The body's ability to breathe and trade oxygen for carbon dioxide is one of its greatest marvels. Awake or asleep, conscious or unconscious, our bodies breathe automatically without thought on our part. When we are quiet our bodies breathe 15 times a minute on average. Every day an average, moderately active person breathes about 20,000 liters of air.
Our bodies have sophisticated systems for filtering out particles (such as dust and soot, mold, fungi, bacteria and viruses) that can be deposited in our airways and on the surfaces of the air sacs. The estimated 300 million alveoli (air sacs) in our lungs create a surface area of more than 100 square meters, where our blood receives fresh oxygen and releases carbon dioxide and other waste gases produced by our bodies.
You can learn more about the lungs and respiratory system by clicking on the links below: