Air Pollution

1. Air Pollution Chapter 18

2. 18-1 What Is the Nature of the Atmosphere? • Concept 18-1 The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.

3. The Atmosphere Consists of Several Layers • The atmosphere consists of several layers with a different temperature, pressure, and composition • Air pressure drops quickly with elevation • The troposphere is where all the weather occurs • Greatest density (most gas) • The stratosphere contains the ozone layer

4. The Atmosphere Consists of Several Layers • Atmospheric composition: • 78% Nitrogen • 21% Oxygen • 1% trace gases including… • Argon • Carbon Dioxide • Water Vapor • Others… • Water vapor can vary from 0.01% at the dry, frigid poles up to 4% in the hot, humid tropics

5. 18-2 What Are the Major Outdoor Pollution Problems? • Concept 18-2 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.

6. Air Pollution Comes from Naturaland Human Sources • Air Pollution– the presence of chemicals in the air in concentrations high enough to cause harm • Natural sources: • Dust blown by wind • Pollutants from wildfires and volcanoes • Volatile organics released by plants • Human sources: mostly in industrialized and urban areas • Stationary sources – power plants, factories • Mobile sources – motor vehicles, farm equipment

7. Some Pollutants in the Atmosphere Combine to Form Other Pollutants • Primary pollutants– substances emitted into the air • Secondary pollutants– primary pollutants may react with one another or with other chemicals in the air to form new chemicals

8. What Are the Major Outdoor Air Pollutants? • Carbon oxides: • Carbon monoxide (CO) – a highly toxic gas that forms during the incomplete combustion of carbon-containing materials. • Carbon dioxide (CO2)– a major component of the carbon cycle • 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle • 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels) • It is not regulated as a pollutant under the U.S. Clean Air Act • Stay tuned…

9. What Are the Major Outdoor Air Pollutants? • Nitrogen oxides andnitric acid: • Nitrogen oxide (NO)– forms when nitrogen and oxygen gas in air react at temperatures in automobile engines and coal-burning plants. It can also form from lightning and certain soil bacteria. • NO reacts with oxygen in the air to form NO2 • NO2 reacts with water vapor in the air to form nitric acid (HNO3) which is a component of acid deposition • Both NO and NO2 play a role in the formation of smog

10. What Are the Major Outdoor Air Pollutants? • Sulfur dioxide andsulfuric acid: • Sulfur dioxide (SO2)– • About one-third of SO2 in the atmosphere occurs naturally through the sulfur cycle • Two-thirds come from human sources, mostly combustion of coal containing iron sulfide and from oil refining and smelting of sulfide ores • FeS2 + O2 Fe2O3 + SO2 • SO2 reacts with water vapor in the air to form sulfuric acid (H2SO4) which is a component of acid deposition

11. What Are the Major Outdoor Air Pollutants? • Suspended particulate matter (SPM): • Particulate matter – A variety of solid particles small and light enough to remain suspended in the air • Natural sources – forest fires, volcanoes, dust storms • Human sources – combustion of various materials • The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5).

12. What Are the Major Outdoor Air Pollutants? • Ozone (O3): • Ozone – unstable and highly reactive form of oxygen • Stratospheric ozone– “good” ozone that protects us from damaging UV radiation • Ground level ozone– “bad” ozone that is a major component of photochemical smog • Solar radiation splits an O off of NO2 that bonds to an O2 molecule to create O3

13. What Are the Major Outdoor Air Pollutants? • Volatile organic compounds (VOCs): • Volatile organic compounds – are organic chemicals that have high enough vapor pressures to vaporize and easily enter the atmosphere • VOCs are widely used in household chemicals • Cleaners, disinfectors, paints, fuels, etc. • VOCs are also used as industrial solvents • trichlorethylene (TCE), benzene, and vinyl chloride

14. Science Focus: Detecting Air Pollutants • Chemical instruments • Aircraft • Air pollutant monitors • Biological indicators • Lichens (fungus/algae) • Sensitive to air pollutants • Some are pollutant specific (SO2) • Peppered Moths • Soot from Industrial Revolution in England and U.S. • % of light/dark moths changed

15. Burning Coal Produces Industrial Smog • Industrial smogis a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal. • In most developed countries where coal and heavy oil is burned, industrial smog is not a problem due to reasonably good pollution control or with tall smokestacks that transfer the pollutant to rural areas.

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

17. Core Case Study: South Asia’s Massive Brown Cloud • A huge dark brown cloud of industrial smog, caused by coal-burning in countries such as China and India, stretches over much of southeastern Asia. • In areas beneath the cloud, photosynthesis is reduced interfering with crop development. • Fine particles and droplets in the clouds appear to be changing regional climates

18. Sunlight Plus Cars Equals Photochemicals Smog • Photochemical smogis a mixture of air pollutants formed by the reaction of NO2 and VOCs under the influence of sunlight.

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

20. Worst Smog Cities in the World • Mexico City • Beijing, China • New Delhi, India • Cairo, Egypt • Bangkok, Thailand • Hong Kong • Houston, TX • Los Angeles, CA

21. Several Factors Can Decrease or Increase Outdoor Air Pollution • Outdoor air pollution can be decreased by: • Settling of particles due to gravity, precipitation, sea spray, winds, chemical reactions, and of course, reducing the release of pollutants • Outdoor air pollution can be increased by: • Urban buildings (slow wind dispersal of pollutants) • Hills and mountains (promote temperature inversions) • High temperatures (promote photochemical reactions)

22. Several Factors Can Decrease or Increase Outdoor Air Pollution • Thermal inversion– Warm air moves over cooler air “capping” the atmosphere and trapping air pollutants • Cities with sunny climate, mountains on multiple sides and an ocean on another are susceptible to inversions

23. Several Factors Can Decrease or Increase Outdoor Air Pollution

24. Several Factors Can Decrease or Increase Outdoor Air Pollution • Heat islands– cities and urban areas can be 2º – 10º warmer than the surrounding areas • Caused because buildings and pavement have replaced trees and vegetation • Can increase the likelihood of thermal inversions and increase air pollution, especially the formation of smog

25. 18-3 What Is Acid Deposition and Why Is It a Problem? • Concept 18-3 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.

26. Acid Disposition Is a Serious Regional Air Pollution Problem • Acid deposition– Sulfur dioxides and nitrogen oxides can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface. • Precipitation usually falls as acid rain, but can also be acid fog or acid snow • Acid precipitation has a pH usually 4.4 – 4.7 • Rain typically has a pH of around 5.6

27. Natural Capital Degradation:Acid Deposition, Acid Rain • Tall smokestacks reduce local air pollution but can increase regional air pollution.

28. Acid Disposition Is a Serious Regional Air Pollution Problem

29. Acid Deposition Has a Numberof Harmful Effects • Acid deposition causes harm in a number of ways: • Aquatic ecosystems affected • Loss of crops and trees • Leaching of soil nutrients • Human respiratory irritation • Release of toxic metals • Leached out of the soil and into drinking water sources • Damage to buildings, statues, and monuments

30. Natural Capital Degradation: Air Pollution Damage to Trees

31. Solutions: Acid Deposition, Prevention and Cleanup

32. 18-5 What Are the Health Effects of Air Pollution? • Concept 18-5 Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.

33. Your Body’s Natural Defenses against Air Pollution Can Be Overwhelmed • Respiratory system protection from air pollutants • Hairs in your nose – filter out large particles • Mucus – capture smaller particles • Sneezing and coughing – expels contaminated air • Cilia (tiny hairs) – move mucus to throat to be swallowed or expelled. • Effect of smoking and prolonged air pollution exposure: • Chronic bronchitis – irritation of the bronchial tubes • Emphysema – loss of lung’s elasticity b/c of a buildup of scar tissue

34. Major Components of the Human Respiratory System • Your respiratory system can help protect you from air pollution, but some air pollutants can overcome these defenses.

35. Normal Human Lungs and the Lungs of a Person Who Died of Emphysema • Normal human lungs (left) and the lungs of a person who died of emphysema (right).

36. Air Pollution Is a Big Killer • According to the WHO: 3 Million deaths/year world-wide = 8,200/day • Mostly in Asia • 73% from indoor air pollution • EPA estimates 150,000-350,000 people die a year in the U.S. from air pollution

37. 18-6 How Should We Deal with Air Pollution? • Concept 18-6 Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution.

38. Laws and Regulations Can ReduceOutdoor Air Pollution • In 1970, Congress passed The Clean Air Actand created the Environmental Protection Agency(EPA) to enforce it. • The Clean Air Act was most recently amended in 1990 • National Ambient Air Quality Standards(NAAQS) are established to regulate six major pollutants. • Primary standards – protects human health • Secondary standards – prevents environmental and property damage • The EPA also establishes standards for 188 other hazardous air pollutants(or HAPs) • Mostly chlorinated hydrocarbons, VOC’s, and toxic metals

39. Laws and Regulations Can ReduceOutdoor Air Pollution • How do you remember the six outdoor criteria pollutants regulated by the National Ambient Air Quality Standards(NAAQS)? • NOSCLP– A nose clip will save you from air pollution • Nitrogen oxides • Ozone • Sulfur dioxide • Carbon monoxide • Lead • Particulate matter

40. Case Study: U.S. Air Pollution Can Be Improved • The CAA has reduced emissions of the six criteria pollutants by a total of 49% from 1980-2006. • However, environmental scientists still point out several deficiencies in the Clean Air Act: • The U.S. still relies on cleanup rather than prevention • The U.S. Congress has failed to increase fuel-efficiency standards for automobiles • Regulation of emissions from motorcycles and two-cycle engines remains inadequate • There is little or no regulation of air pollution from oceangoing ships in American ports

41. Case Study: U.S. Air Pollution Can Be Improved • However, environmental scientists still point out several deficiencies in the Clean Air Act: • Airports are exempt from many air pollution regulations • The CAA does not regulate CO2 which is a major greenhouse gas • The CAA has failed to deal seriously with indoor air pollution - Ultrafine particles are not regulated • Urban O3 levels too high • It fails to seriously deal with indoor air pollution • Overall, there is a need for better enforcement of the Clean Air Act.

42. We Can Use the Marketplace to Reduce Outdoor Air Pollution • To help reduce SO2 emissions, the 1990 amendment to the Clean Air Act authorized an emission trading or cap-and-trade program • Enables the 110 most polluting power plants to buy and sell SO2 pollution rights. • Since 1990, the emission trading system has greatly reduced emissions • Sulfur dioxide emission are down 53% • The program has cost less than 10% of original industry projections • The same system is being talked about to combat NO2 and CO2 emissions.

43. There Are Many Ways to Reduce Outdoor Air Pollution • Electrostatic precipitator • Used to attract negatively charged particles in a smokestack into a collector • Can remove 99% of larger particulate matter • Does not remove hazardous ultrafine particles • Produces toxic dust that must be safely disposed of • Uses large amounts of electricity

44. There Are Many Ways to Reduce Outdoor Air Pollution • Wet scrubber • Fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill • Can remove 98% of SO2 and larger particulate matter • Not very effective in removing hazardous fine and ultrafine particles

45. Solutions: Stationary Source Air Pollution

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

47. Solutions: Indoor Pollution, Prevention and Cleanup or Dilution

48. Solutions: Air Pollution, Ways to Prevent It Over the Next 30-40 Yrs.