Presentation on theme: "Air Pollution Chapter 18 Core Case Study: South Asias Massive Brown Cloud Asian Brown Cloud Causes clearing and burning forest for planting crops Burning."— Presentation transcript:
Air Pollution Chapter 18
Core Case Study: South Asias Massive Brown Cloud Asian Brown Cloud Causes clearing and burning forest for planting crops Burning of coal, diesel, and other fossil fuels in industries, vehicles and homes Chemical composition 1/3 rd of it is dust, smoke, and ash Rest is acidic compounds, soot, toxic metals (mercury and lead), hundreds of organic compounds and fly ash Areas impacted much of India, Bangladesh, the industrial heart of China, the Open Sea east of this area Photosynthesis has been reduced by 7-10% Acid in the haze fall to the surface and damage crops, trees, and aquatic life
The Asian Brown Cloud Air pollution connects the world On certain days 25% of particulate matter 77% of black carbon 33% of toxic mercury in the skies above LA can be traced to China Steps taken in China and India to reduce air pollution strict pollution controls standards for coal-burning industries shifting from coal to cleaner burning natural gas
Air Pollution in Shanghai, China, in 2004
18-1 The Atmosphere Consists of Several Layers Atmosphere varies in Density The air we breathe at sea level is denser than the air on top of the worlds highest mountains. Atmospheric pressure Decreases with altitude because they are fewer gas molecules at higher levels
6 Earths Atmosphere Compared to the size of the Earth (12000 km) The atmosphere is very thin (120 km) or (75 miles) After Mt. Pinatubo eruption 1991
Atmospheric Layers The atmosphere consists of layers around the Earth, each one defined by the way temperature changes within its limits. The layer boundaries are: Tropopause Stratopause Mesopause The outermost, the thermosphere, thins slowly, fading into space with no boundary. Troposphere Air mixes vertically and horizontally. All weather occurs in this layer. Stratosphere Temperature is stable to 20 km, then increases due to absorption of UV by the thin layer of ozone. Mesosphere Temperature is constant in the lower mesosphere, but decreases steadily with height above 56 km. Thermosphere This layer extends as high as 1000 km. Temperature increases rapidly after about 88 km. Aurora, caused by collisions between protons and electrons from the Sun and oxygen and nitrogen atoms in the atmosphere. Meteor burning up
Air Movements in the Troposphere Play a Key Role in Earths Weather and Climate Troposphere This is where we live 8 to 14.5 kilometers high (5 to 9 miles) the temperature drops from about 17 to -52 degrees Celsius 75–80% of the earths air mass most dense Closet to the earth's surface Rising and falling air currents: weather and climate Involved in chemical cycli ng
Composition Nitrogen (N 2, 78%) Nitrogen Oxygen (O 2, 21%) Oxygen Argon (Ar, 1%) myriad of other very influential components are also present which include the Water (H 2 O, 0 - 7%), "greenhouse" gases or Ozone (O 3, %), Carbon Dioxide (CO 2, %),WaterOzoneCarbon Dioxide
The Stratosphere Is Our Global Sunscreen Stratosphere extends to 50 kilometers (31 miles) high dry and less dense temperature in this region increases gradually to -3 degrees Celsius, due to the absorption of ultraviolet radiation ozone layer absorbs and scatters the solar ultraviolet radiation ninety-nine percent of "air" is located in first two layers every 1000-m 11% less air pressure Similar composition to the troposphere, with 2 exceptions Much less water O 3, ozone layer, filters UV
Natural Capital: The Earths Atmosphere Is a Dynamic System with Four Layers
O 3 -The Good, the Bad, and the Ugly
O 3 -The Good ( km) blocks solar UV <290 nm Beneficial Ozone that forms in the stratosphere protects life on earth by filtering out most of the incoming harmful UV radiation emitted by the sun
O 3 -The Bad 6-10 km : greenhouse gas absorbs IR emitted by Earth O 3 O 3 (v=1) Harmful or Photochemical ozone forms in the troposphere when various air pollutants undergo chemical reactions under the influence of sunlight. Ozone in the atmosphere near the earths surface damages plants, lung tissue, and some materials such as rubber. It is a strong oxidant and respiratory irritant. Ground level ozone results primarily from motor-vehicle exhaust
O 3 -The Ugly part of smog (bad, too)
18-2 Air Pollution Comes from Natural and Human Sources Air pollution The presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystems, or human-made material. Natural sources Dust blown by wind Pollutants from wildfires and volcanoes Volatile organics released by plants Withdrawing groundwater
Air Pollution Comes from Natural and Human Sources Human sources: mostly in industrialized and/or urban areas Stationary sources Mobile sources
Sources and Types of Air Pollutants
Fig. 18-4, p. 472 Primary Pollutants COCO 2 Secondary Pollutants SO 2 NONO 2 Most hydrocarbons SO 3 Most suspended particles HNO 3 H 2 SO 4 H2O2H2O2 O3O3 PANs SourcesNaturalStationary Mobile Most NO 3 and SO 4 2 salts
Case Study: Air Pollution in the Past: The Bad Old Days Discovery of fire Middle Ages 1700s - Industrial Revolution London, England 1850s dense mixture of coal smoke and fog a prolonged coal fog killed an estimated 2,200 people 1952: yellow fog lasted for 5 days and killed 4, ,000 Londoners Clean Air Act of 1956
Case Study: Air Pollution in the Past: The Bad Old Days (2) United States 1948: Donora, PA; first U.S. air pollution disaster 1963: New York City Global problem Urban areas in China, India and parts of Eastern Europe that depend on coal in industries and in some homes face air pollution levels similar to those in London and America in the 1950s
Some Pollutants in the Atmosphere Combine to Form Other Pollutants Primary pollutants Are harmful chemicals emitted directly into the air from natural processes and human activities. Secondary pollutants Primary pollutants react with one another and with the basic components of air to form new harmful chemicals Air quality improving in developed countries Much more needs to be done in developing countries Indoor pollution: big threat to the poor
Indoor Air Pollution
What Are the Major Outdoor Air Pollutants? Carbon oxides Carbon monoxide (CO) Colorless and highly toxic that forms during the incomplete combustion of carbon-containing materials. Reacts with hemoglobin in blood cells reduces the ability to transport oxygen. Sources Motor vehicles exhaust, burning of forest and grasslands, tobacco smoke, and open fires and inefficient stoves used for cooking. Carbon dioxide (CO 2 ) Colorless, odorless gas. 93% result of natural carbon cycle Rest from burning fossil fuels and clearing CO 2 absorbing forest and grasslands. Emissions have been rising since the industrial revolution
What Are the Major Outdoor Air Pollutants? Nitrogen oxides (NO) and nitric acid (HNO 3 ) Sources- automobiles, coal-burning plants NO reacts with oxygen to form NO 2 (reddish brown gas) NO and NO 2 are collectively called NO x Acid deposition Photochemical smog Human health and environmental impact Nitrous oxide (N 2 O) a greenhouse gas that is emitted from fertilizers and animal waste and by burning fossil fuels
Major Outdoor Pollutants Sulfur dioxide (SO 2 ) and sulfuric acid (H 2 SO 4 ) Description: Colorless, irritating; forms mostly from the combustion of sulfur containing fossil fuels such as coal and oil (S + O 2 SO 2 ); in the atmosphere can be converted to sulfuric acid (H 2 SO 4 ), a major component of acid deposition. Major human sources: Coal burning in power plants (88%) and industrial processes (10%). Health effects: Breathing problems for healthy people; restriction of airways in people with asthma; chronic exposure can cause a permanent condition similar to bronchitis. According to the WHO, at least 625 million people are exposed to unsafe levels of sulfur dioxide from fossil fuel burning. Environmental effects: Reduces visibility; acid deposition of H 2 SO 4 can damage trees, soils, and aquatic life in lakes. Property damage: SO 2 and H 2 SO 4 can corrode metals and eat away stone on buildings, statues, and monuments; SO 2 can damage paint, paper, and leather.
What Are the Major Outdoor Air Pollutants? Particulates Suspended particulate matter (SPM) Variety of particles and droplets (aerosols) small and light enough to remain suspended in atmosphere for short periods (large particles) to long periods cause smoke, dust, and haze. Sources Burning coal in power and industrial plants (40%), burning diesel and other fuels in vehicles (17%), agriculture (plowing, burning off fields), unpaved roads, construction. Human health and environmental impact Nose and throat irritation, lung damage, and bronchitis; aggravates bronchitis and asthma; shortens life; toxic particulates (such as lead, cadmium, PCBs, and dioxins) can cause mutations, reproductive problems, cancer. Reduces visibility; acid deposition of H 2 SO 4 droplets can damage trees, soils, and aquatic life in lakes
What Are the Major Outdoor Air Pollutants? Ozone (O 3 ) Highly reactive, irritating gas with an unpleasant odor that forms in the troposphere as a major component of photochemical smog Sources Chemical reaction with volatile organic compounds (VOCs, emitted mostly by cars and industries) and nitrogen oxides to form photochemical smog Human and environmental impact Breathing problems; coughing; eye, nose, and throat irritation; aggravates chronic diseases such as asthma, bronchitis, emphysema, and heart disease; reduces resistance to colds and pneumonia; may speed up lung tissue aging. Environmental effects: Ozone can damage plants and trees; smog can reduce visibility. Property damage: Damages rubber, fabrics, and paints.
What Are the Major Outdoor Air Pollutants? Volatile organic compounds (VOCs) organic compounds (hydrocarbons) that evaporate easily, usually aromatic Hydrocarbons and terpenes Sources Methane, chlorofluorocarbon, benzene and proprane. vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning Human and environmental impact eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming
Chemical Reactions That Form Major Outdoor Air Pollutants
Statue Corroded by Acid Deposition and Other Forms of Air Pollution, RI, U.S.
Natural Capital: Lichen Species, Vulnerability to Air Pollutants Case Study: When is a Lichen Like a Canary
Case Study: Lead Is a Highly Toxic Pollutant Does not break down in the environment Solid toxic metal and its compounds, emitted into the atmosphere as particulate matter. Sources Paint old houses), smelters (metal refineries), lead manufacture, storage batteries, leaded gasoline (being phased out in developed countries). Human health and environmental impact Accumulates in the body; brain and other nervous system damage and mental retardation (especially in children); digestive and other health problems; some lead-containing chemicals cause cancer in test animals. Can harm wildlife.
Case Study: Lead Is a Highly Toxic Pollutant Reduction of lead (Pb) Unleaded gasoline Unleaded paint 1960 Still problems 2007: toys with Pb paint recalled /3 rd of red long-lasting lipstick manufactured in the US contained surprisingly high levels of lead. Global ban on lead in gasoline and paint
Fig. 18-7, p. 476 SOLUTIONS Lead Poisoning PreventionControl Phase out leaded gasoline worldwide Replace lead pipes and plumbing fixtures containing lead solder Phase out waste incineration Remove leaded paint and lead dust from older houses and apartments Ban use of lead solder Sharply reduce lead emissions from incinerators Ban use of lead in computer and TV monitors Remove lead from TV sets and computer monitors before incineration or land disposal Ban lead glazing for ceramicware used to serve food Test for lead in existing ceramicware used to serve food Ban candles with lead cores Test existing candles for lead Test blood for lead by age 1 Wash fresh fruits and vegetables
Burning Coal Produces Industrial Smog Chemical composition of industrial smog mixture of SO 2, droplets of sulfuric acid, and a variety of suspended solid particles emitted by burning coal Reduction of this smog in urban cities of the United States China and smog
How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog
Fig. 18-8, p. 476 Ammonium sulfate [(NH 4 ) 2 SO 4 ] Ammonia (NH 3 ) Sulfuric acid (H 2 SO 4 ) Carbon monoxide (CO) and carbon dioxide (CO 2 ) Water vapor (H 2 O) Sulfur trioxide (SO 3 ) Oxygen (O 2 ) Sulfur dioxide (SO 2 ) Burning coal and oil Oxygen (O 2 ) Sulfur (S) in coal and oil Carbon (C) in coal and oil
Fig. 18-8, p. 476 Burning coal and oil Oxygen (O 2 ) Stepped Art Ammonium sulfate [(NH 4 ) 2 SO 4 ] Ammonia (NH 3 ) Sulfuric acid (H 2 SO 4 ) Water vapor (H 2 O) Sulfur trioxide (SO 3 ) Oxygen (O 2 ) Sulfur dioxide (SO 2 ) Sulfur (S) in coal and oil Carbon monoxide (CO) and carbon dioxide (CO 2 ) Carbon (C) in coal and oil
Sunlight Plus Cars Equals Photochemical Smog Photochemical Smog Chemical composition is a mixture of air pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbon compounds under the influence of light VOCs + NO 2 + Heat + Sunlight yields Ground level O 3 and other photochemical oxidants Aldehydes Other secondary pollutants
A Model of How Pollutants That Make Up Photochemicals Are Formed
Fig. 18-9, p. 477 PANS and other pollutants Volatile organic compounds (VOCs) Ozone (O 3 ) Oxygen (O 2 ) Nitric oxide (NO) + Oxygen atom (O) Water vapor (H 2 O) Hydrocarbons UV radiation Peroxyacyl nitrates (PANs) Nitrogen dioxide (NO 2 ) Oxygen (O 2 ) Nitric oxide (NO) Oxygen (O 2 ) Nitrogen (N) in fossil fuel Burning fossil fuels
Global Outlook: Photochemical Smog in Santiago, Chile
How can trees Contribute to Photochemical Smog? Trees certainly have environmental benefits Emit oxygen, absorb CO 2, provide shade, and help absorb and remove various pollutants from the air. Some trees (some oak species, sweet gums, Poplars, and Kudzu) in and around urban areas play a large role in smog formation They emit VOCs (like isoprene) that are ingredients in the development of photochemical smog. Plants in urban areas should be trees that emit low levels of VOCs.
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 Outdoor air pollution may be increased by Urban buildings Hills and mountains High temperatures Emissions of VOCs from certain trees and plants Grasshopper effect Temperature inversions
A Temperature Inversion
Fig , p. 478 Warmer air Descending warm air mass Inversion layer Sea breeze Increasing altitude Decreasing temperature
Animation: Formation of photochemical smog
Animation: Thermal inversion and smog
18-3 Acid Disposition Is a Serious Regional Air Pollution Problem Acid deposition, acid rain Local versus regional problems Tall smokestacks reduce local air pollution by increases region air pollution downwind Effects of prevailing winds Where is the worst acid deposition?
When gas pollutants e.g. carbon dioxide, sulfur dioxide, nitrogen dioxide dissolve in rain water, various acids are formed. CO 2 + H 2 O H 2 CO 3 (carbonic acid) SO 2 + H 2 O H 2 SO 3 (sulfurous acid) NO 2 + H 2 O HNO 2 (nitrous acid) + HNO 3 (nitric acid) Acid Deposition Formation
Causes of Acid Rain Sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ) are the primary causes of acid rain. In the US, About 2/3 of all SO 2 and 1/4 of all NO x comes from electric power generation that relies on burning fossil fuels like coal.
Natural Capital Degradation: Acid Deposition, Acid Rain
pH measurements in relation to major coal-burning and industrial plants. (Normal rain has a pH of 5.6)
Current and Possible Future Acid Rain Problem Areas
Fig , p. 480 Potential problem areas because of sensitive soils Potential problem areas because of air pollution: emissions leading to acid deposition Current problem areas (including lakes and rivers)
Increased Acidity Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. The runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone.
Effects of Acid Rain Has a variety of effects, including damage to forests and soils, fish and other living things, materials, and human health. Also reduces how far and how clearly we can see through the air, an effect called visibility reduction. Effects of acid rain are most clearly seen in the aquatic environments Most lakes and streams have a pH between 6 and 8
Buffering Capacity Acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited buffering capacity Lakes and streams become acidic when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it.
In areas where buffering capacity is low, acid rain also releases aluminum ions from soils into lakes and streams; aluminum is highly toxic to many species of aquatic organisms referred to as acid shock. pg
Effects on Wildlife Generally, the young of most species are more sensitive to environmental conditions than adults. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Some acid lakes have no fish.
Acid Rain and Forests Acid rain does not usually kill trees directly. Instead, it is more likely to weaken trees by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil.
Effects of Acid Rain Great Smoky Mountains, NC
Nutrients Acidic water dissolves the nutrients and helpful minerals in the soil and then washes them away before trees and other plants can use them to grow. Acid rain also causes the release of substances that are toxic to trees and plants, such as aluminum, into the soil.
Acid Deposition Has a Number of Harmful Effects Human respiratory disorders Aquatic ecosystems affected Release of toxic metal Toxic lead and mercury Leaching of soil nutrients Loss of crops and trees Damage to buildings, statues, and monuments
Natural Capital Degradation: Air Pollution Damage to Trees in North Carolina, U.S.
Solutions: Acid Deposition, Prevention and Cleanup
Active Figure: Acid deposition
Video: Air pollution in China
Active Figure: Effect of air pollution in forests
18-4 Indoor Air Pollution Is a Serious Problem Developing countries Indoor burning of wood, charcoal, dung, crop residues, coal in open fires or unvented or poorly vented stoves Poor suffer the greatest risk Developed countries Indoor air pollution is greater than outdoor air pollution
Exposure Time spent in various environments in US and less- developed countries
Indoor Air Pollution Is a Serious Problem Why? 11 of the common air pollutants higher inside than outside Greater in vehicles than outside Health risks magnified: people spend 70–98% of their time is indoors
Indoor Air Pollution Is a Serious Problem Who are at greatest risk from indoor air pollution? Children under 5 and the elderly Sick Pregnant women People with respiratory disorders or heart problems Smokers Factory workers
Indoor Air Pollution Is a Serious Problem Four most dangerous indoor air pollutants Tobacco smoke- most preventable Formaldehyde Found in many building material, and household products (plywood, particle board, paneling, high-gloss wood, drapes, furniture, carpets, wallpaper, wrinkle- free coating on permanent –press clothing) The chemical that causes most people in developed countries difficulty Colorless extremely irritating chemical Causes chronic breathing problems, dizziness, skin, eye, sinus irritation, rash, headaches, sore throats, wheezing and nausea EPA estimates that 1 of every 5,000 people who live in manufactured homes for more than 10 years will develop cancer from formaldehyde exposure.
Four most dangerous indoor air pollutants (cont) Radioactive radon-222 gas Seep into houses from underground rock deposits Colorless odorless radioactive gas produced by the natural decay of uranium-238. lung tissue damage, lung cancer Estimated that 7,000 to 30,000 Americans die each year from radon-induced lung cancer Only smoking causes more lung cancer deaths Smokers more at risk than non-smokers Very small particles Asbestos Irritate the nose and throat, damage the lungs, aggravate asthma and bronchitis, and shorten life.
Science: Sources and Paths of Entry for Indoor Radon-222 Gas
(From: Zone pCi/L 1 > <2
Indoor Air Pollution Is a Serious Problem Other possible indoor air pollutants Pesticide residue Pb particles Living organisms and their excrements E.g., Dust mites and cockroach droppings Airborne spores of molds and mildews
Science: Magnified View of a Household Dust Mite in a Dust Ball
Some Important Indoor Air Pollutants
Fig , p. 484 Source: Chlorine-treated water in hot showers Possible threat: Cancer Source: Air fresheners, mothball crystals Threat: Cancer Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer Source: Aerosol sprays Threat: Dizziness, irregular breathing 1,1,1-Trichloroethane Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness Formaldehyde Styrene Nitrogen oxides Source: Carpets, plastic products Threat: Kidney and liver damage Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches Source: Tobacco smoke, woodstoves Threat: Lung cancer Benzo- α -pyrene Particulates Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer Radon-222 Tobacco smoke Source: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease Asbestos Carbon monoxide Methylene chloride Source: Pipe insulation, vinyl ceiling and floor tiles Threat: Lung disease, lung cancer Source: Faulty furnaces, unvented gas stoves and kerosene heaters, woodstoves Threat: Headaches, drowsiness, irregular heartbeat, death Source: Paint strippers and thinners Threat: Nerve disorders, diabetes ChloroformPara-dichlorobenzeneTetrachloroethylene
Sick Building Syndrome (SBS) vs Building Related Illness (BRI)
Sick Building Syndrome A persistent set of symptoms in > 20% population Causes(s) not known or recognizable Complaints/Symptoms relieved after exiting building Linked to inadequate ventilation, new buildings that contain chemicals such as formaldehyde from building products, or biological contaminants like mold or pollen.
Complaints/Symptoms Headaches Fatigue Reduced Mentation Irritability Eye, nose or throat irritation Dry Skin Nasal Congestion Difficulty Breathing Nose Bleeds Nausea
Building Related Illness Clinically Recognized Disease Exposure to indoor air pollutants Recognizable Causes
18-5 Your Bodys Natural Defenses against Air Pollution Can Be Overwhelmed Respiratory system protection from air pollutants Hair in nose, cilia, mucus, sneezing, and coughing Effect of smoking and prolonged air pollution exposure Chronic bronchitis Emphysema- irreversible damage to the air sacs in the lungs
Major Components of the Human Respiratory System
Normal Human Lungs and the Lungs of a Person Who Died of Emphysema
Air Pollution Is a Big Killer 3 Million deaths per year world-wide Mostly in Asia Main causes Heart attacks, respiratory diseases, and lung cancer EPA: proposed stricter emission standards for diesel-powered vehicles Link between international trade and air pollution Cargo ships and pollution
Premature Deaths from Air Pollution in the U.S.
18-6 Laws and Regulations Can Reduce Outdoor Air Pollution (1) United States Clean Air Acts: 1970, 1977, and 1990 EPA National ambient air quality standards (NAAQs) for 6 outdoor criteria pollutants National emission standards for 188 hazardous air pollutants (HAPs) Toxic Release Inventory (TRI)
Clean Air Act Originally signed 1963 States controlled standards 1970 – Uniform Standards by Federal Govt. Criteria Pollutants Primary – Human health risk Secondary – Protect materials, crops, climate, visibility, personal comfort
Clean Air Act 1990 version Acid rain, urban smog, toxic air pollutants, ozone depletion, marketing pollution rights, VOCs 1997 version Reduced ambient ozone levels Cost $15 billion/year -> save 15,000 lives Reduce bronchitis cases by 60,000 per year Reduce hospital respiratory admission 9000/year
PREVENTING AND REDUCING AIR POLLUTION The Clean Air Acts in the United States have greatly reduced outdoor air pollution from six major pollutants: Carbon monoxide Nitrogen oxides Sulfur dioxides Suspended particulate matter (less than PM- 10) Tropospheric Ozone
Laws and Regulations Can Reduce Outdoor Air Pollution (2) Good news in U.S. Decrease in emissions Use of low-sulfur diesel fuel Cuts pollution Developing countries More air pollution
Case Study: U.S. Air Pollution Can Be Improved Rely on cleanup more than prevention of pollution Raise fuel-efficiency for cars, SUVs, and light trucks Better regulation of emissions of motorcycles and two-cycle gasoline engines Regulate air pollution for oceangoing ships in American ports
Case Study: U.S. Air Pollution Can Be Improved (2) Why are airports exempt from many regulations? Regulate greenhouse gas emissions Ultrafine particles are not regulated Urban O 3 levels too high
Case Study: U.S. Air Pollution Can Be Improved (3) What about indoor air pollution? Better enforcement of the Clean Air Acts Intense pressure needed from citizens to make improvements
We Can Use the Marketplace to Reduce Outdoor Air Pollution Emission trading or cap-and-trade program Mixed reactions to program SO 2 emissions down significantly NO 2 will be tried in the future
There Are Many Ways to Reduce Outdoor Air Pollution 1980 –2006 SO 2 emissions from U.S. electric power plants decreased by 66% NO x emissions by 41% Particulate emissions by 28% Older plants not governed by the same regulations New cars have better emissions
Solutions: Stationary Source Air Pollution
Prevention of Air pollution Catalytic converter to oxidize the sulfur to yield sulfur compounds. A lime scrubber in a smokestack may be used In a wet scrubber, a slurry of lime mixed w/ water is sprayed across the exiting gases. The sulfur mixes w/ the calcium, forming the calcium sulfate, which falls to the bottom of the smokestack as bottom ash. Most particulates are removed post combustion Post combustion method
Electrostatic Precipitator Dirty gas Dust discharge Electrodes Cleaned gas
Dirty gas Baghouse Filter Dust discharge Bags
Cyclone Separator Dirty gas Dust discharge Cleaned gas
Dirty gas Dirty water Clean water Wet Scrubber Wet gas Cleaned gas
Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup
Reducing Indoor Air Pollution Should Be a Priority Greater threat to human health than outdoor pollution What can be done? Prevention Cleanup
Movement of Air Into / Out of Homes Amount of air available to dilute pollutants important indicator of the likely contaminant concentration Indoor air can mix with outside air by three mechanisms infiltration natural ventilation forced ventilation
Movement of Air Into / Out of Homes Natural ventilation air exchange that occurs when windows or doors are opened to increase air circulation Forced ventilation mechanical air handling systems used to induce air exchange using fans and blowers Trade-offs cut infiltration to decrease heating and cooling costs vs. indoor air quality problems
Solutions: Indoor Pollution, Prevention and Cleanup or Dilution
What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure
Solutions: Air Pollution, Ways to Prevent It Over the Next 30–40 Years