1. Air Pollution What controls the level? –Amount of pollutants entering the air. –Amount of space into which the pollutants are dispersed. –Mechanisms that remove pollutants from the air. When is it a concern? –Exceed a threshold level –Threshold level depends on concentration and duration of exposure, i.e. dose.

2. Dose = (concentration X exposure)

3. Major Primary Pollutants 1.Suspended particulate matter 2.Volatile organic compounds 3.Carbon monoxide 4.Nitrogen oxides 5.Sulfur oxides 6.Heavy metals 7.Air toxics (radon)

4. PANs = peroxyacetyl nitrates

5. The Hydroxyl Radical: Nature’s Cleanser (?)

6. Sources of These Emissions (Fig. 22-13)? 1)Sulfur dioxides 2)Nitrogen oxides 3)VOC’s 4)Particulate matter 5)Carbon monoxide A) Fuel combustion B) Transportation C) Industrial processes

7. Emission Trends

8. Air Pollution Effects Adversely affects human health –Chronic –Acute –Carcinogenic Damages crops and forests –Necrotic –Chlorotic –Disease and Pest Susceptibility Damage to material & aesthetics –Corrosion –Oxidation –Smog

9. Smog I

10. Smog II

11. Temperature Inversions

12. Vehicles! Photochemical Oxidants (Troposphere Ozone and PANs

13. Four Forms of Acid Deposition

14. pH Scale pH = measurement of H ions in solution Acid precipitation = pH < 5.5

15. Acid Deposition in the U.S. 2/3 sulfuric 1/3 nitric Coal burning power plants

16. Effects of Acid Deposition on Aquatic Ecosystems Alteration of plant and animal reproduction Leaching of other toxic elements, e.g., Al Eutrophic to seemingly oligotrophic conditions Total loss of biota from aquatic ecosystems Alterations of food chains

17. Effects of Acid Deposition on Forest Ecosystems Leaching of nutrients Release of aluminum into solution Rapid changes in soil chemistry Reduced growth and diebacks of plants and animals Increased flooding Increased plant vulnerability to natural enemies Increased soil erosion Increased sedimentation of waterways

18. Ecosystems Impacts are Not Equal. Limestone Buffers Acid Deposition.

19. Clean Air Act of 1970, 1977, 1990 Identifies most widespread pollutants: e.g., particulates, SO, CO, NO, lead = criteria pollutants Set ambient standards = levels that protect environmental and human health Set national ambient air quality standards Set national emission standards for hazardous air pollutants

20. Title IV Clean Air Act 1990 Reduce SO emission 50% below 1980 levels Improve methods of reducing SO emissions Allow emissions allowances and trading Emissions purchases Reduce NO emissions

21. Future Responses to Air Pollution Control Increase fuel efficiency Emission-free vehicles Improving mass transit systems Reducing commuting distances What are some potential societal reactions to these control measures?