THE BREATHING SYSTEM 



489 



search has revealed that helium, another 

 inert gas, leaves the tissues much faster 

 than nitrogen and for that reason has been 

 employed to prevent the sickness. Aviators 

 breathe the gas a few minutes before taking 

 off, thus replacing the nitrogen in their 

 tissues, and when they reach high altitudes 

 they do not suffer from decompression sick- 

 ness. 



The matter of ventilation in living quar- 

 ters has gone through various stages in the 

 past 100 years. It was once thought that 

 night air was bad and that all windows 

 must be battened down tight at night or 

 one would certainly "shiver with the ague." 

 It has since been learned that the "badness" 

 in the night air was mosquitoes and the 

 ague was due to the malarial parasites re- 

 siding in the body of the mosquito that 

 were transmitted by its bite to people. Then 

 someone mistakenly identified tuberculosis 

 with a lack of ventilation, so people went 

 into a period of living out in the open. Win- 

 dows were flung open at night and it was 

 considered in the interests of good health 

 to be covered with snow the following 

 morning while still lying in bed. Today a 

 more sane approach to the problem of 



ventilation has come about, based on sci- 

 entific facts. 



It is true that oxygen is withdrawn from 

 the inspired air and that in an air-tight 

 room after a considerable period of time all 

 of the oxygen would be used up. But who 

 lives in an air-tight room? Most houses are 

 so porous that the exchange through win- 

 dows, doors, and even walls and roof is 

 adequate to take care of all of the oxygen 

 needs of the people residing within. This 

 air turnover likewise rids the room of the 

 accumulated carbon dioxide. However, 

 everyone is familiar with the "stuffiness" 

 common in crowded theaters and other 

 gatherings. This feeling probably arises 

 from the increased humidity and tempera- 

 ture that comes from rebreathed air, min- 

 gled with the usual variety of body odors. 

 Circulating and drying the air restores it 

 to outside freshness. To insure comfort it 

 is necessary only to see that the air in the 

 house is circulated, and this is the princi- 

 ple of air-conditioning which has become 

 popular in recent years. This informa- 

 tion should give comfort to the householder 

 both in keeping his body warm and his 

 budget intact. 



