air pollution

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air pollution

  1. 1. Air Pollution
  2. 2. What is air pollution? <ul><li>contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health </li></ul>
  3. 3. Air Pollution has been around a long time. Roman philosopher, Seneca, wrote of the heavy air of Rome in 61 AD. Edward I of England banned the burning of sea coal in craftsman’s furnaces be prohibited because of foul smelling fumes, 1306. Elizabeth I of England banned the burning of coal while Parliament was in session.
  4. 4. Air Pollution Episodes <ul><li>Meuse Valley (Belgium) - 1930 </li></ul><ul><li>Donora, PA - 1948 </li></ul><ul><li>Poza Rica (Mexico) - 1950 </li></ul><ul><li>London - 1952 </li></ul><ul><li>New York - 1953 to 1966 </li></ul><ul><li>Bhopal (India) - 1984 </li></ul>
  5. 5. London Smog <ul><li>1948: Donora, Pennsylvania, 20 people die due to exposures to air pollution from iron and steel mills, zinc smelters, and acid production. Cold, damp weather accompanied by a thermal atmospheric inversion. </li></ul><ul><li>1952: London, 4,000 people die from air pollution associated with coal burning during similar meterological conditions and fog between Dec 5th-9th. Most admitted to hospital were elderly or already seriously ill. Deaths correlated with concentrations of sulfur dioxide and smoke. </li></ul>
  6. 6. Some Systems of the Human Body Effected <ul><li>Respiratory </li></ul><ul><li>* Bronchitis (acute and chronic) </li></ul><ul><li>* Pulmonary emphysema </li></ul><ul><li>* Lung cancer </li></ul><ul><li>* pneumoconiosis </li></ul><ul><li>* cough </li></ul><ul><li>* chest pain </li></ul><ul><li>Cardiovascular </li></ul><ul><li>Skin and eyes </li></ul><ul><li>Other </li></ul>
  7. 7. Environmental Effects of Air Pollution <ul><li>Ecosystem effects </li></ul><ul><li>Property damage </li></ul><ul><li>Quality-of-life effects </li></ul><ul><li>Global climate change </li></ul>
  8. 8. Examples of Health Effects from Air Toxics <ul><li>Cancer </li></ul><ul><li>Respiratory irritation. </li></ul><ul><li>Reproductive toxicity </li></ul><ul><li>Developmental effects </li></ul><ul><li>Pulmonary toxicity </li></ul><ul><li>Liver toxicity </li></ul>
  9. 9. Sources of Air Pollution <ul><li>Ones emitted through natural processes </li></ul><ul><li>* particulates (naturally occuring ) -> pollen grains, fungus spores, salt spray, smoke particles from forest fires and dust from volcanic eruptions. </li></ul><ul><li>* gaseous pollutants </li></ul><ul><li>CO ->breakdown product in the degradation of hemoglobin </li></ul><ul><li>Hydrogen sulfide->breakdown of cysteine and other S containing aminoacids by bacterial action </li></ul><ul><li>Man-made pollution classified as stationary pollution </li></ul><ul><li>*combustion </li></ul><ul><li>*transportation </li></ul><ul><li>*industrial processes </li></ul><ul><li>*solid waste disposal sources </li></ul>
  10. 10. <ul><li>Carbon Monoxide (CO) </li></ul><ul><li>Volatile Organic Compounds (VOCs) </li></ul><ul><li>Oxides of Nitrogen (NOx) </li></ul><ul><li>Sulfur Dioxide (SO2) </li></ul><ul><li>Particulate Matter (PM10) </li></ul><ul><li>Lead (Pb) </li></ul>Primary Types of Air Pollutants
  11. 11. Particulate Pollutants <ul><li>Dust-solid particles </li></ul><ul><li>Fume-a solid particle, frequently a metallic oxide formed by the condensation of vapors </li></ul><ul><li>Mist-a liquid particle formed by the condensation of a vapor and perhaps by chemical reaction </li></ul><ul><li>Smoke- solid particles formed as a result of incomplete combustion of carbonaceous materials. </li></ul><ul><li>Spray- a liquid particle formed by the atomization of a parent liquid. </li></ul>
  12. 12. Combustion <ul><li>Principal emissions from combustion are particulate pollutants such as fly ash, smoke and SO x &NO x . </li></ul><ul><li>SO emissions function of amount of S present in fuel. Thus combustion of fuel or coal produce significant quantities of SOx. Combustion of S containing coal causes acid rain. </li></ul><ul><li>Nitrogen Oxides (NOx) results from high temperature combustion processes, e.g. cars and utilities. </li></ul><ul><li>Almost any combustion operation operation will produce nitric oxide (NOx) </li></ul><ul><li>Other pollutants of interest from combustion processes are organic acids, aldehydes ammonia and carbon monoxide. </li></ul><ul><li>The amount of carbon monoxide emitted relates to the efficiency of the combustion operation, more efficient combustion operation will oxidize more of the carbon present to carbon dioxide, reducing the amount of carbon monoxide emitted. </li></ul><ul><li>Of the fuels used in stationary combustion, natural gas contains practically no sulfur, and particulate emissions are almost nil. </li></ul>
  13. 13. Acid Rain <ul><li>One effect of combustion of sulfur-containing coal is the formation of acid rain. </li></ul><ul><li>* N ormal, uncontaminated rain has a pH of about 5.6, but acid rain can be as low as pH 2 or even below. </li></ul><ul><li>* In a recent study of Norweigan lakes, more than 70% of the lakes having a pH of less than 4.5 contained no fish, and nearly all lakes with a pH of 5.5and above contained fish. </li></ul>
  14. 14. Acid rain <ul><li>contains high levels of sulfuric or nitric acids , </li></ul><ul><li>contaminate drinking water and vegetation </li></ul><ul><li>damage aquatic life </li></ul><ul><li>erode buildings </li></ul><ul><li>a lters the chemical equilibrium of some soils </li></ul>
  15. 16. Transportation <ul><li>Particularly automobiles using the internal combustion engine constitute a major source of air pollution. </li></ul><ul><li>Particulate emissions from the automobile include smoke and lead particulates, the latter usually as halogenated compounds. </li></ul><ul><li>*Smoke emissions are due to the incomplete combustion of carbonaceous material. </li></ul><ul><li>*Lead emissions relate directly to the addition of tetraethyl lead to the fuel as an antiknock compound . </li></ul><ul><li>Gaseous emissions include CO, NOx, and hydrocarbons. </li></ul>
  16. 17. Industrial Processes <ul><li>Reflect the ingenuity of modern industrial technology. </li></ul><ul><li>Thus, nearly every imaginable form of pollutant is emitted in some quantity by some industrial operation. </li></ul>
  17. 18. Solid Waste Disposal <ul><li>Major source of air pollutants from backyard burning or disposal of solid waste by open burning dumps. </li></ul><ul><li>This produce odor, CO, small amount of NOx, organic acids, hydrocarbons, aldehydes and great quantities of smoke. </li></ul>
  18. 19. Gaseous Pollutants <ul><li>Gaseous pollutants include substances that are gases at normal temperature and pressure as well as vapors of substances that are liquid or solid at normal temperature and pressure. </li></ul><ul><li>* Among the gaseous pollutants of greatest importance: </li></ul><ul><li>Carbon monoxide </li></ul><ul><li>Hydrocarbons </li></ul><ul><li>Hydrogen sulfide </li></ul><ul><li>Nitrogen oxides </li></ul><ul><li>Ozone and other oxidants </li></ul><ul><li>Sulfur oxides </li></ul><ul><li>Carbon dioxide-should be added to this list because of its potential effect on climate. </li></ul>
  19. 20. Gaseous Air Pollutants Significance as Air Pollutant Properties of Importance Formula Name Some are emitted from automobiles and industries others are formed in the atmosphere. Many C x H y or HC Hydrocarbons Damage to vegetation and property. Produced mainly during the formation of photochemical smog. Highly reactive O 3 Ozone Formed during complete combustion. Possible effects in producing changes in global climate. Colourless and odorless CO 2 Carbon Dioxide Product of incomplete combustion. Poisonous. Colourless and odorless CO Carbon Monoxide Major component in the formation of photochemical smog. Brown to orange gas NO 2 Nitrogen Dioxide Produced during high temperature high pressure combustion. Oxidizes to NO 2 . Colourless gas NO Nitric Oxide Relatively inert. Not produced in combustion Colourless gas N 2 O Nitrous Oxide Highly poisonous Rotten egg odor H 2 S Hydrogen Sulfide Highly corrosive Soluble in water to form sulfuric acid SO 3 Sulfur Trioxide Damage to vegetation, property and health Colourless gas, highly soluble in water to form sulfurous acid SO 2 Sulfur Dioxide
  20. 21. Source: http://www2.nature.nps.gov/air/images
  21. 22. Primary and Secondary Pollutants <ul><li>A primary pollutant-one that is emitted as such to the atmosphere. </li></ul><ul><li>A secondary pollutant – formed in the atmosphere by interaction of primary pollutants with each other or with normal components of the air. </li></ul><ul><li>-> The components of automobile exhaust are particularly important in the formation of secondary pollutants. </li></ul>
  22. 23. Photochemical Smog <ul><li>Urbanization high concentration of people, industries and automobiles. </li></ul><ul><li>Exhaust gases from internal combustion engines: CO, CO 2 , HC (hydrocarbons), and nitrogen dioxide (NO 2 ). </li></ul><ul><li>NO 2 is the precursor of photochemical smog. </li></ul><ul><li>In the presence of sunlight, photochemical reactions occur that produce smog. (Photochemical reactions are chemical reactions that involve light photons). </li></ul><ul><li>Local climate can make the problem worse. </li></ul>
  23. 24. Chemical Reactions of Smog <ul><li>A few important reactions: </li></ul><ul><li>Primary pollutant </li></ul><ul><li>(1) NO 2 + h   NO + O ( h  represents a photon) </li></ul><ul><li>fast (2) O + O 2 + M  O 3 + M ( M represents a neutral molecule) </li></ul><ul><li>(3) O 3 + NO  NO 2 + O 2 </li></ul><ul><li>  (4) O + HC (hydrocarbon)  stable product + F.R. (free radical) </li></ul><ul><li>slow (5) O 3 + HC  S.P. + F.R. </li></ul><ul><li>(6) F.R. + HC  S.P. + F.R. </li></ul><ul><li>( Being a stable product doesn’t mean it is pleasant! It can be irritating to our body .) </li></ul><ul><li>(7) F.R. + NO  F.R. + NO 2 </li></ul><ul><li>fast (8) F.R. + NO 2  Stable Product (PAN-Type, Peroxyacetyl Nitrate ) </li></ul><ul><li>(9) F.R. + F.R.  Stable product </li></ul><ul><li>The most important reactions are (1)-(3). </li></ul>Secondary pollutant
  24. 25. <ul><li>The reaction sequence illustrates how nitrogen oxides formed in the combustion of gasoline and other fuels and emitted to the atmosphere are acted upon by sunlight to yield ozone (O 3 ), a compound not emitted as such from a source and hence considered as a secondary pollutant. Ozone in turn reacts with hydrocarbons to form a series of compounds which includes aldehydes, organic acids, and epoxy compounds. Thus, the atmosphere can be viewed as a huge reaction vessel wherein new compounds are being formed while others are being destroyed. </li></ul>
  25. 26. Daily Concentration Variation of Smog Chemicals
  26. 27. Health Effects <ul><li>Much of our knowledge of the effects of air pollution on people comes from the study of acute air pollution episodes. </li></ul><ul><li>*Donoro, Pennsylvania </li></ul><ul><li>*London, England </li></ul><ul><li>In both episodes the illness appeared to be chemical irritation of the respirotory tract.The pollutants affacted a specific segment of the public-those individuals already suffering from diseases of the cardio-respiratory system. </li></ul>
  27. 28. Global Atmospheric Change <ul><li>Global warming and stratospheric ozone depletion has threaten to become dominant environmental issues of 1990’s and onwards. </li></ul><ul><li>CO 2 , N 2 O, CH 4 , O 3 and CFC’s undergo rapid changes in atmospheric conditions. </li></ul><ul><li>Problems of greenhouse effect leading to global warming and </li></ul>
  28. 29. Structure of the Atmosphere
  29. 30. Composition of clean, dry air <ul><li>  </li></ul><ul><li>Component Content Component Content   % by Vol. </li></ul><ul><li>Nitrogen 78.09 </li></ul><ul><li>Hydrogen .00005 </li></ul><ul><li>Oxygen 20.94 </li></ul><ul><li>Methane .00015 </li></ul><ul><li>Argon .93 </li></ul><ul><li>Nitrogen Dioxide .0000001 </li></ul><ul><li>Carbon Dioxide .0318 </li></ul><ul><li>Water vapor .04 </li></ul><ul><li>Ozone .000002 </li></ul><ul><li>Neon .0018 </li></ul><ul><li>Sulfur Dioxide .00000002 </li></ul><ul><li>Helium .00052 </li></ul><ul><li>Carbon Monoxide .00001 </li></ul><ul><li>Krypton .0001 </li></ul><ul><li>Ammonia .000001 </li></ul><ul><li>Xeon .000008 </li></ul><ul><li>  Nitrous Oxide .000025      </li></ul><ul><li>*From Cleaning Our Environment the Chemical Basis of Action </li></ul>
  30. 31. <ul><li>Most of the above concentrations of the gases are not changing. However, CO 2 concentration increasing 1.112 ppm/year. Not only the conc. But also the temperature of atmosphere is increasing. </li></ul>
  31. 32. ATMOSPHERIC CO 2 INCREASE OVER PAST 1000 YEARS Jacob: Intergovernmental Panel on Climate Change (IPCC) document, 2001 Concentration units: parts per million (ppm) number of CO 2 molecules per 10 6 molecules of air CO 2 CONCENTRATION IS MEASURED HERE AS MIXING RATIO
  32. 33. Greenhouse Effect <ul><li>Earth’s atmosphere is slightly warmer than what it should be due to direct solar heating because of a mild case of greenhouse effect… </li></ul><ul><ul><li>The ground is heated by visible and (some) infrared light from the Sun. </li></ul></ul><ul><ul><li>The heated surface emits infrared light. </li></ul></ul><ul><ul><li>The majority of Earth’s atmosphere (N 2 and O 2 ) are not good greenhouse gas. </li></ul></ul><ul><ul><li>The small amount of greenhouse gases (H 2 O, CO 2 ) traps (absorb and re-emit) the infrared radiation, increasing the temperature of the atmosphere… </li></ul></ul>
  33. 34. Greenhouse Effect <ul><li>Visible light (short wavelength) </li></ul><ul><ul><li>Not absorbed by glass </li></ul></ul><ul><ul><li>Passes thru unchanged </li></ul></ul><ul><ul><li>Contacts colored surfaces </li></ul></ul><ul><ul><ul><li>Some reflected </li></ul></ul></ul><ul><ul><ul><li>Some degraded (IR) </li></ul></ul></ul><ul><li>Infrared light (long wavelength) </li></ul><ul><li>Absorbed by glass </li></ul><ul><ul><li>Re-emitted to space and back into greenhouse </li></ul></ul><ul><li>Infrared light (IR) is associated with heat . </li></ul><ul><li>IR is reflected back towards space. Some absorbed by Carbon Dioxide and Water. (Nitrogen and Oxygen do NOT absorb IR light.) </li></ul>
  34. 35. <ul><ul><li>Greenhouse gas are efficient in absorbing IR light … </li></ul></ul><ul><li>The gases in the atmosphere that act like glass in a greenhouse are called greenhouse gases. </li></ul><ul><ul><li>The most important greenhouse gases are: </li></ul></ul><ul><ul><li>H 2 O – Water vapor. </li></ul></ul><ul><ul><li>CO 2 – Carbon Dioxide </li></ul></ul><ul><ul><li>CH 4 – methane </li></ul></ul><ul><ul><li>others: </li></ul></ul><ul><li> - N 2 O </li></ul><ul><li> - O 3 </li></ul><ul><li> - CFCs </li></ul><ul><li> -SF 6 ( sulphur hexafluoride) </li></ul><ul><li>The most abundant greenhouse gas in Earth’s atmosphere is water vapor . Most of the greenhouse heating of Earth’s atmosphere is due to Water vapor absorption of IR radiation emitted by Earth, and then transferring the energy to the surrounding air molecule </li></ul>
  35. 36. Global warming <ul><li>Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occuring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases: </li></ul><ul><li>CO2 </li></ul><ul><li>methane </li></ul><ul><ul><li>emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock. </li></ul></ul><ul><li>nitrous oxide </li></ul><ul><li>Chlofluorocarbons (CFCs), perfluorocarbons (PFCs), & sulfur hexafluoride (SF6) </li></ul><ul><ul><li>These compounds are potent greenhouse gases. In addition to having high global warming potentials, SF6 and many HFCs and PFCs have extremely long atmospheric lifetimes, resulting in their essentially irreversible accumulation in the atmosphere. Sulfur hexafluoride, itself, is the most potent greenhouse gas the IPCC has evaluated. </li></ul></ul><ul><ul><li>generated in a variety of industrial processes </li></ul></ul>
  36. 37. So, what’s the big deal if human CO 2 causes 1 °C temperature increase? <ul><li>An increase in atmospheric temperature (human or natural origin) will lead to the increase in the water vapor content of the troposphere. </li></ul><ul><li>Because water vapor is a strong greenhouse gas, the increase in H 2 O vapor in turn causes enhanced greenhouse effect, raising the temperature more. </li></ul><ul><li>Higher atmospheric temperature will cause more evaporation of water </li></ul><ul><li>Which leads to even higher temperature… </li></ul><ul><li> Runaway Green House Effect! </li></ul>
  37. 38. Consequences of global warming <ul><li>Sea level rise </li></ul><ul><ul><li>Beach erosion </li></ul></ul><ul><ul><li>Coastal wetland loss </li></ul></ul><ul><ul><li>Loss of low-lying territories </li></ul></ul><ul><li>Water resources change </li></ul><ul><ul><li>Precipitation pattern shift </li></ul></ul><ul><ul><li>Increases instances of heavy precipitation </li></ul></ul><ul><ul><li>New burdens on water capture, storage and distribution system to be expected. </li></ul></ul><ul><li>Effects on agriculture </li></ul><ul><ul><li>Changes in the length of growing season </li></ul></ul><ul><ul><li>Growth of undesirable plant species </li></ul></ul>
  38. 39. Consequences of global warming (Continued) <ul><li>Effects on air quality </li></ul><ul><ul><li>Increase in reaction rates and concentrations of certain atmospheric species  increase in O3 in urban areas </li></ul></ul><ul><ul><li>More droughts  widespread forest fire  worsen air quality </li></ul></ul><ul><ul><li>Change in how pollutants are dispersed. </li></ul></ul><ul><li>Impacts on human health </li></ul><ul><ul><li>Changes in patterns of sickness and death. </li></ul></ul><ul><ul><li>Respiratory problems affected by air quality change </li></ul></ul><ul><li>Biodiversity </li></ul><ul><ul><li>Some species may grow too quick and overshoot their reproductive period (e.g. reef corals) </li></ul></ul><ul><ul><li>Forest could be devastated if the rate of climate change outpaced the rate at which forest species could migrate. </li></ul></ul>
  39. 40. Absorption Spectra of Atmospheric Gases Anthes, p. 55 CH 4 CO 2 N 2 O H 2 O O 2 & O 3 atmosphere WAVELENGTH (micrometers)
  40. 41. Carbon dioxide <ul><li>Increase from 280 ppm (1860) to 370 ppm (present) – 31% increase </li></ul><ul><ul><li>Note: 370 ppm = 0.0370% </li></ul></ul><ul><li>Sources </li></ul><ul><ul><li>Burning Fossil Fuels </li></ul></ul><ul><ul><li>Deforestation </li></ul></ul><ul><ul><li>Natural Oxidation </li></ul></ul><ul><li>Sinks </li></ul><ul><ul><li>Photosynthesis </li></ul></ul><ul><ul><li>Oceans </li></ul></ul><ul><ul><li>Atmosphere </li></ul></ul><ul><ul><li>Soil </li></ul></ul><ul><li>Average atmospheric residence time: 500 years </li></ul><ul><li>Anthropogenic increase: 30% </li></ul>
  41. 42. Methane <ul><li>Sources ( anerobic degradation of carbon) </li></ul><ul><ul><li>Wetlands </li></ul></ul><ul><ul><li>Rice Paddies </li></ul></ul><ul><ul><li>Cattle </li></ul></ul><ul><ul><li>Oil & Gas Emissions </li></ul></ul><ul><li>Lifetime (7-10 yrs) </li></ul><ul><li>Projections (10-20 ppb per year increase) </li></ul><ul><li>Absorbs in greenhouse “window” </li></ul>
  42. 43. Chlorofluorocarbons - CFCs <ul><li>Source: Refrigerants, Propellants, Foam Blowing, Cleaning , aerosols, such as deodorants, hairspray, or spray paint (totally a nthropogenic ) </li></ul><ul><li>Sinks: No troposphere sink </li></ul><ul><li>Lifetime: 50 to 1000 years </li></ul>
  43. 44. Atmospheric Temperature (Contribution of Greenhouse Gases to Warming) <ul><li>Carbon Dioxide, CO 2 </li></ul><ul><ul><li>* Contributes 60% of warming </li></ul></ul><ul><li>Trace Gases ( 100 –1000 times less) </li></ul><ul><ul><li>* Contribute 40% of warming </li></ul></ul><ul><ul><li>Methane, CH 4 (15-30% of warming) </li></ul></ul><ul><ul><li>Nitrogen Oxides, NO x (up to 15% of arming) </li></ul></ul><ul><ul><li>Chlorofluorocarbons, CFCs (12% of warming ) </li></ul></ul>
  44. 45. Mean Global Temperature Record
  45. 48. Slowing Global Warming <ul><li>Cut fossil fuel use </li></ul><ul><ul><li>Car makers could dramatically increase the fuel economy of their cars and trucks. </li></ul></ul><ul><ul><li>Most electric utilities still use coal to produce electricity, spewing millions of tons of carbon dioxide and other pollution into the atmosphere every year. Part of the problem could be solved by converting these plants to burn cleaner natural gas. </li></ul></ul><ul><li>Improve energy efficiency </li></ul><ul><ul><li>Our cars and light trucks, home appliances and power plants could be made much more efficient by simply installing the best current technology. Energy efficiency is the cleanest, safest, most economical way to begin to curb global warming. </li></ul></ul><ul><ul><li>We could do much more to save energy in our homes and office buildings. More energy efficient lighting, heating and air-conditioning could keep millions of tons of carbon dioxide out of our air each year. </li></ul></ul><ul><li>Reduce deforestation & plant trees </li></ul><ul><ul><li>Because global vegetation and soils contain about three times as much carbon as the planet's atmosphere, terrestrial ecosystems offer an opportunity to absorb and store (sequester) a significant amount of  carbon dioxide from the atmosphere. By planting trees, preserving forests, and changing cultivation practices to increase soil carbon, for example, it is possible to increase the size of carbon sinks. </li></ul></ul><ul><li>Slow human population growth </li></ul>
  46. 49. <ul><li>The “greenhouse effect” & global warming are not the same thing. </li></ul><ul><ul><li>Global warming refers to a rise in the temperature of the surface of the earth </li></ul></ul><ul><li>An increase in the concentration of greenhouse gases leads to an increase in the the magnitude of the greenhouse effect . (Called enhanced greenhouse effect) </li></ul><ul><ul><li>This results in global warming </li></ul></ul>Greenhouse Effect & Global Warming
  47. 50. OZONE DEPLETION IN THE STRATOSPHERE <ul><li>The ozone hole is: </li></ul><ul><li>--a depletion of ozone in the lower stratosphere </li></ul><ul><li>--that has occurred with increasing severity each spring (since measurements begin in 1970s) </li></ul><ul><li>Ozone in the stratosphere (12-50 km) </li></ul><ul><li>- Maximum 15 – 25 km </li></ul><ul><li>- Ca 90 % in the stratosphere (ozone layer) </li></ul><ul><li>- Protecting against solar UVradiation </li></ul><ul><li>- Anthropogenic emissions result in ozone depletion </li></ul>
  48. 51. CFC’s in relation to depletion of O 3 layer in stratosphere <ul><li>CFCs, a human-developed compound, are particularly destructive to the breakdown of ozone in the atmosphere. </li></ul><ul><li>Molecules containing only fluoride, chloride, and carbon are called fully halogenated CFC’s. They have advantage due to H bond. Because of their chemical stability, low toxicity, and valuable physical properties, these chemicals, versatile and stable in the lower atmosphere. </li></ul><ul><li>CFC compounds are unreactive at Earth’s surface,but if they get into the stratosphere, they can be broken down by high energy UV radiation leads to release of highly reactive CHLORINE atoms ( Cl) </li></ul>
  49. 52. <ul><li>Since CFC's are non-toxic and chemically inert gases in the troposphere they were used extensively in the past.  However, it was found subsequently that CFC's are greenhouse gases with very high global warming potentials and they have a very long atmospheric lifetime. </li></ul><ul><li>A single chlorine atom may destroy hundreds of thousands of ozone molecules during its residence in the stratosphere! </li></ul><ul><li>  </li></ul><ul><li>Their long lifetime means that they can be transported slowly to the stratosphere.  Although CFC's were banned within a few years of the Montreal Protocol in 1987, their long lifetime means that it will take many more years before their atmospheric concentrations level out and then decrease. </li></ul>
  50. 53. Anthropogenic perturbations to stratospheric ozone Role of CFC’s for reaction of Antarctic ozone hole Cl + O 3 ->ClO+O 2 ClO+NO 2 ->CLONO 2 General cycle of ozone destruction in the stratosphere:
  51. 54. Yönetmelikler <ul><li>Endüstriyel Kaynaklı Hava Kirliliğinin Kontrolu Yönetmeliği (Yeni yönetmelik sıra no:91) 07/10/2004-25606 </li></ul><ul><li>Isınmadan Kaynaklanan Hava Kirliliği Yönetmeliği 13/01/2005-25699 </li></ul><ul><li>Endüstri Tesislerinden Kaynaklanan Hava Kirliliğinin Kontrolü Yönetmeliği 22/07/2006-26236 </li></ul>
  52. 55. AMBIENT AIR QUALITY <ul><li>Directive 80/779/EEC on air quality limit values and guide values for sulphur dioxide and suspended particulates, as last amended by Directive 89/427/EEC </li></ul><ul><li>Directive 82/884/EEC on a limit value for lead in the air </li></ul><ul><li>Directive 85/203/EEC on air quality standards for nitrogen dioxide, as last amended by Directive 85/580/EEC </li></ul><ul><li>Directive 96/61/EC concerning integrated pollution prevention and control </li></ul><ul><ul><li>COM/2000/177 : Proposal for a Council Decision on the conclusion on behalf of the European Community of the 1998 Protocol to the 1979 Convention on Long Range Transboundary Air Pollution on Heavy Metals. </li></ul></ul>

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