Explanation : Ozone occurs in two layers of the atmosphere.
The layer closest to the Earth's surface is the
troposphere. Here, ground-level or "bad"
ozone is an air pollutant that is harmful
to breathe and it damages crops, trees and
other vegetation. It is a main ingredient of
Urban smog. Therefore high concentration
of in the lower troposphere is not desirable.
Whereas when it meets to a level about 6
miles up, where it meets the second layer,
the stratosphere it protects life on Earth from