Pollution of the Atmosphere LESSON 2 Pollution of the Atmosphere LESSON 2 FIGURE 10 Damage From Air

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Text of Pollution of the Atmosphere LESSON 2 Pollution of the Atmosphere LESSON 2 FIGURE 10 Damage From Air

  • The Atmosphere 461

    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 he looks off into the distance. Thousands of years ago, in ancient Athens, Greek sculptors created this parade in marble to go at the top of the Parthenon, a temple that honored the goddess Athena.

    Today the parade of warriors no longer graces the Parthenon. Instead, the sculptures are inside a museum in Athens. The sculptures were moved to protect them from more damage. One cause of damage was pollutants in the air. If you look carefully at Figure 10, you can see that some of the stone has been worn away.

    LE SS

    O N 2Pollution of the Atmosphere

    FIGURE 10 Damage From Air Pollution Notice that the warriors’ faces have been worn away. The damage was caused partly by air pollution.

    • Explain how both natural processes and human activities can cause air pollution.

    • Describe how air pollutants affect human health. • Explain what causes smog and how temperature

    inversions affect it and other forms of air pollution. • Explain how acid deposition occurs and describe

    its effects.

    Reading Strategy Before you read, make a three-column KWL chart. In the first column, write what you already know about air pollution. In the second column, write what you want to learn. After reading, complete the chart by filling in what you have learned in the third column.

    Vocabulary air pollution, emission, fossil fuel, primary air pollutant, secondary air pollutant, smog, temperature inversion, acid deposition

    Guiding Question: What are the sources of air pollution?

    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.


    15.2 LESSON PLAN PREVIEW Inquiry Students research the health effects of air pollutants. Real World Students predict how increasing public transpor- tation use might affect a city’s smog levels. Differentiated Instruction Less proficient readers organize 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

  • 462 Lesson 2

    Sources of Air Pollution 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.

    Human Sources People’s activities have influenced air quality. The way we live—for example, our industries, the cars we drive, and the way we produce electricity—has introduced many sources of air pollution. Air pollution can come from point sources or nonpoint sources. In London, power plants and factories act as point sources of emissions. Millions of cars and trucks together make up a moving nonpoint source.

    Most air pollution comes, directly or indirectly, from the combustion of fossil fuels. Fossil fuels are carbon-containing fuels that formed mil- lions of years ago from the remains of living things. Motor vehicles, such as cars and trucks, run by burning fossil fuels. Motor vehicles release an enormous amount of pollutants into the air.

    FIGURE 11 Dust Storm Over a field in Africa, wind blows dust particles into the air.

    How can we ensure everyone has clean air to breathe? Perspective After students have read about human sources of air pollu- tion, reread the following sentence: Most air pollution comes, directly or indirectly, from the combustion of fossil fuels. Have students write a paragraph or two explaining how this statement affects their answer to the Big Question.


  • E�ectSourcePollutant


    Primary Air Pollutants

    Secondary Air Pollutants

    Carbon monoxide (CO) A colorless, odorless gas

    Sulfur dioxide (SO2 ) A colorless gas with a strong, unpleasant odor

    Nitrogen dioxide (NO2 ) A foul-smelling, reddish-brown gas that belongs to a family of compounds called nitrogen oxides

    Volatile organic compounds (VOCs) Carbon-containing chemicals that evaporate easily, producing fumes. Examples include methane, propane, butane, and benzene.

    Particulate matter Solid or liquid particles that are small enough to �oat in the atmosphere—soot, dust, tiny bits of metals

    Lead A heavy metal that is one type of particulate matter

    Tropospheric ozone (O3 ) A colorless gas with an unpleasant odor

    Sulfuric acid (H2SO4 ) and nitric acid (HNO3 )

    Binds to hemoglobin, the oxygen- carrying chemical in blood; deprives cells of oxygen

    Produces secondary pollutants that are part of acid precipitation; causes lung irritation

    Can cause serious lung irritation; contributes to smog and acid precipitation

    Some can cause cancer; some interact with other chemicals to produce ozone in the troposphere.

    Can a�ect breathing and damage lungs

    Can damage body tissues, including those in the nervous system

    Ozone in the stratosphere protects humans from radiation, but ozone in the troposphere can injure living tissues and cause respiratory problems.

    Components of acid precipitation

    The incomplete combustion (burning) of fossil fuels by motor vehicles, industries, and other sources

    Burning of fossil fuels, especially coal, for electricity generation and industry

    A reaction between atmospheric nitrogen and oxygen in combustion engines and during the production of electricity

    Many sources, including vehicle engines, household cleaning products, some industrial processes, and natural processes

    Dust blown by wind; soot and chemicals produced by �res and combustion within engines; particles produced during construction and farming

    Industrial re�nement of metals; in developing nations, gasoline contains lead

    Results from the interaction of sunlight, heat, nitrogen oxides, and volatile organic compounds

    Produced when sulfur dioxide and nitrogen oxides combine with water in the atmosphere

    The Atmosphere 463

    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 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.

  • 464 Lesson 2

    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.



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