Document QgGpr4EzLYyv2m1kbRpxXvgp7

HEAflNG VENTILATINC AIR CONDITIONING GUIDE 1942 velocities (particularly localized drafts) should be avoided since dif ferential cooling of one area of the body may produce surprisingly un pleasant reactions in quite different parts of the body. In a recent experiment16 it was shown that the application of an ice pack to an area of 60 sq cm on the back of the neck for. 15 min caused a drop of 17 F in the skin temperature of the fingers and that this low temperature of the fingers persisted for one hour after the ice pack was removed. ADAPTATION TO HOT CONDITIONS It will be observed from Fig. 1 that a zone ranging from about 70 to 80 F, at 45 per cent relative humidity (or from 66 to 74 deg ET) the body is adequately able to maintain equilibrium through control of radiation and convection losses combined, and evaporative loss. This corresponds to the zone over which the largest percentage of persons find optimum comfort. For higher temperatures, up to an upper limit in the neighbor- Table 2. Physiological Responses to Heat of Men at Rest and at Work* Effective Tbkp Actual Cheek Temp (Deo 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 pt-lb op Wore per Hour Rise in Rectal Temp (Deg Fahr per Hr) Increase in Pulse (BeRaatsteper Min^jwr Approximate Loss in Body Weight by Perspiration (Lb per Or) Total Work Accomplished (Ft-Lb) Rise in Body Temp (Deg Fahr per Hr) Increase in P(BuelsaetsRapteer Min per Hr) Approximate Loss in Body Wt by_ Per spiration (Lb per Hr) 225,000 0.0 o.o 6 6.2 225,000 0.1 0.0 0 0.3 209,000 0.3 0.1 i 0.4 190,000 0.6 0.3 4 0.5 153,000 1.2 0.9 15 0.9 102,000 2.3 2.2 40 1.7 67,000 4.0 4.0 83 2.7 49,000 6.0b 5.9b 137b 4.0b 37,000 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. ^Computed value from exposures lasting less than one hour. hood of 100 F, at 45 per cent relative humidity (or approximately 87 deg ET) control is had through availability of perspiration on the body surface for evaporation. While a fair degree of temperature equilibrium is main tained over this range it is nevertheless had with considerable discomfort. Studies at the John B. Pierce Laboratory of Hygiene16 have indicated the relation between discomfort and the degree of wetting of the body surface by perspiration for lightly clothed subjects in a semi-reclining position, and the investigators there have designated this as the zone of evaporative regulation. Work of the A.S.H.V.E. Research Laboratory17 ,5The Relative Influence of Radiation and Convection Upon the Temperature Regulation of the Clothed Body, by C.-E. A. Winslow, L. P. Herrington and A. P. Gagge (American Journal of Physiology, Vol. 124, October. 1938, p. 51). .\ . ^Relations Between Atmospheric Conditions, Physiological Reactions, and Sensations of Pleasantness, by C.-E. A. .Winslow, L. P. Herrington and A. P. Gagge (American Journal of Hygiene, Vol. 26, July, 1937, P-102). The Reactions of the Clothed Human Body to Variations in Atmospheric Humidity, by C.-E. A. Winslow, L. P. Herrington and A. P. Gagge (American Journal of Physiology, Vol. 124, December, 1938. p. 692). *7Loc. Cit. Note 11. 46 CHAPTER 2. PHYSIOLOGICAL PRINCIPLES over the past two decades has made available data on the relation between sensible perspiration and the atmospheric environment.for normal persons at rest and at work. For colder conditions below 70 F, with 45 per cent relative humidity (or about 66 deg ET) thermal equilibrium is maintained, first, by the amount of clothing worn; second, and to a smaller extent, by limiting availability of heat at the surface by decreasing peripheral blood circu lation, which results in a drop in skin temperature; and third, by an increase in the metabolic rate. Here again, while thermal equilibrium is fairly well maintained, any drop in the skin temperature is accompanied by a certain degree of discomfort. Studies at the A.S.H.V.E. Research Laboratory18 and elsewhere19 during the past two decades have made available a mass of information dealing with the physiological effects of hot atmospheres on workers and means to alleviate the distress and hazards associated therewith. This interest has been termed air conditioning in industry, or the effects of hot atmospheres in industrial hygiene, and is a growing factor in air conditioning applica tions. Table 2 gives some of the physiological responses of men at rest and at work, to hot environments. Recent physiological studies20 indicate that frequent and continued exposure of workers to hot environments results in not only violent but subtle physiological.derangement, affecting the leucocyte count of the blood and other factors dealing with man's mechanism of defense against infection. Another of the deleterious effects of high temperatures is that the blood is diverted from the internal organs to the surface capillaries, in order to serve in the process of cooling. This affects the stomach, heart, lungs and other vital organs, and it is suggested that the feeling of lassitude and discomfort experienced is due in part to the anaemic condition of the brain. 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 tract21. These are considered to be the potent "A S H.V.E. Research Report No. 654--Some Physiological Reactions to High Temperatures and Humidities, by W. J. McConnell and F. C. Houghten (A.S.H.V.E. Transactions. Vol. 29, 1923; p. 129). A S.H.V.E. Research Report No. 672--Further Study of Physiological Reactions, by W. J. McConnell. F. C. Houghten and F. M. Phillips (A.S.H.V.E. Transactions. Vol. 29, 1923. p. 353). A.S.H.V.E. Research Report No. 690--Air Motion, High Temperatures and Various Humidities--Reactions on Human Beings, by W. J. McConnell. F. C. Houghten and C. P. Yaglou (A.S.H.V.E. Transactions. Vol. 30. 1924, p. 167). A.S.H.V.E. Research Report No. 718--Work Tests Conducted in Atmospheres of High Temperatures and Various Humidities in Still and Moving Air, by W. J. McConnell and C. P. Yaglou (A S.H.V.E. Transactions, Vol. 31. 1925, p. 101). A.S.H.V.E. Research Report No. 719--Basal Metabolism Before and After Exposure to High Temperatures and Various Humidities, by W. J. McCon nell, C. P. Yaglou and W. B. Fulton (A.S.H;V.E. Transactions, Vol. 31. 1925, p. 123). A.S.H.V.E. Research Report No. 908--Heat'and Moisture Losses from Men at Work and Application to Air Con ditioning Problems, by F. C. Houghten, W. W. Teague, W. E. Miller and W. P. Yant (A.S.H.V.E. Trans actions, Vol. 37,1931, p. 541). A.S.H.V.E. Research Report No. 1105--Air Conditioning m IndustryPhysiological Reactions of Individual Workers to High Effective Temperatures, by W. L. Fleisher, A. E. Stacey, Jr., F. C. Houghten and M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 45, 1939, p: 59). A.S.H.V.E. Research Report No. 1153--Seasonal Variation in Reactions to Hot Atmospheres, by F. C. Houghten, A. AVRosenberg arid M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 46. 1940). Physiologic Effects of Hot Atmospheres, by F. C. Houghten, M. B. Ferderber and A. A. Rosenberg (Industrial Medicine, January, 1940, p. 7). A.S.H.V.E. Research Report No. 1151--The Peripheral Type of Circulatory Failure in Experi mental Heat Exhaustion, by R. W. Keeton, F. K. Hick. Nathaniel Glickman and M. M. Montgomery (A.S.H.V.E. Transactions, Vol. 46. 1940). "A.S.H.V.E. Research Report No. 1153--Seasonal Variation in Reactions to Hot Atmospheres, by F. C. Houghten. A. A. Rosenberg and M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 46, 1940). 11 Influence of Effective Temperature upon Bactericidal Action of Gastro-Intestinal Tract, by Arnold and Brody (Proceedings Society Exp. Biol. Med;, Vol. 24, 1927, p. 832). 47