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

Fig. 18-3, p. 470

Atmospheric pressure (millibars)

120

Temperature

750 200 400 600 800 1,000

110

Thermosphere 65100

90Mesopause 55

80

70Mesosphere 45

60 Stratopause35

50

Alt

itu

de

(m

iles

)

Alt

itu

de

(ki

lom

eter

s)

40

25Stratosphere

30 Tropopause

20 Ozone layer15

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

Table 18-1, p. 473

Stepped Art

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

SOLUTIONSLead Poisoning

Prevention 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 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

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 radiation

Peroxyacyl 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

fogLakes 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 deposition O3

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 Deposition

Prevention CleanupAdd 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 stove

Cracks in floor

Sump pumpFurnace

Clothes 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 coalDisperse 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

SOLUTIONSIndoor Air Pollution

Prevention 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 Pollution

Outdoor 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