SOME ASPECTS OF HUMAN ECOLOGY IN HOT TROPICAL REGIONS 



Professor Sir David Brunt, Sec.R.S. 

 (London) 



I have always been attracted to that aspect of physiology which deals with the 

 relation of man to his physical environment, by the hope of finding some logical 

 basis for the classification of the climates which occur in different parts of the 

 globe. In Fig. 1 below is reproduced a diagram* in which is given a tentative clas- 

 sification of climates, which I had hoped to test by comparison with data of times of 

 day and year when work of a specified degree of activity became impossible. The 

 line CC was assumed to be the limit to the right of which outdoor work would be try- 



P C , A B 



X> 



40 



50 



SO 



JO 



BO 



90 100 ^ US ao 



TEMPERATURE *F. 



m 



140 150 leo iJO 190 190 200 no 

 (by courtesy of the Physical Society). 

 Figure 1. 

 AA. Heat- stroke limits for nude man resting in still air. 

 BB. Heat- stroke limits for nude man resting in air moving 200ft/min. 

 CC. Limiting conditions for clothed man resting in sunshine with about one- third of skin 



wetted with sweat. 

 DD. Limiting conditions for clothed man walking 3 m.p.h. with about one -third of skin 



wetted with sweat. 

 The broken line represents equivalent temperature 80°F. The figures 500 g, etc., indicate 

 rate of evaporation of sweat in grammes per hour for men of average size in order to main- 

 tain heat balance of the body. 



* from Brunt, D. 1947. Some Physical Aspects of the Heat Balance of the Human Body, 

 Ptoc. Phys. Sac, 59 713. 



213 



