1. OzoneandEarth

2. What is the Ozone? The ozone is a layer in our atmosphere containing three oxygen atoms. In the upper atmosphere it filters ultraviolet light from reaching the Earth’s surface.

3. What is the Ozone? The purpose of the ozone is to filter out photons with shorter wavelengths of UV light from the sun. These UV rays are potentially dangerous to humans when in large doses.

4. Where is the ozone? The ozone is found in the stratosphere. About 10 km – 50 km above the surface.

5. Physical Properties A pale blue gas. Slightly soluble in water. It is diamagnetic and will resist formation of a magnetic field.

6. Depletion Evidence shows that high doses of ozone, created by high doses of pollution and UV rays, can harm lung function. Slow steady decline of about 4% Much Larger decrease in ozone over polar regions

7. Depletion Chlorofluorocarbon (CFC) compounds are found to be the most destructive to ozone layer. It has become a world wide concern. Montreal Protocol has banned the production of CFCs and halons.

8. Ozone Hole There is a “hole” that has formed over the south pole. During the 1980’s and 1990’s the hole was seeming to get larger but the latest observation (2007) has stated that the hole is now the smallest it has been for about a decade.

9. Causes Greatest decrease in ozone has been in the lower stratosphere. Chlorofluorocarbons (CFCs) invented by Thomas Midgley in the 1920’s are the biggest threat to ozone depletion.

10. Causes CFCs were used in : Air conditioning/cooling units Aerosol spray propellants Cleaning chemicals for electronic equiptment When ozone-depleting chemicals reach stratosphere, they release chlorine atoms that can break down tens of thousands of ozone molecules.

11. Consequences Decrease in ozone layer was predicted to be 7% over a 60 year period in early 1980’s By 1985 there was reports of a substantial “hole” in the ozone.

12. Consequences Although the “hole” was only over Antarctica, many believed that the holes could come up in other areas over continents. May speed up the process of global warming. Cooler stratosphere, more stratosphere clouds, more active chlorine.

13. Consequences More UV rays leads to an increase in skin cancer. Also causing more cases of cataracts. Could ruin major cash crops from increase in UV rays Ex: Rice

14. Public Policy U.S.A, Canada, Sweden and Norway all have eliminated the use of CFCs in aerosol spray cans. Montreal Protocol agreed to phase out all production of CFCs and halons completely after a meeting in 1990.

15. Past and Current Events Since the banning of CFC production many countries around the world took note and have become more aware of the situation. There has been a decrease in bromine-containing chemicals.

16. The Future By 2015 the ozone hole is predicted to reduce 1 out of 25 million km. Complete recovery of the Antarctic ozone layer will not occur until the year 2050 or later.

17. Ozone DepletionandGlobal Warming Ozone depleting chemicals are also greenhouse gases. The ozone depletion will lead to the cooling of the stratosphere causing an increase in global warming.

18. Misconceptions CFCs are too heavy to reach the stratosphere. The “ozone hole” is an actual hole in the ozone. The “ozone hole” should be above the sources of CFCs not over Antarctica.

19. Review Ozone is a layer in the stratosphere that is protecting UltraViolet light from getting to Earth’s surface. UV rays are harmful to humans potentially leading to causes of skin cancer and cataracts.

20. Review The ozone depletion is caused from chemicals known as CFCs that are found in aerosol spray propellants. The “ozone hole” is decreasing in size. It may take up to 40 more years to fully recuperate the “hole” over Antarctica.