Ozone

Good Up High-Bad Down Low!

Good Up High!

• Ozone in stratosphere is helpful and necessary. At this altitude, high energy solar radiation splits ordinary oxygen into oxygen atoms. O2 2O

• loose oxygen is very reactive and combine to make ozone O + O2 O3

• Ozone is continually being created and destroyed

• Protects us from UV-B (290-320 nm) which causes skin cancer

• UV exposure caused cataracts –thickening of lens • Photokeratoconjunctivitis-snow blindness/welders eye-

sunburned eye• UV exposure suppresses immune system• Plants are sensitive to changes in UV-B exposure-inhibits

photosynthesis/reduced crop yields• Phytoplankton are inhibited in photosynthesis• Larval development of some fish species disrupted

Bad Down Low!

• Photochemical smogAuto exhaust + sunlight + O2

Exhaust and industrial emissions spew NOx into air• Suns UV rays convert it into NO andO

• O+ O2 O3

• Strong oxidizing agent-reactive• Damage to lung tissue

Ozone Hole-Chemicals that Threaten the Ozone Layer

• Seasonal depletion (thinning) of ozone in stratosphere above Antarctica and the Arctic

• Freons-chlorofluorocarbons (CFC) in 1930 and subsequent molecules that are chemically un-reactive, odorless, nontoxic and noncorrosive. They were inexpensive and used as coolants in air conditioners, propellants in aerosol sprays, cleaners for electronic parts.

• Rowland & Molina in 1974 started researching ozone destruction

• Dramatic Declines in ozone values over Antarctica each spring-“holes” in the ozone.

• Ozone loss is accelerated over frozen continent because the unique Antarctic weather conditions: coldest and most isolated spot on earth. Normally, air is so dry clouds do not form, but during long polar winter ice crystals clouds can form. The surface of these acts as a site for chemical reactions. Since ozone destruction is dependent on sunlight, the molecules build up all winter, enter the polar vortex in spring, and destroy ozone.

• http://www.youtube.com/watch?v=qUfVMogIdr8• NASA Viz

• 1987-Montreal Protocol: 36 nations agree to cut CFCs first limit and then ban CFCs

• Used PREVENTION to solve a serious enviro problem

• Nations worked together• Allowed for economic and creative solutions

to find a safe substitute chemicals.