AIR AND WATER 31 



dwelling rooms ordinarily are very much below that point. 

 Air which is continuously hot and dry does not provide a 

 healthful environment. Persons who live in such air are rest- 

 less, often sleep poorly, and the sensitive membranes of nose, 

 ears, and throat become dry and parched, thus rendering 

 the possessors more susceptible to' cold infections. Further- 

 more, such persons are affected by cold temperatures more 

 readily and more seriously than are others, since in the dry 

 air the skin evaporates water more rapidly and produces 

 the cold feeling. Such persons often urge higher tempera- 

 tures when lower temperatures and higher relative humidity 

 are what they usually need. Tightly closed, highly heated, 

 relatively nonhumid houses are disease breeders, while average 

 temperatures, open windows, and abundant moisture and fresh 

 air predispose toward good health 



