Air and Air Pollution Brian Kaestner Saint Mary’s Hall Brian Kaestner Saint Mary’s Hall Thanks to Miller and Clements

Key Concepts  Structure and composition of the atmosphere  Types and sources of outdoor air pollution  Types, formation, and effects of smog  Sources and effects of acid deposition  Effects of air pollution  Prevention and control of air pollution

The Atmosphere  Troposphere  Stratosphere  78% N, 21% O  Ozone layer  Greenhouse effect Pressure = 1,000 millibars at ground level Atmospheric pressure (millibars) , (SeaLevel) –80– Temperature (˚C) Altitude (kilometers) Altitude (miles) Thermosphere Heating via ozone Mesosphere Stratosphere Ozone “layer” Heating from the earth Troposphere Temperature Pressure Mesopause Stratopause Tropopause Fig. 17.2, p. 418

Outdoor Air Pollution  Primary pollutants  Secondary pollutants Primary Pollutants Secondary Pollutants Sources Natural Stationary COCO 2 SO 2 NONO 2 Most hydrocarbons Most suspended particles SO 3 HNO 3 H 2 SO 4 H2O2H2O2 O3O3 PANs MostandsaltsNO 3 – Mobile SO 4 2 – Fig. 17.4, p. 422 See Table 17-1 p. 421 See Table 17-2 p. 422

Nitric oxideNitrogen dioxideOzone A.M.NoonP.M. Time Parts per million Fig. 17.6, p. 424

Photochemical Smog  Brown-air smog  Photochemical reaction  Photochemical oxidants Solar radiation Ultraviolet radiation NO Nitric oxide Photochemical smog H 2 O Water NO 2 Nitrogen dioxide Hydrocarbons O 2 Molecular oxygen HNO 3 Nitric acid PANs Peroxyacyl nitrates Aldehydes (e.g., formaldehyde) O 3 Ozone O Atomic oxygen Fig. 17.5, p. 424

Industrial Smog  Gray-air smog  Industrial smog  Sulfuric acid  Sulfur dioxide  Particulates Ultra Fine ParticlesFineParticlesLargeParticles Sea salt nuclei Carbon black Pollens Cement dust Oil smoke Combustion nuclei Metallurgical dust and fumes Photochemical smog Insecticide dusts Coal dust Average particle diameter (micrometers or microns) Tobacco smoke Paint pigments Fly ash Milled flour Fig. 17.7, p. 425

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Temperature Inversions  Subsidence inversion  Radiation inversion Warmer air Inversion layer Cool layer Mountain Mountain Valley Decreasing temperature Increasing altitude Fig. 17.8, p. 426

Inversion layer Mountain range Sea breeze Descending warm air mass Decreasing temperature Increasing altitude Fig. 17.8b, p. 426

Regional Outdoor Air Pollution from Acid Deposition  Acid deposition  Wet deposition  Dry deposition Wind Transformation to sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ) Nitric oxide (NO) Acid fog Ocean Sulfur dioxide (SO 2 ) and NO Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Farm Lakes in deep soil high in limestone are buffered Lakes in shallow soil low in limestone become acidic Wet acid deposition (droplets of H 2 SO 4 and HNO 3 dissolved in rain and snow) Fig. 17.9, p. 428

Acid Deposition in the US Fig , p. 428

Potential problem areas because of sensitive soils Potential problem areas because of air pollution: emissions leading to acid deposition Current problem areas (including lakes and rivers) Fig , p. 429

Acid Deposition and Humans  Respiratory diseases  Toxic metal leaching  Decreased visibility  Damage to structures, especially containing limestone  Decreased productivity and profitability of fisheries, forests, and farms

Acid Deposition and Aquatic Systems  Fish declines  Undesirable species  Aluminum toxicity  Acid shock Waterboatman Whirligig Yellow perch Lake trout Brown trout Salamander(embryonic) Mayfly Smallmouthbass Mussel pH Fig , p. 430

Acid Deposition, Plants, and Soil  Nutrient leaching  Heavy metal release  Weakens trees Emissions Effects of Weather Acid deposition Dry weather Low precipitation Increased evapotranspiration Increased transpiration Lake Groundwater SO 2 NO X H2O2H2O2 O3O3 PANsOthers Increased susceptibility to frost, pests, fungi, mosses, and disease Dead leaves or needles Reduced photosynthesis and growth Tree death Damage to tree crown Water deficit Nutrient deficiency Bark damage Direct damage to leaves and needles Leaching of soil nutrients Acids and soil nutrients Damage to fine roots Disturbance of water uptake Disturbance of nutrient uptake Soil acidification Kills certain essential soil microorganisms Release of toxic metal ions Nitrate Sulfate Magnesium Aluminum Calcium Potassium Acids Fig , p. 432 See Connections p. 431

Solutions: Preventing and Reducing Air Pollution  Clean Air Act  National Ambient Air Quality Standards (NAAQS)  Primary and secondary standards  Output control vs. input control

Emission Reduction PreventionDispersion or Cleanup Burn low-sulfur coal Remove sulfur from coal Convert coal to a liquid or gaseous fuel Shift to less polluting fuels Disperse emissions above thermal inversion layer with tall smokestacks Remove pollutants after combustion Tax each unit of pollution produced Fig , p. 442 Electrostatic Precipitator Dirty gas Dust discharge Electrodes Cleaned gas Fig , p. 442

Dirty gas Dirty water Clean water Wet Scrubber Wet gas Cleaned gas Fig d, p. 442

Cyclone Separator Dirty gas Dust discharge Cleaned gas Fig c, p. 442

Cleaned gas Dirty gas Baghouse Filter Dust discharge Bags Fig b, p. 442

Indoor Air Pollution/Sick Building Syndrome Chloroform Para-dichlorobenzene Tetrachloroethylene Formaldehyde Benzo-  -pyrene Styrene Radon-222 Methylene Chloride Tobacco Smoke Carbon Monoxide Asbestos Nitrogen Oxides 1, 1, 1- Trichloroethane Fig , p. 435

Radon  Radon-222  4 picocurie level  Occurs in certain areas based on geology  Associated with uranium and organic material in rock Outlet vents for furnaces and dryers Slab joints Wood stove Cracks in floor Clothes dryer Furnace Radon-222 gas Slab Radium-222 Soil Uranium-238 Sump pump Cracks in wall Open window Openings around pipes Openings around pipes Fig , p. 436

Reducing Indoor Air Pollution PreventionCleanup or Dilution Cover ceiling tiles and lining of AC ducts to prevent release of mineral fibers Ban smoking or limit it to well- ventilated areas Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Prevent radon infiltration Use office machines in well-ventilated areas Use less polluting substitutes for harmful cleaning agents, paints, and other products Use adjustable fresh air vents for work spaces Increase intake of outside air Change air more frequently Circulate building’s air through rooftop greenhouses Use exhaust hoods for stoves and appliances burning natural gas Install efficient chimneys for wood-burning stoves Fig , p. 443