The amount of oxygen in the air has little to do with the amount absorbed in respiration, as this is governed more by the need of the body than by the amount taken into the lungs.
Nature has made a wonderful provision in the protection of the body from extreme changes in the amount of oxygen in the air. This provision increases the degree of intellectual adaptation which is possible in the body. This is shown by the fact that there is a larger amount of oxygen contained at all times in the lungs than is required to supply the red blood cells. It is maintained that the alveolar air contains normally 16% of oxygen. The red blood cells are practically saturated with oxygen as they leave the lungs; however, this amount of oxygen may not be needed by the tissue cells which the red blood cells supply and the amount they absorb upon their return will depend upon what they have given off to the tissue cells.
It can readily be seen that the air in the lungs at no time contains the full percentage of oxygen, since one at no time completely exhales the entire amount of air. In this way the residual air loses some of its oxygen and collects carbon dioxide.
Animal life is sustained by the oxygen in the air while the carbon dioxide is essential to plant life. The oxygen is carried into the lungs during the inhalation which is produced by the expression of Innate Intelligence through the organs of respiration. The oxygen passes into the blood and is combined loosely with the hemoglobin of the red blood corpuscles; then under the direction of Innate it is carried to all the tissue cells of the body. Here the oxygen leaves the blood and is used in the oxidation which is necessary in the metabolism of the body.
The amount of required oxygen varies with different conditions that obtain in the body and is dependent upon age, the activity of the individual and his condition of health. Some authors assert that the average person will inhale about thirty-four pounds of air in twenty-four hours. This would mean a little over seven pounds of oxygen. Only about one-fourth of the oxygen inhaled is absorbed; therefore, according to these figures the individual would absorb on an average of about two pounds of oxygen in twenty-four hours.
Nitrogen (N)
The nitrogen in the air is of more importance to plant life than to animal life. It is of little significance from a hygienic standpoint, yet it is an important constituent of all matter containing protein. Nitrogen tends to regulate or influence the rate of combustion by diluting the oxygen in the air. Respiration does not seem to affect the amount of nitrogen in the air as there is no noticeable difference between the amount of nitrogen in the inspired and expired air.
Argon (A)
In 1894 Lord Rayleigh and Prof. William Ramsay discovered a gaseous substance in the atmosphere which had no chemical affinity. They gave this element the name argon which means in the Greek, “inactive.” So far as is known argon will not combine with any other element.
The atmosphere contains about 0.94% argon, but so far, according to Rosenau, it has not been demonstrated in the body. Argon has no hygienic significance. Helium, krypton, xenon, neon and argon form what is known as the argon group, since they will not unite with other elements to form compounds. These elements are all found in very small quantities in the atmosphere.