Advanced Placement Environmental Science Teacher Ozone Hole Mark Ewoldsen, Ph.D. Advanced Placement Environmental Science Teacher La Cañada High School

Two Atmosphere Layers Stratosphere is above Troposphere Ozone Layer blocks UV radiation Troposphere is where we live Weather and Global Warming 72% of all air is below the cruising altitude of commercial airliners (33000 ft)

Stratospheric Ozone vs. Tropospheric Ozone (Good) vs. Tropospheric Ozone (Bad)

Ozone – Two Faces Stratosphere – Good Ozone Troposphere – Bad Ozone Blocks UV radiation Hole caused by depletion due to CFC’s Troposphere – Bad Ozone Pollution Photochemical smog Eye irritant

Harmful effects of UV radiation Skin cancer such as melanoma(ultraviolet radiation can destroy acids in DNA)

matrix.ucdavis.edu/tumors/tradition/ gallery-ssmm.html

Harmful effects of UV radiation Skin cancer such as melanoma(ultraviolet radiation can destroy acids in DNA) Cataracts and sun burning

www.snec.com.sg/clinical_services/ cataract.asp

Harmful effects of UV radiation Skin cancer such as melanoma(ultraviolet radiation can destroy acids in DNA) Cataracts and sun burning Suppression of immune systems Adverse impact on crops and animals Reduction in the growth of ocean phytoplankton Degradation of paints, plastics, tires

http://www.peakoilproof.com/2011/04/etf-spotlight-australia-ewa.html

Good Ozone Most ionizing

Natural Ozone Hole Winter = no sunlight Air in the polar vortex can get very cold -80C Special clouds called Polar Stratospheric Clouds form as nitric acid trihydrate PSCs are crucial for ozone loss to occur Since there is no sunlight, the air within the polar vortex can get very cold

The ozone hole builds up over the winter months, peaking at around September and breaking up again by December, this data set from 2005                                July                           August                                September              October                                November December

Destroying Good Ozone Chloroflourocarbons discovered (1928) In 1974 Non-toxic, non-flamable refrigerants by DuPont In 1974 Cl + O3 -> ClO + O2 ClO + O3 ---> 2 O2 + Cl In a 1985 Ozone levels had dropped to 10% below normal January levels for Antarctica. http://www.nas.nasa.gov/About/Education/Ozone/history.html

A single chlorine atom removes about 100,000 ozone molecules before it is taken out of operation by other substances

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2. Sun Cl Cl Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. C Cl F UV radiation Cl Cl O O A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2. The chlorine atom attacks an ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2). Cl Cl O O O O O The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO) Cl O O O

Montreal Protocol (1987) International treaty to protect the ozone layer phasing out production of number of substances believed to be responsible for ozone depletion Effective January 1, 1989

Signed Effective