2. Ozone O3O3

3. Ozone Depletion Ozone (O 3 ) –Absorbs harmful UV radiation from sun ozone is produced during lightning storms Chlorofluorocarbons (CFC’s) destroy ozone –CFC’s production was banned in 1977 –CFC’s “live” for hundreds of years

4. banned in U.S. in 1996 Depletion of the Ozone Layer OOzone (O 3 ) in upper atmosphere blocks ultraviolet (UV) light from Sun.  UV causes skin cancer and cataracts. OO 3 depletion is caused by chlorofluorocarbons (CFCs). O 3 is replenished with each strike of lightning. aerosol propellants Uses for CFCs: refrigerants CFCs

5. Freon (CFC’s) Trichlorofluoromethane (Freon-11) Dichlorodifluoromethane (Freon-12) F Cl C F C F CFC-11 and CFC-12 are odorless, nontoxic, nonflammable, and very stable. chlorofluorocarbons

6. Mechanism of Ozone Depletion InitiationCCl 2 F 2 Cl + CF 2 Cl PropagationCl + O 3 ClO + O 2 ClO + O Cl + O 2 Termination Solar radiation A single chlorine molecule can destroy thousands of ozone molecules........ “free radical”

7. Ozone Hole Grows Larger Ozone hole has increased 50% from 1975 - 1985 Ozone, O 3

8. Monthly Change in Ozone TOMS Total Ozone Monthly Averages

10. Ultraviolet Radiation Skin cancer Cataracts Sun-glasses UVA & UVB protection

11. Greenhouse Effect vs. Ozone Hole Greenhouse Effect Depletion of O 3 (ozone layer)... causes skin cancer and cataracts Caused by CFC's (chlorofluorocarbons) destroying ozone layer Replace CFC's in AC & refrigerators Global Warming by trapping heat on Earth Caused by buildup of CO 2 carbon dioxide Plant trees to slow down and burn less fossil fuels that produce CO 2 Alike Different Related to Earth's Atmosphere Man-made problem Environmental Issues Ozone Hole Different Topic