Explanation:

In an pollution free stratosphere, the production and destruction of ozone are in balance and hence the concentration of O3 remains constant with time. When CFC’s are released into the lower troposphere, they diffuse up into the stratosphere since their lifetime is 50-100 years when CFCs reach the middle stratosphere, UV radiation liberates the chlorine atom.Like an infection that grows more and more virulent, the continent-size hole in Earth's ozone layer keeps getting bigger and bigger.Each year since the late 1970s, much of the protective layer of stratospheric ozone above Antarctica has disappeared during September, creating what is popularly known as the ozone hole.Ozone depletion is a growing problem, but by banning the use of CFCs countries of the world hope to eventually restore the ozone balance to the Earth’s atmosphere. However, right now ozone loss is more than ozone produced. The most critical area seen with decreased ozone is over Antarctica. There are stratospheric cloud and ice particles that are not present in the stratosphere in warmer regions.
CFC + UV -> Cl
Cl is then able to destroy as man as 100,000 O3 molecules.