Ch. 18

8. What is the key concept for this section? Summarize the U.S. air pollution laws and how they have worked to reduce pollution. Explain how these laws can be strengthened, according to some scientists.

Legal, economic, and technological tools can help us to clean up air pollution, but the best solution is to prevent it. Putting much greater emphasis on preventing air pollution. The power of prevention is clear. In the United States, the air pollutant with the largest drop in its atmospheric level was lead, which was banned as a component of gasoline and other products. Sharply reducing emissions from older coal-burning power and industrial plants, cement plants, oil refineries, and waste incinerators. Approximately 20000 older coal-burning power plants, industrial facilities in the United States have not been required to meet the air pollution standards for new facilities under the Clean Air Acts. Continuing to improve fuel efficiency standards for motor vehicles. Regulating more strictly the emissions from motorcycles and two-cycle gasoline engines used in devices such as chainsaws, lawnmowers, generators, scooters, and snowmobiles. The EPA estimates that using a typical riding gas-powered lawn mower for 1 hour creates as much air pollution as driving 34 cars for an hour. Setting much stricter air pollution regulations for airports and oceangoing ship in U.S. waters. Sharply reducing indoor air pollution

5. What is the key concept for this section? What is acid deposition and how does it form? What are its major environmental impacts on lakes, forests, human-built structures, and human health? List three major ways to reduce acid deposition. Explain the connections among low-sulfur cola, atmospheric warming, and toxic mercury.

Acid deposition is caused mainly by coal-burning power plants and motor vehicle emissions, and in some regions it threatens human health, aquatic life and ecosystems, forests, and human build structures. Most coal-burning power plants, ore smelters, and other industrial facilities in more-developed countries use tall smokestacks to vent the exhausts from burned fuel at a high altitude. The exhausts contain sulfur dioxide, suspended particles, and nitrogen oxides, and the smokestacks send them high into the atmosphere where wind can dilute and disperse them. Use of such smokestacks reduces local air pollution, but it can increase regional air pollution downwind. These acidic substances remain in the atmosphere for 2-14 days depending mostly on prevailing winds, precipitation, and other weather patterns. During this period, they descend to the earth's surface in two forms: wet deposition, consisting of acidic rain, snow, fog, and cloud vapor with a pH of less than 5.6, and dry deposition, consisting of acidic particles. The resulting mixture is called acid deposition--sometimes termed acid rain. Most dry deposition occurs within 2-3 days of emission, fairly near the industrial sources, whereas most wet deposition takes place within 4-14 days in more distant downwind areas. Acid deposition has been occurring since the Industrial Revolution began in the mid-1700s. In 1872, British chemist Robert A. Smith coined the term acid rain after observing that rain was eating away stone in the walls of buildings in major industrial areas. Acid deposition is the result of human activities hat disrupt the natural nitrogen cycle and sulfur cycle by adding excessive amounts of nitrogen oxides and sulfur dioxide to the atmosphere. Acid deposition is a regional air pollution problem in areas that lie downwind from coal-burning facilities and from urban areas with large numbers of cars. In some areas, soils contain basic compounds such as calcium carbonate or limestone that can react with a neutralize, or buffer, some inputs of acids. The areas most sensitive to acid deposition are those with thin, already acidic soils that provide no such natural buffering and those where the buffering capacity of soils has been depleted by decades of acid deposition. Most of the world's forests and lakes are not being destroyed or seriously harmed by acid deposition. Rather, this regional problem is harming forests and lakes that lie downwind from coal-burning facilities and from large, motor vehicle-dominated cities without adequate pollution controls.

7. What is the key concept for this section? Describe the human body's defenses against air pollution, how they can be overwhelmed, and the illnesses that can result. Approximately how many people die prematurely from air pollution each year in the world and in the United States? What percentage of these deaths are caused by indoor air pollution? Describe the health threat from diesel fumes.

Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke. Your respiratory system helps to protect your from air pollution in various ways. Hair in your nose filter out large particles. Sticky mucus in the lining of your upper respiratory tract captures smaller particles and dissolves some gaseous pollutants. Sneezing and coughing expel contaminated air and mucus when pollutants irritate your respiratory system. In addition, hundreds of thousands of tiny mucus-coated, hair-like structures, called cilia, line your upper respiratory tract. They continually move back and forth and transport mucus and the pollutants it traps to our throat where they are swallowed or expelled. Prolonged or acute exposure to air pollutants, including tobacco smoke, can overload or break down these natural defenses. Fine and ultra-fine particulates can get lodged deep in the lungs and contribute to lung cancer, asthma, heart attack, and stroke. According to the National Institutes of Health, almost 7% of the U.S. population suffers from asthma and an average of about 14 asthma sufferers die each day from asthma attacks. According to a 2009 study by Daniel Lack and other NOAA scientists, the world's 100,000 or more diesel powered cargo ships emit almost half as much particulate pollution as do the world's 760 million cars. This is largely because many cargo ships burn low-grade oil called bunker fuel in which the concentration of polluting sulfur is 30 times higher than that of diesel fuel sold at the pumps of U.S. gas stations.

1. Describe the nature, origins, and harmful effects of the massive South Asian Brown Clouds.

Air pollution is no longer viewed as primarily a localized urban problem. These enormous, dense pollution clouds can move across the Asian continent within 3 to 4 days, and satellites have tracked the spread of such could s from northern China across the Pacific Ocean to the West Coast of the United States. Satellite measurements show that these and other long-lived air pollutants from China, India, the United States, or anywhere else on the planet can circle the entire globe in about 2 weeks. Thus, air pollution connects us all.

4. Distinguish between industrial smog and photochemical smog in terms of their chemical composition and formation. List and briefly describe five natural factors that help to reduce outdoor air pollution and six natural factors that help to worsen it. What is a temperature inversion and how can it affect outdoor air pollution levels.

First, particles heavier than air settle out as a result of gravitational attraction to the earth. Second, rain and snow help cleanse the air of pollutants. Third, salty sea spray from the oceans washes out many pollutants from air that flows from land over the oceans. Fourth, winds sweep pollutants away and mix them with cleaner air. Fifth, some pollutants are removed by chemical reactions. For example, SO2 can react with O2 in the atmosphere to form SO3, which reacts with water vapor to form droplets of H2SO4 that fall out of the atmosphere as acidic precipitation. Sic other factors can increase outdoor air pollution. First, urban buildings slow wind speed and reduce the dilution and removal of pollutants. Second, hills and mountains reduce the flow of air in valleys below the, and allow pollutant levels to build up at ground level. Third, high temperatures promote the chemical reactions leading to formation of photochemical smog. Fourth, emissions of volatile organic compounds from certain trees and plants in heavily wooded urban areas can play a large role in the formation of photochemical smog. A fifth factor- the so-called grasshopper effect-occur when air pollutants are transported at high altitudes by evaporation and winds from tropical and temperate areas through the atmosphere to the earth's polar areas. This happens mostly during winter. It explains why, for decades, pilots have reported seeing dense layers of reddish-brown haze over the Arctic. It also explains why polar bears, sharks, and native peoples in remote arctic areas have high levels of various toxic pollutants in their bodies. The six factor has to do the the vertical movement of air. During daylight, the sum warms the air near the earth's surface and most of the pollutants in contains rise to mix with the cooler air above and are dispersed. Under certain atmospheric conditions, however, a layer of warm air can temporarily lie atop the cooler air near the ground, and this is called a temperature inversion. Because the cooler air is denser than the warmer air above it, the air near the surface does not rise and mix with the air above. If this condition persists, pollutants can build up to harmful and even lethal concentrations in the stagnant layer of cool air near the ground. Two types of areas are especially susceptible to prolonged temperature inversions. The first is a town or city located in a valley surrounded by mountains where the weather turns cloudy and cold during part of the year. In such cases, the clouds block much of the winter sunlight that causes air to heat and rise, and the mountains block winds that could disperse the pollutants. As long as these stagnant conditions persist, pollutants in the valley below will build up to harmful and even lethal concentrations. The other type of area vulnerable to temperature inversions is a city with many motor vehicles in an area with a sunny climate, mountains on three sides, and on ocean on the fourth side. Here, the conditions are ideal for the formation of photochemical smog, worsened by frequent thermal inversions. The surrounding mountains prevent the polluted surface air from being blown away by breezes coming off the sea. This describes several cities, including heavily populated Los Angeles, California, which has prolonged temperature inversions.

9. List the advantages and disadvantages of using an emissions trading program to control pollution. Summarize the major ways to reduce emissions from power plants and motor vehicles. What are four ways to reduce indoor air pollution? Why is preventing air pollution more important than controlling it?

One approach to reducing pollutant emissions has been to allow producers of air pollutants to buy and sell government air pollution allotments in the marketplace. Under this system, each power plant is annually given a number of pollution credits, which allow it to emit a certain amount of SO2. A utility that emits less than its allotted amount has a surplus of pollution credits. That utility can use its credits to offset SO2 emissions at another of its plants, keep them for future plant expansions, or sell them to other utilities or to private citizens or groups. An emissions trading program is also being used to control NOx emissions. However, environmental and health scientists strongly oppose the use of a cap-and-trade program for controlling emissions of toxic mercury from coal-burning power plants and industries. They warn that operators of coal-burning plants who choose to buy permits instead of sharply reducing their mercury emissions will create toxic hotspots with unacceptably high levels of mercury. Test for radon and formaldehyde inside your home and take corrective measures as needed. Do not buy furniture and other products containing formaldehyde. Test your home or workplace for asbestos fiber levels and check for any crumbling asbestos materials. If you smoke, do it outside or in a closed room vented to the outside. Make sure that wood-burning stoves, fireplaces, and kerosene- and gas-burning heaters are properly installed, vented and maintained. Install carbon monoxide detectors in all sleeping areas. Use fans to circulate indoor air. Grow house plants, the more, the better. Do not store gasoline, solvents, or other volatile hazardous chemicals inside a home or attached garage. Remove your shoes before entering your house to reduce inputs of dust lead, and pesticides.

10. What are the two key concepts for this section? How have human activities depleted ozone in the stratosphere? List five harmful effects of such depletion. Explain how Sherwood Rowland and Mario Molina alerted the world to this threat. What has the world done to reduce the threat of ozone depletion in the stratosphere? How might projected climate change undermine this progress? What are the three big ideas for this chapter? Discuss the relationship between the South Asian Brown Clouds and the way in which people have violated the three scientific principles of sustainability. Explain how we can apply these principles to the problems of air pollution.

Our widespread use of certain chemicals has reduced ozone levels in the stratosphere and allowed more harmful ultraviolet radiation to reach the earth's surface. To reserve ozone depletion, we must stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals. This annual observed loss of ozone has been called an ozone hole. A more accurate term is ozone thinning. Colorized satellite data show a sharp drop in total ozone above Antarctica every September that got more pronounced every year from 1980 to 2000. This trend had generally leveled off by 2011. When the seasonal thinning ends each year, huge masses of ozone-depleted air above Antarctica flow northward, and these masses linger for a few weeks over parts of Australia, New Zealand, South America, and South Africa. These agreements set an important precedent because nations and companies worked together, using a prevention approach to try to solve a serious environmental problem. This approach worked for three reasons. First, there was convincing and dramatic scientific evidence of a serious problem. Second, CFCs were produced by a small number of international companies and this meant there was less corporate resistance to finding a solution. Third, the certainty that CFC sales would decline over a period of years because of government bans unleashed the economic and creative resources of the private sector to find even more profitable substitute chemicals. Outdoor air pollution, in the form of industrial smog, photochemical smog, and acid deposition, and indoor air pollution are serious global problems. Each year, at least 2.4 million people die prematurely from the effects of air pollution; indoor air pollution, primarily in less-developed countries, causes about two-thirds of these deaths. We need to give top priority status to the prevention of outdoor and indoor air pollution throughout the world and the reduction of stratospheric ozone depletion.

3. What is the key concept for this section? What is air pollution? Distinguish between primary pollutants and secondary pollutants and give an example of each. List the major outdoor air pollutants and their harmful effects. What is the role of the South Asian Brown Clouds in atmospheric warming, according to some scientists? Explain the connections between South Asian Brown Clouds, food production, and solar power. Describe the effects of lead as a pollutant and how we can reduce our exposure to this harmful chemical. Give examples of a chemical method and a biological method for detecting air pollutants.

Pollutants mix in the air to form industrial smog, primarily as a result of burning coal, and to form photochemical smog, caused by emissions from motor vehicles, industrial facilities, and power plants. Air pollution is the presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystems, or human-made materials, or to alter climate. Note that almost any chemical in the atmosphere can be come a pollutant if it occurs in a high enough concentration. The effects of air pollution range from annoying to lethal. Air pollutants come from natural and human sources. Natural sources include wind-blown dust, pollutants from wildfires, and volcanic eruptions, and volatile organic chemicals released by some plants. Most natural air pollutants are spread out over the globe or removed by chemical cycles, precipitation, and gravity. But in areas experiencing volcanic eruptions or forest fires, chemicals emitted by these events can temporarily reach harmful levels. Scientists classify outdoor air pollutants into two categories: Primary pollutants are chemical or substances emitted directly into the air from natural processes and human activities at concentrations high enough to cause harm. While in the atmosphere, some primary pollutants react with one another and with other natural components of air to form new harmful chemicals, called secondary pollutants. Five natural factors help reduce outdoor air pollution.

6. What is the key concept for this section? What is the major indoor air pollutant in many less-developed countries? What are the top three indoor air pollutants in the United States? Give three reasons why they present a serious threat to human health. Explain why radon-222 is an indoor air pollution threat, how and where it occurs, and what can be done about it.

The most threatening indoor air pollutants are smoke and soot from the burning of wood and coal in cooking fires, cigarette smoke, and chemicals used in building materials and cleaning products. In less developed countries, the indoor burning of wood, charcoal, dung, crop residues, coal and other fuels in open fires or in unvented or poorly vented stoves exposes people to dangerous levels of particulate air pollution. workers, including children, are also exposed to high levels of indoor air pollution in countries where there are few if any pollution laws or regulations. According to the WHO and the World Bank, indoor air pollution is the world's most serious air pollution problem, especially for poor people. EPA studies have revealed some alarming facts about indoor air pollution. First, levels of 11 common pollutants generally are 2 to 5 times higher inside U,S, homes and commercial buildings than they are outdoors, and in some cases, they are as much as 100 times higher. Second, pollution levels inside cars in traffic-clogged urban areas can be up to 18 times higher than outside levels. Third, the health risks from exposure to such chemicals are magnified because most people in developed urban areas spend the majority of their time indoors or inside vehicles. When radon gas from such deposits seeps upward through the soil and is released outdoors, it disperses quickly in the air and decays to harmless levels. However, in buildings above such deposits, radon gas can enter through cracks in a foundation's slab and walls, as well as through well water, opening around sump pumps and drains, and hollow concrete blocks. Once inside, it can build up to high levels, especially in ventilated lower levels of homes and buildings.

2. What is the key concept for this section? Define density, as it relates to the atmosphere, and atmospheric pressure and explain why both are two important atmospheric variables. Define troposphere, stratosphere, and ozone layer. What are the major differences between the troposphere and stratosphere?

The two innermost layers of the atmosphere are the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer. We live under a thin blanket of gases surrounding the earth, called the atmosphere. It divided into several spherical layers defined mostly by temperature differences. The density, or the number of gas molecules per unit of air volume, varies throughout the atmosphere because gravity pulls its gas molecules toward the earth's surface. This means that lower layers have more gases in them than upper layers do, and are more densely packed with molecules. Thus, the air we breathe at sea level has a higher density the the air we would inhale on top of a high mountain. Another important atmospheric variable is atmospheric pressure--the force, or mass, per unit area of a column of air. This force is caused by the bombardment of a surface such as your skin by the molecules in air. Atmospheric pressure decreases with altitude because there are fewer gas molecules at higher altitudes. Density and atmospheric pressure are important because they play major roles in the weather. About 75-90% of the earth;s air mass is found in the troposphere, the atmospheric layer closest to the earth's surface. This layer extends only about 17 kilometers above sea level at the equator and 6 kilometers above sea level over the poles./ IF the earth were the size of an apple, this lower layer containing the air we breath would be no thicker than the apple's skin. Much of the atmosphere's small amount of ozone is concentrated in a portion of the stratosphere called the ozone layer, found roughly 17-26 kilometers above sea level.