NATS 101 Lecture 23 Air Pollution Meteorology - PowerPoint PPT Presentation

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NATS 101 Lecture 23 Air Pollution Meteorology

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  1. NATS 101Lecture 23Air Pollution Meteorology

  2. AMS Glossary of Meteorology • air pollution—The presence of substances in the atmosphere, particularly those that do not occur naturally. • These substances are generally contaminants that substantially alter or degrade the quality of the atmosphere. • The term is often used to identify undesirable substances produced by human activity, that is, anthropogenic air pollution. • Air pollution usually designates the collection of substances that adversely affects human health, animals, and plants; deteriorates structures; interferes with commerce; or interferes with the enjoyment of life.

  3. Major Air Pollution Episodes of Historic Significance • Some of the worst events in the last two centuries occurred in London • Key ingredients: calm winds, fog, smoke particles from coal burning • 1873 - 700 deaths • 1911- 1150 deaths • 1952 - 12,000 deaths (Dec 5 - 9) • Last event led to the Parliament passing a Clean Air Act in 1956


  5. Major U.S. Air Pollution Episodes of Historic Significance • U.S. air quality degraded shortly after the beginning of the industrial revolution • Coal burning in Central and Midwest U.S. • 1939 St. Louis Smog Nov 28 • 1948 Donora, PA in the Monongahela River Valley • 20 deaths, 1000’s took ill in 5 days Oct 27 • Prompted Air Pollution Control Act of 1955 • Ignored automobiles

  6. Major U.S. Air Pollution Episodes of Historic Significance • 1960s - NYC had several severe smog episodes • 1950s onward – LA had many smog alerts from an increase in industry and motor vehicle use • Led to passage of the Clean Air Act of 1970 (updated 1977 and 1990) • Empowered Federal Government to set emission standards that each state had to meet

  7. U.S. Air Pollution Examples Smog in San Gabriel Valley, 1972. (Photo: EPA.) 1963 photo of a severe smog episode in New York City. (Photo: AP/Wide World Photo, EPA Journal Jan/Feb 1990.)

  8. Even remote areas are affected by pollution Canyon on a clear day Canyon on a smog day Air Pollution in Grand Canyon Nice link to Lyndon Valley State College that has useful material for a NATS-type course

  9. Primary PollutantsInjected directly into atmosphere • Carbon Monoxide (CO) • odorless, colorless, poisonous gas • byproduct of burning fossil fuels • body acts as if CO is O2 in blood, can result in death • Nitrogen Oxides (NOx, NO) • NO - nitric oxide • emitted directly by autos, industry

  10. Primary Pollutants • Sulfur Oxides (SOx) • SO2 - sulfur dioxide • produced largely through coal burning • responsible for acid rain problem • Volatile Organic Compounds (VOCs) • highly reactive organic compounds • released through incomplete combustion and industrial sources • Particulate Matter (dust, ash, smoke, salt) • 10 um particles (PM10) stay lodged in your lungs • 2.5 um particles (PM2.5) can enter blood stream

  11. L.A. Sky Colors Dec 2000 Mark Z. Jacobson Secondary PollutantsForm in atmosphere from chemical-photochemical reactions that involve primary pollutants • Sulfuric Acid H2SO4 • major cause of acid rain • Nitrogen Dioxide NO2 • brownish hue

  12. Secondary Pollutants • Ozone O3 • colorless gas • has an acrid, sweet smell • oxidizing agent • Primary and secondary pollutants are found in the two types of smog: • London-type smog • LA-type photochemical smog (LA AQMD) SMOG = SMOKE + FOG

  13. Human Response to One Hour Pollutant Exposure (Turco, p194) CO sticks to hemoglobin, forming carboxyhemoglobin (COHb), which reduces the capacity of hemoglobin to carry O2 to cells

  14. Physiology of Exposure to CO COHb level is 5%-15% for cig puffers!

  15. Human Response to One Hour Pollutant Exposure (Turco, p194)

  16. Human Response to One Hour Pollutant Exposure (Turco, p194)

  17. Human Response to One Hour Pollutant Exposure (Turco, p194)

  18. Table 12-2, p.328

  19. Beijing Air Pollution Record Pollution Levels AQI > 300 - Hazardous 11-5-2005 AFP Photo Where’s Beijing? 11-4-2005NASA MODIS Visible Beijing smog during 2008 summer olympics

  20. Pollution Knows No Boundaries April 2001 China Dust Transport Across Pacific Fig. 12-4, p.322

  21. U.S. Pollutant Trends1940-1995 • Most pollutants decreased after the 1970 Clean Air Act Lead Particulates SO2 VOC’s CO NO2 is Leveling Off Fig. 12-9, p.328

  22. AQI > 150 for CO, SO2, NO2, O3 and PM Fig. 12-10, p.329


  24. 90% total pollutants 10% total pollutants Table 12-1, p.320

  25. Percentage of Primary Pollutants Fig. 12-2a, p.320

  26. Percentage of Primary Sources Fig. 12-2b, p.320

  27. Air Pollution Weather • Strong low-level inversion Subsidence inversion that diurnal heating does not break or weaken significantly • Weak surface winds Persistent surface anticyclone • Sunny weather for photochemical smog • Hot weather to accelerate O3 production

  28. Fig. 12-12, p.333

  29. Top of Mixing Layer Fig. 12-13, p.333

  30. Valleys Trap Pollutants L.A. is in a basin surrounded by mountains that trap pollutants and usually has onshore flow that creates frequent inversions. Pollutants can only escape through narrow canyons Fig. 12-15, p.334

  31. Leading Edge of Sea Breeze and “Smog Front” over Inland SoCal Fig. 12-14, p.333

  32. Air Pollution Dispersion • Air pollution dispersion is often studied with simple models, termed Box Models.  How is a box defined for the LA basin? Box Model Boundaries for the LA Basin • Ventilation factor is a simple way of relating concentrations of pollutants to parameters that modulate the dispersion of pollutants in a local environments. • An increase in either the mixing height or the wind speed increases the effective volume in which pollutants are allowed to mix. • The larger the volume, the lower the pollution concentration. • How does a box model work?

  33. Mixing Height Length = Wind Speed Time Ventilation Factor (VF) Volume ~ Length  Height VF = Mixing Height  Wind Speed

  34. Acid Rain and Deposition • Sulfur dioxide (SO2) and oxides of nitrogen (NOx) within clouds (including fog) form acidic particles when they react with water: SO2 + H2O  H2SO4 (sulfuric acid) NOx + H2O  HNO3 (nitric acid) • Acid Rain is worse downstream of the point sources of pollution • Acid Rain affects Trees, Lakes, Structures • Acid Deposition is a world-wide problem

  35. pH is logarithmic scale. An one unit change denotes a factor of 10 difference. Fig. 12-17, p.338

  36. pH = 5.6 for pristine rain

  37. Acidified Forest in Czechoslovakia Fig. 12-19, p.339

  38. Impact on Aquatic Organisms

  39. Sandstone Figure in Germany Herr Schmidt-Thomsen Herr Schmidt-Thomsen 1908 1968

  40. Summary • Air Pollutants – Long History • Primary: CO, NOx, SOx, VOC, PM • Secondary: H2SO4, NO2, O3 • Global Problem - Knows No Boundaries! • Serious Health Consequences • US Air Improving - Clean Air Act But It is Degrading in Emerging Economies • Air Pollution Weather and Air Dispersion • Acid Rain

  41. NATS 101Lecture Ozone Depletion

  42. Supplemental References for Today’s Lecture Danielson, E. W., J. Levin and E. Abrams, 1998: Meteorology. 462 pp. McGraw-Hill. (ISBN 0-697-21711-6) Moran, J. M., and M. D. Morgan, 1997: Meteorology, The Atmosphere and the Science of Weather, 5th Ed. 530 pp. Prentice Hall. (ISBN 0-13-266701-0)

  43. Review: Ultraviolet (UV) Absorption UV Visible IR O2 and O3 absorb UV (shorter than 0.3 m) Therefore, reductions in the level of O3 would increase the amount of UV radiation that penetrates to the surface Ahrens, p 36

  44. Hazards of Increased UV • Increase number of cases of skin cancers • Increase in eye cataracts and sun burning • Suppression of human immune system • Damage to crops and animals • Reduction in ocean phytoplankton

  45. Disassociation of O2 absorbs UV < 0.2 m O2 + UV  O + O O3 forms when O2 and O molecules collide O2 + O  O3 Disassociation of O3 absorbs 0.2-0.3 m UV O3 + UV  O2 + O Balance exists between O3 creation-destruction CFC’s disrupts balance Natural Balance of Ozone Danielson et al, Fig 2.28

  46. CFC’s make up many important products Refrigerants Insulation Materials Aerosol Propellants Cleaning Solvents Sources of CFC’s

  47. Commonly Used CFC’s Name Formula Primary Use Residence Time (50% decrease) CFC-11 CCl3F Propellant ~55 years CFC-12 CCl2F2 Refrigerant ~100 years CFC-113 C2Cl3F3 Cleaning Solvent ~65 years It would take 10-20 years for CFC levels to start falling if all production ended today due to leakage of CFC’s from old appliances, etc.

  48. Chronology of Ozone Depletion 1881 Discovery of ozone layer in stratosphere 1928 Synthesis of CFC’s for use as a refrigerant 1950s Rapid increase in use of CFC’s 1974 Description of ozone loss chemical reactions 1979 Ban of CFC use in most aerosol cans in U.S. 1980s Growth of CFC use worldwide 1985 Discovery of Antarctic ozone hole 1987 Adoption of Montreal Protocol calling for a 50% reduction in use of CFC’s by 1998

  49. Chronology of Ozone Depletion 1989 Confirmation of ozone declines in mid-latitudes of Northern Hemisphere and in the Arctic 1990 Montreal Protocol amended to require a complete phase out of all ozone depleting chemicals by 2000 1990 U.S. requirement for recycling of CFC’s 1992 Discovery of high levels of ClO over middle and high latitudes of Northern Hemisphere 1992 Further amendment of Montreal Protocol calling for an accelerated phase out by ozone depleting chemicals 2100 Time needed for ozone layer to heal completely?