1. Ozone is made of three oxygen atoms - O 3 Ozone

2. OZONE – A Greenhouse gas Greenhouse gas. Near ground it is a nasty pollution In the stratosphere it protects us from UV radiation

3. Tropospheric ozone  Tropospheric ozone results from photochemical reaction involving air pollution.  Toxic  Greenhouse gas  Ozone in the troposphere is an anthropogenic ozone.  Responsible for positive forcing ~ 0.35 W/m2

4. The Stratospheric Ozone Layer  Stratosphere ozone is formed naturally from the action of solar UV radiation on atmospheric oxygen  The lower stratosphere is the location of most atmospheric ozone.

5. Solar UV Radiation UV Radiation is blocked by the ozone layer UV Radiation also forms the ozone layer.

6. Solar Spectrum

7. Regions of the Solar Spectrum

8. Regions of the Solar UV Spectrum

9. Ozone depletion – Ozone Hole The ozone "hole" is really a reduction in concentrations of ozone in the stratosphere.

10. Chlorine acts as a catalyst to destroy the Ozone layer

11. How does Chlorine get into the Stratosphere? chlorofluorocarbons (CFCs). – CFC-12 (CF2Cl2) (freon) – CFC-11 (CFCl3) Have 100 year atmospheric lifetimes

12. Health and Environmental Effects  Skin Cancer.  Premature aging of the skin and other skin problems  Cataracts and other eye damage  Immune system suppression Immune system damage  Damage to the DNA in various life-forms.

13. What should we do?

14. The Montreal Protocol International treaty for the control on the production and consumption of ozone-depleting substances. It was agreed on in 1987. President Regan signed in 1988. Globally emission of ODPs has been drastically reduced to around 10% of original levels.

15. EPA – Ozone Depletion Program Under Clean Air Act (CAA), EPA is responsible for programs that protect the stratospheric ozone layer Command and Control Strategy – Halt the production of ozone-depleting substances (ODS). – Ensure refrigerants and halon fire extinguishing agents are recycled properly. – identifying alternative to ODS. – banning the release of OD refrigerants. – handling of ODS, the evaluation of substitutes, and efforts to educate the public.

16. Will take 50 years to Recover The latest estimates are that as long as production and release of CFC's is regulated properly, global ozone levels should recover by 2050.