Question

What are the principles of ozone thinning and depletion?

Answer 1

CFCs and others

Explanation:

In the upper atmosphere, ozone concentration have been decreasing as a result of chlorine, bromine and fluorine attacks. CFCs, halons, and other chlorinated, brominated or fluorinated chemicals contain these. According to Rowland (1990):

1. "The CFCs emitted in surface by human activities are extremely stable. Although they are inactive in the lower atmosphere, they have a very long redidence time (nearly 100 years). Soilis able to hold some CFCs from the atmosphere at Earth's surface but it is not a major sink."

2. "There is a great mixing in our atmosphere, the CFCs eventurally wander upward and enter the stratosphere (where ozone layer is located). Once they have ended in elevations above most of the stratospheric ozone, they might be destroyed by the energetic UV radiation (UVC). This process frees chlorine, bromine, flüoride, etc. (all reactive atoms."

3. "The reactive atom may then enter into reactions that destroy ozone in the upper atmosphere."

4. "The result of the depletion of ozone is an increase in the amount of ultraviolet B (UVB) radiation that hits Earth's surface. UVB is a skin cancer triggering agent.

Reference:
Rowland, F. S. (1990). Stratospheric Ozone Depletion by Chlorofluorocarbons. AMBIO, 19 (6-7): 281-292.