Nylds Hinch
Nederland High School Nederland, Texas 77627
Air Pollution
The consideration of the air we breathe has been one of the most fundamental and profitable endeavors in scientific, philosophical, and medical thought. Thc very roots of systematic scientific reasoning had their origin in the observations and speculations of the 6th century B.C. philosophers. Anaximene initiated the pneumatic theory and this finally emerged as a relationship between air, fire, and breath or body heat. The same fundamental questions resulted in the discoveries of the gases by Blacli-carbon dioxide, Cavendish-hydrogen, Rutheford-nitrogen, and Priestly and Lavoisier-oxygen, not to mention Boyle and Hook (1, p. 5). Even though man did not recognize the global hazard to the human race until about two decades ago, air pollution has been around a long time. The earliest pollution of significance occurred from volcanic activity and wind storms which destroyed entire cities and all life in them. The first serious pollution of the air by man began with the burning of coal. From the beginning, coal fouled the air producing soot and the irritating fumes of sulfur dioxide (2, p. 16). The earliest laws to control air pollution by man began about 1273 when King Edward I passed a law prohibiting the use of one type of coal. In 1300 King Richard 111 taxed coal heavily to retard its use. In 1661 King Charles I1 had a study made of the cloud over London. This study indicated tbat a relationship existed between the cloud and a number of fatal diseases prevalent at the time (2, p. 16). I n America, the industrial revolution ushered air pollution onto the scene. With the passage of time, pollutants other than coal by-products became important to man's health. The first known air pollution disaster in the United States occurred in Donora, Pennsylvania in 1948 (2, p. 18). Froni this time on air pollution began to loom on the horizon of importance to man's survival. An air pollutant may be defined in several ways. Probably the best definition identifies air pollutants as only those substances in sufficient concentration to produce a measurable harmful effect on man or other animals, vegetation, or material. Pollutants may he any natural or artificial composition of matter capable of being air born. This includes solid particles, liquid droplets or gases, or various admixtures of these forms (8, p. 5). Two general groups of pollutants are those emitted from identifiable sources and those produced in the air by interaction among two or more primary pollutants, or by reaction with normal atmospheric constituents, with or without photoactivation (8, p. 12). The pollutants emitted from an identifiable source are called primary emissions while those produced by reaction or mixture in the air are called
secondary pollutants (8, p. 12, 13, 15). Upwards of one hundred specific substances have been found and identified as air pollutants. This list contains metallic elements, organic compounds, and inorganic compounds (2, p. 39). The activities tbat produce air pollution consist of the burning, vaporizing and dividing of materials (2, p. 41). Some examples of air pollution encountered ~ncludesuspended particles produced by burning-soot; gaseous sulfur dioxide; carbou monoxide; nitrogen oxides; vaporized benzene-soluble coal-tar derivatives and any comhination of these and other materials not mentioned. This horrible mixture was named smog in 1911 by Dr. Harold Antoine Des Voeux in his report, "The Glasglow Episode," on a great London air pollution disaster which killed 1,150 people (2, p. 18). The exact chemistry of smog formation and composition is not known. There arc, however, several obvious factors which have been identified in smog formation. I n a period of windlessness, a layer of warmer air intermittently sits over a layer of cooler air, thus acting like a lid on a pot. Without the push of wind, air pollutants collect and cannot be dispersed vertically or horizontally. The result is a thickening mass of pollution in an air container (2, p. 25). This pot may contain the oxides of nitrogen formed by any high temperature combustion process-especially combustion in the automobile engine; the sulfur dioxide formed from the burning of gasoline, fuel oil, and coal; and hydrocarbons including carbon dioxide, carbon monoxide, and benzene soluble coal-tar by-products (4, p. 83). A city's atmosphere is thus a large chemical mixing howl in which chemical reactions may take place. The final ingredient is supplied by the sun. Solar radiation causes the various motor-vehicle and industrial emissions to react with one another in the atmosphere. These reactants plus water vapor, which is also a product of combustion, in the presence of sunlight, undergo photochemical reactions and produce smog and ozone (2,p. 92). The final product is capable of causing many symptoms including burning eyes, dirty skin, respiratory diseases, cancer, and death (8, p. 336). There is no doubt that air pollution exists. The question is, who is to blame? In the past industly has been blamed for our troubles. It has been recently recognized however, that most of the pollution which exists a t lung level comes from domestic sources (1, p. 206). Some examples of this domestic pollution include garbage burning, sewage treatment, home heating, leaf burning and automobile pollution (2, p. 6). Two thirds of the hydrocarbons contributing to smog from automobiles come from engine exhaust and about one third from crankcase blowby. Of the 450 tons of Volume 46, Number 2, February 1969
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nitrogen oxides lost from automobiles per day in Los Angeles 99y0 is in the exhaust gases. This 450 tons is estimated to be two thirds of the amount entering the atmosphere from all sources (1, p. 192). These numbers are startling, but gloom is compounded when it is realized that every gasoline engine pollutes the air ($8 P. 81). In addition to domestic air pollution we have air pollution by industries who are meeting consumer demands. These sources include smelters, refineries, pulp and paper mills, cement factories, fertilizer plants, and asphalt plants; also included are the trucking, rail, and airhne industries (2, p. 6). The take-off of one commercial jet airliner under full load emits pollutants a t a rate equivalent to 10,000 passenger cars (2, p. 89). According to the Tucker Report on Los Angeles, one metallurgical plant alone puts into the air fifty tons of sulfur d~oxide every twenty-four hours. This is twenty-five times as much as is produced by all the city's automobiles (4, p. 131). I n industrial use of fuels a ton of fuel oil produces 600 pounds of sulfur oxides, 27 pounds of nitrogen oxides, and five pounds of solids when burned. A ton of coal produces 200 pounds of solids, 40 pounds of sulfur oxides, and eight pounds of nitrogen oxides when burned (2, p. 43). Chicago receives 25,000 tons of air pollutants a day (t,p. 43). I n one month dustfall in Chicago's loop totaled 125 tons per square mile (2, p. 34). An average home collects two pounds of dust per week in the United States (2, p. 53). I n Wheeling, West Virginia, 590 tons of dust fell on a sinale sauare mlle in one dav (2, P. 34) Why is air important to man? Each day the average male human requires thirty pounds of air, 23/4 pounds of food, and 4l/2 pounds of water. Man can live five weeks without food and five days without water, but only about five minutes without air. Air is essential to the senses of sight, smell, and hearing. Pollution assults the first two senses mentioned (5, p. 336). Since man is so dependent on air a further case need not be built to defend it, if there is adequate air of sufficient purity. The truth is though, that an excess of pure air is not available. Contrary to popular belief man is not a t the bottom of a seemingly endless sea of air. A better picture of the air available may be obtained by looking a t a desk globe of the earth. The habitable portion of the atmosphere would only he about as thick as the varnish on the globe's surface (2, p. 23). Another item of interest to man in regard to air pollution is the relationship between ecological changes and weather as ever increasing amounts of fuel are burned, more and more carbon dioxide is emitted into the air; at the same time millions of square miles of carbon dioxide absorbing vegetation are being destroyed to provide roads and cities. As a result the carbon dioxide in the atmosphere is increasing by six million tons a year. This increase in carbon dioxide can raise earth's temperature by what is known as the greenhouse effect. The trapped heat could raise the temperature by forty degrees Farenheit within 500 years, at the present rate. A change even half this great would cause violent air circulation and destructive storms unlike any ever seen on earth. The polar caps would melt and inundate many costal cities (2, p. 129, 130).
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Of more eminent concern to man is the effect of air pollution on his biological health. The true test of health hazard to the general public from any particular atmosphere is the ability of this atmosphere, when inhaled, to produce physiological deterioration in exposed persons, and especially in those haviug respiratory or cardiovascular diseases (4, p. 5). The insidious thing about smog is that it does not necessarily initiate immediately fatal attacks of respiratory and cardiac trouble. The results are of a more subtle form in which lung irritants so increase respiratory and cardiac difficulties for those already ill from these diseases that a few of the more acutely sick are pushed across death's threshold (4, p. 136). The most susceptible are premature infants, the newborn, the elderly, the infirm, and the diseased (5, p. 336). Specifically the symptoms may range from discomfort, illness, chronic disease, to acute sickness or death (4, p. 336). The pollutants may irritate the mucous membrane by specific toxic reactions, by allergenic activity, or by carcinogenic activity (1, p. 180, 181). I n Donora, Pennsylvania, in 1948, the production of steel, wire, zinc, and sulfuric acid supplied enough air pollution to produce a fog that enveloped the area during a thermal inversion. Forty-three percent of the population became ill; twenty people died, and 5,910 became sick. Their symptoms were chest constriction, headache, vomiting, nausea, and irritation of the eyes, nose, and throat (2, p. 18). Clinical tests and experimental studies have been made to determine the spcoific effects of air pollution on hnmans. Although generalizations have been made, it has also been noted that several different pollutants may have very nearly the same effect on a human; for example, irritation may be the predominant effect of sulfur dioxide, formaldehyde, and acrolein, and to some extent of chlorine and ozone. In addition, the physiological response of increased airway resistance is common to many irritants and is also prodnced by inert dusts (5, p. 347, 348). To complicate matters more, it is not always known to what extent pollutants interact in combination to produce physiological responses, or what responses are related to each pollutant (5, p. 349). A few of the more common pollutants and their effects have been studied carefully; these include carbon monoxide, lead, ozone, sulfur oxides, coal-tar derivatives, soot, and dust. Carbon monoxide and lead poisoning have been found to be an occupational hazard to downtown traffic policemen, auto mechanics, and truck drivers (5, p. 337). Carbon monoxide can produce a spectrum of symptoms ranging from mild discomfort through headache, visual difficulty, personality changes, ataxia, paralysis, coma, and death 1 p. 1 8 1 Lead affects the nervous system. Both airborn lead and carbon monoxide come from burning fuels and cigarettes; and a cumulative dose over a period of time may produce any of the symptoms previously mentioned (1, p: 182). Airborn lead comes from burned gasoline wh~ch contains the antiknock compound tetraethyl lead. Lead also comes from smoking cigarettes made from tobacco which was grown on fields where lead insecticides were used in the past. The tobacco plant concentrates the lcad into its leaf and the smoker accumulates lead poisons (5, p. 353). While carbon monoxide combines with
hemoglobin 210 timcs as readily as oxygen (5, p. 358) lead interferes with the development and maturation of red blood cells (5, p. 353) thus attacking respiration in two ways. The level of incidence of carbon monoxide has been found to he as high as 500 ppm in the air in heavy traffic (2, p. 94). Symptoms from carbou monoxide usually appear a t as low as 100 ppm (5, p. 458). A cigarette smoker may have as high as 8% of his hemoglobin in the form of carboxy-hemoglobin (5, p. 359). Add this to traffic carbon monoxide, and poisoning is very likely. Additional products of tobacco combustion, as with other fuels, are oxides of nitrogen and complex tars containing benzo (a) pyrene (5, p. 340). Benzo (w) pyrene mixed with fiue dust has been found to produce cancer in laboratory animals when it was introduced into their lungs. I n every case living cancer appeared in the test animals (8, p. 66). Ozone is a by-product of smog formation and photoactivat,ion. At one time it was thought to be healthful in small amounts. I t is now known however, that as little as one ppm is highly irritating over a period of time. One ppm for eight hours a day for one year has produced bronchitis, fibrosis, and bronchiolitis in rodents (8, p. 359). Sulfur dioxide can be detected by odor a t as low as 3 ppm. One ppm can produce physiological response in man. Research indicates that ciliary action is changed by the presence of sulfur dioxide; this is accompanied hy proliferation of the mucous glauds (5, p. 360). The principal effect of sulfur dioxide a t low concent,ration is increased inability to move air ill and out of the lungs (3, p. 360). Sulfuric acid is also formed in t,he atmosphere when sulfur dioxide reacts with ozone and water vapor in the presence of the oxides of nitrogen. The effect of sulfuric acid on man's respiratory system is the same as for sulfur dioxide, but to a greater degree (3,p. 352). Particles in the air are a very important source of pollution. An average home collects two pounds of dust per week. There are 3 X 10"ust particles in every cubic foot of air. With every breath you inhale
4 X lo4 to 7 X lo4 dust particles. City dwellers inhale one pound and seven ounces of dust a year (2, p. 53). Soot particles large enough to be subject to gravity are usually caught by mucous in the nose and throat (5, p. 351). These include part,icles that are over five microns in diameter (4, p. 78). The smaller particles are likely to he deposited in the deeper portions of the lungs of city dwellers. The blackened tissue is probable evidence that some of the sooty materials which were inhaled have been retained in the lungs. The soot itself has not been related to a specific disease in community exposure. I t is however, the chemicals absorbed on the soot which cause discase in man when soot is involved (5, p. 351). A small though significant amount of radioactive material exists in the air. The size of the particle will determine its destination within the body. The terminal site, the kind of radiation, and the amount of radioactive material are factors which influence the final effect. I t has been clearly proven t,hat inhalation of radioactive particles can produce lung cancer in experimental animals (5, p. 340). The foregoing discussion has clearly validated the importance of air pollution aud its effect on mall. There is no doubt in the writer's mind that this problem must be effect,ively dealt with in the near future. It is likely that air pollution is a more imminent danger to man than the thermonuclear weapons about which he worries so much. The failure of man to solve these problems may well put him in a position analogous to the S shaped curve of a bacterial culture population growth. Literature Cited (1) FAHBER, SEYMOUR iM.,"The Air We Breathe" (Editor:
Wilson, R.), Charles C. Thomas, Springfield, Ill., 1961. (2) LEWIS,H. R . , "With Every Breath We Take," Crown Publishing, h e . , New York, 1965. (3) STERN, A. C., "Air Pollution,'' Academic Press, Inc., New York. - .~~~ , 1962. -(4)MILLS, C. A,, "Air Pollution and Community Health," Christopher Publishing Co., Boston, Mnss., 1954.
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