Document 37568y5kGNOo4ZgeyvnBXEDe3

FILE NAME: Wagner (WAG) DATE: 0000 DOC#: WAG034 DOCUMENT DESCRIPTION: Book Excerpt - Work is Dangerous to Your Health [Dusts] i i TOISYDOAUNRGEHREOAULTSH A Handbook of Health Hazards in the Workplace and What You Can Do About Them Jeanne M. Stellman, Ph.D. Susan M, Daum, M.D. With Contributions by j James L. Weeks, M.s. Steven D, Stellman, ph.d . Michael E. Green, ph.d. With illustrations by Lyda Pola PANTHEON BOOKS A Division of Random House, New York A -23 8 Chemical Hazards [ 167 DUSTS Dusts usually cause disease only in the lungs. Lung dis ease that results from dusts is called pneumoconiosis, de rived from the Greek pneumo-, meaning "lung," coni-, meaning '`dust," and -osis, meaning "reaction." The devel opment of pneumoconiosis depends on the type of dust and the susceptibility of the individual worker, and is also aftected by duration of exposure and by exposure to other chemicals or to cigarette smoke at the same time. Particle size affects the toxicity of dusts: the smaller the particle, the farther down into the lungs it can go, and also the greatei the amount of dust that will be retained by the body. A general rule is: The more dust retained, the more severe the resulting illness. Dust particles may be so small they are visible onlv by microscopic analysis. Particles this size be have essentially like air, passing practically unimpeded through the protective baniers of hair and mucus in the upper airways. The air sacs and small air tubes therefore receive a very large close, and the intensity of lung reaction is greater than if the same quantitv of larger particles had been inhaled. Inorganic M ineral and Chemical Dusts Silica. Inhaling tne free, finely divided dust of silicon dioxide causes a form of pneumoconiosis called silicosis. The dust may be in crystalline form, as in quartz, cristobalite, and tridymite, or in non-crystalline form, as in opal. The smaller and mote compact crystalline forms (quartz, tridy mite) cause the greater lung scarring since they have the most dangerous particle size: 0.05 microns to 5 microns (1 inch contains 25,400 microns). Silicosis may develop either rapidly or slowly. The rapiddeveloping variety occurs most commonly among workers in the manufacture or packing of abrasive soap powders, A-239 WORK IS DANGEROUS TO YOUR HEALTH among sand blasters, especially those working in enclosed tanks), and among tunnel workers using high-power drills on rock. These workers are exposed to tremendous amounts of very finely divided crystalline silica. The chemical inter action between silica dust and lung tissue may be height ened by the presence of alkali or acid. In rapid-developing or acute silicosis, symptoms may ap pear as soon as 8 to 18 months after the first exposure. The main symptom is shortness of breath, at first occurring only during physical activity, but soon appearing aftei less and less exertion, until eventually the victim is short of breath even while at rest. This is caused by the many small round lung scars that develop from irritation by silica dust. The^e hard, inelastic scars--just like those on the skin that result from an operation--make the lungs stiff, so that it takes more work to inflate them with air. T he scars also thicken the walls of the air sacs, blocking the transfer of oxvgen into the blood, low blood oxygen is a characteristic finding m sili cosis. Tire area surrounding each scar becomes stretched and distorted, breaking down the normally tiny, delicate air sacs so that they form larger, thicker-walled sacs--a form of local ized emphysema. Further reaction to the silica may cause the scars to join into larger scars; some may occupy the en tire lung. T h is process, progressive massive fibrosis, is fre quently accompanied by increased susceptibility to tuber culosis and other infections. Finally the heart, which must pump blood through these stiff, inelastic lungs, becomes weakened and enlarged and fails to pump effectively. The course of chronic or slowly progressive silicosis is very similar to that of acute silicosis, except that rather than developing quickly, it arises after many years of exposure and may take many more years to become worse. T h e legal standard for silica exposure depends on the form of the dust. Protective apparatus is useful only for emergencies, and would be difficult to work in for a full working day. A- 240 Chemical Hazards l 169 T h e prevalence of silicosis in workers exposed to silica dust is probably very high. A survey showed that in the pe riod 1950-1958 there were 12,000 cases in 26 states. This may be a gross underestimate of the true numbers, as the study was based mainly on workers over 50 and already dis abled. Another variation of rapidly progressive silicosis results from exposure to diatomite, a non-crystalline silica used in filters, insulating materials, absoibents, and polishes. It pro duces a \er> fine dust capable of causing severe illness. Shaver's disease is a similar, rapidly progresshc disease caused by inhalation of bauxite fumes. These fumes are emitted by electric furnaces in the production of corundum or refining of aluminum ores, and consist of extremely small particles (0.02-0 05 microns). Coal dusts. Exposure to soft-coal dust causes simple pneuinocoyuosiSj or black lung. Soft (bituminous) coal contains little silica. Large amounts of the black dust are deposited in the lungs, especially at the end of the small air tubes just before they enter the air sacs. This peculiar location and the properties of the dust itself give the disease the characterestics both of bronchitis and emphysema and of silicosis. Like emphysema, it shows up late or not at all on chest X-rays and in most simple lung-function tests. Like silicosis, it leads to lung scarring, which makes the lungs stiff and may lead to heart strain. " Complicated pneumoconiosis" results when the small scars of simple pneumoconiosis join together to form large masses of scar tissue. These masses, which are stony hard, may occupy more than one-half of the lung. As the scars pull together, they rip the air-sac walls behind them and cause severe emphysema. Respiratory infections, and especially tuberculosis, may be a fatal complication of black lung. Among workers exposed to coal dust, smoking cigarettes appears to make black lung more frequent and more severe. Anthracite, or hard coal, which contains more silica, A-241 7 I7O ] WORK IS DANGEROUS TO YOUR HEALTH causes a lung disease more like silicosis. It shows up on X-rays fairly early and leads to symptoms of respirator) dis ease only years later. Large scars taking up almost the whole lung are a particularly common effect of hard-coal dust. For many years, doctors thought the amount of lung scar ring or disease that resulted from coal dust depended on the exact silica content of the dust. But ample information shows that silica-free coal can produce both the \ery small scars and the very large ones. Some doctors, mans of whom work for the compensation insurance companies 01 the coal companies, still do not believe that bituminous coal causes any illness. This shows that doctors are not immune from bias in the interpretation of scientific facts, especially when the facts have economic consequences for major industries The standard for coal dust, under the Coal Mine Safety Act of 1969, is 3 million particles per cubic foot of air. How ever, the Bureau of Mines has not conducted enough in spections to ensure that this limit is maintained, not even the weekly spot inspections of "especially hazaidous mines" required by law. It has either not given fines, or lias failed to collect on fines it has given. With this sort of enforceuient, it is not surprising that coal miners are dying from accidents at a rate of approximately one man every other working day, a rate higher than that of i960, before the Coal Mine Safety Act went into effect. Young miners ex posed to coal dust in mines where inspectors never come will develop black lung that will show up at least 10 years from now. Carbon black is produced by burning creosote oil, tar oils, or petroleum distillates in a shallow iron pan and then collecting the resulting soot. Slight variations in the process produced channel black, furnace black, and acetylene black. In England the word "carbon black" is used for the same products as the word " soot." {Most of the research on the health effects of this dust comes from England.) In this country, "carbon black" refers to the specific product oE the A- 24 2 Chemical Hazards [ I71 incomplete burning of natural gas or oil: essentially pure carbon, containing less than 1 percent mineral impurities and no silica. Exposure to large quantities, as in the manu facture of rubber or inks or the production of carbon black itself, causes pneumoconiosis identical to that produced by soft coal, with emphysema, abnormalities of the small air tubes, and lung scarting that may lead to progressive massis e fibrosis. Graphite, also called plumbago, has numerous industrial uses as a lubricant, a conductor of heat and electricity, and a carbon carrier in steels. Natural graphite can contain from 2 to 10 percent silica after it is freed of the tock from which it is mined. Synthetic graphite contains less than 1 percent silica and often none at all, Pneumoconiosis can result from both natural and synthetic gTaphite. The illness and the medical findings are similar to those found in black lung. Synthetic gTaphite and graphite with low silica content produce lung disease like that caused by soft coal. Graphite with higher silica content produces a disease more like sili cosis. Asbestos is a fibrous mineral that, like cotton, can be made into thread and cloth. Unlike cotton fibers, its fibers are as strong as piano strings. It is virtually indestructibleheatproof, fireproof, and resistant to most chemicals. Be cause of these properties, it has found its way into more than 3,000 products, from potholders and children's toys to weld ing rods and industrial and household insulation. No fac tory or home is without asbestos, and almost no group of workers is without potential exposure. .Asbestos fibers are extremely fine. Fibers that can be seen with the naked eye or under an ordinary light microscope actually consist of thousands of smaller fibers called fibrils. It takes a specially potverful microscope, called an electron microscope, to magnify enough to make individual asbestos fibrils visible, as they are so small that there are 1 million of them to an inch. (For comparison, there are approxi- 172 ] WORK JS DANGEROUS TO YOUR H E A L T H mately 630 human hairs, side by side, to an inch.) When such very fine fibers get into the air, they float like water vapor and never settle, They are not trapped by the mucus or hairs of the nose or air passages, and can enter the air sacs of the lungs without any hindrance. Based on the usual method of dust counts, which measure onl) fibeis large; than 5 microns and lease uncounted the majority of smaller and more dangerous fibers, it is estimated that in an S-hour da), at the legal limit of 5 fibers per cub.c ccntimete; of air, a person breathes 15 million fibers. .Many of these remain trapped in the lungs. Once they are inside the bod) they remain as indestructible as they were outside it. An asbestos fiber you breathe when you are i 3 tears old mat stay in )Our lungs until you die. Although the body's mechanisms cannot destroy the as bestos fiber, they try \ery hard to isolate it. 0 \e r a period of io to 20 years individual fibers or groups of fibers may be surrounded with a thick wall of scar tissue. \\ hen these scais form in the air-sac walls, the lungs become inelastic, hard and contracted, smaller than normal. This means the\ hold less air and the body must work harder to fill them. The heart must work harder to pump blood through them Since the scars are situated in the delicate air-sac walls, they block the transfer of oxygen to the bloodstream. Lou blood oxy gen and decreased lungiolum e are what doctors find in a pa tient with asbestosis. The main symptom is shortness of breath. Frequent respiratory infections aie an additional problem, as the slightest infection can cause severe shortness of breath and even death in a person with asbestosis. Ciga rette smoking appears to increase the frequency and severity of asbestosis. Extensile studies have been made of asbestosis in asbestosinsulation workers, most of whom spend only about half their working time handling asbestos. This is a low exposure compared with workers who handle asbestos all the time In spite of this " low" exposure, t out of e\ery 10 asbestos- A- 244 Chemical Hazards [ 173 insulation workers dies of asbestosis. Occupational groups that may hate generally higher exposures to asbestos dusts include shipyard workers, asbestos-manufacturing workers, and asbestos-textile workers. T h e British Threshold Stan dard for asbestos is 2 fibers per cubic centimeter. The American standard is 5 fibers per cubic centimeter, to be reduced to 2 in 1976. T here is already scientific evidence that these standards are inadequate to protect workers from asbestosis. Asbestos dust has another, even more serious effect: it causes body cells to turn cancerous. Scientists do not knots' exactly why this happens. The reason may be the long resi dence of the dust in the lungs, or the ability of asbestos to adsorb other harmful chemicals onto its surface. The sur face of asbestos fibers may hold carcinogenic (cancer-produc ing) chemicals in contact with the body's cells, which he roine malignant many years later. Workers detelop cancers after at least 20 to 30 years hate elapsed. Asbestos can cause cancer in seteral parts of the body. Mesothelioma is a cancer of the membrane lining of the chest or abdomen. Normally this membrane is microscopi cally thin and acts to lubricate the trails of the chest and abdomen so that the lungs and intestines can move without rubbing or friction. In mesothelioma the lining becomes thickened and the chest or abdomen fills with fluid. Even tually the cancer otergrows the body, the way a weed over grows a garden, and kills the victim. There is no known cure, and the cancer usually cannot be removed surgically. Mesothelioma is believed to occur only after exposure to asbestos. Prior to the introduction of asbestos into our so ciety at the turn of the century, mesothelioma was so rare that it was unheard of by most doctors. Then the only cases appeared to result from exposure to natural deposits of as bestos, or to asbestos-rich soil in farming country. Mesothe lioma can result from small doses of asbestos, well below the current threshold limit. T here are reports of mesotheliomas A- 245 msttsmasst 174 ] WORK IS DANGEROUS TO YOUR H E A L T H resulting from onl) one day of work in a ship)ard, or de veloping in asbestos workers' wires vh o were exposed when washing their husbands' work clothes. Insulation workers get mesothelioma whether they smoke or not. One in 10 asbestos-insulation workers dies of mesothelioma. Asbestos also causes cancer of the air tubes in the lungs. Lung cancer occurs mainly m asbestos workers who also smoke cigarettes. An asbestos Yorker who smoker has qz times the chance of dr ing of lung cancer that a pci son has who neither smokes noi works with asbestos. One out of esery 5 asbestos workers dies of lung cancer, and about 1 out of e\ery 30 smokers dies of it Cancers of the intestinal Table 16. Causes of Death A mong A sbestos-Insulation Workers CAUSE PERCENTAGE OF TOTAL CAUSES OF DEATH Cancer, all types 40 4 LMuensgothcaelnicoemra 173 33 COathnecrercaonfcetrhse intestines i r.t 7-7 Asbestosis 5-5 All other causes 54 1 tract are also common in asbestos workers. They ha\e about 3 times as many cancers of the stomach, large intestine (colon), and rectum as the general population. Eecause asbestos is so common and so hazardous, special methods of preventing exposure must be used. The impor tant and necessary goal of these methods is that no asbestos A - 24 6 Chemical Hazards [ 175 dust should be released into the work or general environ ment, and none should get into an>one's lungs. One way to prevent a harmful substance from causing disease is not to use it. Numerous substitutes for asbestos have been tried. Each has its own hazards. Some are touted as harmless, but the) have been in use for too short a time for long-term effects to be seen. A general rule seems to be that any substance with the properties of asbestos, any sub stance as strong and indestructible, does not belong in your lungs and will do harm if it gets in. Substitutes now in use are fibrous glass, rock wool, sodium silicate, and polyure thane. The rules for handling fibrous glass are identical to the rules for handling asbestos. The British have experi mented with asbestos-free calcium silicate block and pipe covering; this substitute is not generally available in the United States. Modifications of asbestos may prevent some dust expo sures. Various coatings have been designed to keep installed asbestos--or fibrous glass--from flaking. These should be used on all asbestos blocks, and especially on the asbestos lin ings of air-conditioning ducts. (Contamination of the air in urban office buildings from asbestos-lined ducts is being studied in several cities.) Dust suppressants are also used in asbestos cloth such as that in insulation blankets. (Fibrous glass has been substituted for asbestos as the filler in the blanket.) These blankets are not only cleaner to install but also cleaner to rip out. Work practices specifically designed to release little or no dust into the air have been introduced for processes re quiring asbestos. T heir use for all operations involving as bestos (or other hazardous substances) will allow workers to control the safety of their own workplaces, and free them from dependence on all-too-infrequent inspections. If the correct, safe work practices cannot be followed, the job should not be done. Isolation of a hazardous process is an important way o A- 24 7 176 ] WORK IS DANGEROUS TO YOUR H E A L T H limiting the number of people exposed Isolation of asbestos processes has an added avantage: it puts most of the work in shops equipped with proper ventilation and with tools de signed for the special problems of asbestos. Shops can be equipped with strong general ventilation and hoods that even the best-ventilated field equipment cannot ii\al. Pr fabrication can be done in such shops, or in the factor) from which the asbestos supplies come. (The factory, of course, is really a giant shop and must also ha\e properl) designed and functioning equipment and \entilation.) Prefabricated blocks can be shipped, net, in plastic bags labeled with the exact aiea where the) m il be used. Insulation blocks can be bought prescored, or scored in the shop with a properl)' ventilated gang saw. Pads and blankets for calves and ma chinery can also be made up in the shop. The fibrous glass or asbestos-cloth blanket is unrolled, wetted, and rerolled. Thoroughly dampened b) this procedure, the blanket is then cut to shape m a well-functioning lateral-draft hood. Repair work can also be done in the shop. Convenient sized sections of pipe assembly can be brought to the shop, the insulation stripped, the pipes or insulation fixed, and new or iepaired lagging put on. Only small repair jobs should be done at the job site. Unfortunately, all work cannot be brought to the shop. Demolition and some removal operations must be per formed on the job site. These operations too must be iso lated, both from other workers and from the general com munity. Other workers must be kept off the job site during the operations. Trade crafts not directly involved in the rip-out should not be scheduled to do any work while the area is contaminated. The surrounding community can be protected by plastic tenting that completely encloses the work area and is equipped uTith a portable industrial vac uum cleaner to create a negative-pressure exhaust ventila tion within it. A ll of the dust liberated within the tent stays A-248 Chemical Hazards [ 177 there, because of the inward pull of air created by the ex haust system. The spraying of insulation cement must also be isolated on the job site. Many cities are now abolishing the use of asbestos-containing cement for spraying operations. How ever, work rules for the use of substitutes such as fibrous glass are the same. Only materials thoroughly mixed with water should be used. M ixing must be done in an enclosed system, such as a plastic bag with a valve for a hose. Cement shot dry from the nozzle of the sprayer and then passed through water onto the steel is dangerous because it sprays the entire workplace. It should not be used The spray area should be sealed off from the outside and from the rest of the building with large plastic or plastic-coatcd tarpaulins. T h e tarpaulins must reach through window areas into the building to pretent any loss of hazardous dust at the bottom of the enclosure, and must seal off elevator shafts and stair wells. Xo other workers should be in the area while it is con taminated. During spraying operations, air levels of asbestos may be higher than too fibers per cubic centimeter, and the sprayer must wear a powered air-punfymg or air-supplied respirator. "Wet cement that falls on the floor should be immediately shoseled or vacuumed up and disposed of. Large power tools, such as band saws and gang saws, can be equipped with good local \encilation. The usual system for a hxed installation shop is a high-volume exhaust system that draws the dust into a baghouse. Special tables for cut ting asbestos have perforations, and a down-draft pulls the dust down through the holes into a disposable container. Larger pieces of asbestos debris go into a plastic bag at the side of the table. Some of this equipment has been successfully modified for field use. Smaller power tools, such as saber saws'or rotary saws for cutting cement board, can be fitted with an industrial vacuum cleaner that creates a high-airflow, lowvolume draft leading to a bag, The air stream can be moved WORK IS DANGEROUS TO YOUR HEALTH past the saw blade at a rate three times faster than the saw blade moves. One word of caution: these ventilated power hand saws are not as safe as the larger ventilated shop tools, and should be used only for those jobs that cannot be biought to the shop. They should never be substituted for band saws, which can be attached to dust collectors of much greater efficiency. The perforated down-draft -worktable can also be operated on the job site with an industrial \acuum cleaner creating the draft. Whether such dust collectors are installed on pow er equip ment or are part of hoods or of a general \ entilation system, they must be tested with dust counts to see if they are safe If they are found to be operating properly. a pressure gauge can be installed on the exhaust duct to indicate whether adequate \entilation is being supplied for each job. All the workman has to do then is see if the pressure as shown on the meter is at a safe value. If it is, the job is being done in a safe en\ ironrnent. If not, the job should wait until the exhaust equipment is working properly. Asbestos cement can be prepackaged in convenient-sized plastic bags with a valve for the nozzle of a hose. Water is introduced and the cement is kneaded right in the bag. (If the water is introduced the night prior to use, no kneading will be necessary.) Very little dust is liberated by this pro cedure. Housekeeping is another important part of preventing exposure. Good housekeeping begins before the job starts, with the laying of plastic dropcloths. A t the end of the day, all debris can be wrapped up and thrown away. In between, the smaller dust should be vacuumed up with industrial vacuum cleaners into strong, single-use inner bags that can be removed and sealed. Asbestos or other harmful dusts should never be swept up by hand. Cleanup can be per formed either by the workers doing the job or by special cleanup crews. A- 2 50 Chemical Hazards I 179 Disposable work, clothes, made of material such as resinimpregnated paper, are recommended. No one else has to handle them, and they can be placed in plastic bags at the end of the day. They help prevent the spread of contamina tion outside the work area. The clothes should be removed and thrown out before leaving the work area, or in a special "dirty" locker room, so that street clothes do not come in contact with them. In field operations, the work van can have a " clean" locker room for street clothes and a " dirty" one for work clothes. Asbestos brought home on work clothes has been responsible for disease in wives and chil dren of workers. Ail these special procedures arc to be used in addition to the general procedures of industrial hygiene discussed in Chapter 9, Safe use of a substance as harmful as asbestos shows that both simple and sophisticated techniques can be developed and applied to protect workers. M ineral wool, rock wool, and fibrous glass are synthetic materials (silicates) with properties similar to asbestos, which makes them both useful and harmful. There are over 70 varieties of fibrous glass. Since diseases resulting from these substances probably take a long time to show up, and the substances have only been in widespread use for 10 to 15 vears, it is not surprising that little disease due to them has actually been reported. Studies on animals, however, show that they can cause lung scarring and also some cancers. This should be warning enough. Fibrous glass should be handled as carefully as asbestos and the same protective measures applied to its use. It also causes skin irritation, and may cause acute bronchitis and asthma if inhaled. T alc is very similar to asbestos. Its particles are mostly flat, like little plates, but may also be fibrous. It is usually found in deposits mixed with asbestos, and it is not clear)if the health effects o f talc are from the asbestos or from'the talc itself. (American cosmetic talc tends to have less mixed asbestos than French.) A - 2 51 i 8o ] WORK. IS DANGEROUS TO YOUR HEALTH T he effects of talc are similar to those of asbestos, al though they have not been as carefully studied. T alc is also a very fine dust, with some particles so small that they can not be seen with the usual optical microscope. These smaller particles, the most dangerous ones to the body, are not counted by routine dust counts. Once in the lungs, talc stays there and cannot be removed by body mechanisms. T h e effects show up 20 or 30 years after exposure. T alc causes lung scarring similar to that in asbestosis Mesotheliomas have also been reported, and cancer of the lungs and the intestinal tract may also occur, though there have been too few studies for definite proof. T alc has found its way into some foods. Scientists, concerned that talc may cause intestinal cancer, have requested that talc addithes in foods be banned by the Food and Drug Administration. Beryllium causes lung, skin, liver, and kidney disease, however, the effects on the lungs are the most prominent and disabling. Acute betylhosis is a severe, pneumonia-like lung inflammation that can occur after brief, intensive ex posure, or prolonged exposure to low concentrations. It may result from extremely low exposure in some workers, de pending on individual susceptibility. T h e typical symptoms are cough with phlegm that can be bloody, ses ere shortness of breath, and weight loss over the first few weeks. The chest X-rays may be normal initially, even though the worker is seriously ill. T h e lung inflammation may be se%ere enough to block oxygen transfer into the blood. T h is disease is 11 equently fatal, and those who recover may have sustained permanent damage to the lungs. Chronic berylliosis may develop after 1 year or even up to 20 years of exposure. Chest X-rays may be abnormal for many years before symptoms begin. A t first the symptoms may be mild, slowly progressing to a more severe and dis abling illness in ivhich chronic inflammation makes the lungs stiff and unable to transfer oxygen to the bloodstream. T he heart is affected by years of straining to pump blood A-252 Chemical Hazards [ I8l through the inelastic lungs. The final stage of the disease is similar to asbestosis. Iron, barium, tin. Siderosis (iron), baritosis (barium), and slanosis (tin) are caused by compounds such as iron oxide, tin oxide, and barium sulfate, which give rise to dusts that are insoluble in lung tissue but not irritating. Because these dust deposits are visible on chest X-rays, they are included under pneumoconiosis, but they do not cause symptoms and apparently do not produce disability. Oigatiic Dusts Organic dusts ma) contain plant fibeis or fungi, bacteria, and their products. They act upon the lungs in a different manner from mineral dusts. The diseases they cause are fre quently the result of an allergic reaction to the inhaled dust. For example, the disease called byssinosis or brown lung is caused by an allergy-like reaction to cotton dusts (and also to the dusts of flax and hemp). T he severity of reaction de pends on the susceptibility of the individual worker to the allergi-producing qualities of the dust. Although a susceptible cotton worker may develop this reaction at any time in her or his working life, it usually be gins after only a short exposure. The first reaction generally occurs when the worker returns to the mill after a few days off--a weekend or a vacation. Because of this pattern of re action, the initial stages have been called "Monday fever." The first reaction is like an asthma attack, with shortness of breath, severe air hunger, chest tightness, and a dry cough. These symptoms are caused by the narrowing of the medium and small air tubes and by the accumulation of excessive amounts of thick mucus in the tubes. The air has difficulty moving out of these narrowed tubes, and makes a wheezing sound. A single such attack is extremely frightening and uncomfortable, but causes no permanent lung damage. R e peated attacks, however, may damage the lungs. In the initial stages, these attacks occur only on the first A- 253