The most common gas in air is oxygen.

Oxygen only makes up a quarter of air, but is essential for most living things.

There are other gases in air such as carbon dioxide. This gas isn't harmful to some living things.

We do not take in and release gases when we breathe.

We inhale when we take air in. The lungs expand as the air enters them.

Gases are not exchanged during breathing.

The lungs release oxygen into the blood, and it goes to all parts of our bodies.

The blood sends carbon dioxide into the lungs and we then release it.

As the result the air we that we inhale has more carbon dioxide. The air that we exhale has more oxygen.