The earth has a layer called the ozone. This layer protects all life from the sun's harmful radiation. But human activities that cause pollution have damaged the ozone. The ozone layer is divided into several layers of the atmosphere. The first and lower region is called the troposphere. It extends about 10 kilometers in altitude from the earth's surface. All human activity happens in the troposphere. The next layer is the stratosphere and it continues up from the troposphere about 50 kilometers more.
Commercial air traffic such as airplanes operate in the lower part of the stratosphere. Most atmospheric ozone is concentrated in this layer. The ozone layer absorbs a portion of the radiation from the sun and most importantly, it absorbs ultraviolet light called UVB rays.
UVB rays have harmful effects such as causing skin cancers, cataracts, and it also harms some crops, certain materials, and some forms of marine life. Due to different kinds of pollution including air pollution, the ozone layer is being destroyed allowing the harmful sun rays to hit the earth's ground and do damage to the many things that are on earth.
What happens as a result of this is ozone depletion. Ozone depletion is caused by the release of chlorofluorocarbons (CFCs) which are used as insulating foams and solvents. Although CFCs are heavier than air, they are eventually carried into the stratosphere in a process that can take as long as 2-5 years. Measurements of CFCs are made from balloons, aircrafts, and satellites. When CFCs reach the stratosphere, the ultraviolet radiation from the sun causes them to break apart and release chlorine atoms that react with ozone, starting chemical cycles of ozone destruction that deplete the ozone layer.
Ozone depletion has many effects on the earth. The effects it has on human health are that laboratory and epidemiological studies show that UVB rays cause nonmelanoma skin cancer and plays a major role in malignant melanoma development.
UVBs have also been linked to cataracts. All sunlight contains some of these rays that's why it's always important to limit exposure to the sun. Other health effects include immune system suppression.
UVB rays also affect the growth and development of plants. Indirect changes such as changes in plant form, how nutrients are distributed within the plant, and timing of developmental phases and secondary metabolism are also affected. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
http://www.ciesin.org/TG/OZ/oz-home.html - Ozone Depletion
http://ess.geology.ufl.edu/HTMLpages/ESS/GLY1033_notes/lecture4.html - Stratospheric Ozone Depletion
http://www.epa.gov/ozone/resource/public.html - EPA Ozone Information
http://www.geocities.com/RainForest/Vines/4030/index.html - More Ozone Depletion Information