CHAPTER 15: AIR POLLUTION, CLIMATE CHANGE AND OZONE DEPLETION Objectives 1. List and briefly describe the two bottom layers of the atmosphere. Compare the function of ozone in the troposphere with the function of ozone in the stratosphere. List and define the two categories of outdoor air pollutants. Distinguish indoor from outdoor air pollutants. 2. List eight major classes of outdoor air pollutants. Distinguish photochemical from industrial smog. Explain how outdoor air pollution is commonly reduced, and how it is commonly increased. 3. Distinguish between acid rain, wet and dry deposition. Mention the primary causes of acid depositions. Discuss the difficulties involved in reducing acid depositions. Summarize the progress made in reducing U.S. acid deposition. List the effects of acid deposition. 4. Assess the significance of the problem of indoor air pollution. List the 11 common and four most dangerous indoor air pollutants. 5. Summarize air pollution effects on human health, plants, aquatic life, and materials. Understand how the human lungs protect them from the effects of air pollutant exposures. 6. Summarize the Clean Air Act. List six ways to strengthen the Clean Air Act. Summarize the concept of “emissions trading.” Evaluate the pros and cons of this strategy. Evaluate the effectiveness of pollution prevention vs. pollution cleanup strategies. Contrast this with the efforts at reducing indoor air pollution in the U.S. 7. Summarize consensus views of the scientific community about climate change. Describe patterns of timing of past glacial and interglacial periods. List the four greenhouse gases that humans contribute to the lower atmosphere. Outline the correlation between historical CO2 records and atmospheric temperature. Note the five findings of the IPCC. 8. Distinguish between global warming and enhanced global warming. Briefly discuss the major effects of enhanced global warming. Discuss both the beneficial and the harmful effects of enhanced global warming. 9. Note the major challenges of dealing with global warming. Note the two schools of thought about potential global warming actions, and the four strategies associated with them. Summarize the role of individual governments and the international community. 10. Define ozone depletion and the ozone hole. Briefly describe what is happening to ozone in the stratosphere. Evaluate the status of the ozone holes over Antarctica and the Arctic Ocean. Describe the effects of increased ultraviolet radiation at the Earth’s solid and liquid surfaces. Note the proposed remedial strategies for the ozone-thinning problem. Key Terms {(Terms are listed in the same font style as they appear in the text.)} 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 122 acid deposition (p. 347) acid deposition (p. 350) acid rain (p. 350) air pollution (p. 346) brown-air smog (p. 349) buffer (p. 352) cap-and-trade program (p. 358) carbon dioxide (CO2) (p. 347) carbon footprint (p. 375) carbon monoxide (p. 347) carbon oxides (p. 347) chronic bronchitis (p. 355) cilia (p. 359) Clean Air Acts (p. 356) Copenhagen Protocol (p. 378) criteria air pollutants (p. 356) dry deposition (p. 350) emissions trading policy (p. 358) emphysema (p. 355) enhanced greenhouse effect (p. 362) formaldehyde (p. 355) glacial and interglacial periods (p. 361) global change in climate (p. 363) 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. global cooling (p. 360) global warming (p. 360) global warming (p. 362) Grasshopper effect (p. 350) gray-air smog (p. 349) greenhouse effect (p. 362) greenhouse gases (p. 362) hazardous air pollutants (HAPs) (p. 356) indoor air pollution (p. 346) industrial smog (p. 349) local weather (p. 363) lung cancer (p. 355) methane hydrates (p. 368) mobile sources (p. 346) Montreal Protocol (p. 378) National Ambient Air Quality Standards (NAAQS) (p. 356) natural greenhouse effect (p. 362) nitrogen oxides and nitric acid (p. 347) output approaches (p. 360) ozone (p. 348) ozone hole (p. 377) ozone layer (p. 346) ozone thinning (p. 377) particulates (p. 348) photochemical oxidants (p. 349) 49. photochemical reaction (p. 349) 50. photochemical smog (p. 348) 51. photochemical smog (p. 349) 52. prevention approaches (p. 352) 53. primary pollutants (p. 346) 54. primary standard (p. 356) 55. radioactive radon or radon222 (p. 348) 56. secondary pollutants (p. 346) 57. sick building syndrome (p. 354) 58. state of the Arctic (p. 368) 59. stationary sources (p. 346) 60. stratosphere (p. 346) 61. sulfur dioxide and sulfuric acid (p. 347) 62. temperature inversion (p. 350) 63. tipping point (p. 363) 64. troposphere (p. 345) 65. volatile organic compounds (p. 348) 66. volatile organic compounds (VOCs) (p. 348) 67. wet deposition (p. 350) Chapter 15 Outline 15-1 Major Air Pollution Issues A. The Earth’s atmosphere consists of several concentric layers with different temperatures, pressures, and composition. B. About 75–80 % of the Earth’s air mass is found in the troposphere, the atmospheric layer closest to the Earth’s surface. 1. This layer extends about 11 miles above sea level at the equator and about five miles above the poles. 2. About 99 % of the volume of air is made up of nitrogen (78 %) and oxygen (21 %) with the rest consisting of water vapor, argon, carbon dioxide, and traces of several other gases. 3. This layer is also responsible for short-term weather and long-term climate. C. The stratosphere is the second layer of the atmosphere and extends from 11 to 30 miles above the Earth’s surface. Ozone is concentrated in this layer from 11–19 miles above sea level. 1. Ozone is produced when oxygen molecules interact with ultraviolet radiation (3 O 2 + UV 2 O3). This “global sunscreen” keeps about 95 % of the sun’s harmful UV radiation from reaching the Earth’s surface. 2. This ozone layer protects us from sunburn, cataracts, cancer of skin and eye, and damage to our immune system. D. Air pollution is the presence of chemicals in the atmosphere in concentrations high enough to affect climate, materials, and organisms’ health. Air pollution comes mostly from natural sources and human sources. 1. Natural sources of air pollution such as dust particles, organic chemicals released by plant decay, forest fires, etc., rarely reach harmful levels. 2. Outdoor air pollutants are classified into two categories: primary pollutants that enter directly into the troposphere (soot, carbon monoxide), and secondary pollutants that may form when primary pollutants interact with one another or with the air to form new pollutants. 3. Cities generally have higher pollution levels than rural areas. Winds can carry these pollutants away from their source to other areas. 4. Indoor air pollutants can come from outside air and chemicals used or produced inside buildings. In developing countries, the main source is from wood or coal cooking stoves. 5. The major air pollutants are: carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, particulates, ozone, volatile organic compounds (VOCs), and radioactive radon gas. E. There are two forms of smog: photochemical smog is formed by the reaction of nitrogen oxides and volatile hydrocarbons under the influence of sunlight. Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted by burning coal and oil. F. Outdoor air pollution can be reduced by chemical precipitation, sea spray, and winds and increased by urban buildings, mountains, and high temperatures. Six factors can increase outdoor air pollution: urban buildings, hills and mountains, natural emissions, high temperatures, temperature inversions, and the grasshopper effect where volatile compounds are carried from tropical or temperate areas to the poles. G. Sulfur dioxide, nitrogen oxides, and particulates react in the atmosphere to produce acidic chemicals that travel long distances before coming back to earth. Tall smokestacks reduce local pollution but can increase regional pollution. 1. The acidic substances return to earth in one of two forms: a. Wet deposition as acidic rain, snow, fog, and vapor with a pH less than 5.6. b. Dry deposition as acidic particles. 2. Acid deposition is a problem in areas downwind from coal-burning facilities and urban areas. 3. Many acid-producing chemicals generated in one country end up in other countries due to prevailing winds. H. Acid deposition can cause or worsen respiratory disease, attack metallic and stone objects, decrease atmospheric visibility, kill freshwater fish, and kill mountain top forests. I. Progress has been made in reducing acid deposition in the U.S., but there is a long way to go. The 1990 amendments to the Clean Air Act have lead to significant reductions in SO2 and NO2 emissions from coal-fired power and industrial plants. Controlling acid deposition is a politically controversial issue. J. Indoor air pollution is usually a much greater threat to human health than outdoor air pollution. 1. EPA studies have shown the following: a. Levels of 11 common pollutants are two to five times greater inside homes and commercial buildings than outside. b. Inside cars in traffic-clogged areas, the pollution may be 18 times higher than outside. c. Health risks are magnified because people usually spend 70–98 % of their time indoors or in vehicles. Air Pollution, Climate Change, and Ozone Depletion 123 2. Sick-building syndrome has been linked to various air pollutants, and new buildings are apt to be more prone to this than old building due to less air exchange. 3. The EPA lists the four most dangerous indoor air pollutants in developed countries as cigarette smoke, formaldehyde, radioactive radon-222 gas, and very small fine and ultrafine particles. 4. In developing countries, as many as 2.8 million people die prematurely each year from breathing elevated levels of indoor smoke and particulates. K. The respiratory system has several ways to help protect you from air pollution—nose hairs, lung cilia, sneezing, coughing, and mucus. 1. Prolonged or acute exposure to air pollutants can overload or break down the natural defenses. 2. Several respiratory diseases can develop such as asthma, lung cancer, chronic bronchitis, and emphysema. 3. People with respiratory diseases, older adults, infants, pregnant women, and people with heart disease are especially vulnerable to air pollution. L. Each year, air pollution kills about three million people, mostly from indoor air pollution in developing countries. Air pollution deaths in the U.S. range from 150,000 to 350,000 people per year. 15-2 Dealing with Air Pollution A. The Clean Air Acts in the United States have greatly reduced outdoor air pollution from six major pollutants. 1. The U.S. Congress passed Clean Air Acts in 1970, 1977, and 1990. 2. National air quality standards (NAQS) were established for six outdoor criteria pollutants. 3. Two limits were established: a primary standard is set to protect human health and a secondary standard is set to prevent environmental and property damage. 4. EPA has established national emission standards for 188 hazardous air pollutants (HAPs) that may cause serious health and ecological effects—OCs, chlorinated hydrocarbons, toxic metals. 5. Good news is that the six criteria air pollutants decreased 53 % between 1970 and 2005 even with increases in energy consumption, miles traveled, and population. 6. Smog levels did not drop any between 1993 and 2003 after dropping in the 1980s, because of ground-level ozone. B. The reduction in outdoor air pollution in the U.S. occurred for two reasons: U.S. citizens insisted that laws be passed and enforced to improve air quality, and the country was affluent enough to afford the controls and improvements. To improve, the focus now should be on prevention, improving fuel-efficiency and engine emission standards, and enforcement of the existing laws. C. Allowing producers of air pollutants to buy and sell government air pollution allotments in the marketplace can help reduce emissions. The Clean Air Act of 1990 allows an emissions trading policy that permits companies to buy and sell SO2 pollution rights. 1. These pollution credits may be purchased by anyone and then not used if they so desire. 2. This method allows “hot spots” to continue to exist. Spot monitoring to check for emissions should be done. 3. Between 1980 and 2002 this scheme reduced SO2 emissions by 40 % in the U.S. 4. Emissions trading has been expanded to include NO2, particulate emissions, and volatile organic compounds, and to include the combined emissions of SO2, NO2, and mercury from coal-burning power plants. 5. The Clear Skies initiative of 2001 has been criticized as a way for the big polluters to continue polluting. This plan is not a good one for reducing toxic mercury in the environment. D. Figure 15-12 summarizes ways to reduce emissions of SO2, NO2, and particulate matter from electric power plants and industrial plants that burn coal. E. Coal-burning plants already in existence in 1970 were not required to meet the new Clean Air Act standards. A 1977 rule in the Clean Air Act (New Source Review) requires older plants to upgrade pollution control equipment when they expand or modernize the facilities. F. Figure 15-13 lists a number of ways to prevent and control air pollution from motor vehicles. G. Indoor air pollution is a greater threat to human health, but little effort has been spent on reducing it. 1. Figure 15-14 suggests several ways to reduce indoor air pollution. 2. In developing countries, indoor air pollution can be reduced by use of clay or metal stoves and vents to the outside, and by use of solar cookers in sunny areas. This would also reduce deforestation. H. There is a need to focus on preventing air pollution of all types in developing countries. 1. At present there is an output approach to controlling pollution. 2. We need to shift focus to preventing air pollution. 3. Figure 15-15 shows ways to prevent air pollution over the next 30–40 years. 124 Chapter 15 15-3 Future Temperature and Climate Change: Climate has been changing throughout the Earth’s history, leading to global warming and cooling periods. A. Geologic records and atmospheric measurements (as far back as 1980) provide a wealth of information about past atmospheric temperatures and climate. B. Certain gases (greenhouse gases) in the atmosphere absorb heat and warm the lower atmosphere —a natural process called the greenhouse effect warms the lower troposphere and surface. C. The four natural greenhouse gases are water vapor, carbon dioxide, methane, and nitrous oxide. 1. Measurements of CO2 concentrated in glacial ice correlate fairly closely with estimated variations in the average global surface temperature during the past 160,000 years. 2. Since the beginning of the industrial revolution, human sources of carbon dioxide, methane, and nitrous oxide have increased significantly in the lower atmosphere by the use of fossil fuels, burning vegetation to clear land for farming, and deforestation. These inputs are causing enhanced greenhouse effect, or global warming. D. Global climate change is a broader term that refers to changes in any aspects of the Earth’s climate. Global warming refers to temperature increases in the troposphere, which can cause climate change. There is evidence that the Earth’s troposphere is warming. 1. The five findings of the IPCC that support the scientific consensus that the troposphere is very likely getting warmer are these: a. The 13 warmest years since 1861 have occurred since 1990. b. Since 1906 the average global temperature has risen 0.74 degrees centigrade, with most increase occurring since 1980. c. The average sea level rose by 4 –8 inches over the past 100 years. d. Glaciers and floating sea ice in some parts of the world are melting and shrinking. e. Permafrost is melting in the Arctic because of the doubling of Arctic temperatures. E. Enhanced global warming may have some severe consequences including rapid surface temperature changes, mega forest fires, greater rate of desertification, premature extinctions, more intense storms, and the spread of tropical infectious diseases. F. The oceans have warmed up by at least 0.5 Celsius. One of the main results will be that less and less carbon dioxide can dissolve in the oceans as they warm up—worsening global warming. Others have suggested that some aerosol particles can reflect more sunlight in the upper troposphere and, hence, lead to a temperature drop. Others have focused on increasing plant cover to remove more carbon dioxide from the atmosphere. But both ideas have been described as short-term fixes that cannot resolve the long-term problem of global warming. The effects of future cloud distribution are uncertain. G. According to a report release by a NASA scientist in 2006, we have no more than a decade to act to prevent or slow down an irreversible or prolonged global warming trend. 15-4 Some Possible Effects of Global Warming: A warmer troposphere could have both beneficial and harmful effects for human and non-human species, and ecosystems. The world’s poor and wild species will suffer the most. A. Some temperate and Boreal countries will get warmer and dryer or warmer and wetter, and hence can lead to severe changes in agriculture. Tropical and equatorial areas may suffer from excessive heat and droughts, and decreased food production. B. A recent study has indicated that drought areas have tripled between 1979 and 2002. This will lead to water scarcity or shortages for millions of people and wildlife. C. Some areas such as Europe, Canada, and the northern U.S. will get flooded more frequently. D. The Arctic is warming at a rate of 2 –3 times faster than the rest of the Earth, and snow cover has declined by 10 %. Arctic summer without floating ice will accelerate the warming of the lower atmosphere. This is hastening the melting of the Greenland ice sheet, which can lead to 23 feet of sea level rise, ultimately. E. Studies have indicated that there is at least a 90 % chance that global sea levels will rise a maximum of two feet by the end of the 21st century. This will threaten coastal estuaries, fisheries, and agricultural lowlands, and will contaminate coastal aquifers and flood coastal cities. The Indian Ocean country of Maldives will cease to exist. F. A warmer atmosphere will lead to the melting of methane hydrates under the Arctic Ocean permafrost, which will increase methane and carbon dioxide emissions, and hence, increase global warming. G. Some scientists believe that global warming will disrupt the present ocean currents that are constantly redistributing heat and carbon dioxide. That will alter some of the present climatic belts. Air Pollution, Climate Change, and Ozone Depletion 125 H. According to the 2007 IPCC report, a warmer climate change can expand the ranges of some wild life and those that cannot adapt will become prematurely extinct, particularly coral reefs, alpine and arctic tundra, as well as coastal wetlands. This will affect crop production, negatively in some areas and positively in others (wetter, longer growing seasons). I. More people will die from heat waves in the summer than from cold winter conditions. Tropical diseases like malaria and dengue fever will spread into temperate and higher elevation areas. 15-5 Dealing with Global Warming: Dealing with climate change is a difficult issue because it is a global issue, the effects will last a long time, the harmful and beneficial effects are not uniform, and some suggested solutions are controversial. A. There is disagreement over what we should do about the threat of global warming, and as a result, two schools of thought have emerged from this controversy: 1. Reduce greenhouse gas emissions. 2. Some warming is unavoidable but we must devise some strategies to reduce its harmful effects. B. The solutions offered for slowing the rate and degree of global warming come down to four major strategies: improve energy efficiency to reduce fossil fuel use; shift from carbon-based fossil fuels to a mix of carbon-based and carbon-free renewable energy resources; store as much CO2 as possible in soil, in vegetation, underground, and in the deep ocean; and stop cutting down tropical forests. C. Governments can help by taxing pollution quantities and energy use, regulating carbon dioxide as a pollutant, increasing subsidies and tax breaks for saving energy, decreasing subsidies and tax breaks for using fossil fuels, and funding the transfer of green technologies to developing countries. D. The Kyoto Protocol, developed in 1997, would require 38 developed countries to cut emissions of some gases by about 5.2 % below 1990 levels by 2012, but the U.S. withdrew in 2001. The treaty went into effect in 2005 with 189 national signatories, minus Australia and the U.S. E. Countries could work together to develop a new international protocol to slowing global warming, particularly China and India. 1. Many countries, companies, cities, states, and provinces are reducing greenhouse gas emissions, improving energy efficiency, and increasing their use of carbon-free renewable energy independently. 2. Great Britain reduced its CO2 emissions to its 1990 level by the year 2000, well ahead of the Kyoto target goal. China reduced it CO2 emissions by 17 % between 1997 and 2000 by phasing out coal subsidies, shutting down inefficient coal-fired electric plants, and restructuring its economy toward use of renewable energy resources. 3. Some major global companies have established targets to reduce their greenhouse gas emissions by 10–65 % from 1990 levels by 2010. 4. Some individuals, colleges, and schools are reducing greenhouse gas emissions and wasting less energy. 15-6 Ozone Depletion in the Stratosphere A. Less ozone in the stratosphere will allow more harmful UV radiation to reach Earth’s surface. The overwhelming consensus of researchers is that ozone depletion is a serious threat to all organisms on Earth. B. Widespread use of a number of useful and long-lived chemicals has reduced ozone levels in the stratosphere, including the family of coolants known as chlorofluorocarbons (CFCs). Freons are the most widely used of these. 1. CFCs remain in the atmosphere because they are insoluble in water and chemically unreactive. 2. Over 11–20 years these chemicals are lifted into the stratosphere, mostly by convection currents and turbulent mixing of air. 3. CFC molecules break down under the influence of high-energy UV radiation. Chlorine is released and is highly reactive. Fluorine, bromine, and iodine are also released. This causes ozone to be broken down faster than it is formed. 4. These CFC molecules can last in the stratosphere for 65–385 years. 5. In 1988, after 14 years of delay tactics, the CFC industry acknowledged that CFCs were depleting the ozone and agreed to stop manufacturing them. 6. Rowland and Molina received the Nobel Prize in chemistry in 1995 for their work on CFCs. C. Ozone loss is often called the ozone hole, but it is actually ozone thinning. During four months of each year up to half of the ozone in the stratosphere over Antarctica is depleted, and the area of thinning has been consistently growing since its discovery. There is also an 11–38 % ozone thinning over the Arctic from February to June. 1. The total area of stratosphere that suffers from ozone thinning varies from year to year. In 2003 the area was the second largest ever. 2. The primary culprits are CFCs and other ozone depleting chemicals (ODCs). 126 Chapter 15 3. The polar vortex is a swirling mass of very cold air that is isolated from the rest of the atmosphere for several months. Ice crystals in this mass collect CFCs and other chemicals and set up conditions for ozone breakdown. 4. It is unlikely that the Arctic thinning will be as severe as that over Antarctica, but it is predicted that the worst ozone thinning will be between 2010 and 2019. D. Increased UV radiation reaching the Earth’s surface from ozone depletion is harmful to human health, crops, forests, animals, phytoplanktons, and artificial materials. Figure 15-26 lists the effects of ozone depletion. E. Exposure to UV radiation is a major cause of skin cancer (malignant melanoma). F. To reduce ozone depletion we must stop producing ozone-depleting chemicals. 1. If we immediately stop producing all ozone-depleting chemicals it will take 50 years for the ozone layer to return to 1980 levels and about 100 years to return to pre-1950 levels. 2. The goal of the 1987 Montreal Protocol was to cut emissions of CFCs (but not ODCs) by about 35 % between 1989 and 2000. 3. Representatives met again in 1990 and 1992 and adopted the Copenhagen Protocol, an amendment that accelerated the phasing out of key ozone-depleting chemicals. 4. These international agreements have now been signed by 189 countries. Air Pollution, Climate Change, and Ozone Depletion 127