304 RESPIRATION 



The discomforts of warm or cold air are not usually associated 

 with rise or fall of internal body temperature. When suffering 

 great discomfort from sitting in a very cold room, I have found 

 the rectal temperature slightly raised rather than lowered, and 

 on going to an uncomfortably warm room there was a slight fall 

 in rectal temperature. Persons going unaccustomed into very 

 warm air may become faint or suffer from nausea or headache 

 without any appreciable rise of body temperature. There appears 

 to be a fall of arterial pressure owing to failure on the part of the 

 vasomotor center to compensate for the increased flow of blood 

 through the skin in a warm atmosphere, and this probably ac- 

 counts for the more striking symptoms. In any case persons soon 

 become more or less acclimatized within limits to the effects of 

 warm air. One can observe this in miners who become accustomed 

 to warm places in mines, or in people who become accustomed to 

 Turkish baths. 



It is somewhat noteworthy that men accustomed to hard outdoor 

 work seem to be much less sensitive to heat or cold indoors than 

 other persons. This is probably due to the fact that though they 

 are not accustomed to external heat they are accustomed to what 

 in this reference comes to much the same thing, namely, greatly 

 varied internal heat production, which involves the same capacity 

 for vasomotor adaptation as exposure to external heat or cold. 

 Those who are most affected by external heat or cold indoors are 

 persons who are not only unaccustomed to external heat, but are 

 also unaccustomed to hard muscular exertion. 



Part of the discomfort of warm air in rooms is due to its drying 

 effect on the skin and particularly the upper air passage. Winter 

 air warmed to a temperature of about 70° F. is very dry; and if 

 the skin and upper air passages are kept warm by the air they lose 

 far more moisture than usual and become uncomfortable. With 

 cold air the inside of the nose is kept cool, and during expiration 

 moisture condenses in it, so that it is kept moist in spite of the fact 

 that the cold air contains very little moisture. With warm dry air, 

 on the other hand, there is much evaporation during inspiration 

 and little or no condensation during expiration, so that the nose 

 is apt to become very dry ; and this appears to lead to swelling of 

 the mucous membrane. 



The combination of physiological disturbances produced b} 

 warm air in a room is apt to be attributed to chemical impurities 

 in the air. Owing to this fact, and general ignorance as to the 

 physiology, as distinguished from the chemistry, of respiration, 



