Unit 5: Air Pollution
Objectives:
1. Recognize that pollution affects the air, land, freshwater and the oceans.
2. Discuss the composition of the Earth's atmosphere and the distribution of its gasses.
3. Describe how global wind patterns are created and how this affects the air pollution.
4. List the major sources and effects of the five primary air pollutants.
5. Describe how photochemical smog is formed and how it affects humans.
6. Recognize where and how thermal inversions form.
7. List types and sources of indoor air pollution.
8. Describe "sick building syndrome".
9. Discuss methods of reducing automobile pollution.
10. Explain how acid rain forms.
11. Discuss the effects of acid rain on terrestrial and aquatic ecosystems.
12. Recognize the provisions of the Clean Air Act (1977) and its revision (1990).
13. Describe how human activities may be leading to a green house effect of our atmosphere.
14. Briefly discuss consequences of a warmer planet.
15. Discuss the causes and concerns associated with ozone depletion.
16. Discuss ways to reduce air pollution.
17. Describe various forms of visual or aesthetic pollution.
18. Discuss the various sources and effects of noise pollution.
Notes: Air Pollution
1. The atmosphere contains 78% Nitrogen, 20% oxygen, and a 1% mixture of Argon, Carbon Dioxide, Water vapor, and some other trace gasses. Combined theses gasses make up our air.
2. The atmosphere is held in place by Earth's gravity.
3. Air is dynamic and constantly moving and mixing.
4. Wind is caused by the unequal heating of the Earth's surface. Hot air rises and is replaced by cooler air at the surface (wind).
5. Local winds result from pressure differences between high and low pressure systems. They can be very intense.
6. Large scale movement of air is called Global winds. Global winds such as the trade winds helped early sailing ships move goods between the Europe and the Americas.
7. Global winds move pollution around the globe.
8. Wind that carries dust, pollen, odors, and particulates from burning forests and volcanoes, is not considered pollution.
9. Air pollution results from man-made activities such as automobile exhaust, chemical fumes, and factory smoke.
10. Air pollution is usually made of heavy particulates that stay near the earth's surface.
11. Industrialized urban areas create great amounts of air pollution that drifts downwind and affects other areas.
12. Primary air pollutants are those that are unchanged when they leave their source. Five primary air pollutants include:
1. Carbon Monoxide (CO) 2. Sulfur oxides - sulfur dioxide (SO2) and sulfur trioxide (SO3) 3. Volatile Organic Compounds (VOCs) - contain carbon and hydrogen 4. Particulates - small particles of various toxic compounds 5. Nitrogen oxides - nitric oxide (NO) and nitrogen dioxide (NO2)
13. Carbon monoxide is a deadly odorless gas released from the incomplete burning of gasoline, coal or wood. The largest source of CO is the automobile. (# 2 is tobacco!) Concentrations of as little as 0.001 can kill after exposure for several hours (e.g. sleeping)
14. Sulfur dioxides form when coal or oil are burned. They are a known lung irritant. Sulfur dioxides can also lead to acid rain.
15. Smog is a combination of smoke and fog. In 1952 thick smog killed over 4000 people in London.
16. Volatile organic compounds (VOCs) are derived from many man-made chemicals such as benzene, formaldehyde, chloroflorocarbons and various hydrocarbons that are remnants of incomplete burning of gasoline or diesel.
17. Particulates are small pieces of solid material dispersed in the atmosphere. These include smoke particles, asbestos, insulation, lead, arsenic, PCBs, dioxin, pesticides, dust and ash from industrial processes.
18. Particulates can damage lungs, or lead to lung cancer from heavy exposure (factory workers, miners, etc.)
19. Nitrogen oxides are mainly caused by automobile exhaust. They react with other chemicals in the air creating Secondary air pollutants.
20. Most secondary air pollutants require ultraviolet light to form. These new forms of air pollution are called Photochemical Smog.
21. The two worse photochemical smog compounds are Ozone (O3) and Peroxyacetylnitrates. Both of theses compounds are highly reactive and damage lung tissue and irritate the eyes.
22. Thermal inversions can trap photochemical smog leading to hazardous conditions for people with respiratory problems.
23. Los Angeles, Salt Lake City, Phoenix and Denver all have problems with thermal inversions because they are surrounded by mountains that trap warm polluted air.
24. Indoor air pollution from synthetic compounds in furniture, glues, paint, carpets and other man-made objects is often more hazardous then outdoor air pollution. (see figure 21-4). It can lead to a condition known as "Sick Building Syndrome".
25. The EPA estimates that approximately 6000 people die from cancer each year resulting from indoor air pollution.
26. The single largest contributing factor to air pollution is the automobile.
27. The best and most effective way to limit automobile pollution is to reduce the amount of driving and to change driving habits.
28. The US Gov't and other countries have set regulations to control emissions from cars forcing the automobile industry to reduce emissions.
29. Innovations that have helped to reduce automobile pollution include:
Unleaded gas Catalytic converters Positive crankcase ventilation valve (PVC) Gas caps with ventilation control valves Fuel injectors and electronic ignition
30. Catalytic converters reduce the amount of three substances:
Carbon monoxide (CO) - a poisonous gas that is colorless and odorless Hydrocarbons or volatile organic compounds (VOCs) - produced mostly from unburned fuel that evaporates
Sunlight breaks these down to form oxidants, which react with oxides of nitrogen to cause ground level ozone (O3), a major component of smog.
Nitrogen oxides (NO and NO2, together called NOx) - contributes to smog and acid rain, and also causes irritation to human mucus membranes
31. Other sources of air pollution include industry and wood burning stoves.
32. Acid deposition (acid rain) is an unfortunate result of air pollution.
33. Acid rain results when electric power plants and industry burn coal or oil and emit large amounts of sulfur dioxide (SO2) and nitrogen oxides (NOx). 34. Acid deposition may be either dry or wet. Dry deposition will form an acid solution when it comes into contact with water.
35. Acid rain has its most harmful effects after the pH falls below 5.5 These include:
Damaging limestone buildings and statues. Killing fish and aquatic organisms (trout especially) Turns inorganic mercury into the more toxic methylmercury, which then accumulates in fish and affects top carnivores and humans. Weakens and kills trees, by leaching calcium , potassium and other nutrients from the soil. Kills tree roots and many kinds of fish by releasing ions of aluminum, lead , mercury and cadmium from the soil. Makes trees more susceptible to disease.
36. Emissions of sulfur dioxide are responsible for 60-70 % of the acid deposition that occurs globally. More than 90 % of the sulfur in the atmosphere is of human origin. The main sources of sulfur include:
Coal burning - coal typically contains 2-3 % sulfur so when it is burned sulfur dioxide is liberated. The smelting of metal sulfide ores to obtain the pure metals. Metals such as zinc, nickel, and copper are all commonly obtained in this manner. Volcanic eruptions - although this is not a widespread problem, a volcanic eruption can add a lot of sulfur to the atmosphere in a regional area. Organic decay.
37. After being released into the atmosphere, sulfur dioxide can either be deposited on the Earth's surface in the form of dry deposition or it can undergo the following reactions to produce acids that are incorporated into the products of wet deposition
SO2 + H2O »»» H2SO3 (Sulfuric acid)
38. Some 95 % of the elevated levels of nitrogen oxides in the atmosphere are the result of human activities. The remaining 5 % comes from several natural processes. The major sources of nitrogen oxides include:
Combustion of oil, coal, gas. Bacterial action in soil. Forest fires. Volcanic action. Lightning.
39. Acids of nitrogen form as a result of the following atmospheric chemical reactions
2NO2 + H2O »»» HNO2 + HNO3 (Nitric acids)
Finally, the concentrations of both nitrogen oxides and sulfur dioxides are much lower than atmospheric carbon dioxide, which is mainly responsible for making natural rainwater slightly acidic. However, these gases are much more soluble than carbon dioxide and therefore have a much greater effect on the pH of the precipitation.
40. The Clean Air Act of 1990 is an amendment to previous clean air acts that date back to 1955. In part, it says:
"An Act to amend the Clean Air Act to provide for attainment and maintenance of health protective national ambient air quality standards, and for other purposes."
Reduce urban smog by 15 % by 1996 and 3% per year until air-quality standards are met. Utilities must reduce the release of sulfur dioxide by one-half by the year 2000 Utilities must reduce the release of nitrogen dioxides by one-third by the year 2000 Dirty Utilities can buy and sell "pollution credits" from clean utilities. Passenger cars must emit 60% less nitrogen oxide and 40% less hydrocarbons by the year 2003 Auto-emissions must last 100,000 miles Toxic emissions must be reduced by 90% by the year 2000 Production of chlorofluorocarbons (CFC's) will be banned by the year 2000
Also, it mandated the installment of the Best Available Technology to reduce the amount of air toxics.
41. Humans have contributed to global warming by:
burning oil, coal, and natural gas to heat homes, power cars, and produce electricity deforestation and clearing land for growth and agriculture
42. The most important Greenhouse gasses are:
Carbon Dioxide - most abundant. It has increased 15% in 45 years
Chlorofluorocarbons (CFC's) - also depletes ozone
Methane (CH4) - from deforestation, cattle and livestock, landfills
Nitrogen Oxides (NOx) - from fertilizers, auto emissions, livestock waste
43. Consequences of global warming include:
Worsening health effects (heat stress, increased air pollution allergy disorders, increased insect vector diseases such as malaria, dengue and yellow fever, encephalitis and cholera) Rise in sea level causing substantial losses in coastal land and flooding of coastal cities Disruption of the water cycle which will increase flooding in some areas and droughts in other areas Changes in forested areas and grasslands, increase desertification in other areas. This in turn will greatly affect wildlife. For example, the loss of prairie potholes would adversely affect 50% of North American waterfowl that utilize the potholes for breeding. Challenges to agriculture and the food supply. 44. The Ozone layer occurs between 12-25 km form earth's surface. It protects all living things from harmful ultraviolet light. Exposure to UV rays can damage DNA.
45. A thinning (hole) in the Ozone layer was discovered over Antarctica in 1985.
46. Ozone thinning is the result of Chlorofluorocarbons (CFC's) and the cleaning solvents carbon tetrachloride and methyl chloroform. CFC's are/were used in refrigerants, hair spray cans and spray paint cans.
47. Ozone (O3) depletion results from the following process:
Cl + O3 ---- ClO + O2
48. Aesthetic pollution involves assaults on the senses such as sight, smell, and hearing.
49. Visual pollution may be billboards or litter or even light pollution of the night sky.
50. Noise pollution is a constant drum of sound from living in a modern mechanized society. It includes noise from cars, planes, machinery, radios, phones, etc.
51. Aesthetic pollution is highly subjective and cannot be gauged by numbers.