Pollution of the Atmosphere LESSON 2 Guiding Question: What are the sources of air pollution? • Explain how both natural processes and human Reading Strategy Before you read, make a three-column activities can cause air pollution. KWL chart. In the first column, write what you already know • Describe how air pollutants affect human health. about air pollution. In the second column, write what you want • Explain what causes smog and how temperature to learn. After reading, complete the chart by filling in what inversions affect it and other forms of air pollution. you have learned in the third column. • Explain how acid deposition occurs and describe Vocabulary air pollution, emission, fossil fuel, its effects. primary air pollutant, secondary air pollutant, smog, temperature inversion, acid deposition CROWDED TOGETHER, the horses in the parade seem to be fight- ing for space. The horse in the forefront is rearing, possibly frightened by the other horses and riders nearby. The rider, in contrast, appears calm as 15.2 LESSON PLAN PREVIEW he looks off into the distance. Thousands of years ago, in ancient Athens, Inquiry Students research the Greek sculptors created this parade in marble to go at the top of the health effects of air pollutants. Parthenon, a temple that honored the goddess Athena. Real World Students predict Today the parade of warriors no longer graces the Parthenon. Instead, how increasing public transpor- the sculptures are inside a museum in Athens. The sculptures were moved tation use might affect a city’s smog levels. to protect them from more damage. One cause of damage was pollutants Differentiated Instruction in the air. If you look carefully at Figure 10, you can see that some of the Less proficient readers organize stone has been worn away. information about the sources and effects of acid deposition. 15.2 RESOURCES Scientific Method Lab, Acid Rain and Seeds • Outdoors Lab, What’s in the Air? • Lesson 15.2 Worksheets • Lesson 15.2 Assessment • Chapter 15 Over- view Presentation GUIDING QUESTION FOCUS Divide the class into small groups and have each group sit in a circle. Have one student in each circle name a source of air pollution. Then, have the student to his or her right name another source. Have them continue around the circle naming different sources until the group runs out of ideas. FIGURE 10 Damage From Air Pollution Notice that the warriors’ faces have been worn away. The damage was caused partly by air pollution. The Atmosphere 461 FIGURE 11 Dust Storm Over a field in Africa, wind blows dust particles into Sources of Air Pollution the air. Air pollution can be caused by natural processes and human activities. The cars, trucks, and industries of modern Athens have released pollut- ants that have contributed to the damage to the Parthenon. Both human activities and natural processes cause outdoor air pollution, which is the release of damaging materials into the atmosphere. The substances released are called emissions. Some emissions, such as smoke and soot, consist of tiny particles, or particulate matter. Others are gases such as sulfur dioxide and carbon monoxide. Natural Processes Natural processes produce a great deal of the world’s air pollution. Winds sweeping over dry land can create huge dust storms, as seen in Figure 11. Winds sometimes blow dust across oceans from one continent to another. Volcanic eruptions release tiny solid par- ticles and gases into the atmosphere. Fires in forests and grasslands also produce smoke, soot, and gases. Human activities can make some natural pollution worse. For exam- ple, some farming and grazing practices strip most plants from the soil. When there are few plant roots to hold soil in place, wind erosion may occur. Wind erosion can lead to dust storms. BIG QUESTION Human Sources People’s activities have influenced air quality. The How can we ensure everyone has way we live—for example, our industries, the cars we drive, and the way clean air to breathe? we produce electricity—has introduced many sources of air pollution. Air Perspective After students have read about human sources of air pollu- pollution can come from point sources or nonpoint sources. In London, tion, reread the following sentence: power plants and factories act as point sources of emissions. Millions of Most air pollution comes, directly or cars and trucks together make up a moving nonpoint source. indirectly, from the combustion of Most air pollution comes, directly or indirectly, from the combustion fossil fuels. Have students write a of fossil fuels. Fossil fuels are carbon-containing fuels that formed mil- paragraph or two explaining how this statement affects their answer to lions of years ago from the remains of living things. Motor vehicles, such the Big Question. as cars and trucks, run by burning fossil fuels. Motor vehicles release an enormous amount of pollutants into the air. 462 Lesson 2 Primary and Secondary Air Pollutants Pollutants may do harm directly, or they may cause chemical reac- tions that produce harmful compounds. Primary air pollutants, such as soot and carbon monoxide, are pol- lutants released directly into the troposphere. Primary air pollutants may cause damage themselves, or they may react with other products to cause damage. Harmful products produced when primary air pollutants react chemically with other substances are called secondary air pollutants. Secondary air pollutants include tropospheric ozone and sulfuric acid. The table in Figure 12 describes some pri- mary and secondary air pollutants. FIGURE 12 Air Pollutants Primary air pollutants are released directly into the troposphere. Secondary air pollutants, in contrast, are the products of chemical reactions between primary air pollutants and other substances. Primary Air Pollutants Pollutant Source Eect Carbon monoxide (CO) The incomplete combustion (burning) Binds to hemoglobin, the oxygen- A colorless, odorless gas of fossil fuels by motor vehicles, carrying chemical in blood; deprives industries, and other sources cells of oxygen Sulfur dioxide (SO2 ) Burning of fossil fuels, especially coal, Produces secondary pollutants that A colorless gas with a strong, unpleasant odor for electricity generation and industry are part of acid precipitation; causes lung irritation Nitrogen dioxide (NO2 ) A reaction between atmospheric Can cause serious lung irritation; A foul-smelling, reddish-brown gas that belongs nitrogen and oxygen in combustion contributes to smog and acid to a family of compounds called nitrogen oxides engines and during the production of precipitation electricity Volatile organic compounds (VOCs) Many sources, including vehicle engines, Some can cause cancer; some Carbon-containing chemicals that evaporate household cleaning products, some interact with other chemicals to easily, producing fumes. Examples include industrial processes, and natural produce ozone in the troposphere. methane, propane, butane, and benzene. processes Particulate matter Dust blown by wind; soot and chemicals Can aect breathing and damage Solid or liquid particles that are small enough to produced by res and combustion lungs oat in the atmosphere—soot, dust, tiny bits of within engines; particles produced metals during construction and farming Lead Industrial renement of metals; in Can damage body tissues, including A heavy metal that is one type of particulate developing nations, gasoline contains those in the nervous system matter lead Secondary Air Pollutants Pollutant Source Eect Tropospheric ozone (O3 ) Results from the interaction of sunlight, Ozone in the stratosphere protects A colorless gas with an unpleasant odor heat, nitrogen oxides, and volatile humans from radiation, but ozone organic compounds in the troposphere can injure living tissues and cause respiratory problems. Sulfuric acid (H2SO4 ) and nitric acid (HNO3 ) Produced when sulfur dioxide and Components of acid precipitation nitrogen oxides combine with water in the atmosphere The Atmosphere 463 FIGURE 13 Effects of Air Pollution A runner in the Beijing Olympic Games wears a mask to protect his respiratory system from air pollution. Beijing has severe air pollution. Before the 2008 Olympic Games, the city made a major effort to clean its air. How Air Pollutants Affect Your Health Air pollutants can damage the respiratory system, interfere with the body’s uptake of oxygen, and cause cancer. Outdoor air pollution is a big health problem. Air pollutants can do seri- ous harm to the respiratory system, which transports oxygen into your body and removes carbon dioxide. Some air pollutants can cause cancer. Respiratory System Problems Have you ever inhaled dust and then started coughing? Particles in the dust irritated your respiratory system, making you cough. Similarly, air pollutants irritate people’s air passages and lungs. If people are exposed over and over to air pollution, they may develop harmful respiratory conditions. Asthma, bronchitis, and emphy- sema have all been linked to air pollutants. The Effect of Carbon Monoxide How do the cells of your body obtain the oxygen they need? The air that you inhale contains oxygen. This oxygen passes from the lungs into the bloodstream. There, oxygen binds to hemoglobin. Hemoglobin is a molecule in red blood cells that combines chemically with oxygen. The red blood cells then carry the oxygen to the cells of the body. However, if there is carbon monoxide in the air, the carbon monoxide will bind to hemoglobin, replacing some of the oxygen that the blood would normally carry. Therefore, carbon monoxide interferes with your body’s ability to deliver oxygen to cells. This can cause headaches, tired- ness, and nausea. Over time, carbon monoxide can damage the heart because the heart muscle has to work harder than normal to deliver oxy- gen to cells. In high concentrations, carbon monoxide can be fatal. Cancer Trace amounts of some air pollutants may contribute to cancer. Soot, for example, can cause cancer if it is inhaled frequently. Benzene, which is a volatile organic compound in gasoline, has also been linked to cancer.