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LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER • SCOTT E. SPOOLMAN
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18 Air Pollution
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• 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
Core Case Study: South Asia’s Massive Brown Clouds
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The South Asia's Brown Clouds (cont'd.)
Fig. 18-1a, p. 474
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• The two innermost layers of the atmosphere – Troposphere – supports life – Stratosphere – contains the protective ozone
layer
18-1: What is the Nature of the Atmosphere?
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• 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
The Atmosphere Consists of Several Layers
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Fig. 18-2, p. 475
Atmospheric pressure (millibars)
Temperature
Thermosphere
Mesosphere
Altit
ude
(mile
s)
Altit
ude
(kilo
met
ers)
Stratosphere
Ozone layer
Pressure Troposphere
(Sea level) Pressure = 1,000 millibars
at ground level Temperature (˚C)
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• Troposphere – 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
Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate
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• Stratosphere – 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
The Stratosphere Is Our Global Sunscreen
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• 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
18-2: What Are the Major Outdoor Pollution Problems?
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• 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
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• Human sources – Mostly in industrialized and/or urban areas – Stationary sources – power plants and
industrial facilities – Mobile sources – motor vehicles
Air Pollution Comes from Natural and Human Sources (cont’d.)
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• Primary pollutants – Emitted directly into the air
• Secondary pollutants – From reactions of primary pollutants
Some Pollutants in the Atmosphere Combine to Form Other Pollutants
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Sources and Types of Air Pollutants
Fig. 18-3, p. 477
Primary Pollutants CO CO2 Secondary Pollutants
SO2 NO NO2 CH4 and most
other hydrocarbons SO3
Most suspended particles H2O2 H2SO4
PANs Most NO3
– and SO42– salts
Natural Source Stationary Human Source
Human Source
Mobile
N2O
O3
HNO3
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• Carbon oxides – Carbon monoxide (CO); carbon dioxide (CO2)
• Nitrogen oxides (NO) and nitric acid (HNO3) – Acid deposition; photochemical smog
What Are the Major Outdoor Air Pollutants?
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• Sulfur dioxide (SO2) and sulfuric acid (H2SO4)
• Particulates – Suspended particulate matter
• Ozone • Volatile organic compounds (VOCs)
– Methane
What Are the Major Outdoor Air Pollutants? (cont’d.)
Chemical Reactions That Form Major Outdoor Air Pollutants
Table 18-1, p. 480
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• 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?
Burning Coal Produces Industrial Smog
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Burning coal and oil
Oxygen (O2)
Stepped Art
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
Fig. 18-8, p. 481
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• Photochemical smog • VOCs + NOx + Heat + Sunlight yields:
– Ground level O3 and other photochemical oxidants
– Aldehydes – Other secondary pollutants
Sunlight Plus Cars Equals Photochemical Smog
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PANS and other pollutants Volatile organic compounds (VOCs)
Ozone (O3) Oxygen (O2)
Nitric oxide (NO) + Oxygen atom (O)
Water vapor (H2O) Hydrocarbons UV radiation Peroxyacyl nitrates (PANs) Nitrogen dioxide (NO2)
Oxygen (O2) Nitric oxide (NO)
Oxygen (O2) Burning fossil fuels
Nitrogen (N) in fossil fuel
Fig. 18-9, p. 483
Photochemical Smog
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• 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
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• 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
Several Factors Can Decrease or Increase Outdoor Air Pollution (cont’d.)
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A Temperature Inversion
Fig. 18-11, p. 484
Warmer air
Increasing altitude
Decreasing temperature
Sea breeze
Inversion layer Inversion layer
Descending warm air mass
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• 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
18-3: What Is Acid Deposition and Why Is It a Problem?
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• 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?
Acid Disposition Is a Serious Regional Air Pollution Problem
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Natural Capital Degradation: Acid Deposition
Fig. 18-12, p. 485
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
Lakes in deep soil high in limestone are buffered
Lakes in shallow soil low in limestone become acidic
Wind
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Current and Possible Future Acid Rain Problem Areas
Fig. 18-13, p. 486
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• 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.
Acid Deposition Has a Number of Harmful Effects
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Fig. 18-15, p. 488
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
Tax SO2 emissions
Add lime to neutralize acidified soils
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• 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
18-4: What Are the Major Indoor Air Pollution Problems?
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• 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
Indoor Air Pollution Is a Serious Problem
Fig. 18-17, p. 489
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
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
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• 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.)
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• 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)
Indoor Air Pollution Is a Serious Problem (cont’d.)
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• 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
Case Study: Radioactive Radon Gas (cont’d.)
Fig. 18-19, p. 491
Outlet vents for furnace, dryer, and woodstove
Open window
Openings around pipes
Cracks in wall
Slab joints
Wood stove
Clothes dryer
Cracks in floor
Sump pump Furnace
Uranium-238 Radon-222 gas
Soil
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• Air pollution can contribute to: – Asthma – Chronic bronchitis – Emphysema – Lung cancer – Heart attack – Stroke
18-5: What Are the Health Effects of Air Pollution?
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• The respiratory system protects from air pollutants through: – Hair – Cilia – Mucus
• Effects of smoking and prolonged air pollution exposure – Chronic bronchitis – Emphysema
Your Body’s Natural Defenses Against Air Pollution Can Be Overwhelmed
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Major Components of the Human Respiratory System
Fig. 18-21, p. 492
Epithelial cell
Cilia Nasal cavity
Oral cavity Goblet cell (secreting mucus)
Pharynx (throat)
Mucus Trachea (windpipe)
Bronchus Bronchioles
Right lung Alveolar duct
Bronchioles Alveolar
sac (sectioned)
Alveoli
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• 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
Air Pollution Is a Big Killer
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Premature Deaths from Air Pollution in the U.S.
Fig. 18-22, p. 493
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• Legal, economic, and technological tools can help us to clean up air pollution
• However, the best solution is to prevent it
18-6: How Should We Deal with Air Pollution?
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• 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
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• 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
Laws and Regulations Can Reduce Outdoor Air Pollution (cont’d.)
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• Emission trading or cap-and-trade program – Success depends on:
• How low initial cap is set • How often it is lowered
We Can Use the Marketplace to Reduce Outdoor Air Pollution
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• 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
There Are Many Ways to Reduce Outdoor Air Pollution
Solutions
Stationary Source Air Pollution
Prevention Reduction or Disposal
Burn low-sulfur coal or remove sulfur from coal
Convert coal to a liquid or gaseous fuel
Remove pollutants from smokestack gases
Switch from coal to natural gas and renewables
Tax each unit of pollution produced
Disperse emissions (which can increase downwind pollution) with tall smokestacks
Fig. 18-25, p. 495
Fig. 18-26, p. 496
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
Get older, polluting cars off the road
Set strict emission standards
Solutions
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• Greater threat to human health than outdoor pollution
• What can be done? – Prevention – Cleanup
Reducing Indoor Air Pollution Should Be a Priority
Fig. 18-27, p. 496
Indoor Air Pollution
Prevention
Ban indoor smoking Use adjustable fresh air vents for work spaces
Reduction and Dilution
Set stricter formaldehyde emissions standards for carpet, furniture, and building materials
Circulate air more frequently
Circulate a building’s air through rooftop greenhouses
Prevent radon infiltration
Use less polluting cleaning agents, paints, and other products
Use efficient venting systems for wood-burning stoves
Solutions
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• How can we avoid producing these pollutants in the first place? – Place political and economic pressure on
government officials and companies
We Can Emphasize Pollution Prevention
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• 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
18-17: How Have We Depleted Ozone in the Stratosphere & What Can We Do?
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• Ozone is thinning over Antarctica and the Arctic
• Chlorofluorocarbons (CFCs) – Persistent chemicals that attack ozone in the
stratosphere
Our Use of Certain Chemicals Threatens the Ozone Layer
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Ozone Degradation
Fig. 18-30, p. 498
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• Ozone protects the earth’s surface from damaging UV radiation – Human health concerns – UV radiation affects plankton
Why Should We Worry About Ozone Depletion?
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• Stop producing ozone-depleting chemicals immediately
• Agreements with a prevention approach: – Montreal Protocol
• Cut emissions of CFCs
– Copenhagen Amendment • Accelerated phase-out
We Can Reverse Stratospheric Ozone Depletion
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• 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
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• 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
Big Ideas (cont’d.)
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• 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
Tying it All Together