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Air and Air Pollution 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 Fig. 17-2 p. 419/ see also fig. 17-3 p. 420 The Atmosphere Troposphere: 75-80% of mass of the atmosphere 78% N, 21% O, 1-4% H2O(v), 1% Ar and .037%CO2 Stratosphere: much less H2O(v), and much more O3. Ozone layer: Beneficial in the stratosphere damaging in the troposphere (smog). Greenhouse effect: necessary for life 8-17 km Outdoor Air Pollution Primary pollutants: from both natural and human (anthropogenic) sources See Table 17-1 p. 420 See Table 17-2 p. 422 Secondary pollutants: from chemical reactions that occur in the atmosphere with the primary pollutants Indoor Pollutants: Come from infiltration from outside polluted air and various chemicals used or produced inside buildings Fig. 17-4 p. 421 Photochemical Smog Brown-air smog due to NO2 Factors that influence: topography, population density, industry, fuels used, urbanization, high temperatures Photochemical reactions (see pg. 423-424) Photochemical oxidants (PAN’s, NO2, and O3 ) Oxidize compounds in air or lungs Irritate lungs, damage plants Fig. 17-6 p. 424 Photochemical Smog • At the high temperatures of the car's combustion chamber (cylinder), nitrogen and oxygen from the air react to form nitric oxide (NO): Step 1: N2 + O2 -----> 2NO • Some of the nitric oxide (NO) reacts with oxygen to form nitrogen dioxide NO2): Step 2: 2NO + O2 -----> 2NO2 • When the nitrogen dioxide (NO2) concentration is well above clean air levels and there is plenty of sunlight, then an oxygen atom splits off from the nitrogen dioxide molecule: Step 3: NO2 ---------->NO + O (sunlight) • This oxygen atom (O) can react with oxygen molecules (O2) in the air to form ozone (O3): Step 4: O + O2 -----> O3 (ozone) Industrial Smog See pg. 423 Gray-air smog: Suspended particles and soot Industrial smog: largely due to burning of coal and release of sulfur impurities Sulfuric acid Sulfur dioxide Particulates: < 10 microns dangerous to health Fig. 17-8 p. 426 Temperature Inversions Subsidence inversion: Fig. 17-9 p. 427 Warm air mass moves over a cold air mass and decreases vertical mixing Radiation inversion: Inversion layer Increasing altitude occurs at night, air near ground cools faster than air above. Sun rise heats up the air and usually diminishes by noon Descending warm air mass Sea breeze Mountain range Decreasing temperature Figure 17-9 (2) Page 427 Slide 12 Regional Outdoor Air Pollution from Acid Deposition Acid deposition: due to tall smokestacks pollution is decreased locally and increased regionally and transformed in the atmosphere as it is spread downwind and deposited as acid deposition acid acidic particles rain snow fog and cloud vapor Wet deposition: Fig. 17-10 p. 428 Dry deposition: Acid Deposition in the US Fig. 17-11 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 Fig. 17-14 p. 431 Acid Deposition, Plants, and Soil Nutrient leaching Heavy metal release Weakens trees Fig. 17-15 p. 432 Prevention Reduce air pollution by improving energy efficiency Reduce coal use Cleanup Add lime to neutralize acidified lakes Add phosphate fertilizer to neutralize acidified lakes Increase natural gas use Increase use of renewable resources Burn low-sulfur coal Remove SO2 particulates, and NOx from smokestack gases Remove Nox from motor vehicular exhaust Tax emissions of SO2 Figure 17-16 Page 433 Indoor Air Pollution/Sick Building Syndrome Fig. 17-17 p. 434 Radon Radon-222 4 picocurie level Occurs in certain areas based on geology Associated with uranium and organic material in rock Fig. 17-18 p. 436 Effects of Air Pollution on Living Organisms and Materials Damage to mucous membranes Respiratory diseases (see Fig. 17-19 p. 438) Damage to plant leaves and roots Reduction in primary productivity Deterioration of materials (See Table 17-3 p. 440) Solutions: Preventing and Reducing Air Pollution Clean Air Act: passed 1970, 1977, and 1990 National Ambient Air Quality Standards (NAAQS) Primary and secondary standards: primary set to protect human health; secondary set to prevent environmental and property damage Emission Reduction Fig. 17-22 p. 441 Fig. 17-23a p. 442