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The Atmosphere and Air Pollution

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  1. The AtmosphereandAir Pollution a

  2. Origin of Modern Atmosphere • original atmosphere surrounded the homogenousplanet Earth and probably was composed of H and He • second atmosphere evolved from gases from molten Earth • H2O, CO2, SO2, CO, S2, Cl2, N2, H2, NH3, and CH4 • allowed formation of oceans and earliest life • modern Atmosphere • evolved after Cyanobacteria started photosynthesizing • oxygen produced did not reach modern levels until about 400 million years ago

  3. Earth’s Atmosphere • compared to the size of the Earth (104 km), the atmosphere is a thin shell (120 km).

  4. AtmosphereLayers • Exosphere • Thermosphere • (Ionosphere) • Mesosphere • Stratosphere • Troposphere

  5. Troposphere • 8 to 14.5 kilometers high (5 to 9 miles) • most dense • the temperature drops from about 17 to -52 degrees Celsius • almost all weather is in this region

  6. Stratosphere • extends to 50 kilometers (31 miles) high • dry and less dense • temperature in this region increases gradually to -3 degrees Celsius, due to the absorption of ultraviolet radiation • ozone layer absorbs and scatters the solar ultraviolet radiation • ninety-nine percent of "air" is located in first two layers • every 1000-m 11% less air pressure

  7. Composition • Nitrogen (N2, 78%) • Oxygen (O2, 21%) • Argon (Ar, 1%) • myriad of other very influential components are also present which include the Water (H2O, 0 - 7%), "greenhouse" gases or Ozone (O3, 0 - 0.01%), Carbon Dioxide (CO2, 0.01-0.1%),

  8. Importance of the Atmosphere • Physicists • physical properties and processes that take place between the radiant energy and atmospheric gases • Chemists • behavior of the chemical materials in the atmosphere • the ways in which lightning causes the formation of substances • chemistry of the ozone layer and of chemicals introduced from industrial processes

  9. Astronomers and space scientists • the layer through which they must peer before entering the realms of space • Meteorologists, climatologists and geographers • lower layers of the atmosphere • predicting the weather • investigating climatic regions • examine the effects of climate and weather on human society

  10. Outdoor Air Pollution

  11. Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs 2 – NO3 and salts SO4 Most – Natural Sources Stationary Mobile

  12. Major Sources of Primary Pollutants Stationary Sources • Combustion of fuels for power and heat – Power Plants • Other burning such as Wood & crop burning or forest fires • Industrial/ commercial processes • Solvents and aerosols Mobile Sources • Highway: cars, trucks, buses and motorcycles • Off-highway: aircraft, boats, locomotives, farm equipment, RVs, construction machinery, and lawn mowers

  13. 54 million metric tons from mobile sources in 1990

  14. Human Impact on Atmosphere • Adds CO2 and O3 to troposphere • Global Warming • Altering Climates • Produces Acid Rain • Releases NO, NO2, N2O, and NH3 into troposphere • Produces acid rain • Releases SO2 into troposphere • Releases toxic heavy metals (Pb, Cd, and As) into troposphere • Burning Fossil Fuels • Using Nitrogen fertilizers and burning fossil fuels • Refining petroleum and burning fossil fuels • Manufacturing air/products.html

  15. Criteria Air Pollutants EPA uses six "criteria pollutants" as indicators of air quality • Nitrogen Dioxide: NO2 • Ozone: ground level O3 • Carbon monoxide: CO • Lead: Pb • Particulate Matter: PM10 (PM 2.5) • Sulfur Dioxide: SO2 • Volatile Organic Compounds: (VOCs) EPA established for each concentrations above which adverse effects on health may occur

  16. Nitrogen Dioxide (NO2) • Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air • Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth • Sources: fossil fuels combustion, power plants, forest fires, volcanoes, bacteria in soil • Class: Nitrogen oxides (NOx) • EPAStandard: 0.053 ppm

  17. Mobile Source Emissions: Nitrogen Oxides

  18. Ozone (O3) • Properties: colorless, unpleasant odor, major part of photochemical smog • Effects: lung irritant, damages plants, rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%, • Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products • Class: photochemical oxidants

  19. Ozone (O3) • 10,000 to 15,000 people in US admitted to hospitals each year due to ozone-related illness • Children more susceptible • Airways narrower • More time spent outdoors

  20. Mobile Source Emissions: Hydrocarbons – Precursors to Ozone

  21. Carbon Monoxide (CO) • Properties:colorless, odorless, heavier than air, 0.0036% of atmosphere • Effects:binds tighter to Hb than O2, mental functions and visual acuity, even at low levels • Sources:incomplete combustion of fossil fuels 60 - 95% from auto exhaust • Class:carbon oxides (CO2, CO) • EPAStandard:9 ppm • 5.5 billion tons enter atmosphere/year

  22. Mobile Source Emissions - CO

  23. Lead (Pb) • Properties: grayish metal • Effects: accumulates in tissue; affects kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high] • Sources: particulates, smelters, batteries • Class:toxic or heavy metals • EPAStandard: 1.5 ug/m3 • 2 million tons enter atmosphere/year

  24. Suspended Particulate Matter (PM10) • Properties: particles suspended in air (<10 um) • Effects: lung damage, mutagenic, carcinogenic, teratogenic • Sources:burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields • Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides • EPA Standard: 50 ug/m3 (annual mean)

  25. Mobile Source Emissions: Fine Particulate Matter (PM2.5)

  26. Sulfur Dioxide (SO2) • Properties: colorless gas with irritating odor • Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators • Sources:burning high sulfur coal or oil, smelting or metals, paper manufacture • Class: sulfur oxides • EPA Standard: 0.3 ppm (annual mean) • Combines with water and NH4 to increase soil fertility

  27. VOCs (Volatile Organic Compounds) • Properties: organic compounds (hydrocarbons) that evaporate easily, usually aromatic • Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming • Sources:vehicles(largest source),evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning • Class: HAPs (Hazardous Air Pollutants) • Methane • Benzene • Chlorofluorocarbons (CFCs), etc. • Concentrations indoors up to 1000x outdoors • 600 million tons of CFCs

  28. Other Air Pollutants • Carbon dioxide • ChloroFluoroCarbons • Formaldehyde • Benzene • Asbestos • Manganese • Dioxins • Cadmium • Others not yet fully characterized

  29. Factors that increase and/or decrease pollution • Local climate (inversions, air pressure, temperature, humidity) • Topography (hills and mountains) • Population density • Amount of industry • Fuels used by population and industry for heating, manufacturing, transportation, power • Weather: rain, snow,wind • Buildings (slow wind speed) • Mass transit used • Economics

  30. Thermal Inversion cool air Pollutants cool air warm air (inversion layer) warm air • surface heated by sun • warm air rises (incl. pollutants) • cools off, mixes with air of equal density & disperses • surface cools rapidly (night) • a layer of warm air overlays surface • polluted surface air rises but cannot disperse ⇒ remains trapped

  31. Smog Forms ...when polluted air is stagnant (weather conditions, geographic location) Los Angeles, CA

  32. Pollution • The term “Smog” (smoke and fog) was first used in 1905 to describe sulfur dioxide emission • In 1952, severe pollution took the lives of 5000 people in London • “It isn’t pollution that’s harming the environment. It’s the impurities in our air and water that are doing it.” FormerU.S. Vice President Dan Quayle 97annual.html

  33. Photochemical Smog UV radiation H2O + O2 Primary Pollutants NO2 + Hydrocarbons Secondary Pollutants HNO3 O3 nitric acid ozone Photochemical Smog Auto Emissions

  34. Solar radiation Photochemical Smog Ultraviolet radiation NO Nitric oxide O Atomic oxygen O2 Molecular oxygen NO2 Nitrogen dioxide H2O Water Hydrocarbons PANs Peroxyacyl nitrates Aldehydes (e.g., formaldehyde) O3 Ozone HNO3 Nitric acid P h o t o c h e m i c a l S m o g

  35. Indoor Air Pollution

  36. Why is indoor air quality important? • 70 to 90% of time spent indoors, mostly at home • Many significant pollution sources in the home (e.g. gas cookers, paints and glues) • Personal exposure to many common pollutants is driven by indoor exposure • Especially important for susceptible groups – e.g. the sick, old and very young

  37. Exposure • Time spent in various environments in US and less-developed countries

  38. House of Commons Select Committee Enquiry on Indoor Air Pollution (1991) • “[There is] evidence that 3 million people have asthma in the UK… and this is increasing by 5% per annum.” • “Overall there appears to be a worryingly large number of health problems which could be connected with indoor pollution and which affect very large numbers of the population.” • [The Committee recommends that the Government] “develop guidelines and codes of practice for indoor air quality in buildings which specifically identify exposure limits for an extended list of pollutants…”

  39. Sources of Indoor Air Pollutants • Building materials • Furniture • Furnishings and fabrics • Glues • Cleaning products • Other consumer products • Combustion appliances (cookers and heaters) • Open fires • Tobacco smoking • Cooking • House dust mites, bacteria and moulds • Outdoor air

  40. Important Indoor Air pollutants • Nitrogen dioxide • Carbon monoxide • Formaldehyde • Volatile Organic Compounds (VOCs) • House dust mites (and other allergens, e.g. from pets) • Environmental tobacco smoke • Fine particles • Chlorinated organic compounds (e.g. pesticides) • Asbestos and man-made mineral fibres • Radon

  41. Health Effects Nitrogen dioxide • Respiratory irritant • Elevated risk of respiratory illness in children, perhaps resulting from increased susceptibility to respiratory infection; inconsistent evidence for effects in adults • Concentrations in kitchens can readily exceed WHO and EPA standards

  42. Health Effects Carbon monoxide • An asphyxiant and toxicant • Hazard of acute intoxication, mostly from malfunctioning fuel-burning appliances and inadequate or blocked flues • Possibility of chronic effects of long-term exposure to non- lethal concentrations, particularly amongst susceptible groups

  43. Health Effects Formaldehyde • Sensory and respiratory irritant and sensitizer • Possible increased risk of asthma and chronic bronchitis in children at higher exposure levels • Individual differences in sensory and other transient responses • Caution over rising indoor concentrations

  44. Health Effects Volatile Organic Compounds (VOCs) • Occur in complex and variable mixtures • Main health effects relate to comfort and well-being, but benzene (and other VOCs) are carcinogenic • Concern about possible role of VOCs in the aetiology of multiple chemical sensitivity; also implicated in sick building syndrome

  45. Health Effects House dust mites • House dust mites produce Der p1 allergen, a potent sensitizer • Good evidence of increased risk of sensitization with increasing allergen exposure, but this does not necessarily lead to asthma • Small reductions in exposure will not necessarily lead to reduced incidence and/or symptoms • Indoor humidity is important

  46. Health Effects Fungi and bacteria • Dampness and mould-growth linked to self-reported respiratory conditions, but little convincing evidence for association between measured airborne fungi and respiratory disease • Insufficient data to relate exposure to (non-pathogenic) bacteria to health effects in the indoor environment

  47. Health Effects Environmental tobacco smoke (ETS) • Sudden infant death syndrome • Lower respiratory tract illness • Middle ear disease • Asthma 12 million children exposed to secondhand smoke in homes

  48. Health Effects Fine particles • Consistent evidence that exposure to small airborne particles (e.g. PM10) in ambient air can impact on human health; mechanisms uncertain • Chronic Obstructive Pulmonary Disease and Cardiovascular Disease patients and asthmatics probably at extra risk • Relative importance of indoor sources is unknown

  49. Health Effects Radon • Can cause lung cancer • Estimated that 7,000 to 30,000 Americans die each year from radon-induced lung cancer • Only smoking causes more lung cancer deaths • Smokers more at risk than non-smokers