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American Society of Heating and Ventilating Engineers Guide, iqjj''; Chapter 15--Air Pollution Fly-Ash, Cinders The term fly-ash is usually applied to the extremely small particles ash, and the term cinder to the larger particles of coke and ash which 1 - discharged with the gases of combustion from burning coal. re- AIR POLLUTION AND HEALTH Many kinds of dusts and gases are capable of producing pathology a changes which may cause ill health. The harmful effects depend largeh l upon the chemical and physical nature of the impurities, and the con f centration, length of time, and conditions under which they are breathed/l Dust particles must be minute in size to be inhaled at all, although fairlv^ large particles may gain access to the upper air passages. 'p $ The human body possesses remarkable filtering media for protecting the lungs. Small hairs which line the nasal passages, and a multitude of ? microscopic hairs, called cilia, in the epithelial lining in the bronchial tubes intercept many of the dust particles before they reach the lungs, I The constant inhalation of dusts in city air irritates the mucous mem-1 branes of the nose, throat, and lungs, and eventually may produce dis- / comfort and a series of minor respiratory disorders. The pigmented lung | of the city dweller is an example of the pathological change produced over I a period of years. This condition may be of no clinical importance, but ( an exaggeration of it in the coal miner results in anthracosis or dark spots 1 on the lung due to the presence of pigment in the lymph channels which " impairs the functioning of the lung cells under stress. Effects of Solids Bronchitis is the chief condition associated with exposure to thick dust, and follows upon inhalation of practically any kind of insoluble and noncolloidal dust. : Atmospheric dust in itself cannot be blamed for causing tuberculosis, but it appears to have a marked influence in aggravating the disease once it has started. There is, _however, quite reliable evidence that carbon pigment, one of the atmospheric dusts, tends to wall off local tuberculosis rather than to. further its spread. The sulphurous fumes and tarry matter in smoke are probably more dangerous than' the carbon.. In foggy weather the accumulation of these substances in the lower strata may be such as to cause irritation of the eyes, nose, and respiratory passages, leading to asthmatic breathing and bronchitis and, in extreme cases, to death. The Meuse Valley fog disaster will probably become a classic example in the history of gaseous air pollution. Released in a. rare combination of atmospheric calm and dense fog, it is believed that sulphur dioxide and other toxic gases from the industrial region of the valley caused 63 sudden deaths, and injuries to several hundred persons. Physical examination showed difficult breathing, rapid pulse, cyanosis, cardiac dilation, and a redness and inflammation of the mucosa of the nose, mouth, throat, trachea, and bronchi. Carbon monoxide from automobiles and from chimney gases con stitutes another important source of aerial pollution in busy cities. During, heavy traffic hours and under atmospheric conditions favorable to concentration, the air of congested streets is found to contain enough CO 260 [7 re the health of those exposed over a period of several hours, W'^arly if their activities call for deep and rapid breathing. In open ordinary conditions the concentration of CO in. city air is g.^ to be insufficient to affect the average city dweller or pedestrian. ^duiion of Solar Radiation Tu'g"joss of light, particularly the occlusion of solar ultra-violet light j 1 to smoke and soot, is beginning to be^recognized as a health problem 116 anV industrial cities. Measurements of solar radiation in Baltimore1 1? Actinic methods show that the ultra-violet light in the country was m oer cent greater than in the city. In New York City2 a loss as great as 50 per cent in visible light was found by the photo-electric cell method. The effect of air pollution on the health of city dwellers is difficult to determine, owing to the slowness pf its manifestations. The aesthetic and economic objections to air pollution are so definite, and the effect of airborne: pollen can be shown so readily as the cause of hay fever and other allergic diseases, that means and expenses of prevention or elimination of this pollution have seemed justifiable to the public. AIR POLLUTION IN INDUSTRY In many industrial processes, sufficient amounts of dusts, fumes,' and vapors are liberated to be injurious to the health of.workers. Some dusts are poisonous (lead, mercury, arsenic, manganese, and cadmium) and some act as irritants (silica, steel, iron, and granite).- Certain dusts may produce catarrhal conditions and increase susceptibility to such diseases as bronchitis, pneumonia, and tuberculosis. Silicious dust is especially harmful because it has a direct damaging action upon the tissue of the lungs, but organic dusts, both animal and vegetable (hair, pollen, textile, and fiber), do.not seem to affect the lungs at all, although they may cause considerable discomfort in the upper respiratory passages to persons sensitive to them. Industrial gases and fumes-act specifically upon the, mucous mem branes, the lungs, blood, skin, and eyes. Some extremely poisonous gases act after very short exposures. Among these are carbon monoxide, hydrogen sulphide, ammonia, chlorine, bromine, arsine,, arid-cyanogen. The industrial processes which liberate harmful substances are too manifold and the effects too diverse to be considered here, where dis cussion is limited to the commonest and most serious with which the ventilating engineer may be confronted, namely, carbon monoxide, lead, and silica; For a more thorough treatise on the subject reference should be made to books by Hamilton3, Rosenau4, ahd Henderson and Haggard6. Carbon Monoxide Poisoning Carbon monoxide is a common form of poisonous industrial gas, met with in mines, foundries,' coke-oven sheds, garages, and houses. Its action ' 'Effects of Atmospheric Pollution upon Incidence of Solar Ultra-Violet Light, by J. H. Shrader. M. H. Coblentx and F. A. Korff {American Journal of Public Health, p. 7, Vol. 19. 1929). Studies in Illumination,-by J. E. Ives (U.-S. Public fiealtkiService Bulletin,fioi, 197,1930)., . Mndustrial Poisons in the United States,, by Alice.Hamilton. `Preventive Medicine and Hygiene, by Milton J. Rosenau. ' v `: ` 'l!":'V: Noxious Oases, by Y. Henderson and H. Haggard. ' ' v'V 261 v I I ! i i i r E *