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Stratospheric Ozone 75% of Mass below 17 km >390 nm nm 2000 m—0.8 bar 5500 m—0.5 bar (18,000 feet) Image courtesy of

Light Image courtesy of

Sunlight Spectrum UVA= nm UVB= nm UVC=<280 nm

Stratospheric Vs. Tropospheric Ozone Image courtesy of

Ozone Depletion O 2 + hv  O + O O + O 2  O 3 O 3 + hv (<290 nm)  O 2 + O O 3 + Cl  O 2 + ClO ClO + O  O 2 + Cl O 3 + O  2O 2 Cl can catalyze destruction of O 3 100,000 times

Overall ~5% Global Decrease in Stratospheric Ozone Predicted Figure by UMB OpenCourseWare.

Cancer Causing DNA Breakage due to UV rays Image courtesy of

Melanoma Image courtesy of visualsonline.cancer.govvisualsonline.cancer.gov

Carcinomas Image courtesy of

Antarctic Ozone Hole 5% loss in O3  500% increase at 287 nm Image courtesy of NOAA Research

Polar Vortex, Spring Image courtesy of NASA Goddard Space Flight Center

Polar Stratospheric Clouds (PSC) Antarctic Spring Polar Vortex Stratospheric clouds made of ice (nitric acid) Sunlight initiate reactions Heterogeneous chemistry (on particles)

Image courtesy of NASA Goddard Space Flight Center

Index Card How can we solve this problem?

Solutions US Clean Air Act: Venting of CFC/HCFC Refrigerants Illegal July1, 1992

Regulations Source: NASA

Solved? By 2050 Hydro Halocarbons (HFCs) Single manufacturer (Dupont) Scientific consensus Simple chemistry Source:

Image courtesy of Leland McInnes, WikipediaLeland McInnes, Wikipedia