174 BIOLOGY AND HUMAN LIFE 



inhaling fumes in a closed or poorly ventilated garage, since this 

 gas is produced when a motor is driven with insufficient air. 



142. Summary on breathing and ventilation. It is only in 

 recent times that we have found out the close connection there 

 is between our breathing habits and conditions and our health, 

 happiness, and efficiency. The most important details that have 

 been discovered are the following: 



1. Outdoor air is better than indoor air in every way. 



a. It is better for playing, even in the cold and rain ; suitable cloth- 

 ing will make up for these. 



h. It is better for work, since a person can accomplish more in a 

 given time when breathing outdoor than when breathing in- 

 door air. 



c. It is better for health, even to sleep out of doors. 



2. Nose breathing is in every way better than mouth breathing. 



a. Where mouth breathing is due to adenoids, these growths should 



be removed. 



b. Where mouth breathing is due to bad habits, these habits should 



be corrected. 



3. Deep breathing is better than shallow breathing. 



a. Where shallow breathing is due to improper clothing, the cloth- 

 ing should be changed. 



h. Where shallow breathing is due to habit, correct habits should 

 be acquired through outdoor games, outdoor work, etc. 



4. Ventilation is necessary not only to keep down the proportion 



of CO2 and to keep up the proportion of ogygen in the air, but 

 also to (a) regulate the moisture, {b) regulate the temperature, 

 {c) keep the air moving, {d) remove disagreeable odors, (e) re- 

 move gases and fumes, (/) remove dust. 



5. A person suffocated or drowned is not to be given up for dead be- 



fore every possible effort to resuscitate him has been made in vain. 



6. Dust as a source of danger to the health of the body and to the 



lungs in particular is discussed more fully in Chapter XXXVI. 



a. Mechanical dust, soot, and smoke (including tobacco smoke) 



coat the lining of the air sacs and reduce the breathing surface. 



b. Hard dust may scratch the lining of the air sacs and thus in- 



crease exposure to infection. 



c. Dust carrying microbes is a direct source of danger. 



d. Chemical dust and fumes may poison the blood. 



