ADAPTATIONS OF HUMAN BODY TO VARYING THERMAL CONDITIONS 



303 



moderate temperature range (20°-27°C, 

 68°-81°F), the effect of humidity is over- 

 emphasized. 



TABLE XIII 



The Stress Effect of Rising Effective 



Temperature on Circulation and 



Water Balance 



(American Society of Heating and 



Ventilating Engineers, 2) 



* Computed for exposures lasting less than 

 one hour. 



tive humidity in the hot zone. It should be 

 remembered that Fig. 10 appUes to nude 

 subjects in a semi-rechning position. The 

 comfort chart of the American Society of 

 Heating and Ventilating Engineers was 

 based on studies with subjects who were 

 allowed a certain freedom of movement and 

 had a substantially higher metabolism. 

 They were fully clothed under cold condi- 

 tions and stripped to the waist under hot 

 conditions. 



Physical Cost of Excess Clothing Under Hot 

 Conditions 



Aside from simple over-heating, the prin- 

 cipal effects of clothing under warm condi- 

 tions are (1) a possible reduction of solar heat 

 gain and an increase in evaporative efficiency 

 under certain circumstances, and (2) an in- 

 crease in circulatory stress and dehydration 

 effects where more clothing is required for 

 other reasons than is desirable from a purely 

 thermal standpoint. In Table XIV, the vari- 



20 



25 



30 



35 



80 - 



70 

 60 



50 

 40 

 30 

 20 



lO 



60 



65 



70 



75 80 85 90 95 



DRV^ULB TEMPERATURE °? 



100 



105 



110 



Fig. 10. The relation of air movement, relative humidity, and operative temper 

 comfort as experienced by unclothed subjects at rest 



100 

 90 

 60 



70 



60 



50 

 40 

 30 

 20 



10 



115 



ature, to thermal 



The general relations of sensations of com- 

 fort[]are presented graphically in Fig. 10, 

 plotted on the abscissa against dry-bulb tem- 

 perature and on the ordinate against air 

 movement in the cool zone and against rela- 



able dehydration stress that may be imposed 

 by clothing is illustrated. These results show 

 the sweat secretion of a young male subject 

 working on a bicycle ergometer with a total 

 heat production of 279 kg. cal. per hr. This 



