The Ozone Layer The Earth's atmosphere is divided into several layers. The next layer, the stratosphere, continues from 10 km to about 50 km.
Ozone is a molecule containing three oxygen atoms.
It is blue in color and has a strong odor. Normal oxygen, which we breathe, has two oxygen atoms and is colorless and odorless. Ozone is much less common than normal oxygen. Out of each 10 million air molecules, about 2 million are normal oxygen, but only 3 are ozone. However, even the small amount of ozone plays a key role in the atmosphere.