Document rxLzBDEpyxoQ3wwVLErELOp2V

American Society of.Heating and Ventilating Engineers Guide, 1936 Table 1. Physiological Responses to Heat of Men at Rest and at Work EriTCTTTE Temp. Actual Cheek Temp (Deg Fahr) 60 _______ 70 _______ 80 96.1 85 96.6 90 97.0 95 97.6 100 99.6 105 104.7 110 -- Men at Rest Men at Work 90,000 it-lb of Work per Hour Rise in Rectal Temp (Deg Fahr per Hoar) Increase in Pulse Rate (Beats per Min per Hour) Approximate Loss in Body Weight by Perspiration (Lb per Hr) Total Work Accomplished (Ft-lb) Rise in Body Temp (Deg Fahr per Hr) Increase in Pulse Rate (Beats per Min per Hr) Approximate Loss in Body Wt. by Per- epiration (Lb per Hr) 0.0 0.0 0.1 0.3 0.9 2.2 4.0 5.9b 6 0 i 4 15 40 83 137b 0.2 0.3 0.4 0.5 0.9 1.7 2.7 4.0b 225,000 225,000 209,000 ' 190,000 153,000 102,000 67,000 49,000 37,000 0.0 0.1 0.3 0.6 1.2 2.3 4.0 6.0b 8.5b 6 7 11 17 31 61 103b 158b 237b 0.5 0.6 0.8. 1.1 1.5 2.0 2.7 3.5b 4.4b "Data by A.S.H.V.E. Research Laboratory. bComputed value from exposures lasting less than one hour. The'stomach loses some of its power to act upon the food, owing to a diminished secretion of gastric juice, and there is a corresponding loss in the antiseptic and antifermentive action which favors the growth of bacteria in the intestinal tract6. These are considered to be the potent factors in the increased susceptibility to gastro-intestinal disorders in hot summer weather. The victim may lose appetite and suffer from indiges tion, headache and general enervation, which may eventually lead to a premature old age. . In warm atmospheres, particularly during physical work, a considerable amount of chloride is lost from the system through sweating. The loss of this substance may lead to attacks of cramps, unless the salts are replaced in the drinking water. In order to relieve both cramps and fatigue, Moss6 recommends the addition of 6 grams of sodium chloride and 4 grams of potassium chloride to a gallon of water. The deleterious physiologic effects of high temperatures exert a power ful influence upon physical activity, accidents, sickness and mortality. Both laboratory and field data show clearly that physical work in warm atmospheres is a great effort, and that production falls progressively as the temperature rises. The incidence of industrial accidents reaches a minimum at about 68 F, increasing above and below that temperature. Sickness and mortality rates increase progressively as the temperature rises. EFFECTS OF COLD The action of cold on human beings is not well known. Cold affects the human organism in two ways: (1) through its action on the body-as a whole, and (2) through its action on the mucous membranes of the upper respiratory tract. Little exact information is available on the latter. On exposure to cold, the loss of heat is increased considerably and only `Influence of Effective Temperature upon Bactericidal Action of Gasto-Intestinal Tract, by Arnold and Brody (Proceedings Society Exp. Biol. Med. Vol. 24. 1927, p. 832). Some Effects of High Air Temperatures upon the Miner, by K. N. Moss (Transactions Institute of Mining Engineers, Vol. 66, 1924, p. 284). 60 Chapter 3__ Ventilation and Air Conditioning Standards within certain limits is compensation possible by increased heat produc tion and decreased peripheral circulation. The rectal temperature often rises upon exposure to cold but the pulse rate and skin temperature fall. The blood pressure increases, owing to constriction in the peripheral vessels and to thickening of the blood. The subcutaneous tissues and muscles form reservoirs for storing the water which leaves the blood. In extremely cold atmospheres compensation becomes inadequate. The body temperature falls and the reflex irritability of the spinal cord is markedly affected. The organism may finally pass into an unconscious state which ends in death. Cannon showed that excessive loss of heat is associated with increased activity of the adrenal medulla7. The extra output of adrenin hastens heat production which protects the organism against cooling. Bast8 found a degeneration of thyroid and adrenal glands upon exposure to cold. Effects of Temperature Changes A moderate amount of variability in temperature is known to be beneficial to health, comfort, and the performance of physical and mental work. On the other hand, extreme changes in temperature, such as those experienced in passing from a warm room to the cold air out of doors, appear to be harmful to the tissues of the nose.and throat which are the portals for the entry of respiratory diseases. Experiments show that chilling causes a constriction of the blood vessels of the palate, tonsils and throat, which is accompanied by a fall in the temperature of the tissues. On rewarming, the palate and throat. do not always regain their normal temperature and blood supply. This anaemic condition favors bacterial activity and it is believed to play a part in the inception of the common cold and other respiratory diseases. It is believed, that.the lowered resistance, is due. to ft diminution in the number and', phagocytic activity of -the; .leucqoyfes,'"(white blood cells) brought about by exposure to coid and by changes in temperature. Sickness records in; industries.'seem ^'.'strengthen this belief. TheIndustrial Fatigue Research Board' of' England9 found that in workers exposed to high temperatures g5id.,to changes in temperature, namely, steel melters, puddlers, and tiri-piafe millmen, there is an excess of all sickness, the excess among the puddlers being due chiefly to respiratory diseases and rheumatism. The causative factor was not the heat itself but the sudden changes in temperature to which the workers were exposed. The tin-plate millmen who were not exposed to chills, since they work almost continuously throughout the shift, had no excess of rheumatism and respiratory diseases. On the other hand, the blast-fumacemen, who work mostly in the open, showed more respiratory sickness than the steel workers. This experience in British factories is well in accord with the findings in American industries10. According to these data the highest Studies on the Condition of Activity of Endocrine Glands, by W. B. Cannon, A. Guerido, S. W. Britton and E. M. Bright (American Journal of Physiology, Vol. 79, 1926, p. 466). Studies in Exhaustion Due to Lack of Sleep, by T. H. Bast, J. S. Supernaw, B. Liebermari and J. Munro (American Journal of Physiology, Vol. 85, 1928, p. 135). Fatigue and Efficiency in the Iron and Steel Industry, by H. M. Vernon (Industrial Fatigue Research Board, Report No. 5, 1920, London). "Iron Foundry Workers Show Highest Percentage of Deaths from Pneumonia (Statistical Bulletin, Metropolitan Life Insurance Company, 1928). 61