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Air Pollution
Core Case Study: South Asia’s Massive Brown Cloud
Asian Brown Cloud• Causes• Chemical composition• Areas impacted
Air pollution connects the world
Steps taken in China and India to reduce air pollution
The Asian Brown Cloud
Air Pollution in Shanghai, China, in 2004
18-1 What Is the Nature of the Atmosphere?
Concept 18-1 The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.
The Atmosphere Consists of Several Layers
Atmosphere varies in• Density• Atmospheric pressure
Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate
Troposphere • 75–80% of the earth’s air mass• Closet to the earth's surface• Chemical composition of air• Rising and falling air currents: weather and
climate• Involved in chemical cycling
The Stratosphere Is Our Global Sunscreen
Stratosphere• Similar composition to the troposphere, with 2
exceptions• Much less water• O3, ozone layer, filters UV
• Location
Fig. 18-3, p. 470
Atmospheric pressure (millibars)
120
Temperature
750 200 400 600 800 1,000
110Thermosphere 65
100
90Mesopause 55
80
70Mesosphere 45
60 Stratopause 3550
Alti
tude
(mile
s)
Alti
tude
(kilo
met
ers)
40
25Stratosphere
30 Tropopause
20 Ozone layer 15
10 Pressure Troposphere 5(Sea level)0
–80 –40 0 40 80 120Temperature (˚C)
Pressure = 1,000 millibars at ground level
18-2 What Are the Major Outdoor Pollution Problems?
Concept 18-2 Pollutants mix in the air to form industrial smog, mostly the result of burning coal, and photochemical smog, caused by motor vehicle, industrial, and power plant emissions.
Air Pollution Comes from Natural and Human Sources (1)
Air pollution
Natural sources• Dust blown by wind• Pollutants from wildfires and volcanoes• Volatile organics released by plants • Withdrawing groundwater
Case Study: Air Pollution in the Past: The Bad Old Days (1)
Discovery of fire
Middle Ages
Industrial Revolution
London, England• 1850s• 1952: yellow fog• 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
Some Pollutants in the Atmosphere Combine to Form Other Pollutants
Primary pollutants
Secondary pollutants
Air quality improving in developed countries
Much more needs to be done in developing countries• Indoor pollution: big threat to the poor
Fig. 18-4, p. 472
Primary Pollutants
CO CO2Secondary Pollutants
SO2 NO NO2
Most hydrocarbons SO3
Most suspended particles HNO3 H2SO4
H2O2 O3 PANs
Sources Natural Stationary
Mobile
Most NO3− and SO4
2− salts
What Are the Major Outdoor Air Pollutants? (1)
Carbon oxides • Carbon monoxide (CO)• Carbon dioxide (CO2) • Sources • Human health and environmental impact
What Are the Major Outdoor Air Pollutants? (2)
Nitrogen oxides (NO) and nitric acid (HNO3)• Sources• Acid deposition• Photochemical smog• Human health and environmental impact
Sulfur dioxide (SO2) and sulfuric acid (H2SO4)• Sources• Human health and environmental impact
What Are the Major Outdoor Air Pollutants? (3)
Particulates• Suspended particulate matter (SPM)• Fine• Ultrafine
• Sources
• Human health and environmental impact
What Are the Major Outdoor Air Pollutants? (4)
Ozone (O3)• Sources• Human and environmental impact
Volatile organic compounds (VOCs)• Hydrocarbons and terpenes• Sources• Human and environmental impact
Chemical Reactions That Form Major Outdoor Air Pollutants
Statue Corroded by Acid Deposition and Other Forms of Air Pollution, RI, U.S.
Science Focus: Detecting Air Pollutants
Chemical instruments
Satellites
Nanotechnology
Biological indicators• Lichens
Natural Capital: Lichen Species, Vulnerability to Air Pollutants
Case Study: Lead Is a Highly Toxic Pollutant (1)
Does not break down in the environment
Sources
Human health and environmental impact• Most vulnerable
Case Study: Lead Is a Highly Toxic Pollutant (2)
Reduction of lead (Pb)• Unleaded gasoline• Unleaded paint
Still problems• 2007: toys with Pb paint recalled• Global ban on lead in gasoline and paint
Fig. 18-7, p. 476
SOLUTIONS
Lead PoisoningPrevention ControlPhase 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 apartmentsBan use of lead solderSharply 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
Reduction of this smog in urban cities of the United States
China and smog• Human deaths
Fig. 18-8, p. 476
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
Sunlight Plus Cars Equals Photochemical Smog
Photochemical Smog• Chemical composition• Sources
VOCs + NO2 + Heat + Sunlight yields• Ground level O3 and other photochemical oxidants• Aldehydes• Other secondary pollutants
Human health and environmental impact
Fig. 18-9, p. 477
PANS and other pollutantsVolatile organic compounds (VOCs)
Ozone (O3)
Oxygen (O2)Nitric oxide (NO)
+ Oxygen atom (O)Water vapor (H2O)
Hydrocarbons UV radiationPeroxyacyl nitrates (PANs) Nitrogen dioxide (NO2)
Oxygen (O2)
Nitric oxide (NO)
Oxygen (O2)
Nitrogen (N) in fossil fuel
Burning fossil fuels
Global Outlook: Photochemical Smog in Santiago, Chile
Denver’s Brown Cloud:http://www.infrastructurist.com/wp-content/uploads/brown-cloud.jpg
Several Factors Can Decrease or Increase Outdoor Air Pollution (1)
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 (2)
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
Fig. 18-11, p. 478
Warmer air Descending warm air mass
Inversion layer Inversion layer
Sea breezeIncreasing altitude
Decreasing temperature
18-3 What Is Acid Deposition and Why Is It a Problem?
Concept 18-3 Acid deposition is caused mainly by coal-burning power plant and motor vehicle emissions, and in some regions, threatens human health, aquatic life and ecosystems, forests, and human-built structures.
Acid Disposition Is a Serious Regional Air Pollution Problem
Acid deposition, acid rain• Formation• Local versus regional problems• Effects of prevailing winds• Buffers• Where is the worst acid deposition?
Fig. 18-12, p. 479
WindTransformation 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 depostion (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 shallow soil low in limestone become acidic
Lakes in deep soil high in limestone are buffered
Fig. 18-13, 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)
Acid Deposition Has a Number of Harmful Effects (1)
Human respiratory disorders
Aquatic ecosystems affected
Release of toxic metals
Acid Deposition Has a Number of Harmful Effects (2)
Leaching of soil nutrients
Loss of crops and trees
Damage to buildings, statues, and monuments
Fig. 18-14a, p. 481
Emissions
SO2 H2O2 PANs
NOxAcid depositionO3 Others
Direct damage to leaves and bark
Reduced photosynthesis and growth
Increased susceptibility to drought, extreme cold, insects, mosses, and disease organisms
Soil acidification Tree death
Leaching of soil nutrients
Release of toxic metal ions
Root damage Reduced nutrient and water uptakeAcids
Lake
Groundwater
Science Focus: Hubbard Brook Study Effects of Acid Rain
White Mountains, NH, U.S.
Experimentation supports:• Trees do not suffer from direct contact with acid
rain• Nutrients are leached out of the soil• Effect of Ca2+ on regrowth of the forest
We Know How to Reduce Acid Deposition
Prevention approaches
Clean up• Add lime to neutralize acidified lakes and soil• Add phosphate fertilizer to neutralize acidified
lakes
Fig. 18-15, p. 483
SOLUTIONS
Acid DepositionPrevention Cleanup
Add lime to neutralize acidified lakes
Reduce coal use
Burn low-sulfur coal
Add phosphate fertilizer to neutralize acidified lakes
Increase natural gas use
Increase use of renewable energy resources
Remove SO2 particulates and NOx from smokestack gasesRemove NOx from motor vehicular exhaust
Tax emissions of SO2
Reduce air pollution by improving energy efficiency
Indoor Air Pollution
18-4 What Are the Major Indoor Air Pollution Problems?
Concept 18-4 The most threatening indoor air pollutants are smoke and soot from wood and coal cooking fires (a hazard found mostly in developing countries) and chemicals used in building materials and products.
Indoor Air Pollution Is a Serious Problem (1)
Developing countries• Indoor burning• Poor suffer the greatest risk
Developed countries• Indoor air pollution is greater than outdoor air
pollution
Indoor Air Pollution Is a Serious Problem (2)
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 (3)
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 (4)
Four most dangerous indoor air pollutants• Tobacco smoke• Formaldehyde• Radioactive radon-222 gas• Very small particles
Sources of these pollutants
Human health risks
Indoor Air Pollution Is a Serious Problem (5)
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
Sick-building syndrome
Some Important Indoor Air Pollutants
Science: Magnified View of a Household Dust Mite in a Dust Ball
Case Study: Radioactive Radon Gas
Sources
Human health risks
Testing for radon
Correcting a radon problem
Fig. 18-18, p. 485
Outlet vents for furnaces and dryers
Openwindow
Cracks in wallOpenings around pipes
Slab joints
Wood stoveCracks in floor Sump
pumpFurnaceClothes dryer
Slab Radon-222 gas
Uranium-238
Soil
18-5 What Are the Health Effects of Air Pollution?
Concept 18-5 Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.
Your Body’s Natural Defenses against Air Pollution Can Be Overwhelmed
Respiratory system protection from air pollutants• Role of cilia, mucus, sneezing, and coughing
Effect of smoking and prolonged air pollution exposure• Chronic bronchitis• Emphysema
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
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 How Should We Deal with Air Pollution?
Concept 18-6 Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution.
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)
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 (1)
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 O3 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
Is 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• SO2 emissions down significantly
• NO2 will be tried in the future
There Are Many Ways to Reduce Outdoor Air Pollution
1980 –2006• SO2 emissions from U.S. electric power plants
decreased by 66%• NOx emissions by 41%• Particulate emissions by 28%
Older plants not governed by the same regulations
New cars have better emissions
Fig. 18-22, p. 491
SOLUTIONS
Stationary Source Air Pollution
Prevention
Burn low-sulfur coal Disperse emissions above thermal inversion layer with tall smokestacksRemove sulfur from
coal
Remove pollutants after combustionConvert coal to a
liquid or gaseous fuel
Shift to less polluting energy sources
Tax each unit of pollution produced
Dispersion or Cleanup
Fig. 18-23, p. 491
SOLUTIONS
Motor Vehicle Air Pollution
Prevention CleanupUse mass transit Require emission
control devicesWalk or bike
Use less polluting fuels
Improve fuel efficiency
Inspect car exhaust systems twice a year
Get older, polluting cars off the road
Give large tax write- offs or rebates for buying low-polluting, energy efficient vehicles
Set strict emission standards
Reducing Indoor Air Pollution Should Be a Priority
Greater threat to human health than outdoor pollution
What can be done? • Prevention• Cleanup
Fig. 18-24, p. 492
SOLUTIONS
Indoor Air PollutionPrevention Cleanup or DilutionClean ceiling tiles and line AC ducts to prevent release of mineral fibers
Use adjustable fresh air vents for work spaces
Ban smoking or limit it to well-ventilated areas Increase intake of outside
air
Change air more frequently
Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Circulate a building’s air
through rooftop greenhousesPrevent radon
infiltration
Use efficient venting systems for wood-burning stoves
Use office machines in well-ventilated areas
Use less polluting substitutes for harmful cleaning agents, paints, and other products
Use exhaust hoods for stoves and appliances burning natural gas
What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure
We Need to Put More Emphasis on Pollution Prevention
Output approaches
New shift to preventing outdoor and indoor pollution• Pressure from citizens
Fig. 18-26, p. 493
SOLUTIONS
Air PollutionOutdoor IndoorImprove energy efficiency to reduce fossil fuel use
Reduce poverty
Distribute cheap and efficient cookstoves or solar cookers to poor families in developing countries
Rely more on lower-polluting natural gas
Rely more on renewable energy (especially solar cells, wind, and solar-produced hydrogen)
Reduce or ban indoor smoking
Transfer energy efficiency, renewable energy, and pollution prevention technologies to developing countries
Develop simple and cheap tests for indoor pollutants such as particulates, radon, and formaldehyde