Ozone layer depletion xom


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Ozone layer depletion xom

  1. 1. Ozone is a colorless gas,consist of 3 oxygenmolecules,found in the upper atmosphere of the Earth andformed by the action of ultraviolet radiation on oxygen.Ozone forms a layer in the stratosphere, which protects lifeon Earth from the harmful effects of ultraviolet radiation.The ozone layer is a region in the stratosphere, between17 and 25 km above the earth’s surface.Without the ozone layer WE WOULD ALL DIE (because UVlight kills all living tissue).This layer absorbs about 97-99% of the harmfull UV rays.
  2. 2. Ozone Absorption in the UV Band• UV radiation includes wavelengths from 200 to 400 nm• UV-A 320-400 nm• UV-B 200-320 nm• UV-C 200-290 nm• UV-C • Nearly all UV-C is absorbed in the upper atmosphere• UV-B • 90% of UV-B is absorbed by the atmosphere, mostly by O 3• UV-A • Not strongly absorbed by the atmosphere
  3. 3. o Presence of chloroflurocarbones(CFCs)o Hydrofluorocarbons (HCFCs): They are much less harmful to stratospheric ozone than CFCs,But HCFCs they still cause some ozone destruction and are potent greenhouse gaseso methyl chloroform (used in industry — for vapour degreasing, some aerosols, cold cleaning, adhesives and chemical processing)o Presence of halons (used in fire extinguishers).o Presence of oxides of nitrogeno Presence of bromide such as methyl bromine (used as a pesticide).o Hydrogen chlorideo Carbon tetrachloride(industrial solvent)o Hyrdobromofluorocarbon(HBFCs)o Bromochloromethane(BCM)
  4. 4. What is CFC (freon)?? A hydrocarbon or haloalkan that contain chlorine,flourine and carbon atoms CFC or freon damage the ozone layer when released in the envionment,but also saves lives by keeping food from spoiling , fire fighting and sterilization of surgical tools. Non toxic Non-flammable Noncorrosive Inexpensive long-lived“Dream Chemical” U.S government banned the production of freon.
  5. 5. • CFC-11 (trichlorofluoromethane - CFCl3)• CFC-12 (dichloro-difluoromethane - CF2Cl2)• CFC-113 (trichloro-trifluoroethane - C2F3Cl3)• CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2)• CFC-115 (chloropentafluoroethane - C2F5Cl)
  6. 6. Air ConditionersRefrigeratorsFire extenguisherSpray cansPesticidesInsulation materialsCleaners for electronic partsSterilizing medical instruments
  7. 7. United States accounts for largest part of world-wide consumption o CFC’s 29% of global consumption of CFC is from US Americans use six times more CFC’s than globalaverage Vehicle air conditioners accounted for about75% of annual CFC emissions in the US in 1990 Since 1978 the use of CFC’s in aerosol cans hasbeen banned in many countries; however,worldwide, aerosol cans still account of 25% ofCFC emissions.
  8. 8. The Antarctic ozone hole was discovered in 1985 by Britishscientists Joesph Farman, Brian Gardiner, and Jonathan Shanklin ofthe British Antarctic Survey.
  9. 9. 400 Figure 21-22 350 Page 485 October monthly meansTotal ozone (Dobson units) 300 250 200 150 100 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year
  10. 10. 100 200 300 400 1950 1960 1970 1980 1990 2000 1950 100 200 300 4001950 19601960 19701970 19801980 19901990 20002000 100 200 300 400
  11. 11. ozone layer depletio (4).FLV
  12. 12. Skin cancerPremature aging (photoaging) of theskinSun burn
  13. 13. This long-wavelength (low-energy) form of UV This shorter-wavelength (high-energy) form of UV radiationradiation causes aging of the skin, tanning, and causes sunburn, premature aging, and wrinkling. It is largelysometimes sunburn. It penetrates deeply and may responsible for basal and squamous cell carcinomas andcontribute to skin cancer. plays a role in malignant melanoma. Ultraviolet A Ultraviolet B HairThin layer of dead cells Squamous cells Epidermis Basal layer Sweat gland Melanocyte cells Dermis Blood vessels Basal cell Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma
  14. 14. Each 1% loss of ozone leads to a 2% increase in UVradiation striking the earth.A 2% increase in UV radiation results in a 5% to 7%increase in skin cancer, including a 1% increase indeadly malignant melanomaAn additional 940,000 cases annually of basal-celland squamous-cell skin cancerAn additional 30,000 cases annually of melanomaskin cancer (often fatal). There are 9,000 Americandeaths per year from this now.
  15. 15. Protect the skin against the solar radiation using skin creams with SPF or other sunscreen.
  16. 16. • Stay out of the sun especially between 10 A.M and 3 P.M• Donot expose yourself to the sun if you are taken antibiotics and contraceptive pills• Examine your skin and scalp at least once a month for moles or warts that change in size,shape,color,or sores that keep oozing,bleeding and crusting over.if you observe any of this signs,consult a doctor immediately.
  17. 17. Solutions : Protecting the Ozone LayerStop producing CFCs orReduce emission of ozone deplating chemicals thatcontains CFC.Reduce the uses of aerosol sprays.Uses of aerosol spray that is free in CFCs compound instead.properly recycle old CFCsUse safe alternativesEducate other governments for environmental policiesMontreal Protocol 36 nations:Goal: reduce CFCs by 35% by 2000Copenhagen Protocol
  18. 18. http://www.bom.gov.au/lam/Students_Teachers/ozanim/ozoanim.shtmlwww.theozonehole.com/ozonedestruction.html australia.jrn.msu.edu/.../ozonepage.htmlhttp://www.nas.nasa.gov/About/Education/Ozone/ozonelayer.htmlhttp://www.bcairquality.ca/101/ozone-depletion-intro.htmlhttp://www.ozonedepletion.info/education/ozone.html