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232 CHAPTER >13 1949 Guide' 17 Performance in Relation to Environmental Temperature, by L. W. Eichna W. B. Bean, W. F. Ashe and N. Nelson, (Bulletin of Johns Hopkins Hospital, Vol. 7b' 1945, p. 25-58). ' 17 Physiological Response of' Subjects Exposed to High Effective Temperatures and Elevated Mean Radiant Temperatures, by C. M. Humphreys, Oscar Imalis and Carl Gutberlet (A.S.H.V.E. Journal Section, Healing, Piping & Air ConditioningMarch, 1946, p. 101). ** Life, Heat and Altitude, by David B. Dill (Harvard University Press, Cam bridge, 1938). , 70 The Upper Limits'of Environmental Heat and Humidity Tolerated by Accli matized Men, Working in Hot Environments, by Ludwig W. Eichna, William F. Ashe William B. Bean and Walter B. Shelley (The Journal of Industrial Hygiene and Toxi cology, Vol. 27, March, 1945, p. 59). *1 A.S.H.V.E. Research Report No. 1188--Local Cooling of Workers in Hot Industry, by F. C. Houghten, M. B. Ferderber and Carl Gutberlet (A.S.H.V.ETransactions, Vol. 47,1941, p. 403). 77 A.S.H.V.E. Research Report No. 673--Determination of the Comfort Zone, by F. C. Houghten and C. P. Yaglou (A.S.H.V.E. Transactions, Vol. 29,1923, p. 361). A.S.H.V.E. Research Report No. 691--Cooling Effect on Human Beings Produced by Various Air Velocities, by F. C..Houghten and C. P. Yaglou (A.S.H.V.E. Trans actions, Vol. 30, 1924, p. 193)> A.S.H.V.E. Research Report No. 717--Effective Temperature with Clothing, by C. P. Yaglou and W. E. Miller (A.S.H.V.E. Trans actions, Vol. 31, 1925, p. 89). A.S.H.V.E. Research Report No. 755--Effective Temperature for Persons Lightly Clothed and Working in Still Air, by F- C. Hough ten, W. W. Teague and W. E. Miller (A.S.H.V.E. Transactions, Vol. 32, i926, p. 315). How to Use the Effective Temperature Index and Comfort Charts, by C. P. Yaglou, W. H. Carrier, Dr. E. V. Hill, F. C. Houghten and J.- H. Walker (A.S.H.V.E. Trans actions, Vol. 38, 1932, p. 410). ** A.S.H.V.E. Research Report No. 1196--Comfort with Summer Air Condition ing, by Thomas Chester, N. D. Adams, C. R. Bellamy, G. D. Fife, E. P. Heckel, Dr. W. J. McConnell, F. C. McIntosh, A.1 B. Newton, B. F. Raber and C. Tasker. (A.S.H.V.E. Transactions; Vol. 48,1942, p. 107). *4 Conditions for Comfort, by C. S. Leopold (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, June, 1947, p. 117). . 77 A.S.H.V.E. Research Report No.. 1102--Shock Experiences of 275 Workers ' : After Entering and Leaving Cooled and Air Conditioned Offices, by A. B. Newton, F. C. Houghten, Carl Gutberlet, R. W. Qualley and M. C. W. Tomlinson (A.S.H.V.E. Transactions, Vol. 44,1938, p. 571). Physiologic Adjustments of Human Beings to Sudden Change in Environment, by N. Glickman, T. Inouye, S. E. Telser, R. W. Keeton,,F. K. Hick and M. K. Fahnestock, A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, July, 1947, p. 10]. 74 A.S.H.V.E. Research Report No. 1055--Cooling Requirements for Summer' Comfort Air Conditioning, by F. C. Houghten, F. E. Giesecke, C.- Tasker and Carl Gutberlet (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 145). 77 A.S.H.V.E. Research Report No. 1012--Study of. Summer Cooling in the Re search Residence for the Summer of 1934, by A. P. Kratz, S. Konzo, M. K. Fahne stock and E. L. Broderick (A.S.H.V.E. Transactions, Vol. 41,1935, p.,207). 77 A.S.H.V.E. Research Report No. 755-rEffective Temperature for Persons , Lightly Clothed and Working in Still Air, by F. C. Houghten, W. W. Teague and W. E. Miller (A.S.H.V.E. Transactions, Vol. 32, 1926, p. 315). 77 A Practical System of Units for the Description of the Heat Exchange of Man with His Environment, by A. P. Gagge, A. C. Burton, and H. C. Bazett (Science, Vol. 94, 1941, p. 428). ., . Thermal Insulation of Clothing, by C. P. Yaglou (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, Sept. 1948, p. 107). 71 Application of Air- Conditioning to Premature Nurseries in Hospitals, by C. P. . Yaglou, Philip Drinker, and K. D. Blackfan (A.S.H.V.E. Transactions, Vol. 36; .1930, p. 383). - CHAPTER 13 air conditioning in the prevention AND TREATMENT OF DISEASE Control of Airborne Infection, Value of Air Cooling Under Tropical Conditions, Treatment of Disease, Operating Rooms, Nurseries for Premature Infants, Fever Therapy, Cold Therapy, Allergic Disorders, Oxygen Therapy, General Hospital Air Conditioning THE late war caused an increase of interest in the preventive aspects of air conditioning. It reemphasized the importance of the control of airborne infection and demonstrated the value of air cooling under tropical conditions for the prevention of heat rash, for promoting proper rest and sleep, and in the convalescence of patients. CONTROL OF AIRBORNE INFECTION The majority of airborne diseases are spread indoors where people gather. Any program of air sanitation is influenced by a number of factors. In the winter months, the closing of doors, windows and other means of access to the outside air to conserve warmth as well as the crowding of persons indoors provides conditions conducive to a high incidence of contagion. This seasonal phenomenon, illustrated in Fig. 1 which represents a study made by the U. S. Public Health Service, will concern the ventilating engineer in so far as air quality, determined by temperature, humidity, air replenishment and type of air movement and by freedom from contamina tion, is a major intrinsic factor. Apart from the seasonal picture of air-, borne contagion are such extrinsic factors as rate of turnover of personnel and the marked susceptibility of the recruit in comparison with permanent personnel1 as shown in Fig. 2 by studies of military personnel housed in barracks. These extraneous variables and the factor of contact infection (direct spray) tend to complicate any evaluation of the effectiveness of air sanitation for elimination of micro-organisms in droplet-nuclei and drop let-dust. Thus, control measures may eliminate consistently 90 per cent of airborne organisms in laboratory tests, but cannot effect a decrease in actual incidence of infection exceeding 30 per cent. Thirty per cent may be the maximal reduction in infection possible by air treatment methods. The distinction should be clearly drawn, therefore, between the effective ness of a procedure in laboratory tests and its effectiveness and applicability in actually reducing the incidence of airborne disease. On the other hand, recent studies suggest that inhalation of dust borne bacteria is more im portant than direct inhalation of infectious droplets or droplet nuclei in the spread of respiratory tract infections8. The following sequence of events has been postulated as occurring in a large proportion of intra-ward infections: (a) ejection of relatively large protected infective particles from patients,- (b) rapid venting or settling of these particles so that those remaining airborne are in low con centration, (c) survival of infective particles to permit, the accumulation of high concentrations on surfaces, (d) repeated reintroduction of infective particles into the air under the stimulus of ward activities or by air currents of the order of 50 fpm over the floor, and (e) extension of infective areas by air turbulence throughout the ward or hospital. The most important link 233