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Air Pollution
Chapter 18
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
120
Atmospheric pressure (millibars)
1,000
200
400
600
800
75
0
110
100
90
Temperature
Thermosphere
65
Mesopause
55
Mesosphere
70
60
Stratopause
45
35
50
Stratosphere
40
25
30
Tropopause
Ozone layer
20
10 Pressure
(Sea 0
level)
Altitude (miles)
Altitude (kilometers)
80
–80
Troposphere
80
40
–40
0
Temperature (˚C)
120
15
5
Pressure =
1,000 millibars
at ground level
Fig. 18-3, p. 470
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
Primary Pollutants
CO CO2
SO2 NO NO2
Most hydrocarbons
Most suspended particles
Secondary Pollutants
SO3
HNO3 H2SO4
H2O2 O3 PANs
Most NO3− and SO42− salts
Sources
Natural
Stationary
Mobile
Fig. 18-4, p. 472
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
Stepped Art
Table 18-1, p. 473
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
SOLUTIONS
Lead Poisoning
Prevention
Control
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
Ban lead glazing for
ceramicware used to
serve food
Sharply reduce lead
emissions from
incinerators
Remove lead from TV sets
and computer monitors
before incineration or land
disposal
Ban candles with lead
cores
Test for lead in existing
ceramicware used to
serve food
Test blood for lead by
age 1
Test existing candles for
lead
Ban use of lead in
computer and TV
monitors
Wash fresh fruits and
vegetables
Fig. 18-7, p. 476
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
Ammonium sulfate [(NH4)2SO4]
Ammonia (NH3)
Sulfuric acid (H2SO4)
Water vapor (H2O)
Sulfur trioxide (SO 3 )
Carbon monoxide (CO)
and
carbon dioxide (CO2)
Oxygen (O2)
Sulfur dioxide (SO2)
Burning coal and oil
Oxygen (O2)
Sulfur (S) in
coal and oil
Carbon (C) in
coal and oil
Stepped Art
Fig. 18-8, p. 476
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
PANS and other pollutants
Volatile organic
compounds (VOCs)
Ozone (O3)
Oxygen (O2)
Nitric oxide (NO)
+
Oxygen atom (O)
Water
vapor
Hydrocarbons (H O)
UV radiation
2
Peroxyacyl
nitrates
Nitrogen dioxide (NO2)
(PANs)
Oxygen (O2)
Nitric oxide (NO)
Oxygen (O2)
Burning fossil fuels
Nitrogen (N) in fossil fuel
Fig. 18-9, p. 477
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
Descending warm air mass
Warmer air
Inversion layer
Inversion layer
Sea breeze
Increasing
altitude
Decreasing temperature
Fig. 18-11, p. 478
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?
Wind
Transformation to
sulfuric acid (H2SO4)
and nitric acid (HNO3)
Nitric oxide (NO)
Windborne ammonia gas
and some soil particles
partially neutralize acids
and form dry sulfate and
nitrate salts
Sulfur dioxide
(SO2) and NO
Acid
fog
Dry acid deposition
(sulfur dioxide gas and
particles of sulfate and
nitrate salts)
Wet acid depostion
(droplets of H2SO4
and HNO3 dissolved
in rain and snow)
Lakes in shallow
Lakes in deep
soil low in
soil high in
limestone
limestone are
become acidic
buffered
Fig. 18-12, p. 479
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)
Fig. 18-13, p. 480
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
Emissions
SO2 NOx
Acid
HO
deposition 2 2 O3
PANs Others
Direct damage to
leaves and bark
Reduced
photosynthesis
and growth
Tree death
Soil acidification
Leaching
of soil
nutrients
Acids
Release
of toxic
metal ions
Increased
susceptibility to
drought, extreme
cold, insects,
mosses, and
disease organisms
Root
damage
Reduced nutrient
and water uptake
Lake
Groundwater
Fig. 18-14a, p. 481
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
SOLUTIONS
Acid Deposition
Prevention
Cleanup
Reduce coal use
Add lime to
neutralize acidified
lakes
Burn low-sulfur coal
Increase natural gas use
Increase use of
renewable energy
resources
Add phosphate
fertilizer to
neutralize acidified
lakes
Remove SO2
particulates and NOx
from smokestack gases
Remove NOx from motor
vehicular exhaust
Tax emissions of SO2
Reduce air pollution by
improving energy
efficiency
Fig. 18-15, p. 483
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
Outlet vents for furnaces and dryers
Open
window
Cracks in wall
Openings
around pipes
Slab joints
Wood stove
Cracks
Clothes
in floor
Furnace dryer
Sump
pump
Radon-222 gas
Uranium-238
Soil
Fig. 18-18, p. 485
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
SOLUTIONS
Stationary Source Air Pollution
Prevention
Burn low-sulfur coal
Remove sulfur from
coal
Convert coal to a
liquid or gaseous
fuel
Shift to less polluting
energy sources
Dispersion or
Cleanup
Disperse emissions
above thermal
inversion layer with tall
smokestacks
Remove pollutants
after combustion
Tax each unit of
pollution produced
Fig. 18-22, p. 491
SOLUTIONS
Motor Vehicle Air Pollution
Prevention
Use mass transit
Walk or bike
Cleanup
Require
emission
control devices
Use less polluting
fuels
Improve fuel
efficiency
Get older, polluting
cars off the road
Give large tax writeoffs or rebates for
buying low-polluting,
energy efficient
vehicles
Inspect car
exhaust
systems twice
a year
Set strict
emission
standards
Fig. 18-23, p. 491
Reducing Indoor Air Pollution Should
Be a Priority
 Greater threat to human health than outdoor
pollution
 What can be done?
• Prevention
• Cleanup
SOLUTIONS
Prevention
Indoor Air Pollution
Cleanup or Dilution
Clean ceiling tiles and line
AC ducts to prevent
release of mineral fibers
Ban smoking or limit it to
well-ventilated areas
Set stricter formaldehyde
emissions standards for
carpet, furniture, and
building materials
Prevent radon
infiltration
Use office machines in
well-ventilated areas
Use less polluting
substitutes for harmful
cleaning agents, paints,
and other products
Use adjustable fresh air
vents for work spaces
Increase intake of outside
air
Change air more
frequently
Circulate a building’s air
through rooftop
greenhouses
Use efficient venting
systems for woodburning stoves
Use exhaust hoods for
stoves and appliances
burning natural gas
Fig. 18-24, p. 492
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
SOLUTIONS
Air Pollution
Outdoor
Indoor
Improve energy efficiency
to reduce fossil fuel use
Reduce poverty
Rely more on lowerpolluting natural gas
Distribute cheap and
efficient cookstoves or
solar cookers to poor
families in developing
countries
Rely more on
renewable energy
(especially solar cells,
wind, and solarproduced hydrogen)
Transfer energy
efficiency, renewable
energy, and pollution
prevention technologies
to developing countries
Reduce or ban
indoor smoking
Develop simple and
cheap tests for indoor
pollutants such as
particulates, radon, and
formaldehyde
Fig. 18-26, p. 493