At rest, the average adult inhales around 20 percent oxygen in the air and exhales about 15 percent oxygen, according to HowStuffWorks. People inhale and exhale approximately 7 or 8 liters of air each minute or 11,000 li... More »

Humans exhale oxygen, carbon dioxide and nitrogen. Humans inhale these same gases, though in different proportions to exhalation; that is, oxygen is exchanged for carbon dioxide during breathing. More »

Inhaling happens when a special muscle within the chest, called the diaphragm, contracts and expands the lungs, pulling in air. Conversely, exhaling occurs when the diaphragm relaxes and air is pushed out of the lungs. More »

About 4 percent of exhaled air is carbon dioxide, and 16 percent is oxygen. The majority of exhaled air — approximately 79 percent — is nitrogen. Carbon dioxide is released into the environment because is it a waste prod... More » Science Biology

During a pulmonary function test, the patient uses a mouthpiece attached to a machine that measures the amount of air the patient inhales and exhales, according to MedlinePlus. The patient also sits in a booth so that th... More » Health Diagnostics & Imaging

The process of breathing performs a number of important gas exchanges through inhalation and exhalation. When someone inhales, they contract and move their diaphragm, which allows the lungs to expand. This is a part of t... More »

Human beings require air because, like all other animals, they are aerobic organisms who require oxygen, which is a component of air. While oxygen is found in water, humans evolved to extract the oxygen from air, as bird... More »