itself is not a specific poison, 2, Law Enforcement Industrial laws are valueless un less enforced. The method of law enforcement in industry is usually through factory inspection and the actual checking up of the efficiency of protective devices. Competent factory inspection insures the con trol of industrial hazards and the maintenance of acceptable sanitary conditions. 3. Education The worker needs to realize the danger of certain health hazards as well as does the employer....Protec tive measures may be required by law and provided by the employer, but if the worker does not under stand the necessity for their use much of their protective value is lost. Wholesome, common-sense education is the means by which the need for intelligent use of pro tective measures is impressed upon the workers. 4. Scientific Study of Industrial Haz ards The correct, basis of industrial law rests on comprehensive scien tific understanding of the hazards that are to be controlled. The proper control and prevention of the health hazards of industry and their effect upon the health and physical condition of the worker ' can be obtained only through care ful and thorough scientific investi gations. The maintenance of ade quate industrial sickness records by employers in order to determine the cause of sickness among workers, and to gauge the efficiency of measures used to reduce health hazards is an important part of the study of industrial hazards. Dusts as Explosion Hazards The National Safety Council has called attention to this matter in its Safe Practices Pamphlet No. 34 on the sub ject "Industrial Explosion Hazards." A. partial list of flammable dusts is given here: Sugar Dextrin Starch Cocoa Flour Grain Maize Fine wood dust Fertilizer Charcoal Coal Lampblack Sulphur Metallic dyes Oat husks Malt Spices Coffee Rice milling Alfalfa Wool Flax' Cotton Celluloid Gum Paper Tanning bark Cork Bronze Iron Hemp Oakum Powdered drugs Aluminum Antimony Hard rubber Powdered milk Zinc Leather Magnesium Soap powder Shellac Methods of Dust Collection for Study Methods by which dust may be col lected and studied as to chemical con tent, size of particles and amount per unit o f air, have been the cause of much research and investigation. These methods may be briefly summarized as follows:' 1. Settling. 2. Counting. ........ 3.... Filtering..... 4. Scrubbing. 5. Electrical precipitation. Settling usually produces a pilingup effect so that the counting of sepa rate particles is impossible. Counting. An efficient jet dust counter has been devised by Owens. Filtering has long been used, es pecially by the Bureau of M ines; differ ent substances have been used for the filter, such as cotton, nitrocellulose, glass wool, paper and alundum crucibles of the insoluble type, and sugar as the best example of the soluble type. The difficulty with filter collectors is that they clog and resist the air flow, there by preventing the possibility of getting the true quantitative dust content of the sample being tested. Scrubbing methods (so-called be cause of the admixture of the dust, particles with water) are much used because of the cheapness of water. The Drinker collector is an efficient kind of scrubber collector. The United States Public Health Service and the U. S. Bureau of Mines have recently made use of an apparatus in their field work, called an impinger. By means of this instrument the air is impinged at a high velocity on a wet surface and then bubbled through alayer of water. Large volumes of air can be sampled and the efficiency has been found to be between 93 and 96 percent, according to conditions. Electric precipitation has been practiced for some time, the most not able example being the Cottrell precipi tator, used extensively to collect smoke. A modification of the Cottrell device represents the best type o f electric pre cipitation collector and one from which the particle size may lie studied, as well as the chemical constitution of the dust. Wherever there is a noticeable amount of dust produced in a given industrial process, the important steps in the investigation of the dust hazard would b e: 1. The quantitative estimation of crys talline silicon dioxide in the sample of air breathed by workmen. 2. A chemical analysis of the dust sample. 3. A computation of a frequency dis tribution of the particle size. 4. Examination of workmen for physi cal effects. ....Outline of a Typical Dust Study The United States Public Health Service has recently published a mono graph entitled "The Health of Workers in Dusty Trades." The method used in this study is here outlined: 1. Physical examinations for the pur pose of determining general .physical conditions. . The data from this procedure gave important physical differences; the industrial rating of the individual; the group to which he belonged; and lastly, aided in the selection of cases for special study. 2. Special physical examinations to de termine the problem of specific disease of the respiratory system, This entailed a special study of lung pathology resulting from dust exposure. 3. Sickness records of the nature and severity of disabling illnesses. These record cards showed all ab sences from work lasting two days or longer. Diagnoses were made in all cases. 4. Occupational environment. Chemical and petrographic an alyses of all dust samples. Summary Dr. Edgar L. Collis calls attention to the following points with reference to exposure to d ust: 1. Inhalation of all forms of dust is. accompanied by diminished power of chest expansion, 2. Diminished power of chest expansion so produced is accompanied by high blood pressure. 3. Animal dusts (apart from the pres ence in them of disease germs) when inhaled, .produce relatively fewer effects than do vegetable and mineral dusts. 4. Vegetable dusts, when inhaled, tend to produce a type of chest affection best described as asthmatic. 5. Of mineral dusts, those composed of calcium salts are least injurious. 6. Inhalation of mineral dusts, which do not contain free silica tends to pro duce irritation of the upper air DUST Courtesy Metropolitan Life Ins. Co. Figure 5. Drinker electric precipitator in use for determination of lead fvmes from casting of bronae. passages and respiratory diseases other than a fibrous reaction. 7. Inhalation of mineral dusts which contain free silica is associated with an excess of scar tissue formation, an excess which bears a direct relation to the amount of free silica present 8. In general, dusts appear to.be more injurious as their chemical composi tion differs from that, of the human body or from the elements of which the body is normally composed. BIBLIOGRAPHY 1. "Industrial Health," Kober and Hayhurst, P. Blakiston's Son and Co., Philadelphia, Pa. 2. "Masks and Respirators for Protec tion against Dusts and Fumes." Barreto et al, Journal of Industrial Hygiene, 9:26-41, January, 1927. 3. "Studies on the Industrial Health Problem--II--A Review of the Methods used for Sampling Aerial Dust." Dr. Leonard Greenburg, U. S. P. H. S. Reports, April 17,1925. 4. "Dust Respirators--Their Construc tion and Filtering Efficiency." Katz, Smith and Meiter, U. S. Bureau of Mines Technical Paper No. 394, 1926. 5. "Pneumonoconiosis: A Summary of Present Knowledge." Dr. E. L. Collis, Medical Journal of Australia, pp. 721-25, November 27, 1926. 6. "Health of Workers in a Portland Cement Plant" Dr. L. R, Thomp son et al. U. S, Public Health Serv ice Bulletin No. 176, 1928. ACKNOWLEDGMENT This pamphlet ukis written by Dr. C. 0 . Sappington, Director of the Di vision of Industrial Health, National Safety Council, Grateful acknowledg ment for suggestions is made to Dr. C.-E. A. Winslow, Dr. Robt. S. Quinby, Dr. Otto P. Geier, Dr. C. F. N. Schram, Dr. Loyal A. Shoudy, Dr. Wm. A. Sawyer, Dr. Lome E. Hastings, Dr. Volney S. Cheney, Dr. Emery R. Hay hurst, Dr. Henry F. Smyth, Dr. Cecil K. Drinker, Dr. Thomas R. Crowder, Dr. L. R. Thompson, Dr. Wade Wright, Dr. R. G. Leland, Mr. Howell Cheney, Mr. J. M. Woltz, Mr. S. E. Whiting. 6/28-3M 8 HEALTH PRACTICES PAMPHLET NO. 4 How the Industrial Health Division serves the members of the % f, NATIONAL SAFETY COUNCIL FIRST: . SECOND: THIRD: FOURTH: F i f t h .SIXTH: SEVENTH: Provides a consultation service with an industrial medical authority who is D i rector of this Division on the staff of the Council. Questions are fully an swered on industrial health hazards and methods and policies of industrial health administration. In conjunction with eminent authorities in the industrial health field, a series of pamphlets on pertinent industrial health subjects is being prepared. Publicity material such as bulletins (for employee education and inspiration), pamphlets and articles of a technical nature to be published in the various or gans of the National Safety Council, is part of the program. W ill make available the high points in the successful experience of the out standing medical services of industry. Will give talks to interested foremen, executives, nurses and physicians. Will continue to gather research statistical data bearing on industrial health procedures in order to evaluate future types of endeavor in industrial health practice. W ill be represented on health hazard committees, thus making available scien tific information concerning the prevention and control of occupational dis eases.