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DO NOT EDIT--Changes must be made through “File info” printcode=a Chapter 12 Section 1 What Causes Air Pollution? Air Section 2 Air, Noise, and Light Pollution Section 3 Acid Precipitation Why It Matters The Los Angeles, California, skyline at dusk reveals unhealthy levels of air pollution. What are some approaches that urban areas can take to improve air quality? CASESTUDY Learn more about the effects of air pollution in the case study The Health Effects of Ground- Level Ozone on pages 310–311. Online enVirOnmental Science HMDScience.com Go online to access additional resources, including labs, worksheets, multimedia, and resources in Spanish. Image©Deborah Davis/Getty Credits: Images 302 DO NOT EDIT--Changes must be made through “File info” printcode=a 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 30 20 Emissions (in thousands of tons) 10 0 Electricity production Industry Transportation Other sources Source: U.S. Environmental Protection Agency. Chapter 12: Air 303 DO NOT EDIT--Changes must be made through “File info” printcode=a 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. 304 Unit 4: Water, Air, and Land ECOFACT DO NOT EDIT--Changes must be made through “File info” printcode=a 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 ve- hicles. 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 gaso- line, 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 auto- mobiles, 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 ap- proximately 70 percent more efficiently and with about 40 percent fewer emis- sions 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. Chapter 12: Air 305 Connect to MATH DO NOT EDIT--Changes must be made through “File info” printcode=a 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.

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