The majority of ozone, approximately 90%, is found in the stratosphere. This layer starts around 10–16 kilometers (6–10 miles) above Earth's surface and extends up to about 50 kilometers (31 miles) in altitude. The region within the stratosphere with the highest ozone concentration is often referred to as the "ozone layer".
A smaller portion of ozone, around 10%, is present in the troposphere, the layer closest to Earth's surface.
