Does the atmosphere contain about 78 percent of oxygen true or false?

The atmosphere we breath is actually mostly nitrogen (70% roughly). The 22% of oxygen in the air is used by our body to give the blood cells oxyen which is transported to the parts of the body that use it to make energy by combusting glucose with it. The byproduct, carbon dioxide, is expelled through the lungs. Therefore, the portions of what gases we inhale and exhale are different.