ABSTRACT
Carbon dioxide is produced in the process of breathing. The inspiration (ambient) air contains 21% oxygen, and very little carbon dioxide. The expiration air contains 17% oxygen, and 4% carbon dioxide. If the ventilation is inadequate, i.e. there is no supply of fresh air, the percentage of oxygen in the ambient air gets reduced, while the percentage of carbon dioxide increases. If the oxygen concentration in the breathing air becomes less than 10-12%, a person becomes unconscious. This condition can be treated by administering oxygen.
