Environmental Science: Toward a Sustainable Future Richard T. Wright

1. Environmental Science: Toward a Sustainable FutureRichard T. Wright Chapter 21 Atmospheric PollutionPPT by Clark E. Adams

2. Atmospheric Pollution • Air-pollution essentials • Major air pollutants and their sources • Impacts of air pollutants: health and environment • Bringing air pollution under control • Unresolved issues

3. Incorrect Assumptions about Air Pollutants • There are threshold levels of tolerable air pollutants • Dilution is the solution to air pollution • Air pollutants can be assimilated by nature • Air pollutants do not travel • Air pollution accidents will not happen

4. Pollutants and Atmospheric Cleansing • Air pollutants: gases and aerosols in the atmosphere that have harmful effects • Level of air pollution determined by: • The amount of pollutants entering the air • The amount of space into which the pollutants dispersed • Mechanisms that remove pollutants from the air

5. The Hydroxyl Radical: Nature’s Cleanser

6. The Appearance of Smog

7. Impacts of Smog: Temperature Inversion

8. Air Pollution Effects • Adversely affects human health • Damages crops and forests • Highly corrosive

9. Suspended particulate matter Volatile organic compounds Carbon monoxide Nitrogen oxides Sulfur oxides Heavy metals Ozone Air toxics Major Air Pollutants and Their Sources (see Table 21-1)

10. Major Air Pollutant Sources

11. Major Air Pollutants: Primary (see next slide) • Primary pollutants derived directly from burning fuels and wastes • Particulates • Hydrocarbons • Carbon monoxide • Nitrogen oxides • Sulfur dioxides

13. Major Pollutants: Secondary (see next slide) • Secondary air pollutants derive from reactions that occur between primary pollutants and other atmospheric chemicals • Ozone • PANs • Acids: sulfuric and nitric

15. Comparison of Growth vs. Emissions

16. Acid Deposition

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

19. Major Sources of SO2 Emitters

20. Impacts of Air Pollutants on Human Health • Chronic: gradual deterioration of a variety of physiological functions over a period of years • Acute: life-threatening reactions within a period of hours or days • Carcinogenic: cancer-causing

21. Impacts of Air Pollutants on Human Health • Chronic example: lead poisoning • Acute example: death – Bhopal, India • Carcinogenic example: lung cancer

22. The Respiratory System

24. Impacts of Air Pollutants on the Environment • Plants • Necrotic: kills plant cells • Chlorotic: destroys chlorophyll, reducing photosynthesis • Increases susceptibility to disease and pests Ozone most serious pollutant

25. Ozone Impact on Crop Yields

26. Impacts of Air Pollutants on the Environment • Forests • Leaching of nutrients • Release of aluminum into solution • Rapid changes in soil chemistry • Reduced growth and diebacks of plants and animals

27. Impacts of Air Pollutants on the Environment • Forests • Increased plant vulnerability to natural enemies • Increased soil erosion • Increased flooding • Increased sedimentation of waterways

28. Impacts of Air Pollutants on the Environment • Materials • Loss of color • Oxidation • Corrosion • Decreased real estate values

29. Effects of Acid Deposition • Alteration of plant and animal reproduction • Leaching of other toxic elements, e.g., aluminum • Eutrophic to oligotrophic conditions • Total loss of biota from aquatic ecosystems • Alterations of food chains

30. Trends in Automobile Emissions

32. Impact of Buffers on Acid Deposition

33. Bringing Air Pollution under Control • Clean Air Act identifies most widespread pollutants: e.g., particulates, SO, CO, NO, lead = criteria pollutants • National Ambient Air Quality Standards (NAAQS) set levels that protect environmental and human health

34. Bringing Air Pollution under Control • NAAQS: also set national ambient air quality standards • National Emission Standards for Hazardous Air Pollutants set national emission standards for hazardous air pollutants

35. Control Strategies • Command-and-control: regulate air pollution so criteria pollutants remain below primary standard level • Lack of enforcement and compliance • 37% reduction of air pollutants • Forced compliance with state implementation plan (SIP)

36. Particulates VOCs Automobile emissions Acid rain Catalytic converter Reasonably available control strategy (RACT) Scrubbers Coal washing Match Control Strategies on Right with Air Pollutants on Left

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

38. Industry’s Response to Title IV • Fuel switching • Scrubbers • Emissions allowance trading • Using low-sulfur coals

40. Unresolved Issues • Costs versus benefits of air pollution control • Status of “new source” review and enforcement • Improving fuel efficiency – hybrid cars • Improving mass transit systems • Reducing commuting distances

41. End of Chapter 21