18 Air Pollution

Core Case Study: South Asia’s Massive Brown Clouds The South Asian Brown Clouds Stretch across much of India, Bangladesh, China, and the western Pacific Ocean Air pollution connects the world Pollutants can circle the globe in about two weeks Stricter air pollution standards and continued shifts towards cleaner fuels are needed

The South Asia's Brown Clouds (cont'd.) Figure 18.1: The South Asian Brown Clouds are gigantic clouds of dust, smoke, soot, and other pollutants that stretch over much of South Asia. One is visible here over eastern China. Fig. 18-1a, p. 474

18-1: What is the Nature of the Atmosphere? The two innermost layers of the atmosphere Troposphere – supports life Stratosphere – contains the protective ozone layer

The Atmosphere Consists of Several Layers Atmosphere – thin blanket of gases surrounding the Earth Density – number of gas molecules per unit of air volume Density decreases as you move higher in the atmosphere

Atmospheric pressure (millibars) Temperature Thermosphere Mesosphere Altitude (kilometers) Altitude (miles) Stratosphere Figure 18.2: Natural capital. The earth’s atmosphere is a dynamic system that includes four layers. The average temperature of the atmosphere varies with altitude (red line) and with differences in the absorption of incoming solar energy. Question: Why do you think most of the planet’s air is in the troposphere? Ozone layer Troposphere Pressure (Sea level) Pressure = 1,000 millibars at ground level Temperature (˚C) Fig. 18-2, p. 475

Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate 75–80% of Earth’s air mass Closest to Earth's surface Composition of gases 78% nitrogen; 21% oxygen Rising and falling air currents and greenhouse gases play a major role in weather and climate

The Stratosphere Is Our Global Sunscreen Similar composition to the troposphere except that it contains: Much less water Ozone layer (O3) Filters 95% of harmful UV radiation Allows life to exist on land

18-2: What Are the Major Outdoor Pollution Problems? Pollutants mix in the air to form industrial smog Primarily as a result of burning coal and photochemical smog Caused by emissions from motor vehicles, industrial facilities, and power plants

Air Pollution Comes from Natural and Human Sources Air pollution – presence of chemicals in the atmosphere Concentrations high enough to harm organisms, ecosystems, human-made materials, and to alter climate Natural sources Dust blown by wind Pollutants from wildfires and volcanoes Volatile organics released by plants

Air Pollution Comes from Natural and Human Sources (cont’d.) Mostly in industrialized and/or urban areas Stationary sources – power plants and industrial facilities Mobile sources – motor vehicles

Some Pollutants in the Atmosphere Combine to Form Other Pollutants Primary pollutants Emitted directly into the air Secondary pollutants From reactions of primary pollutants

Sources and Types of Air Pollutants Primary Pollutants CO CO2 Secondary Pollutants N2O SO2 NO NO2 CH4 and most other hydrocarbons SO3 HNO3 H2SO4 Most suspended particles H2O2 O3 PANs Most NO3– and SO42– salts Natural Source Stationary Human Source Figure 18.3: Human inputs of air pollutants come from mobile sources (such as cars) and stationary sources (such as industrial, power, and cement plants). Some primary air pollutants react with one another and with other chemicals in the air to form secondary air pollutants. Human Source Mobile Fig. 18-3, p. 477

What Are the Major Outdoor Air Pollutants? Carbon oxides Carbon monoxide (CO); carbon dioxide (CO2) Nitrogen oxides (NO) and nitric acid (HNO3) Acid deposition; photochemical smog Does the benefit of the lessened atmospheric warming due to the South Asian Brown Clouds outweigh their harmful effects? Critical Thinking Question: Science Focus 18.1

What Are the Major Outdoor Air Pollutants? (cont’d.) Sulfur dioxide (SO2) and sulfuric acid (H2SO4) Particulates Suspended particulate matter Ozone Volatile organic compounds (VOCs) Methane

Chemical Reactions That Form Major Outdoor Air Pollutants Table 18-1: Chemical Reaction That Form Major Outdoor Air Pollutants Table 18-1, p. 480

Acid Deposition Figure 18.4: Acid deposition and other forms of air pollution have damaged this statue in Rome, Italy. The nose and part of the forehead have been restored. Fig. 18-4, p. 478

Case Study: Lead Is a Highly Toxic Pollutant In air, water, soil, plants, and animals Does not break down in the environment Impacts human health and environment Children are most vulnerable Can cause death, brain damage, and paralysis How can we reduce lead in the environment?

Burning Coal Produces Industrial Smog Chemical composition of industrial smog Sulfur dioxide, sulfuric acid, and suspended solid particles Formed from the burning of fossil fuels Carbon monoxide, carbon dioxide, and soot result How are pollutants formed from burning coal and oil?

Carbon monoxide (CO) and Ammonium sulfate [(NH4)2SO4] Ammonia (NH3) Sulfuric acid (H2SO4) Water vapor (H2O) Sulfur trioxide (SO 3 ) Oxygen (O2) Sulfur dioxide (SO2) Sulfur (S) in coal and oil Carbon monoxide (CO) and carbon dioxide (CO2) Carbon (C) in coal and oil Burning coal and oil Oxygen (O2) Note: This is a carry-over animation from 17e. No modifications have been made to the animation itself; we have simply updating the figure number and page number in the lower-right corner. Figure 18.8: This is a greatly simplified model of how pollutants are formed when coal and oil are burned. The result is industrial smog. Stepped Art Fig. 18-8, p. 481

Sunlight Plus Cars Equals Photochemical Smog VOCs + NOx + Heat + Sunlight yields: Ground level O3 and other photochemical oxidants Aldehydes Other secondary pollutants

PANS and other pollutants Nitrogen (N) in fossil fuel Photochemical Smog PANS and other pollutants Volatile organic compounds (VOCs) Ozone (O3) Oxygen (O2) Nitric oxide (NO) + Oxygen atom (O) Water vapor (H2O) UV radiation Hydrocarbons Peroxyacyl nitrates (PANs) Nitrogen dioxide (NO2) Oxygen (O2) Nitric oxide (NO) Oxygen (O2) Burning fossil fuels Figure 18.9: A greatly simplified model of how the pollutants that make up photochemical smog are formed. Nitrogen (N) in fossil fuel Fig. 18-9, p. 483

Several Factors Can Decrease or Increase Outdoor Air Pollution Outdoor air pollution may be decreased by: Settling of particles due to gravity Rain and snow Salty sea spray from the ocean Winds Chemical reactions

Several Factors Can Decrease or Increase Outdoor Air Pollution (cont’d Outdoor air pollution may be increased by: Urban buildings Hills and mountains High temperatures Emissions of VOCs from certain trees and plants The grasshopper effect Temperature inversions Warm air above cool air prevents mixing

A Temperature Inversion Warmer air Descending warm air mass Inversion layer Inversion layer Sea breeze Increasing altitude Figure 18.11: A temperature inversion, in which a warm air layer sits atop a cooler air layer, can take place in either of the two sets of topography and weather conditions shown here. Normally, the air temperature decreases steadily with increasing altitude within the troposphere, but during an inversion, there is a layer of air that is warmer than the cooler air above and below (see graph). Decreasing temperature Fig. 18-11, p. 484

18-3: What Is Acid Deposition and Why Is It a Problem? Caused mainly by coal-burning power plants and motor vehicle emissions Threatens human health, aquatic life and ecosystems, forests, and human-built structures in some regions

Acid Disposition Is a Serious Regional Air Pollution Problem Acid deposition Sulfuric acid and nitric acid compounds Wet deposition – rain, snow, fog, cloud vapor Dry deposition – particles Substances remain in the atmosphere 2- 14 days What are some ways in which your daily activities contribute to acid deposition?

Natural Capital Degradation: Acid Deposition Wind Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Windborne ammonia gas and some soil particles partially neutralize acids and form dry sulfate and nitrate salts Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain and snow) Nitric oxide (NO) Sulfur dioxide (SO2) and NO Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Acid fog Figure 18.12: Natural capital degradation. Acid deposition, which consists of rain, snow, dust, or gas with a pH lower than 5.6, is commonly called acid rain. Soils and lakes vary in their ability to neutralize excess acidity. Lakes in shallow soil low in limestone become acidic Lakes in deep soil high in limestone are buffered Fig. 18-12, p. 485

Current and Possible Future Acid Rain Problem Areas Figure 18.13: This map shows regions where acid deposition is now a problem and regions with the potential to develop this problem. Such regions have large inputs of air pollution (mostly from power plants, industrial facilities, and ore smelters) or are sensitive areas with naturally acidic soils and bedrock that cannot neutralize (buffer) additional inputs of acidic compounds. Question: Do you live in or near an area that is affected by acid deposition or an area that is likely to be affected by acid deposition in the future? (Data from World Resources Institute and U.S. Environmental Protection Agency) Fig. 18-13, p. 486

Acid Deposition Has a Number of Harmful Effects Human health Respiratory disorders; toxins from fish Release of toxic metals Aquatic ecosystems Lowers pH and kills organisms Leaching of soil nutrients Forest damage Damage to buildings, etc.

Solutions Acid Deposition Prevention Cleanup Reduce coal use and burn only low-sulfur coal Add lime to neutralize acidified lakes Use natural gas and renewable energy resources in place of coal Add phosphate fertilizer to neutralize acidified lakes Remove SO2 and NOx from smokestack gases and remove NOx from motor vehicular exhaust Figure 18-15: There are several ways to reduce acid deposition and the damage. Questions: Which two of these solutions are the best ones? Why? Add lime to neutralize acidified soils Tax SO2 emissions Fig. 18-15, p. 488

18-4: What Are the Major Indoor Air Pollution Problems? The most threatening indoor air pollutants: Smoke and soot from the burning of wood and coal in cooking fires (mostly in less- developed countries) Cigarette smoke Chemicals used in building materials and cleaning products

Indoor Air Pollution Is a Serious Problem In developing countries Indoor burning of wood, charcoal, dung, crop residues, coal Greatest risk to low-income populations In developed countries Indoor air pollution is greater than outdoor air pollution Chemicals used in building materials

Chloroform Source: Chlorine-treated water in hot showers Possible threat: Cancer Para-dichlorobenzene Source: Air fresheners, mothball crystals Threat: Cancer Tetrachloroethylene Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer Formaldehyde Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness 1,1,1-Trichloroethane Source: Aerosol sprays Threat: Dizziness, irregular breathing Styrene Source: Carpets, plastic products Threat: Kidney and liver damage Nitrogen oxides Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches Benzo-α-pyrene Source: Tobacco smoke, woodstoves Threat: Lung cancer Particulates Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease Figure 18-17 Numerous indoor air pollutants are found in most modern homes. Question: To which of these pollutants are you exposed? Radon-222 Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer Tobacco smoke Source: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease Asbestos Source: Pipe insulation, vinyl ceiling and floor tiles Threat: Lung disease, lung cancer Carbon monoxide Source: Faulty furnaces, unvented gas stoves and kerosene heaters, woodstoves Threat: Headaches, drowsiness, irregular heartbeat, death Methylene chloride Source: Paint strippers and thinners Threat: Nerve disorders, diabetes Fig. 18-17, p. 489

Indoor Air Pollution Is a Serious Problem (cont’d.) Indoor air pollution risk Children under five and the elderly Sick Pregnant women People with respiratory disorders or heart problems Smokers Factory workers

Indoor Air Pollution Is a Serious Problem (cont’d.) Four most dangerous indoor air pollutants in more-developed countries Tobacco smoke Formaldehyde Radioactive radon-222 gas Very small (ultrafine) particles Other indoor pollutants Pesticide residues, lead particles, air-borne spores (mold, mildew)

Case Study: Radioactive Radon Gas Sources Underground deposits of certain minerals Human health risks Decays into Polonium-210 Can expose the lungs to high amounts of radiation How can you test for and correct a radon problem?

Case Study: Radioactive Radon Gas (cont’d.) Outlet vents for furnace, dryer, and woodstove Open window Cracks in wall Openings around pipes Slab joints Wood stove Cracks in floor Sump pump Clothes dryer Furnace Radon-222 gas Slab Figure 18.19: There are a number of ways that radon-222 gas can enter homes and other buildings. Question: Have you tested the indoor air where you live for radon-222? Uranium-238 Soil Fig. 18-19, p. 491

18-5: What Are the Health Effects of Air Pollution? Air pollution can contribute to: Asthma Chronic bronchitis Emphysema Lung cancer Heart attack Stroke

Your Body’s Natural Defenses Against Air Pollution Can Be Overwhelmed The respiratory system protects from air pollutants through: Hair Cilia Mucus Effects of smoking and prolonged air pollution exposure Chronic bronchitis Emphysema

Major Components of the Human Respiratory System Epithelial cell Cilia Nasal cavity Oral cavity Goblet cell (secreting mucus) Pharynx (throat) Trachea (windpipe) Mucus Bronchus Bronchioles Alveolar duct Right lung Figure 18.21: Major components of the human respiratory system can help to protect you from air pollution, but these defenses can be overwhelmed or breached. Bronchioles Alveolar sac (sectioned) Alveoli Fig. 18-21, p. 492

Air Pollution Is a Big Killer 3.2 million deaths per year worldwide Mostly in Asia; 1.2 million in China 150,000 to 350,000 in the United States EPA proposed stricter emission standards for diesel-powered vehicles 125,000 die in U.S. each year from diesel fumes Emissions from one truck = 150 cars

Premature Deaths from Air Pollution in the U.S. Figure 18.22: Distribution of premature deaths from air pollution in the United States, mostly from very small, fine, and ultra-fine particles added to the atmosphere by coal-burning power plants. Questions: Why do the highest death rates occur in the eastern half of the United States? If you live in the United States, what is the risk at your home or where you go to school? Fig. 18-22, p. 493

18-6: How Should We Deal with Air Pollution? Legal, economic, and technological tools can help us to clean up air pollution However, the best solution is to prevent it

Laws and Regulations Can Reduce Outdoor Air Pollution United States Clean Air Acts: 1970, 1977, and 1990 created regulations enforced by states and cities EPA National ambient air quality standards for six outdoor pollutants Carbon monoxide, nitrogen dioxide, sulfur dioxide, suspended particulate matter, ozone, and lead

Laws and Regulations Can Reduce Outdoor Air Pollution (cont’d.) EPA’s national emission standards for 188 hazardous air pollutants (HAPs) Toxic Release Inventory (TRI) Some successes in the United States Decrease in emissions Use of low-sulfur diesel fuel Less-developed countries Have more challenges with reducing air pollution

We Can Use the Marketplace to Reduce Outdoor Air Pollution Emission trading or cap-and-trade program Success depends on: How low initial cap is set How often it is lowered

There Are Many Ways to Reduce Outdoor Air Pollution Stationary source air pollution Motor vehicle air pollution Less-developed countries are far behind developed countries in implementing solutions Non-existent and/or weak laws

Solutions Stationary Source Air Pollution Prevention Reduction or Disposal Burn low-sulfur coal or remove sulfur from coal Disperse emissions (which can increase downwind pollution) with tall smokestacks Convert coal to a liquid or gaseous fuel Remove pollutants from smokestack gases Figure 18.25 There are several ways to prevent, reduce, or disperse emissions of sulfur oxides, nitrogen oxides, and particulate matter from stationary sources such as coal-burning power plants and industrial facilities (Concept 18-6). Questions: Which two of these solutions do you think are the most important? Why? Switch from coal to natural gas and renewables Tax each unit of pollution produced Fig. 18-25, p. 495

Motor Vehicle Air Pollution Solutions Motor Vehicle Air Pollution Prevention Cleanup Walk bike or use mass transit Require emission control devices Inspect car exhaust systems twice a year Improve fuel efficiency Figure 18.26: There are a number of ways to prevent and reduce emissions from motor vehicles (Concept 18-6). To find out what and how much your car emits, go to www.cleancarsforkids.org. Questions: Which two of these solutions do you think are the most important? Why? Get older, polluting cars off the road Set strict emission standards Fig. 18-26, p. 496

Reducing Indoor Air Pollution Should Be a Priority Greater threat to human health than outdoor pollution What can be done? Prevention Cleanup

Solutions Indoor Air Pollution Prevention Reduction and Dilution Ban indoor smoking Use adjustable fresh air vents for work spaces Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Circulate air more frequently Circulate a building’s air through rooftop greenhouses Figure 18.27: There are several ways to prevent or reduce indoor air pollution. Questions: Which two of these solutions do you think are the best ones? Why? Prevent radon infiltration Use less polluting cleaning agents, paints, and other products Use efficient venting systems for wood-burning stoves Fig. 18-27, p. 496

We Can Emphasize Pollution Prevention How can we avoid producing these pollutants in the first place? Place political and economic pressure on government officials and companies

18-17: How Have We Depleted Ozone in the Stratosphere & What Can We Do? Widespread use of certain chemicals has: Reduced ozone levels in the stratosphere Allowed more harmful ultraviolet radiation to reach the earth’s surface To reverse ozone depletion: Stop producing ozone-depleting chemicals Adhere to the international treaties that ban such chemicals

Our Use of Certain Chemicals Threatens the Ozone Layer Ozone is thinning over Antarctica and the Arctic Chlorofluorocarbons (CFCs) Persistent chemicals that attack ozone in the stratosphere

Ozone Degradation Figure 18-30: Natural Capital Degradation: These colorized satellite images show ozone thinning over Antarctica during September of 1980 (left), 2000 (center), and 2011 (right). Ozone depletion of 50% or more occurred in the dark blue and purple areas. Fig. 18-30, p. 498

Why Should We Worry About Ozone Depletion? Ozone protects the earth’s surface from damaging UV radiation Human health concerns UV radiation affects plankton

We Can Reverse Stratospheric Ozone Depletion Stop producing ozone-depleting chemicals immediately Agreements with a prevention approach: Montreal Protocol Cut emissions of CFCs Copenhagen Amendment Accelerated phase-out

Big Ideas Outdoor air pollution, in the forms 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 those deaths

Big Ideas (cont’d.) 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

Tying it All Together Three principles of sustainability Rely more on direct and indirect forms of solar energy than on fossils fuels Recycle and reuse much more of what we use Use a diverse set of nonpolluting or low- polluting renewable energy resources