In his book, "The Living Temple"[3], the doctor speaks as follows on the importance of breathing pure air: "The purpose of breathing is to obtain from the air a supply of oxygen, which the blood takes up and carries to the tissues.

Oxygen is one of the most essential of all the materials required for the support of life....

The amount of oxygen necessarily required for this purpose is about one and one-fourth cubic inches for each breath....

In place of the one and one-fourth cubic inches of oxygen taken into the blood, a cubic inch of carbonic acid gas is given off, and along with it are thrown off various other still more poisonous substances which find a natural exit through the lungs.
The amount of these combined poisons thrown off with a single breath is sufficient to contaminate, and render unfit to breathe, three cubic feet, or three-fourths of a barrel, of air.

Counting an average of twenty breaths a minute for children and adults, the amount of air contaminated per minute would be three times twenty or sixty cubic feet, or one cubic foot a second....