5O BURNING OR OXIDATION 



40. How to Breathe. Air, which is essential to life and 

 health, should enter the body through the nose and not 

 through the mouth. The peculiar nature and arrangement 

 of the membranes of the nose enable the nostrils to clean, 

 and warm, and moisten the air which passes through them 

 to the lungs. Floating around in the atmosphere are dust 

 particles which ought not to get into the lungs. The nose 

 is provided with small hairs and a moist inner membrane 

 which serve as filters in removing solid particles from the 

 air, and in thus purifying it before its entrance into the 

 lungs. 



In the immediate neighborhood of three Philadelphia high 

 schools, having an approximate enrollment of over 8000 

 pupils, is a huge manufacturing plant which day and night 

 pours forth grimy smoke and soot into the atmosphere which 

 must supply oxygen to this vast group of young lives. If the 

 vital importance of nose breathing is impressed upon these 

 young people, the harmful effect of the foul air may be greatly 

 lessened, the smoke particles and germs being held back by 

 the nose filters and never reaching the lungs. If, however, 

 this principle of hygiene is not brought to their attention, 

 the dangerous habit of breathing through the open, or at least 

 partially open, mouth will continue, and objectionable matter 

 will pass through the mouth and find a lodging place in the 

 lungs. 



There is another very important reason why nose breath- 

 ing is preferable to mouth breathing. The temperature of 

 the human body is approximately 98 F., and the air which 

 enters the lungs should not be far below this temperature. 

 If air reaches the lungs through the nose, its journey is rela- 

 tively long and slow, and there is opportunity for it to be 

 warmed before it reaches the lungs. If, on the other hand, 

 air passes to the lungs by way of the mouth, the warming 



