Stratospheric Ozone

Questions

1. What is the chemical and physical behavior of ozone in the stratosphere?
2. What is the current status of our stratospheric ozone layer?
3. How has the level of ozone changed over time?
4. What affects the concentration of ozone in the stratosphere?

Lecture Notes

• Lecture Notes
• Powerpoint Slides
• Powerpoint Slides (large)

News Articles

• A Significant Ozone Hole is Reported Over the Arctic (New York Times)
• Say Bye-Bye to Primatene Mist (At Least in its Current Form) (Chicago Tribune)
• Record Stratospheric Ozone Loss in the Artic in Spring of 2011

Background Information

• Stratospheric Ozone Protection - Progress Report (EPA April 2007)
• Questions and Answers about the Environmental Effects of the Ozone Layer Depletion and Climate Change: 2010 Update (Environmental Effects Assessment Panel)
• The Antarctic Ozone Hole - From Discovery to Recovery, a Scientific Journey
• Ozone Hole Watch
• Montreal Protocol

Take Away (Main) Points

1. In the mid- 1970s a thining of the ozone layer in the stratosphere was detected. This developed into a region over the South Pole called "a hole in the ozone". This "hole" was an exceptionally thin layer of ozone.
2. The Montreal Protocol(1987) was a successful negotiation to stop the production of the Chlorofluorocarbons that damage the stratospheric ozone layer. It has been called the most successful treaty ever.
3. It will take several more decades for the ozone layer to return to the levels that existed before we released destructive gases into our atomosphere due to the long lifetime of Chlorofluorocarbons in the atmosphere.
4. Ozone is made naturally in the stratosphere from the action of sunlight on oxygen. It is a molecule with three oxygen atoms.
5. The ozone layer is important because it filters our high energy ultraviolet radiation.
6. If the ozone layer were to become too thin we would expect a rise in the incidence of skin cancer, eye cataracts and crop failures.
7. Chlorofluorocarbons (CFCs) led to ozone destruction. One chlorine atom released from a CFC can destroy hundreds of moledules of ozone in a catalytic action where the chlorine is used and regenerated and used again.