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

The Atmosphere  Troposphere: 75-80% of mass of the atmosphere  Stratosphere: much less H 2 O (v), and much more O 3.  78% N, 21% O, 1-4% H 2 O (v), 1% Ar and.037%CO 2  Ozone layer: Beneficial in the stratosphere damaging in the troposphere (smog).  Greenhouse effect: necessary for life Fig p. 419/ see also fig p km

Outdoor Air Pollution  Primary pollutants: from both natural and human (anthropogenic) sources  Secondary pollutants: from chemical reactions that occur in the atmosphere with the primary pollutants See Table 17-1 p. 420 See Table 17-2 p. 422 Fig p. 421  Indoor Pollutants: Come from infiltration from outside polluted air and various chemicals used or produced inside buildings  Indoor Pollutants: Come from infiltration from outside polluted air and various chemicals used or produced inside buildings

Photochemical Smog  Brown-air smog due to NO 2  Photochemical reactions (see pg )  Photochemical oxidants (PAN’s, NO 2, and O 3 ) Oxidize compounds in air or lungs  Irritate lungs, damage plants  Photochemical oxidants (PAN’s, NO 2, and O 3 ) Oxidize compounds in air or lungs  Irritate lungs, damage plants Fig p. 424 Factors that influence: topography, population density, industry, fuels used, urbanization, high temperatures

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 + O > 2NO Some of the nitric oxide (NO) reacts with oxygen to form nitrogen dioxide NO2): Step 2: 2NO + O > 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: NO >NO + O (sunlight) This oxygen atom (O) can react with oxygen molecules (O2) in the air to form ozone (O3): Step 4: O + O > O3 (ozone)

Industrial Smog  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 p. 426 See pg. 423

Temperature Inversions  Subsidence inversion: Warm air mass moves over a cold air mass and decreases vertical mixing  Radiation inversion: occurs at night, air near ground cools faster than air above. Sun rise heats up the air and usually diminishes by noon Fig p. 427

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  Wet deposition: acid rain snow fog and cloud vapor  Dry deposition: acidic particles Fig p. 428

Acid Deposition in the US 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 Fig p. 431

Acid Deposition, Plants, and Soil  Nutrient leaching  Heavy metal release  Weakens trees Fig p. 432

PreventionCleanup Reduce air pollution by improving energy efficiency Reduce coal use Increase natural gas use Increase use of renewable resources Burn low-sulfur coal Remove SO 2 particulates, and NO x from smokestack gases Remove No x from motor vehicular exhaust Tax emissions of SO 2 Add lime to neutralize acidified lakes Add phosphate fertilizer to neutralize acidified lakes Figure Page 433

Indoor Air Pollution/Sick Building Syndrome Fig p. 434

Radon  Radon-222  4 picocurie level  Occurs in certain areas based on geology  Associated with uranium and organic material in rock Fig p. 436

Effects of Air Pollution on Living Organisms and Materials  Damage to mucous membranes  Respiratory diseases (see Fig 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 p. 441 Fig a p. 442