Ozone is a gas naturally present in the atmosphere, but in very low quantities. It is colorless and has a very strong odor that gave it its name (from Greek ozein, odor). About 90% of the atmospheric ozone is located in the stratosphere (region between an altitude of about 10 and 50 km) and comprises what one calls the ozone layer. It absorbs a large part of ultraviolent rays which are very dangerous in heavy doses, and thus protects life on Earth. (1)
The protective ozone layer must not be confused with the ozone present at low altitude (in the troposphere) and linked to urban pollution. It is only loosely linked to stratospheric ozone. Gases due to pollution can not plug up the hole in the ozone layer.
The hole in the ozone layer