1. Air Pollution
Chapter 18

2. Core Case Study: South Asia’s Massive Brown Cloud
Asian Brown Cloud
Causes-
Dust, smoke ash from drought and clearing/burning forests
Acidic compounds from burning coal, diesel and other fossil fuels, soot, toxic metals organic compounds and fly ash
Areas impacted-India, Bangladesh, industrial China, open sea east of the area
Air pollution connects the world--pollution is tracked to other parts of world

3. 18-1 What Is the Nature of the Atmosphere?
Concept The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.
Atmosphere varies in
Temperature
Density- most dense at ground level
Atmospheric pressure-decreases with altitude
Layers of Atmosphere
Troposphere Mesophere
Stratosphere Thermosphere

4. Natural Capital: The Earth’s Atmosphere Is a Dynamic System with Four Layers

5. Layers of the Atmosphere (1)
Troposphere
75–80% of the earth’s air mass
Closet to the earth's surface
Chemical composition of air
Rising and falling air currents: weather and climate
Involved in chemical cycling
Stratosphere
Similar composition to the troposphere, with 2 exceptions
Much less water
O3, ozone layer, filters UV
Location

6. Layers of Atmosphere (2)
Mesosphere
48-80km (30-50 Mi)
Few molecules here
Temp drops with increasing altitude
Thermosphere
80+ km (50+ miles)
UV absorbed and converted to heat so temp increases with altitude

7. Greenhouse Effect

8. Greenhouse Gases H2O: most prevalent
CO2: only 7% of CO2 comes from human activities--but we are making an impact!
CH4: very potent as a gg (21x greater than CO2)
1/3 from natural sources: plants, wetlands, termites
2/3 from humans: rice paddies, landfill (decomposition), oil/gas wells, cows (belching)
N2O: fertilizers, animal wastes, burning fossil fuels (270x more potent than CO2)

9. 18-2 What Are the Major Outdoor Pollution Problems?
Concept Pollutants mix in the air to form industrial smog, mostly the result of burning coal, and photochemical smog, caused by motor vehicle, industrial, and power plant emissions.

10. Air Pollution Comes from Natural and Human Sources
Natural sources
Dust blown by wind
Pollutants from wildfires and volcanoes
Volatile organics released by plants
Withdrawing groundwater
Human sources: mostly in industrialized and/or urban areas
Stationary sources
Mobile sources

11. Case Study: Air Pollution in the Past: The Bad Old Days
Discovery of fire
Middle Ages
Industrial Revolution
London, England
1850s
1952: yellow fog
Clean Air Act of 1956
United States
1948: Donora, PA; first U.S. air pollution disaster
1963: New York City
Global problem

12. Some Pollutants in the Atmosphere Combine to Form Other Pollutants
Primary pollutants: emitted directly into troposphere
Secondary pollutants: React with something in troposphere to form pollutant
Air quality improving in developed countries
Much more needs to be done in developing countries
Indoor pollution: big threat to the poor

13. Sources and Types of Air Pollutants

14. What Are the Major Outdoor Air Pollutants? (1)
Carbon oxides
Carbon monoxide (CO) and Carbon dioxide (CO2)
Sources -car exhaust, burning forests, smoke
Human health and environmental impact-impairs ability of blood to carry oxygen
Nitrogen oxides (NO) and nitric acid (HNO3)
Sources-auto engines, coal-burning plants, lightning (NO)
Acid deposition-Forms HNO3 in air
Photochemical smog-NO/HNO3 in sunlight
Human health and environmental impact - irritates eyes, nose, throat, lungs, suppress plant growth
Sulfur dioxide (SO2) and sulfuric acid (H2SO4)
Sources- natural part of sulfur cycle, burning coal. industry
Human health and environmental impact- Acid deposition, reduce visibility, aggravate breathing problems

15. What Are the Major Outdoor Air Pollutants? (2)
Particulates-
Suspended particulate matter (SPM)
Fine- ave. diameter <10 micrometers
Ultrafine <2.5 micrometers
Sources-coal-burnign power, industry, vehicles, plowed fields, construction, smoke
Human health and environmental impact- irritate lung/throat, toxins can cause mutations (lead, PCBs)
Ozone (O3)- “bad” troposphere; “good” stratosphere
Sources- phorochemical smog
Human and environmental impact-breathing issues
Volatile organic compounds (VOCs)
Hydrocarbons
Sources-plants, wetlands, rice paddies, landfills, cows
Human and environmental impact- dizziness, death

16. Chemical Reactions That Form Major Outdoor Air Pollutants

17. Case Study: Lead Is a Highly Toxic Pollutant
Does not break down in the environment
Sources
Human health and environmental impact
Most vulnerable
Reduction of lead (Pb)
Unleaded gasoline
Unleaded paint
Still problems
2007: toys with Pb paint recalled
Global ban on lead in gasoline and paint

18. Burning Coal Produces Industrial Smog
Chemical composition of industrial smog (Gray Air Smog)
Suspended particles + SO2 or H2SO4 from burning coal and oil
Reduction of this smog in urban cities of the United States - rarely a problem today
China and smog: Huge amounts of Ind. Smog
Human deaths

19. How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog

20. Sunlight Plus Cars Equals Photochemical Smog
Photochemical Smog- Brown Air Smog
Chemical composition:
mix of primary and secondary pollutants
Sources- vehicle exhaust + sun+ VOCs from trees or cars
VOCs + NO2 + Heat + Sunlight yields
Ground level O3 and other photochemical oxidants
Aldehydes-
Other secondary pollutants-
Human health and environmental impact- respiratory irritation

21. A Model of How Pollutants That Make Up Photochemicals Are Formed

22. Animation: Formation of photochemical smog

23. Several Factors Can Decrease or Increase Outdoor Air Pollution
Outdoor air pollution may be decreased by
Settling of particles due to gravity
Rain and snow
Salty sea spray from the ocean
Winds
Chemical reactions
Outdoor air pollution may be increased by
Urban buildings
Hills and mountains
High temperatures
Emissions of VOCs from certain trees and plants
Grasshopper effect
Temperature inversions

24. A Temperature Inversion

25. Animation: Thermal inversion and smog

26. 18-3 What Is Acid Deposition and Why Is It a Problem?
Concept Acid deposition is caused mainly by coal-burning power plant and motor vehicle emissions, and in some regions, threatens human health, aquatic life and ecosystems, forests, and human-built structures.
Acid deposition, acid rain
Formation-SO2/NOx combine with water
Local versus regional problems
Taller stacks: reduce local/increase regional pollution downwind
Effects of prevailing winds greater problem in East
Buffers-CaCO3 soil neutralizes
Less than pH 5.6 is acid; US average 4.5; Eastern forests can be 2.3

27. Natural Capital Degradation: Acid Deposition, Acid Rain

28. Current and Possible Future Acid Rain Problem Areas

29. Acid Deposition Has a Number of Harmful Effects
Human respiratory disorders- bronchitis, asthma
Aquatic ecosystems affected-kills fish (esp. below 4.5)
acid shock: runoff of acid rain into water system (snow melt/spring rain)
Aluminum toxicity: AL ions released into lake from soils –asphyxiate fish (causes too much mucus in gills)
Release of toxic metals-—(Lead, copper) from water pipes to contaminate drinking water.
Al, Pb, Cd, Hg: dissolved from soil and released: TOXIC
Leaching of soil nutrients-1st can add N and S to soil to stimulate plant growth BUT then acids leach essential plant nutrients
Loss of crops and trees- Weakens Trees (Synergistic Effect between acid and ozone)
Damage to buildings, statues, and monuments

30. We Know How to Reduce Acid Deposition
Prevention approaches
Clean up
Add lime to neutralize acidified lakes and soil
Add phosphate fertilizer to neutralize acidified lakes

31. Active Figure: Acid deposition

32. Active Figure: Effect of air pollution in forests

33. 18-4 What Are the Major Indoor Air Pollution Problems?
Concept The most threatening indoor air pollutants are smoke and soot from wood and coal cooking fires (a hazard found mostly in developing countries) and chemicals used in building materials and products.

34. Indoor Air Pollution Is a Serious Problem (1)
Developing countries
Indoor burning
Poor suffer the greatest risk
Developed countries
Indoor air pollution is greater than outdoor air pollution
Why?
11 of the common air pollutants higher inside than outside
Greater in vehicles than outside
Health risks magnified: people spend 70–98% of their time is indoors

35. Indoor Air Pollution Is a Serious Problem (2)
Who are at greatest risk from indoor air pollution?
Children under 5 and the elderly
Sick
Pregnant women
People with respiratory disorders or heart problems
Smokers
Factory workers
Four most dangerous indoor air pollutants
Tobacco smoke
Formaldehyde
furniture stuffing, paneling, foam insulation, particleboard
Radioactive radon-222
naturally occurring radioactive gas made by decay of U_238
Seeps into house through foundation from rocks
Very small particles
burning creates soot
Developing countries: lots of indoor fires for heat, cooking
Human health risks

36. Indoor Air Pollution Is a Serious Problem (3)
Other possible indoor air pollutants
Pesticide residue
Pb particles
Living organisms and their excrements
E.g., Dust mites and cockroach droppings
Airborne spores of molds and mildews
Sick-building syndrome

37. Case Study: Radioactive Radon Gas
Sources
Human health risks
Testing for radon
Correcting a radon problem

38. 18-5 What Are the Health Effects of Air Pollution?
Concept Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.
Respiratory system protection from air pollutants
Role of cilia, mucus, sneezing, and coughing
Effect of smoking and prolonged air pollution exposure
Chronic bronchitis
Emphysema

39. Air Pollution Is a Big Killer
3 Million deaths per year world-wide
Mostly in Asia
Main causes-indoor pollution
US: Diesel fumes lead to cancer
EPA: proposed stricter emission standards for diesel-powered vehicles
Link between international trade and air pollution-
Cargo ships: diesel fuel
Premature Deaths from Air Pollution in the U.S.

40. 18-6 How Should We Deal with Air Pollution?
Concept Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution.

41. Laws and Regulations Can Reduce Outdoor Air Pollution
United States
Clean Air Acts: 1970, 1977, and 1990
EPA
National ambient air quality standards (NAAQs) for 6 outdoor criteria pollutants
National emission standards for 188 hazardous air pollutants (HAPs)
Toxic Release Inventory (TRI)
Good news in U.S.
Decrease in emissions
Use of low-sulfur diesel fuel
Cuts pollution
Developing countries
More air pollution

42. We Can Use the Marketplace to Reduce Outdoor Air Pollution
Emission trading or cap-and-trade program
Mixed reactions to program
SO2 emissions down significantly
NO2 will be tried in the future

43. Solutions: Stationary Source Air Pollution

44. Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup

45. Reducing Indoor Air Pollution Should Be a Priority
Greater threat to human health than outdoor pollution
What can be done?
Prevention
Cleanup

46. Solutions: Indoor Pollution, Prevention and Cleanup or Dilution
Greater threat to human health than outdoor pollution
What can be done?
Prevention
Cleanup

47. What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure

48. We Need to Put More Emphasis on Pollution Prevention
Output approaches
New shift to preventing outdoor and indoor pollution
Pressure from citizens