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printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” Why ItMatters CASESTUDY 302 resources in Spanish. worksheets, multimedia,and resources, includinglabs, Go onlinetoaccessadditional Level Ozoneonpages310–311. The HealthEffects ofGround- air pollutioninthecasestudy moreLearn abouttheeffects of air quality? urban areas can take to improve What are someapproaches that unhealthy levelsofairpollution. skyline atduskreveals The LosAngeles,California, Acid Precipitation Section 3 Air, Noise,andLightPollution Section 2 What CausesAirPollution? Section 1 Chapter 12 HMDScience.com EN Online Vir onmental Science Air

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Section 1 What Causes Air Objectives Name five primary air pollutants and give sources Pollution? for each. Name the two major sources of In most places in the United States, the air we breathe is fairly clean. In some air pollution in urban areas. places in the world, though, this is not the case. Areas of India and Bangladesh Describe the way in which have air that is so polluted it harms people’s health. smog forms. Clean air consists mostly of nitrogen and oxygen gas, as well as very small amounts of argon, carbon dioxide, and water vapor. When harmful substances Explain the way in which build up in the air to unhealthy levels, the result is air pollution. a thermal inversion traps Much air pollution is the result of human activities, but pollutants can also air pollution. come from natural sources. A volcano, for example, can spew clouds of particles

and sulfur dioxide, SO2, into the atmosphere. Natural pollutants also include dust, pollen, and spores. Key Terms air pollution Primary and Secondary Pollutants primary pollutant A pollutant that is put directly into the air by human activity is called a secondary pollutant primary pollutant. An example of a primary pollutant is soot from smoke. smog Figure 1.1 shows some sources of primary air pollutants. Secondary pollut- temperature inversion ants form when primary pollutants react with other primary pollutants or with naturally occurring substances such as water vapor. An example of a secondary pollutant is ground-level ozone. Ground-level ozone forms Check for Understanding when the ultraviolet rays of the sun cause emissions from cars, trucks, Explain How is ground-level ozone an and other sources to react with oxygen in the atmosphere. example of a secondary pollutant?

Figure 1.1

Primary Air Pollutants Each day in the United States, hundreds of thousands of tons of polluting emissions that result from human activity enter the air.

Sources of Primary Air Pollutants in the U.S. (Per Day) 80

70 Carbon monoxide (CO) Nitrogen oxides (NOx) 60 Particulate matter (PM) 50 Sulfur oxides (SOx) Volatile organic compounds (VOCs) 40

Emissions (in thousands of tons) 10

0 Electricity production Industry Transportation Other sources

Source: U.S. Environmental Protection Agency.

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figure 1.2 Primary Air Pollutants

Pollutant Description Primary Sources Effects

Carbon monoxide (CO) CO is an odorless, colorless, Sources of CO are cars, CO interferes with the blood’s ability poisonous gas. It is trucks, buses, small to carry oxygen, slowing reflexes produced by the incomplete engines, and some industrial and causing drowsiness. In high burning of fossil fuels. processes. concentrations, CO can cause death.

Nitrogen oxides (NOx ) When combustion (burning) NOx comes from burning fuels NOx can make the body vulnerable to temperatures exceed in vehicles, power plants, and respiratory infections, lung diseases,

538°C, nitrogen and industrial boilers. and cancer. NOx contributes to the oxygen combine to form brownish haze seen over cities and to nitrogen oxides. acid precipitation.

Sulfur dioxide (SO2) SO2 is produced by SO2 comes mostly from SO2 contributes to acid precipitation as chemical interactions burning fossil fuels. sulfuric acid. Secondary pollutants that

between sulfur and oxygen. result from reactions with SO2 can harm plant life and irritate the respiratory systems of humans.

CVolatileonn eorganicct to LAW VOCs are organic chemicals VOCs come from burning VOCs contribute to smog formation and compounds (VOCs) that vaporize readily and fuels. Vehicles are a major can cause serious health problems, such form toxic fumes. source of VOCs. as cancer. They may also harm plants.

Particulate matter Particulates are tiny Most particulates come from Particulates can form clouds that (particulates or PM) particles of liquid or construction, agriculture, reduce visibility and cause a variety of solid matter. forestry, and fires. Vehicles respiratory problems. Particulates have and industrial processes also also been linked to cancer. As well, they contribute particulates. may corrode metals and erode buildings and sculptures.

Sources of Primary Air Pollutants As shown in Figure 1.2 above, household products, power plants, and motor vehicles are sources of primary air pollutants such as carbon monoxide, nitrogen oxide, sulfur dioxide, and chemicals called volatile organic compounds (VOCs). Carbon monoxide gas is an important component of the exhaust from vehicles. Vehicles are also a major source of emissions of nitrogen oxides. Coal-burning power plants are another source of nitrogen oxides. Sulfur dioxide gases are formed when coal Connect to LAW and oil, which contain sulfur, are burned. Power plants, refineries, and metal smelters contribute much of the sulfur dioxide emissions to the Off with His Head! air. Vehicles and gas station spillage make up most of the human-made Around 1300 ce, King Edward I of emissions of volatile organic compounds. VOCs are also found in many England forbade the burning of coal household products. while Parliament was in session. “Be it known to all within the sound of my Particulate matter can also pollute the air and is usually divided into voice,” King Edward I said, “whosoever fine and coarse particles. Fine particles enter the air from fuel burned by shall be found burning coal shall suffer vehicles and coal-burning power plants. Sources of coarse particles are the loss of his head.” cement plants, mining operations, incinerators, wood-burning fireplaces, fields, and roads.

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The History of Air Pollution ECOFACT Air pollution is not a new phenomenon. Whenever something burns, Sea-Coal pollutants enter the air. Two thousand years ago, Seneca, a Roman In 12th-century London, wood was philosopher and writer, complained about the foul air in Rome. In 1273, becoming too scarce and expensive to England’s King Edward I ordered that burning a particularly dirty kind of use as a fuel source. Large deposits coal called sea-coal was illegal. One man was even executed for disobey- of sea-coal, found off the northeast ing this medieval “clean air act.” coast of England, provided a plentiful alternative. However, this soft coal The world air-quality problem is much worse today because modern did not burn efficiently. The sea-coal industrial societies burn large amounts of fossil fuels. As represented in produced much smoke and not much Figure 1.3, most air pollution in industrialized countries comes from mo- heat. The smoke emanated from tor vehicles and industry. London homes and factories and combined with fog to produce smog. Motor Vehicle Emissions Figure 1.3 Almost one-third of our air pollution comes from gasoline burned by vehicles. Sources of Air Pollution The refinery shown in this photograph is a According to the U.S. Department of source of volatile organic compounds. The truck in the foreground is emitting Transportation, Americans drove their nitrous oxide into the atmosphere. vehicles over three trillion miles in 2010. Roughly 90 percent of that mileage was from passenger and other light-duty vehicles. The rest was from trucks and buses.

Controlling Vehicle Emissions The Clean Air Act, passed in 1970 and strengthened in 1990, gives the Envi- ronmental Protection Agency (EPA) the authority to regulate vehicle emissions in the United States. The EPA required the gradual elimination of lead in gasoline, and as a result, lead pollution has been reduced by more than 90 percent in the United States. In addition, catalytic converters, which are required in automobiles, clean exhaust gases of pollutants before the pollutants are able to exit the tailpipe. The EPA indicates that light-duty cars and trucks in 2010 burned fuel approximately 70 percent more efficiently and with about 40 percent fewer emissions of carbon dioxide than they did in 1975. In addition, cars and trucks produce approximately 95 percent fewer emissions of pollutants other than carbon dioxide than they did in the 1970s. ©A. T. Willett/Alamy Images T. ©A.

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Connect to MATH California Zero-Emission Vehicle Program Utility Incentives for A catalytic converter, as shown in Figure 1.4, is used to control emissions Zero-emission Vehicles from most American vehicles. In California, motor vehicles account for The Los Angeles Department of Water more than half of the ozone and particulate matter that pollutes the air. To and Power provides discounts of improve air quality, the state’s Air Resources Board established the Zero- $0.025 per kilowatt hour (kWh) for Emission Vehicle (ZEV) program in 1990 and has continued to update it to electricity used to recharge electric encourage the development of less-polluting vehicles. ZEV programs have vehicles. If the energy charge per kWh also been adopted in Maine, Massachusetts, New York, and Vermont. is $0.02949 and you use 150 kWh of Zero-emission vehicles have no tailpipe emissions, no emissions from electricity per month to recharge your gasoline, and no emission-control systems, which deteriorate over time. vehicle, how much money would you Battery-powered electric vehicles are the only true ZEVs at the moment, save on your electric bill each month? but there are three types of partial ZEVs. One type is clean, fuel-efficient each year? How much would you save hybrid cars, which are powered by both batteries and gasoline engines. if you had three electric cars? There are many models of hybrid cars, including models that are re- charged by plugging in to a power source. Vehicles powered by hydrogen would emit only water vapor. As of 2011, such hydrogen-powered vehicles are still mostly in the prototype stage of development.

Figure 1.4

Car Emission The catalyst material in a catalytic converter (top) speeds up a chemical reaction that changes exhaust emissions to less harmful substances. The text below the images shows a car’s contribution to air pollution.

Interior • Car seats may be covered in plastic that contains a volatile organic compound called vinyl chloride.

Body and Frame • Steel smelters send thousands of metric tons of sulfur dioxide into the air each year. • Many auto factories in Mexico, Eastern Europe, and some Exhaust Asian countries lack pollution-control devices. • Car exhaust is a major source of nitrogen oxides, carbon Fuel Tank monoxide, and hydrocarbons. • When filling the car with gasoline, VOCs • In developing countries, car exhaust may contain over a escape into the atmosphere. thousand poisonous substances.

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Figure 1.5 ECOFACT Industrial Pollution In 1996, the federal government established standards to reduce Air Pollution’s Impact on Birds emissions of VOC-producing chemicals used in dry cleaning. Scientists in Finland have documented the effects of harmful emissions from a copper smelter in Finland on two species of birds that live nearby. The two species of birds respond differently to the pollutants containing heavy metals and acidic substances. One species appears to suffer directly from the toxic effects of the pollutants. The other species suffers because the amount of insect food for its nestlings has been reduced. When heavy metal emissions from the smelter decreased, a rapid improvement in breeding success and a decrease in the heavy metal found in the bones of nestlings was observed.

Industrial Air Pollution Figure 1.6 Many industries, as well as power plants that generate electricity, burn Scrubber Scrubbers work by fuel to produce energy. They usually burn fossil fuels. Burning fossil fuels spraying gases with water, which releases sulfur dioxide and nitrogen oxides into the air. Power plants that removes many pollutants. produce electricity emit at least two-thirds of all sulfur dioxide and more than one-third of all nitrogen oxides that pollute the air. Some industries, such as the dry cleaning industry shown in Figure 1.5, also produce VOCs. VOCs are chemical compounds that form toxic fumes. Oil refineries, chemical manufacturing plants, furniture refinishers, and automobile repair shops also contribute to the VOCs in the air.

Regulating Air Pollution from Industry The Clean Air Act requires many industries to use scrubbers or other pollution-control devices. Scrubbers remove some of the more harmful substances that would otherwise pollute the air. A scrubber, as shown in Figure 1.6, is a machine that moves gases through a spray of water that dissolves many pollutants. Electrostatic precipitators are machines used in cement factories and coal-burning power plants to remove dust particles from smoke-stacks. In an electrostatic precipitator, gas containing dust particles is blown through a charged chamber. An electrical charge is transferred to the dust particles, which causes them to stick to one another and the sides of the chamber. The clean gas is released from the chamber, and the concentrated dust Check for Understanding particles can then be collected and removed. Electrostatic precipitators Describe Name two pollution-control remove more than 20 million tons of ash generated by coal-burning power devices. State how they help to limit the

©Michael Newman/PhotoEdit plants from the air each year in the United States. amount of pollutants in air.

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Figure 1.7 Smog Smog The diagram below shows When air pollution hangs over urban areas and reduces visibility, it is how smog is formed. Large cities with dry, sunny climates and millions of called smog. As you can see in Figure 1.7, smog results from chemical automobiles often suffer from smog. reactions that involve sunlight, air, automobile exhaust, and ozone. Pollutants released by vehicles and industries are the main causes of smog.

Temperature Inversions The circulation of air in the atmosphere usually keeps air pollution from reaching dangerous levels. During the day, the sun heats the surface of Earth and the air near Earth. The warm air rises through the cooler air above and carries pollutants away from the ground and into the atmosphere. Sometimes, however, pollution is trapped near the Earth’s surface. Usually, air temperatures decrease with altitude, but sometimes a temperature inversion occurs when the air above is warmer than the air below. Figure 1.8 shows how a temperature inversion traps pollutants near Earth’s surface. The warmer air above keeps the cooler air at the surface from moving upward. Pollutants are trapped below with the cooler air. If a city is located in a valley, the city has a greater chance of experiencing temperature inversions. Los Angeles, which is surrounded on three sides by mountains, often has temperature inversions that trap smog in the city.

Normal situation Temperature inversion Figure 1.8 Solar Escaping Solar Trapped radiation pollutants radiation pollutants Air Circulation Normal air Cooler air Cool air circulation is shown at left. A Cool air Warm inversion temperature inversion, in which layer pollutants are trapped near Earth’s surface, is shown at right. Warm air Cool air

Section 1 Formative Assessment

Reviewing Main Ideas Critical Thinking 1. Name five primary air pollutants, and give 5. Making Decisions Read the passage on the important sources for each. California Zero-Emission Vehicle Program. Should automobile makers be made to adhere 2. Name the two major sources of air pollution in to quotas of zero-emission vehicles set by states, urban areas. even if it causes automakers to lose revenue? 3. Describe the way in which smog forms. 6. Analyzing Relationships Can you think of 4. Define the term temperature inversion. Explain any other possible type of pollution-control how temperature inversion traps pollutants near device that could be used to remove particulates Earth’s surface. from smokestacks in a manner similar to an electrostatic precipitator?

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©UNEP Air Pollution Long-Term HealthEffectsof Air Pollution Short-Term Effectsof Air Pollution onHealth dollars ayearinhealthcoststotreat respiratory diseasescausedbyairpollution. American LungAssociationhasestimatedthatAmericanspaytensofbillions as emphysema,heartdisease,andlungcancerare citedascausesofdeath.The no deathcertificateslistthecauseofasairpollution.Instead,diseasessuch pollution todisease.Butbecauseaddstheeffects ofexistingdiseases, problems are mostaffected byairpollutants.Decadesofresearch havelinkedair People whoare veryyoungoroldandpeoplewhohaveheartlung Pollution Air, Noise, andLight Figure 2.1 may damage thelungs ofchildren. maypollution medical conditionssuffered worsen by and olderpeople emphysema, lung cancer, exposure disease. andheart Long-term to air onhealth that effects haveLong-term linked include to airpollution been asthma andemphysema worse. Pollution can make also theconditionofindividualswhosuffer from respiratoryand upper infections, such asbronchitis andpneumonia. coughing; tightness to theeyes,irritation inthechest; nose, andthroat; onpeople’s ofairpollution effects health include headache; nausea; are reversible iftheirexposure decreases. to airpollution The short-term Many onpeople’s ofairpollution oftheeffects health are short-term and This policeofficerwearsasmogmaskashedirectstrafficinBangkok, Thailand. waste causedby lightpollution. Describe solutionstoenergy noise pollution. health problemscausedby Describe three human be prevented. air pollutionandhow itcan Explain whatcausesindoor human health. effects ofairpollutionon effects andthree long-term Describe three short-term Key Terms decibel (dB) asbestos sick-building syndrome Section 2 Air Chapter 12: Objectives 309 Connect to CHEMISTRY

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Connect to CHEMISTRY Indoor Air Pollution Formaldehyde The quality of air inside a home or a building is sometimes worse Formaldehyde is a colorless gas that than the quality of the air outside. Chemicals that are used to make has a strong odor. It is a very common carpets, building materials, paints, and furniture are major sources industrial and commercial chemical of pollutants in buildings. Figure 2.2 shows examples of some indoor that is used to make building materials air pollutants. and household products. Significant Buildings that have very poor air quality have a condition called amounts of formaldehyde are found in sick-building syndrome. Sick-building syndrome is most common in adhesives in plywood, particle board, furniture, and carpet. Other sources hot places where buildings are tightly sealed to keep out the heat. In may be foam insulation, gas stoves, Florida in the early 1990s, for example, a newly built, tightly sealed county tobacco smoke, and dry-cleaned courthouse had to be abandoned. Half of the people who worked there clothing. Formaldehyde may cause eye developed allergic reactions to fungi that were growing in the air-condi- irritation, burning sensations in the tioning ducts, ceiling tiles, carpets, and furniture. throat, nausea, and difficulty breathing. Identifying and removing the sources of indoor air pollution is the most effective way to maintain good indoor air quality. Ventilation, or Check for Understanding mixing outdoor air with indoor air, is also necessary for good air quality. Apply Why is sick-building syndrome Activities such as renovation and painting, which produce indoor air most common in hot places? pollution, require good ventilation.

CASESTUDY The Health Effects of Ground-Level Ozone You have learned that the ozone layer in the stratosphere shields Earth from the harmful effects of ultraviolet radiation from the sun. At the surface of the Earth, however, ozone is a human-made air pollutant that at certain concentrations damages human health. Ozone forms from the reaction of volatile organic compounds (VOCs)

and nitrogen oxides (NOx) in the presence of heat and sunlight. High concentrations of ozone form in the atmosphere on sunny days that

have high temperatures. The sources of VOCs and NOx emissions are largely motor vehicles, power plants, gasoline vapors, and chemical solvents. Most ozone pollution forms in urban and suburban areas. However, ozone-producing chemicals may be transported hundreds of kilometers from their source. As ozone concentrations in the atmosphere increase, greater numbers of people may experience harmful health effects of ozone on the lungs. Some of the short-term effects of ozone on health include irritation Children who engage in vigorous outdoor of the respiratory system, a reduction in lung function, the aggravation of activities when pollutant concentrations asthma, and inflammation to the lining of the lungs. Scientists believe that are often high may have a greater risk of developing asthma or other ozone may have other damaging effects on human health. Lung diseases respiratory illnesses. such as bronchitis and emphysema may be aggravated by ozone. ©Neal Preston/Corbis

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Figure 2.2 Indoor Pollutants Some indoor air pollutants and their sources are shown here.

CASESTUDY

A therapist performs a lung- function test on a patient by using a machine that measures various aspects of lung function.

Critical Thinking

Scientists believe that permanent lung injury may result Critical Thinking from repeated short-term exposure to ozone pollution. 1. Making Decisions Write a brief paragraph Children who are regularly exposed to high concentrations explaining whether or not lung-function tests of ozone may have reduced lung function as adults. should be mandatory for children who live in Exposure to ozone may also accelerate the natural decline urban areas where high concentrations of ozone in lung function that is part of the aging process. are frequent. Those who are most at risk from ozone include 2. Making Decisions If lung-function tests children, adults who exercise or work outdoors, older become mandatory, who will pay for these tests, people, and people who suffer from respiratory diseases. and who will provide the equipment? Should In addition, there are some healthy individuals who have these tests be performed at school, in a doctor’s unusually high susceptibility to ozone. ©SPL/Photo Researchers, Inc. ©SPL/Photo Researchers, office, or at a hospital?

Chapter 12: Air 311 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 312 Asbestos a structurethatwasbuiltwithasbestos. fibers. The workerisremovingdebrisfrom the human ear Faintest soundheardby Whisper Conversation Lawnmower Portable CDplayer Chainsaw Car horn Rock concert Jet engine Rocket engine Noise Figure 2.3 figure 2.4 Commn Noises Water, Air, and Land Unit 4: Intensity of Asbestos formsinlong, thin Intensity 90–120 (dB) 100 110 120 140 180 30 60 90 0 Noise Pollution used asaninsulatorused andasafire retardant, extensively anditwas used States. dB for8hours. Personal listening are devices notregulated inthe United Institutes ofHealth, thesafe threshold forpersonal listening is85 devices must notproduce more than 100dBofnoise. According to theNational vehicles andlawn mowers, andby insulation. In Europe, MP3players pain. Noise can pollution controlled be by such devices asmufflers on is 10timestheintensity Asoundof120dBisat of10dB. thethreshold of 10 dBresults ina10-foldincrease insoundintensity. For example, 20dB United States. who smoke. Radon cause isthesecond-leading oflung cancer inthe air passages. Such damage can lead to cancer, among especially people In thelungs, radon can destroy material thegenetic incellsthat linethe to dust particles. inhale people When thedust, radon enters theirlungs. holes infoundations into homes, offices, andschools, where itadheres curs naturally intheEarth’s crust. Radon through can seep cracks and is produced by thedecay ofuranium, aradioactive element that oc Radon isacolorless, tasteless, odorless gas. It radioactive. isalso Radon Radon Gas Figure 2.4 loud soundshave caused whales anddolphins to strand onbeaches. negative impact onorganisms onland andintheoceans. For example, ing at theage of80than mostdoat Americans 30.Noise can have also a found that living inaquietenvironment people had inAfrica better hear loss, likely dueto theprevalence listening ofportable devices. study One since the1970s. About 14.9percent have ofteens permanent hearing cells inour ears. Hearing loss has roughly doubled intheUnited States living.modern It isirritating, anditdamages our by hearing destroying payUnwanted we anditisoneoftheprices for pollution, soundisnoise strength andresistance to heat are called Several minerals that inlong, form andthat thinfibers are valued fortheir Asbestos The intensity ofsoundismeasured inunitscalled shows theintensity commonnoises. ofsome Each increase of tos andasbestos fibers removal from abuilding. remove asbestos from buildings. school taken thisthreat Billions seriously. ofdollars have spent been to eventually failure. dieofheart intheUnited States Schools have haveof thedisease more andmore difficultybreathing andmay and scar thelungs, which causes asbestosis. thedisease Victims in theairisdangerous. Asbestos that fibers are inhaled can cut most asbestos products intheearly 1970s. Exposure to asbestos in building materials. The U.S. government of theuse banned asbestos Figure 2.3 . Asbestos isprimarily decibels shows asbes (dB). - - -

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©A Rroom with Views/Alamy Images Light Pollution Light Pollution skyglow, whichisaneffectoflightthatcandramaticallyreduceourviewthenightsky. Figure 2.5 sources—the most energy-efficient source of light—where possible. possible. light—where of source energy-efficient most sources—the sodium low-pressure use to and needed when only used is light that so controls time use to are solutions other Two downward. directed is it so light shielding includes waste energy to solution One waste. migration saving season, many birds. grate at night. In Chicago, lights oftallbuildings are the during dimmed lights at hatching time. Light can cause also problems forbirds that mi- may communities beachesturn offtheir turtle Some notsurvive. near sea towards light. Theymay move thewrong way towards street lights and ouraffect environment. Hatching baby instinctively turtles move sea ishes our viewofthenight sky, asshownin stress, inhumans. andanxiety Also, light inurban pollution areas dimin- Research suggests that light can pollution increase headaches, fatigue, Another important environmental concern of lighting is energy energy is lighting of concern environmental important Another 4. 3. 2. 1. Section 2 ReviewingMainIdeas associated with lightassociated with pollution. Describe caused by pollution. noise Describe canpollution prevented. be Describe short-term onhealth. ofairpollution effects Describe This viewofHongKongshowshowlightinginurbanareascancause several to theenergy waste solutions ofthehumansome health problems waystwo air inwhich indoor andthe effects the long-term Formative Assessment Figure 2.5 , andcan negatively 6. 5. CriticalThinking type ofenvironment.type you wouldcontrol thegrowth ofmold in this is high andtheventilation ispoor. how Explain new, tightly buildings sealed where thehumidity Analyzing Relationships arepollution similar. ways andlightExplain pollution inwhich noise andlight of noise inthissection. pollution Making Comparisons Light Pollution. Go to Btofindthefieldstudy Appendix light pollution? Identify Che

FieldStudy What aresomeeffectsof What c Air Chapter 12: k f Read the descriptions Read the descriptions o Molds can grow in r Understanding 313 DO NOT EDIT--Changes must be made through “File info” printcode=a

Section 3 Objectives Acid Precipitation Explain the causes of acid precipitation. Imagine that you are hiking through the forests of the Adirondack Mountains in Explain how acid precipitation New York. You come to a lake and sit down to rest. You are amazed at how clear affects plants, soils, and the water is; it is so clear that you can see the bottom of the lake. But after a few aquatic ecosystems. minutes you feel uneasy. Something is wrong. What is it? Suddenly, you realize that the lake has no fish. Describe three ways that acid precipitation affects humans. What Causes Acid Precipitation? Describe ways that countries The lake described in the introduction, and thousands of lakes through- are working together out the world, are victims of acid precipitation, or acid rain. Acid pre- to solve the problem of cipitation is precipitation—rain, sleet, or snow—that contains a high acid precipitation. concentration of acids. When fossil fuels are burned, they release oxides of sulfur and nitrogen. When the oxides combine with water in the atmo- Key Terms sphere, they form sulfuric acid and nitric acid, which fall as acid precipitation. This acidic water flows over and through the ground, and into acid precipitation lakes, rivers, and streams. Acid precipitation can kill living things, and can pH result in the decline or loss of some local animal and plant populations. acid shock A pH number is a measure of how acidic or basic a substance is. A pH scale is shown in Figure 3.1. As you can see from the scale, the lower the pH number is, the more acidic a substance is; the higher a pH number is, the more basic a substance is. Each whole number on the pH scale indicates a ten-fold change in acidity. Pure water has a pH of 7.0. Normal precipitation is slightly acidic, because atmospheric carbon dioxide dissolves into the precipitation and forms carbonic acid. Normal precipitation has a pH of about 5.6. Acid precipitation has a pH of less than 5.0. Figure 3.2 shows how acid precipitation forms.

Figure 3.1

pH Scale The pH scale measures how basic Human saliva or how acidic a substance is. Below are the pH measurements of some common substances. Tap water

Acid rain Acid rain (extreme) (average) Rain

3.5 4.0 5.0 6.0

Carbonated Lemon soft Tomato Human Sea Household juice Vinegar drink juice Milk blood water Detergents ammonia

1 2 3 4 5 6 7 8 9 10 11 12

Increasing acidity Increasing basicity

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©Simon Fraser/SPL/Photo Researchers, Inc. precipitation canhaveonplants. Acid Precipitation and Plants How Acid Precipitation Affects Soils Figure 3.3 these areas. in increase will problems rain acid that concern growing is There increasing. are fuels fossil of emissions India, and China In ing. improv are conditions remains, work much Though dramatically. emissions cut to industries with worked EPA has the identified, was rain acid of problem the Since places. some in 4.2 as low as been has rain of pH the America, North In time. through changed in water vapor ofplants. clogstheopenings onsurfaces plants. Aluminum causesalso root damage. Sulfur dioxide dissolved toxic released metalsto be by andpossibly absorbed theroots of away by rainwater. Increased causes acidity aluminum andother increases, ofsoil acidity nutrients some are andwashed dissolved changes thebalance ofasoil’s inseveral ways. chemistry the When in theconcentration ofacidiscalled acidification. Acidification Acid precipitation can andwater. lower thepHofsoil This increase shows ofacidprecipitation theharmfuleffects ontrees over time. The pH of precipitation varies around the world and has has and world the around varies precipitation of pH The The treesinthisforestPolandshowthedramaticeffectacid Figure 3.3

- acid precipitation? of comparewith that pure water Compare combine with Figure 3.2 Sulfuric acid acid precipitation. that containstheseacidsiscalled sulfuric andnitricacids. Rainfall water intheatmospheretoform and nitrogenoxidescombinewith Acid Precipitation H Che SO 2 SO 2

c 4 Atmospheric gases

Air Chapter 12: How doesthepHof How Acid precipitation k f o and H r Understanding 2 O Sulfur oxides combine with Nitric acid NO HNO 2 3 315 DO NOT EDIT--Changes must be made through “File info” printcode=a

Figure 3.4 Acid Precipitation and Aquatic Ecosystems Acid Shock Acid shock can cause Aquatic animals are adapted to live in an environment with a particular the death of many fish. pH range. If acid precipitation falls on a lake and changes the water’s pH, acid can kill fish and other aquatic animals. The change in pH is not the only thing that kills fish. Acid precipitation causes aluminum to leach out of the soil surrounding a lake. The aluminum accumulates in the gills of fish and interferes with oxygen and salt exchange. As a result, fish are slowly suffocated. The effects of acid precipitation are worst in the spring, when acidic snow that accumulated during the winter melts and rushes into lakes and other bodies of water. This sudden influx of acidic water that causes a rapid change in the water’s pH is called acid shock. This phenomenon may kill large numbers of fish, as shown in Figure 3.4. Acid shock also affects the reproduction of fish and amphibians. They produce fewer eggs, and these eggs often do not hatch. The offspring that do survive often have birth defects and cannot reproduce.

Acid Precipitation and Humans QUICKLAB Acid precipitation can affect humans in a variety of ways. Toxic metals such as aluminum and mercury can be released into the environment when soil acidity increases. These toxic metals can find their way into crops, water, and fish. The toxins then poison the human body. Acid precipitation can lead to other human health problems. Research QUICKLAB has indicated that there may be a correlation between large amounts of acid precipitation received by a community and an increase in respira- Effects of Acid Precipitation tory problems in the community’s children. Procedure The standard of living of some people is affected by acid precipitation. 1. Place a drop of mixed protozoan culture on a microscope slide and Decreases in numbers of fish caused by the acidification of lakes and place a cover slip on top. streams can influence the livelihood of commercial fishers and people 2. Observe the organisms under involved in the sportfishing industry. Forestry is also affected when trees a microscope. Record your are damaged by acid precipitation. observations. Acid precipitation can dissolve the calcium carbonate in common 3. Use a pipette to place 2–3 drops building materials, such as concrete, marble, and limestone. Some of the of vinegar (which has a pH similar world’s most important monuments are being dissolved by acid precipi- to that of acid precipitation) along tation. These monuments include the Acropolis in Greece, the Taj Mahal one edge of the cover slip. Record in India, ancient temples and pyramids in Egypt and in the rain forests of your observations. Central America, and the Lincoln Memorial in Washington, DC. Analysis 1. Aquatic organisms are adapted to live within a specific range of pH. International Conflict and Cooperation What did you observe when the One problem in controlling acid precipitation is that pollutants may be protozoa came into contact with released in one area and fall to the ground hundreds of kilometers away. the vinegar? For example, some of the acid precipitation that falls in southeastern Can- 2. What effects can acid precipitation ada results from pollution produced in the northeastern United States. have on aquatic ecosystems? Figure 3.5 shows approximate areas of the world that produce pollutants on humans? and areas which are then affected by acid precipitation. Acid precipitation ©David R. Frazier Photolibrary Frazier ©David R.

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Figure 3.5 Global Acid Precipitation Acid precipitation is a global problem.

is an international problem. In the spirit of cooperation, Canada and the United States signed the Canada–U.S. Air Quality Agreement in 1991. Both countries agreed to reduce emissions that flow across the Canada– Check for Understanding U.S. boundary. As a result of this agreement, sulfur dioxide emissions Explain How can pollutants from the in the United States and Canada have been reduced dramatically since United States produce acid precipitation the 1970s. In Europe, similar agreements reduced sulfur dioxide emis- in Canada? sions by about 40 percent over the two decades after 1980, although reductions in emissions of nitrogen oxides have been offset by vehicle exhaust from increased road traffic. Meanwhile, China still burns large amounts of high-sulfur coal without pollution controls. The polluted air that results produces acid precipitation in other parts of Asia that are far from the coal-burning plants in China.

Section 3 Formative Assessment

Reviewing Main Ideas Critical Thinking 1. Explain how acid precipitation forms. 5. Inferring Relationships In addition to negatively affecting forestry and the fishing 2. Describe the harmful effects that acid industry, how might acid precipitation affect precipitation can have on plants, soils, and local economies? aquatic ecosystems. 6. Analyzing Viewpoints Write a short essay in 3. Describe three ways in which acid which you discuss whether or not a country that precipitation can affect humans. releases significant amounts of pollutants into 4. Describe a way in which countries are the air that fall as acid precipitation in another working together to solve the problem of country should be expected to pay some of the acid precipitation. costs of cleanup.

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Maps in Action Light Sources

Earth at night

Map Skills This satellite image of the Earth from space at night shows light sources that are human in origin. The map is a composite image made from hundreds of images taken by orbiting satellites. Use the map of light sources on Earth to answer the questions below.

1. Inferring Relationships Using the brightness able to support large human populations? What are of the light sources on the map as a key, can you some of these places? estimate the locations of some of the most densely 3. Finding Locations Many large cities are seaports populated areas on Earth? Where are some of that are located along the coastlines of the world’s these areas? oceans. From the map, can you pick out light sources 2. Inferring Relationships Some climatic conditions along coastlines that might indicate the sites of large on Earth, such as extreme cold, heat, wetness, or ports? Identify some of these cities by name. a thin atmosphere, make parts of our planet less 4. Inferring Relationships From the differences in habitable than others. Examples of areas on our the density of the light sources, can you pick out any planet that do not support large populations include international borders? deserts, high mountains, polar regions, and tropical rain forests. From the map, can you identify regions of the Earth where climatic conditions may not be ©C. Mayhew & R. Simmon (NASA/GSFC) Mayhew & R. ©C.

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Society and the Environment ECOZine Go online for the latest environmental science at HMDScience.com news and updates on all EcoZine articles. Killer Smog

For the residents of the small Monongahela Valley town of Even as the killer smog choked the valley, the zinc smelter Donora, Pennsylvania, living with the smoke that billowed continued production throughout the night. The smelter from the local zinc smelter was an everyday occurrence— continued sending more gases and dust into the air over until October 26, 1948. On that night, a temperature inversion Donora. The smelter was shut down only when the magnitude and an absence of wind began to trap a deadly mixture of of the problem became apparent—at 6:00 a.m. on Sunday, sulfur dioxide, carbon monoxide, and metal dust that would October 30, 1948. hang in the valley air for five days. Over that period of time, Later that day, a drizzling rain began to fall and washed 20 residents lost their lives and 7,000 other residents— the pollutants from the sky. By the time the rain fell, 20 people about half of the town’s population—suffered some form of were dead. Thousands of other people were at home in bed or respiratory problems. were filling the corridors and examining rooms of the two area hospitals. People who were less affected by the smog suffered The Weekend of the Killer Smog from nausea and vomiting, headaches, and abdominal cramps. Some victims were choking or coughing up blood. By Saturday afternoon, October 29, 1948, the yellowish smog The zinc smelter resumed operation on Monday morning, had become so thick that spectators in the stands at a local October 31. high school football game could not see the players on the field. Only the whistles of the referees could be heard. By nightfall, driving was unsafe. This proved to be catastrophic The Aftermath because doctors recommended that any residents who The smog of Donora was one of the United States’ most suffered from respiratory ailments be evacuated from town. serious environmental disasters. Shortly after the incident, In an attempt to alleviate the suffering of people who were the Pennsylvania Department of Health, the U.S. Public Health struggling to breathe, several local firemen carried oxygen Service, and other agencies undertook investigations. This tanks through the streets to people’s homes. Because of the was the first organized attempt to document the effects of low visibility, the firemen had to feel their way along buildings air pollution on health in the United States. The knowledge and fences. Because the supply of oxygen was limited, only a that air pollution could be linked directly to the deaths of few breaths of oxygen could be given to each person. Eleven individuals resulted in legislation at the local, regional, state, people died that night. A makeshift morgue was set up in the and federal levels. These laws were set to limit emissions of local community center. sulfur dioxide, carbon monoxide, particulate matter, and other pollutants. The greatest legacy of the Donora tragedy was passage of the Clean Air Act of 1970. According to a 2011 report,What the direct Do benefitsYou Think? of amendments to the Clean Air Act of 1990 are estimated to be around $2 trillion and 230,000 fewer deaths by 2020! This is a staggering benefit for the $65 million direct cost of implementation.

What Do You Think? Who do you think should be held responsible for the Donora, Pennsylvania, disaster? Explain your answer. Given what you know about the regulation This historical photo captures the town of Donora, of industrial pollutants under the Clean Air Act, do Pennsylvania, as it is enveloped in smog at noon on you think another incident such as the Donora killer Saturday, October 28, 1948. smog could happen in the United States today? ©Everett Collection Inc/Alamy Images

Chapter 12: Air 319 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 320 Chapter 12 Section 3 Section 2 Section 1 Water, Air, and Land Unit 4: Acid Precipitation WhatCauses Pollution Air, Noise, andLight Summary Air Pollution? • • • • • Objectives • • • Objectives • • • • Objectives by a temperature inversion. by a temperature Pollution nearthesurfaceofEarth canbetrapped visibility is calledsmog. hangsovercitiesandreduces The airpollutionthat Most airpollutioncomesfromvehicles andindustry. reaction takesplace. occurringsubstancesandachemical or withnaturally pollutants ant comesintocontactwithotherprimary pollut- pollutants are formed when a primary Secondary by human activity. pollutantsareputdirectlyintheair Primary precipitation—sometimes inanothercountry.precipitation—sometimes asacid to the groundhundredsofkilometersaway Pollutants areamayfall releasedinonegeographical life. harmsaquatic pH that changein enters alakeorstreamandcausesrapid Acid shockoccurswhenasuddeninfluxofacidicwater ofacids. containsahighconcentration that or snow suchasrain, isprecipitation Acid precipitation sleet, sky and wastesenergy. Inefficient lightingdiminishesourviewofthenight quality oflife. affects humanhealthandthe Noise isapollutantthat aremajorsources ofindoorairpollution. materials outside. Plastics, cleaning chemicals, andbuilding The airindoorsmaybemorepollutedthanthe effects onhumanhealth. both long-andshort-term Air pollutionmayhave temperature temperature smog secondary pollutant primary air pollution Key Terms acid shock pH acid precipitation Key Terms decibel (dB) asbestos sick-building Key Terms inversion pollutant syndrome

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Chapter 12 Review

Reviewing Key Terms 14. Which of the following substances is not involved in the chemical reaction that produces smog? Use each of the following terms in a sentence. a. sunlight 1. air pollution b. particulate matter 2. smog c. automotive exhaust d. 3. temperature inversion ozone 4. sick-building syndrome 15. Which of the following respiratory diseases is 5. pH considered a long-term effect of air pollution on human health? For each pair of terms, explain how the meanings a. emphysema of the terms differ. b. bronchitis 6. primary pollutant and secondary pollutant c. pneumonia 7. asbestos and radon d. all of the above 8. pH and acid precipitation 16. Which of the following substances is a colorless, 9. acidification and acid shock tasteless, and odorless radioactive gas? 10. Concept Map Use the following terms to create a. asbestos a concept map: air pollution, primary pollutant, b. carbon monoxide volatile organic compound, scrubber, secondary c. radon pollutant, smog, and temperature inversion. d. ozone

17. A sound measuring 40 dB has how many times Reviewing Main Ideas the intensity of a sound that measures 10 dB? a. 4 times 11. Which of the following air pollutants is not a b. 30 times primary pollutant? c. 400 times a. particulate matter d. 1,000 times b. ozone 18. Which of the following choices is not an effective c. sulfur dioxide solution to the energy waste related to inefficient d. volatile organic compounds lighting? a. using low-pressure sodium lighting sources 12. A device used to clean exhaust gases before they b. pointing lights on billboards and street signs exit an automobile’s tailpipe is called a(n) upward a. electrostatic precipitator. c. placing light sources on time controls d. shielding light to direct it downward b. catalytic converter. c. scrubber. 19. Which of the following numbers on the pH scale d. None of the above would indicate that a substance is acidic? a. 5.0 13. The majority of sulfur dioxide produced by b. 7.0 industry comes from c. 9.0 d. none of the above a. oil refineries. b. dry cleaners. 20. Normal precipitation has a pH of c. chemical plants. a. 7.0. d. coal-burning power plants. b. 5.6. c. 5.1. d. 4.5.

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Chapter Review

Short Answer Critical Thinking 21. Define the term zero-emission vehicle. What types 28. Making Decisions Five states now have zero- of vehicles qualify as zero-emission vehicles? emission vehicle programs in place that will help 22. List five indoor air pollutants and examples of decrease some primary pollutants. What would sources of each pollutant. be the advantages or disadvantages of a federal program that required automobile makers to 23. Explain the health hazards that radon gas poses produce a set number of ZEVs nationwide? for humans. 29. Making Decisions In some cities, noise- 24. How does acid precipitation damage monuments pollution laws, such as restrictions placed on the such as the Acropolis, the Taj Mahal, and the use of leaf blowers, have been put in place. Do you Lincoln Memorial? think the benefits of noise reduction outweigh the 25. Explain why acid precipitation is a source of costs of enforcing the law? international conflict and why international 30. Inferring Relationships As you read under the cooperation is necessary to resolve the problem. head “International Conflict and Cooperation,” some of the acid precipitation that falls in southeastern Canada is produced by pollutants Interpreting Graphics from the United States. How do the acid The map below shows the pH of precipitation pollutants get from their sources to southeastern measured at field stations in the northeastern Canada? United States in the year 2000. Use the map and 31. Health Asbestos, lead paint, tobacco, and many legend to answer questions 26–27. other products have been linked to adverse effects 26. Which area(s) of the northeastern United States on human health. Research one such case that have the most-acidic precipitation? has been brought into the courts. Describe the allegations and the outcome of the trial and write 27. Are the areas with the least acidic precipitation a paragraph that explains whether you agree or located close to or far from major cities? disagree with the decision. 32. Make a Display Create a display similar to the diagram that appears in Figure 2.2. This diagram may be of your home, your garage, a portion of your school, or a particular classroom in your school. Use the diagram to identify and label potential sources of indoor air pollutants. Photographs may be used to document these sources.

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Chapter Review

Analyzing Data CASESTUDY Use the graph below to answer questions 33 and 34. 37. What are some sources of pollution that 33. Analyzing Data The graph below shows the affect ground-level ozone? How do these estimated changes in air-pollution emissions pollutants lead to increased amounts of in the United States between 1970 and 1997. ground-level ozone? Excluding NOx, which type of emission experienced the greatest decrease over this 38. Think about the effects of ground-level ozone period of time? on human health. What are some approaches STUthatDY urbanSKILL areas can take to combat increases Air-Pollution Emissions in the U.S., in ground-level ozone and protect the health 1970 vs. 1997 of their citizens? 150 250 1970 Why It Matters 120 1997 200 39. What role does Whytemperature It Matters 90 150 inversion play in the air quality Emissions

Emissions 60 100 of Los Angeles? (in thousands of tons) (in millions of tons) What conditions 30 50 cause temperature inversion to occur 0 0 there? Research CO NO VOC PM-10 SO Pb X 2 another urban area Air Pollutants that experiences 34. Interpreting Graphics Why is lead, Pb, shown temperature separately from the other air pollutants? inversion and describe why it occurs. Making Connections 35. Outlining Topics Outline the major sources of air pollution in the United States. Include information about pollution sources and STUDYSKILL pollution types. Predicting Exam Questions Before you take a test, do 36. Writing Persuasively Write a message to a you ever attempt to predict what the questions will be? For legislator that expresses your concern about a particular aspect of air, noise, or light pollution example, of the 10 multiple-choice questions that appear on that is important to you. this page, how many would you have predicted to be asked in a review of this chapter? Before your next test, predict and answer possible exam questions. ©Deborah Davis/Getty Images

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ExplorationLab Simulation The Acid Test Objectives Acid precipitation is one of the effects of air pollution. When pollutants Perform a chemical test that contain nitrogen or sulfur react with water vapor in clouds, dilute that produces sulfur dioxide, a component of acid acid forms. These acids fall to Earth as acid precipitation. precipitation. Often, acid precipitation does not occur in the same place where the pollutants are released. The acid precipitation usually falls some distance Hypothesize what the downwind—sometimes hundreds of kilometers away. Thus, the sites effects of acids that contain sulfur will be on plants. where pollutants that cause acid precipitation are released may not suffer the effects of acid precipitation. Materials Coal-burning power plants are one source of air pollution. These beaker, 50 mL power plants release sulfur dioxide into the air. Sulfur dioxide reacts with clear plastic bags, large (2) the water vapor in air to produce acid that contains sulfur. This acid later houseplants of the same falls to Earth as acid precipitation. type, potted (2) In this investigation, you will create a chemical reaction that produces sodium nitrite (2 g) sulfur dioxide. The same acids that result from coal-burning power plants will form as a result of the reaction. You will see the effects of acid sulfuric acid, 1 M (2 mL) precipitation on living things—in this case, plants. twist tie or tape

Procedure 1. Place 2 g of sodium nitrite in a beaker. Place a plant and the beaker inside a plastic bag. Do not seal the bag yet. CAUTION: Steps 2–4 should be carried out only under a fume hood or outdoors.

2. Carefully add 2 mL of a 1 M solution of sulfuric acid to the beaker. Immediately seal the bag tightly, Step 1 Place a plant and a beaker that contains sodium nitrite into a plastic and secure the bag with a twist tie or bag. Do not seal the bag yet. tape. CAUTION: Because this reaction produces sulfur dioxide, a toxic gas, the bag should have no leaks. If a leak occurs, move away from the bag until the reaction is complete and the gas has dissipated.

3. Seal the same type of plant in an identical bag that does not contain sodium nitrite or sulfuric acid.

4. After 10 minutes, cut both bags open. Move to at least 5 m from the bags as the sulfur dioxide gas dissipates. Keep the plants and bags under the fume hood.

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Day Control Plant Experimental Plant

5. Predict the effects of the experiment on each plant over the next few days. Record your predictions.

6. Observe both plants over the next three days. Record your observations below.

Analysis 1. Examining Data How closely did your predictions about the effects of the experiment on each plant match your observations?

2. Explaining Events What does this experiment suggest about the effects of acid precipitation on plants?

Conclusions 3. Drawing Conclusions In what ways is this a realistic model of acid precipitation?

4. Drawing Conclusions In what ways is this experiment not a realistic simulation of acid precipitation?

Extension 5. Analyzing Models Would you expect to see similar effects occur as rapidly, more rapidly, or less rapidly in the environment? Explain your answer.

6. Building Models Acid precipitation is damaging to plants because it clogs the openings on the surfaces of plants and interferes with photosynthesis. What kind of a safe model would demonstrate the damaging effects of acid precipitation on plant photosynthesis? Would this model be a realistic simulation of acid precipitation?

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