1. air-pollution1 Ozone Depletion: an Example of Pollution Effects on a Global Scale Air pollution can expand beyond a regional area to cause global effects. The stratosphere is the layer of the atmosphere above the troposphere, that is, between 10 miles and 30 miles above sea level. The stratosphere is rich in ozone, the same ozone that acts as a pollutant when found at lower levels (troposphere) of the atmosphere in urban smog.

2. air-pollution2 UV-B is stopped here by the ozone layer in the stratosphere  Polluting ozone is found here

3. air-pollution3 Ozone Depletion Up at the stratospheric level ozone forms a protective layer that serves a vital function: it absorbs the wavelength of solar radiation known as ultraviolet-B (UV-B) associated with sunburns and skin cancers.

4. air-pollution4 Ozone Depletion Several pollutants attack the ozone layer. Chief among them is the class of chemicals, chloro-fluoro-carbons (CFCs). CFCs are used as refrigerants (notably in air conditioners), as agents in some manufacturing processes, and formerly as propellants in spray cans.

5. air-pollution5 Ozone Depletion In the stratosphere, intense UV radiation breaks the CFC molecules apart, releasing the chlorine atoms. These chlorine atoms then react with ozone (O 3 ), breaking O 3 down into ordinary oxygen molecules (O 2 ). The chlorine acts as a catalyst—that is, it takes part in several chemical reactions—yet at the end emerges unchanged and is able to react again.

6. air-pollution6 Ozone Depletion The chlorine acts as a catalyst—that is, it takes part in several chemical reactions—yet at the end emerges unchanged and is able to react again.

7. air-pollution7

8. 8 Ozone Depletion So... because of pollution, the protective ozone layer in the stratosphere is thinning. In the Antarctic, the ozone layer essentially vanishes entirely for a few weeks every year. Fortunately, CFC use has greatly decreased. However, CFC molecules that have already been released into the lower atmosphere (that is, the troposphere) will be making their way up to the stratosphere for decades. So, further O 3 loss (the hole in ozone layer) is expected. As a result, one can anticipate an increase in skin cancers, cataracts (clouding of the lens of the eye), and reduced yields of some agricultural crops.