Only a fraction of HCFCs emitted can be transported to the ozone layer in the stratosphere where their chlorine could deplete ozone. They have many of the useful properties of the CFCs. Because they do not contain chlorine, they are not involved in ozone depletion. Ozone Ozone, formed in the stratosphere by the action of sunlight on oxygen, is also an airborne pollutant near ground level. Ozone Depletion Ozone is continually being formed and destroyed by chemical reactions occurring in the stratosphere.
Ozone depletion occurs if the rate of ozone destruction is increased due to human activities.
The ozone depletion potential is a quantity describing the extent of ozone depletion calculated to arise from the release to the atmosphere of 1 kilogram of a compound relative to the ozone depletion calculated to arise from a similar release of CFC-11. Each winter, over the Antarctic, the atmosphere is isolated from the rest of the world by a natural circulation of wind, called the polar vortex. It is dark and becomes very cold, resulting in the formation of clouds in the ozone layer of the stratosphere. On these clouds inorganic forms of chlorine undergo chemical reactions to give species which, when the sun shines again on Antarctica each spring, are further converted by sunlight into forms that can deplete ozone. The rapid destruction of the majority of the ozone in the region of the Antarctic stratosphere that contains clouds leads to a marked temporary local depletion called the ozone hole.