Document mqJQErywaM9mXeL0EKnwe59vJ

American Society of Heating and Ventilating Engineers Guide, 1936 is due to the fact that the combining power of carbon monoxide with the haemoglobin of the red blood corpuscles is about 300 times greater than that of oxygen. Since the resulting stable combination destroys the power of the haemoglobin to unite with oxygen in the lungs and to supply it to the tissues, the effects are due to lack of oxygen, and the symptoms are those of anoxemia, namely, dizziness, headaches, sleepiness, fatigue, and, in extreme cases, paralysis and death. The dangerous saturation level of the blood with carbon monoxide is about 50 per cent. Even as little as 0'.07 per cent in the air will render, in half an hour, one quarter of the red corpuscles incapable of uniting with oxygen. One to two parts per 10,000 parts of air is set as a safe limit of pollution which may be breathed for a long time without producing perceptible symptoms. Silicosis Silicosis is a chronic disease of the lungs which results from the local physio-chemical action of hydrated silica upon the pulmonary tissue, causing progressive lymphatic fibrosis, and rendering the tissue suscep tible to tuberculosis. The disease is slow in evolution, requiring usually a number of years of exposure. It occurs principally among granite workers, sand blasters, metal miners, metal polishers, potters, and mill stone workers. Lead Poisoning Lead poisoning is the most insidious and most common of all industrial diseases. It occurs principally among lead workers and smelters, lead miners, potters, painters, typesetters, st;ereotypers, plumbers, and workers with glass, gold and silver. Lead, in practically all forms, is a cumulative poison which is absorbed by way of the blood stream, chiefly from the respiratory tract, but also from the digestive tract and from the skin. The effect may be either an acute or chronic poisoning. The principal symptoms are colic, constipation, anemia, headache, anorexia, a bluish line along the edges of the gums, rheumatic pains, and, in extreme conditions, paralysis, blindness, insanity, and death. It has been found6 that 2 mg per day is the smallest dose, by inhalation, which in the course of years may result in lead poisoning. Regular inhalation during the usual working hours of air containing less than 0.2 mg of lead per cubic meter does not seem to produce serious lead poisoning in individuals of representative industrial groups7. Prevention \ The prevention of industrial hazards from dusts and. poisonous gases is largely a ventilation problem consisting of keeping the impurities in air down to a safe concentration- As yet there are no generally accepted standards on which to base the design of the ventilation equipment. Approximate data on the toxicity of various gases and fumes met with in industrial establishments are given in Table 1. Column 5, giving the maximum allowable concentrations for prolonged exposures, was com piled from experiments in which most exposures lasted not more than a Lead Poisoning, by Thomas Morrison Legge (Journal Royal Society Arts, 1929, Vol. 77, p. 1023). What is a Dangerous Quantity of Lead Dust in Air, by C. M. Sails (Industrial Hygiene Bulletin, New York State Department of Labor, 1925). 290 Chapter 15--Air Pollution week, and it is reasonable to assume that over more prolonged exposures such concentrations would cause pernicious effects. Much is known concerning the physiological and pathological effects induced by various types and concentrations of atmospheric pollutants. In the absence of an accepted standard for safe breathing, and because of the slow, cumulative effects of certain kinds of air contaminants, the best procedure is the periodic medical examination of individuals, and the Table 1. Toxicity of Gases and Fumes in Parts per 10,000 Parts of Air* Vapor ob Gab Rapidly Fatal Maximum Concentration POB PROM M to Hour Maximum Concentration por 1 Hour Maximum Allowable fob Prolonged Exposure Carbon monoxide............. Hydrocyanic acid............. Ammonia---------------------Hydrochloric acid gas.---Chlorine.................. ........ Hydrofluoric acid gas. .-- Sulphur dioxide.------------Hydrogen sulphide-......... Carbon bisulphide.______ Phosphene......... ............. Arsine.. ............ ........... Phosgene.__ ............. . Nitrous fumes.. ------------Benzene________________ Toluene and xylene.-------- 40 800-1000 30 50-100 10-20 10 2 4-5 10-30 20 m Over M 2K-7H 190 190 Nitrobenzene._______ ___ Carbon tetrachloride-...... Chloroform.____ Tetrachlorethane Trichlorethylene___ Methyl chloride Methyl bromide____ _ ,, Lead vapor.__ :_________ 243 480 250 73 370 1500-3000 200-400 15-20 m 25 M a & 5-7 11 4-6 M M 1-iM 100-220 240 140 .... 200-400 20-40 -- 10 M 3 _______ 2-3 5 1-2 M 31-47 31-47 1-iM Koo 40 50 70 10 -- i M l Mo Moo M3 Mo l M Moo Mo Moo 16 2 1M 5-10 2 5-6 Original data compiled by Y. Henderson and H. Haggard. (See Noxious Cases, 1927.) Data revised by T. M. Legge. (See Lessons Learned from Industrial Gases and Fumes, Institute of Chemistry of Great Britain and Ireland, London, 1930.) routine measurement and study of the concentration and the physical and chemical characteristics of the dusts to which those individuals are exposed. ABATEMENT OF SMOKE AND AIR POLLUTION Successful abatement of atmospheric pollution requires the combined efforts of the combustion engineer, the public health officer, and the public itself. The complete electrification of industry and railroads, and the separation of industrial and residential communities would aid materially in the effective solution of the problem. In the large cities where the nuisance from smoke, dust and cinders is 291