PURPOSE: Learning is most complete when your entire brain is used. Science is usually an analytical, left-brained activity, but using the creative right side of your brain helps to learn science also.

INSTRUCTIONS: To help you learn each of the following statements, draw a picture, diagram, or formula that shows what the statement describes. This could be a scientific type cross section, or a cartoon, or just an interestingly drawn chemical formula. For more information see Ozone - Good Up High Bad Nearby and  The Process of Ozone Depletion from the US Environmental Protection Agency.

1. The movement of O2 from ocean to air that began with cyanobacteria continues today, as photosynthesis by microorganisms in the oceans supplies most of the oxygen to the atmosphere.

2. As O₂ dissolved throughout the atmosphere, solar radiation began to split O₂, which then recombines to form ozone O₃.

3. Ozone has the unique property of absorbing the frequency of UV that is the most disruptive to the complex molecules of living organisms.

4. Only after the UV was blocked by ozone could more complex living things begin to use the upper areas of the oceans where there was more sunlight.

5. The protective ozone layer and high levels of oxygen allowed complex life to evolve on the planet.

6. Artificial chemicals such as CFCs are depleting the ozone by delivering chlorine high into the atmosphere where each chlorine atom destroys thousands of ozone molecules.

7. Chloroflourocarbons (CFCs) are chemicals that were used as propellants in spray cans, blowing agents to make plastic foam products, and as refridgerants.

8. CFCs, aka Freon, is still used in most refrigeration equipment in homes, offices, cars, and are also used as a cleaning agent in other nations.

9. A global agreement is reducing the amount of CFC produced, but other chemicals also affect ozone, and the CFC already in the atmosphere will be destroying ozone for decades.

10. Not all the effects of ozone depletion can be predicted, but it may directly produce greater skin cancer and cataracts, and may indirectly affect all living things on the surface of the planet by making plants sick.

11. People can help to protect the ozone layer by making sure that the refrigerant from their air conditioners and refrigerators is not leaking, that the Freon is recovered when the machines are serviced, and insist that non-CFC refrigerant be used to recharge the machine or in a new machine, and that all nations stop using CFCs.

12. People can protect themselves from the effects of ozone depletion by using UV sunblock and avoiding excessive exposure to the sun.

Graph courtesy US EPA at http://www.esrl.noaa.gov/csd/assessments/2006/chapters/contentsprefaceexecutivesummary.pdf