1. Environmental Science: Toward a Sustainable Future Richard T. Wright
Chapter 21
Atmospheric Pollution PPT 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. Major Air Pollutants and Their Sources (see Table 21-1)
Suspended particulate matter
Volatile organic compounds
Carbon monoxide
Nitrogen oxides
Sulfur oxides
Heavy metals
Ozone
Air toxics

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

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