156 ELEMENTARY BIOLOGY 



The new understanding of the effects of heat and dampness 

 on the body's comfort and efficiency, and of the relative unim- 

 portance of the percentages of oxygen and carbon dioxid in 

 the air, has not eliminated the problem of ventilation, however. 

 On the contrary, it has made the problem more difficult, for 

 the engineers had about solved the problem of how to supply 

 a given quantity of new air to a room every hour. Now we 

 have to consider the temperature and the moisture, and at the 

 same time remove the disagreeable and sometimes distressing 

 odors that are accumulated in a room full of people at work. 



In many states the laws prescribe a minimum air space for 

 each worker, amounting in most cases to four hundred cubic 

 feet, exclusive of machinery or furniture. In a space of this 

 size it is possible to change the air fast enough to remove the 

 heat and the moisture given off by the body and the organic 

 substances given off by the lungs without causing a draft. 



188. Temperature of air. The prevailing temperature in a 

 living room, schoolroom, or workshop should be kept as nearly 

 as possible at 65 F. When the temperature approaches 70 

 it begins to be too uncomfortable and to affect the efficiency 

 of one's work. 1 



Where the character of the work requires that a lower tem- 

 perature be maintained, as in packing houses and in some 

 chemical works, the body should be provided with warmer 

 clothing, and the humidity of the atmosphere may be higher. 

 In mines, bakeries, tunnels, foundries, rolling mills, or other 

 places where the temperature is necessarily high, workers 

 should wear very light clothing, or even be stripped to the 



1 According to the'studies of engineers, rooms should be warmer or cooler, 

 according to the activities of those who occupy them. This idea is illustrated 



by the following table : 



ROOMS FOR RESTING OR FOR 

 ROOMS FOR ACTIVE OCCUPATIONS SEDENTARY OCCUPATIONS 



Shop for vigorous work, 50- 59 F. Sleeping room, 54-59 F - 



Gymnasium, 60 F. Lecture hall, 6i-64F. 



Shop and room for moderate Living room, office, school, 68 F. 



work, 6i-66 F. Bathroom, 68-72 F. 



