Ozone Problem Lecture-3

Introduction That is, the layer of life-protecting ozone found at the top of the stratosphere. A brief history of the discovery of the ozone 'hole' is included. The general concepts found in this section include the following: –Concentrations of stratospheric ozone represent a balance, established over eons, between creative and destructive forces and this balance, or dynamic equilibrium, has been changed by human activity. –Ozone is formed in the earth's stratosphere and is critical to life on earth as we know it. –There is compelling scientific evidence that ozone is destroyed in the stratosphere and that some human-released chemicals are speeding up the breakdown of ozone in the atmosphere. –CFCs, a human-developed compound, are particularly destructive to the breakdown of ozone in the atmosphere. –Ultraviolet radiation is present in natural outdoor light and can be blocked or filtered by various substances.

Ozone Layer Depletion: Historical Perspective The ozone 'hole', it is really not a hole but rather a thinning of the ozone layer in the stratosphere. We will use the term 'hole' in reference to the seasonal thinning of the ozone layer. –The appearance of a hole in the earth's ozone layer over Antarctica, first detected in –1974: Rowland & Molina theorize CFCs destroy stratospheric ozone molecules –1975: U of M / Harvard papers predict that CFCs deplete Earth’s ozone layer –1985: Ozone holes found over Antarctic –1988: Ozone layer thinning over North Pole –1993: Thinning over mid-latitudes of the Northern Hemisphere –1997: Low values of total ozone occur in Arctic as well as Antarctic

Antarctic Ozone Hole Progression

NO x NMVOCs NO x NMVOCs CONTINENT 2 OCEAN O3O3 Boundary layer (0-2.5 km) Free Troposphere CONTINENT 1 CH 4 itself is an important greenhouse gas, and links climate with air pollution via its influence on tropospheric ozone OH HO 2 VOC, CH 4, CO NO NO 2 h O3O3 O3O3 Hemispheric Pollution Direct Intercontinental Transport greenhouse gas air pollution (smog)

Ozone Layer Depleting Chemicals chlorofluorocarbons (CFCs) carbon tetrachloride (CCl 4 ) methyl chloroform (CH 3 CCl 3 ) hydrochloric acid (HCl) methyl chloride (CH 3 Cl) methyl bromide(CH 3 Br)

International Response to Ozone Layer Depletion 1985: United Nations Environment Program (UNEP) 1987: The Montreal Protocol 1992: Copenhagen Amendments 1998: The Montreal Protocol is affecting stratospheric chemical composition.

International Response to Ozone Layer Depletion : Stratospheric ozone layer recovery will be a slow process and extend into the next century. Scientific Assessment of Ozone Depletion: 1994 and 1998 (World Meteorological Organization). Ozone Depletion Web Page:

Ozone Layer Depleting Chemicals: Chlorine CCl 4 12% CH 3 Cl & HCl 18% CFC-11 23% CFC-12 28% CFC-113 6% HCFC-22 3% CH 3 CCl 3 10%

Ozone Layer Depleting Chemicals: CFCs CFCs are inert, nonreactive, nontoxic, nonflammable. Human-made CFCs used in: –refrigeration –air conditioning –foam blowing –cleaning electronic components –solvents

CFC Reactions Deplete Ozone Layer in Stratosphere CFC Cl UV O3O3 O3O3 O3O3 CFCs

Ozone Depleting Process

Global Stratospheric Ozone Layer Depletion Trend % Deviation from monthly ave.

Biological Effects of Ultraviolet Radiation Sunburn,Premature Aging & PreCancer Cancer of Skin –Basal and Squamous Cell Carcinoma –Melanoma Cataracts Photosensitivity Immune system changes

Immunity humoral system cellular system B Lymphocyte T Lymphocyte Human Immune System can be suppressed by ultraviolet radiation

B Lymphocyte T Lymphocyte Immunoglobulins Foreign Protein Bacteria Cancer Parasites Bacteria-Fungi Viruses

Human Immune System can be suppressed by ultraviolet radiation suppression of immune system increased incidence of infection promotion of cancer growth

The Skin Cancer Epidemic skin cancer is the most common malignancy in the U.S. 1 in 5 Americans will become afflicted ~ 1.0 million new cases this year rates of skin cancer are rising 3 - 5% per year

The Skin Cancer Epidemic Basal cell carcinoma –most common, least aggressive, locally destructive Squamous cell carcinoma –more aggressive, can metastasize Melanoma –most aggressive, ~75% of all skin cancer deaths

The Skin Cancer Epidemic melanoma is increasing in incidence faster than any other cancer lifetime probability of developing melanoma is 1 in new cases of melanoma diagnosed per day, ~ one death per hour

The Skin Cancer Epidemic Problems knowledge: 1/3 of Americans know that melanoma is a kind of skin cancer attitudes: >60% of Americans think people look better with a tan behavior: only 1/4 of the population use sunscreens regularly

Cataracts of Eyes cataracts are when the lens of the eye becomes cloudy 20 million cases worldwide account for half of blindness in the world

BADGOOD

References “Environmental Effects of Ozone Depletion.” AMBIO 24 May(1995): Cook, Elizabeth, ed. Ozone Protection in the United States: Elements of Success. Washington, D.C.: World Resources Institute,1996. UNEP Ozone Depletion Report 1994/ Southern Hemisphere Ozone Hole Size _hole.html _hole.html Health and Environmental Effects of Ultraviolet Radiation. INTERSUN: The Global UV Project. 9 Sep The health impact of solar radiation and prevention strategies. Report of the Environment Council, American Academy of Dermatology. J Am Acad Dermatol 1999; 41:81-99.

Think Globally and Act Locally