The diagram's title can be called, "What's In Our Air."
Air typically contains about 78% nitrogen and 21% oxygen, with the remaining 1% consisting of carbon dioxide, water, and noble gases, depending on the altitude you're on. The human body inhales the oxygen in the air to drive the cellular processes within the body. The carbon dioxide in the air can be attributed to the exhaling of carbon dioxide by humans. The nitrogen that is inhaled is simply exhaled out by the body, unchanged.
