A climber in Russia's Kamchatka Peninsula wears a gas mask to keep noxious volcanic fumes out of his lungs. The vital organs filter air 24 hours a day, providing the body with the oxygen it needs to survive.
Learn more about the human body's respiratory system.
Our lungs fuel us with oxygen, the body's life-sustaining gas. They breathe in air, then extract the oxygen and pass it into the bloodstream, where it's rushed off to the tissues and organs that require it to function.
Oxygen drives the process of respiration, which provides our cells with energy. When we exhale, we produce carbon dioxide as a byproduct. Without this vital exchange, our cells would quickly die and leave the body to suffocate.
Since the lungs process air, they are the only internal organs that are constantly exposed to the external environment. Central to the human respiratory system, they breathe in between 2,100 and 2,400 gallons (8,000 and 9,000 liters) of air each day—the amount needed to oxygenate the 2,400