Air Pollution
Chapter 18
Core Case Study: South Asia’s
Massive Brown Cloud
 Asian Brown Cloud
• Causes• Dust, smoke ash from drought and clearing/burning forests
• Acidic compounds from burning coal, diesel and other fossil
fuels, soot, toxic metals organic compounds and fly ash
• Areas impacted-India, Bangladesh, industrial China, open
sea east of the area
 Air pollution connects the world--pollution is tracked to
other parts of world
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.
 Atmosphere varies in
• Temperature
• Density- most dense at ground level
• Atmospheric pressure-decreases with altitude
 Layers of Atmosphere
Troposphere
Stratosphere
Mesophere
Thermosphere
Natural Capital: The Earth’s Atmosphere
Is a Dynamic System with Four Layers
Layers of the Atmosphere (1)
 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
 Stratosphere
• Similar composition to the troposphere, with 2 exceptions
• Much less water
• O3, ozone layer, filters UV
• Location
Layers of Atmosphere (2)
 Mesosphere
• 48-80km (30-50 Mi)
• Few molecules here
• Temp drops with increasing altitude
 Thermosphere
• 80+ km (50+ miles)
• UV absorbed and converted to heat so temp increases
with altitude
Greenhouse Effect
Greenhouse Gases
 H2O: most prevalent
 CO2: only 7% of CO2 comes from human
activities--but we are making an impact!
 CH4: very potent as a gg (21x greater than CO2)
• 1/3 from natural sources: plants, wetlands,
termites
• 2/3 from humans: rice paddies, landfill
(decomposition), oil/gas wells, cows (belching)
 N2O: fertilizers, animal wastes, burning fossil
fuels (270x more potent than CO2)
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
 Air pollution
 Natural sources
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•
•
•
Dust blown by wind
Pollutants from wildfires and volcanoes
Volatile organics released by plants
Withdrawing groundwater
 Human sources: mostly in industrialized and/or urban
areas
• Stationary sources
• Mobile sources
Case Study: Air Pollution in the Past:
The Bad Old Days
 Discovery of fire
 Middle Ages
 Industrial Revolution
 London, England
• 1850s
• 1952: yellow fog
• Clean Air Act of 1956
 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: emitted directly into
troposphere
 Secondary pollutants: React with something in
troposphere to form pollutant
 Air quality improving in developed countries
 Much more needs to be done in developing
countries
• Indoor pollution: big threat to the poor
Sources and Types of Air Pollutants
What Are the Major Outdoor Air
Pollutants? (1)
 Carbon oxides
• Carbon monoxide (CO) and Carbon dioxide (CO2)
• Sources -car exhaust, burning forests, smoke
• Human health and environmental impact-impairs ability of
blood to carry oxygen
 Nitrogen oxides (NO) and nitric acid (HNO3)
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•
•
•
Sources-auto engines, coal-burning plants, lightning (NO)
Acid deposition-Forms HNO3 in air
Photochemical smog-NO/HNO3 in sunlight
Human health and environmental impact - irritates eyes,
nose, throat, lungs, suppress plant growth
 Sulfur dioxide (SO2) and sulfuric acid (H2SO4)
• Sources- natural part of sulfur cycle, burning coal. industry
• Human health and environmental impact- Acid deposition,
reduce visibility, aggravate breathing problems
What Are the Major Outdoor Air
Pollutants? (2)
 Particulates• Suspended particulate matter (SPM)
• Fine- ave. diameter <10 micrometers
• Ultrafine <2.5 micrometers
• Sources-coal-burnign power, industry, vehicles,
plowed fields, construction, smoke
• Human health and environmental impact- irritate
lung/throat, toxins can cause mutations (lead, PCBs)
 Ozone (O3)- “bad” troposphere; “good” stratosphere
• Sources- phorochemical smog
• Human and environmental impact-breathing issues
 Volatile organic compounds (VOCs)
• Hydrocarbons
• Sources-plants, wetlands, rice paddies, landfills, cows
• Human and environmental impact- dizziness, death
Chemical Reactions That Form Major
Outdoor Air Pollutants
Case Study: Lead Is a Highly
Toxic Pollutant
 Does not break down in the
environment
 Sources
 Human health and
environmental impact
• Most vulnerable
 Reduction of lead (Pb)
• Unleaded gasoline
• Unleaded paint
 Still problems
• 2007: toys with Pb paint
recalled
• Global ban on lead in
gasoline and paint
Burning Coal Produces Industrial Smog
 Chemical composition of industrial smog (Gray
Air Smog)
• Suspended particles + SO2 or H2SO4 from burning coal
and oil
 Reduction of this smog in urban cities of the
United States - rarely a problem today
 China and smog: Huge amounts of Ind. Smog
• Human deaths
How Pollutants Are Formed from Burning
Coal and Oil, Leading to Industrial Smog
Sunlight Plus Cars Equals
Photochemical Smog
 Photochemical Smog- Brown Air Smog
• Chemical composition:
mix of primary and secondary pollutants
• Sources- vehicle exhaust + sun+ VOCs from trees or cars
 VOCs + NO2 + Heat + Sunlight yields
• Ground level O3 and other photochemical oxidants
• Aldehydes• Other secondary pollutants-
 Human health and environmental impact- respiratory
irritation
A Model of How Pollutants That Make Up
Photochemicals Are Formed
Animation: Formation of photochemical
smog
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
 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
Animation: Thermal inversion and smog
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 deposition, acid rain
• Formation-SO2/NOx combine with water
• Local versus regional problems
• Taller stacks: reduce local/increase regional pollution
downwind
• Effects of prevailing winds greater problem in East
• Buffers-CaCO3 soil neutralizes
• Less than pH 5.6 is acid; US average 4.5; Eastern forests
can be 2.3
Natural Capital Degradation: Acid
Deposition, Acid Rain
Current and Possible Future Acid Rain
Problem Areas
Acid Deposition Has a Number of
Harmful Effects
 Human respiratory disorders- bronchitis, asthma
 Aquatic ecosystems affected-kills fish (esp. below 4.5)
• acid shock: runoff of acid rain into water system (snow
melt/spring rain)
• Aluminum toxicity: AL ions released into lake from soils –
asphyxiate fish (causes too much mucus in gills)
 Release of toxic metals-—(Lead, copper) from water pipes
to contaminate drinking water.
Al, Pb, Cd, Hg: dissolved from soil and released: TOXIC
 Leaching of soil nutrients-1st can add N and S to soil to
stimulate plant growth BUT then acids leach essential plant
nutrients
 Loss of crops and trees- Weakens Trees (Synergistic Effect
between acid and ozone)
 Damage to buildings, statues, and monuments
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
Active Figure: Acid deposition
Active Figure: Effect of air pollution in
forests
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
 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 (2)
 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
 Four most dangerous indoor
air pollutants
• Tobacco smoke
• Formaldehyde
• furniture stuffing, paneling,
foam insulation,
particleboard
• Radioactive radon-222
• naturally occurring
radioactive gas made by
decay of U_238
• Seeps into house through
foundation from rocks
• Very small particles
• burning creates soot
• Developing countries: lots of
indoor fires for heat, cooking
Indoor Air Pollution Is a Serious
Problem (3)
 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
Case Study: Radioactive Radon Gas
 Sources
 Human health risks
 Testing for radon
 Correcting a radon
problem
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.
 Respiratory system protection from air pollutants
• Role of cilia, mucus, sneezing, and coughing
 Effect of smoking and prolonged air pollution
exposure
• Chronic bronchitis
• Emphysema
Air Pollution Is a Big Killer
 3 Million deaths per year
world-wide
• Mostly in Asia
• Main causes-indoor
pollution
 US: Diesel fumes lead to
cancer
• EPA: proposed stricter
emission standards for
diesel-powered vehicles
Premature Deaths from Air
Pollution in the U.S.
 Link between international
trade and air pollution• Cargo ships: diesel fuel
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
 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)
 Good news in U.S.
• Decrease in emissions
• Use of low-sulfur diesel fuel
• Cuts pollution
 Developing countries
• More air pollution
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
Solutions: Stationary Source Air
Pollution
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
Solutions: Indoor Pollution, Prevention
and Cleanup or Dilution
 Greater threat to human
health than outdoor
pollution
 What can be done?
• Prevention
• Cleanup
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