Air Pollution

1
Chapter 19

• Air Pollution

2
Core Case Study South Asias Massive Brown Cloud
3
Case Study South Asias Massive Brown Cloud

• A huge dark brown cloud of industrial smog,
  caused by wood fires, cars, and coal-burning in
  countries such as China and India, stretches over
  much of southeastern Asia.
• In areas beneath the cloud, photosynthesis is
  reduced interfering with crop development.
• Fine particles and droplets in the cloud appear
  to be changing regional climates (including
  rainfall).
• May have contributed to floods in 2002 and 2005
  which killed thousands of people in India
  Bangladesh

4
Case Study South Asias Massive Brown Cloud
5
Case Study South Asias Massive Brown Cloud
China
6
Case Study South Asias Massive Brown Cloud
India
7
Chapter Overview Questions

• What layers are found in the atmosphere?
• What are the major outdoor air pollutants, and
  where do they come from?
• What are two types of smog?
• What is acid deposition, and how can it be
  reduced?
• What are the harmful effects of air pollutants?
• How can we prevent and control air pollution?

8
Case Study When Is a Lichen Like a Canary?

• Lichens can warn us of bad air because they
  absorb it as a source of nourishment.

Figure 19-1
9
Core Case Study When Is a Lichen Like a Canary?

• Some lichen species are sensitive to specific
  air-polluting chemicals.
• After the Chernobyl nuclear power plant explosion
  (1986), more than 70,000 reindeer had to be
  killed because they ate highly radioactive
  lichens.
• Because lichens are widespread, long-lived, and
  anchored in place, they can help track pollution
  to its source.

10
STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• The atmosphere consists of several layers with
  different temperatures, pressures, and
  compositions.

Figure 19-2
11

Atmospheric pressure (millibars)
Temperature
Exosphere
Pressure
Thermosphere
Mesopause
Heating via ozone
Mesosphere
Altitude (miles)
Altitude (kilometers)
Stratopause
Stratosphere
Tropopause
Ozone layer
Heating from the earth
Troposphere
Pressure 1,000 millibars at ground level
(Sea level)
Temperature (C)
Fig. 19-2, p. 440
12
STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• The atmospheres innermost layer (troposphere) is
  made up mostly of nitrogen (78) and oxygen
  (21), with smaller amounts of argon (0.93) and
• CO2 (0.038 380 ppm), plus 0.01 to 4 water
  vapor.
• Ozone (03) in the atmospheres second layer
  (stratosphere) filters out 95 of the suns UV
  radiation that is harmful to us and most other
  species.

13
AIR POLLUTION

• Some primary air pollutants may react with one
  another or with other chemicals in the air to
  form secondary air pollutants (see below).

Figure 19-3
14

Primary Pollutants
Secondary Pollutants
CO
CO2
SO2
(NO NO2)
NOx
SO3
3 Sources
Most hydrocarbons
H2SO4
HNO3
Most suspended particles
H2O2
O3
PANs
Natural
Most NO3 and SO42 salts
Stationary
Mobile
Fig. 19-3, p. 442
15
Major Air Pollutants

• Carbon oxides
• Carbon monoxide (CO) is a highly toxic gas that
  forms during the incomplete combustion of
  carbon-containing materials (such as?)
• 93 of carbon dioxide (CO2) in the troposphere
  occurs as a result of the natural carbon cycle.
• 7 of CO2 in the troposphere occurs as a result
  of human activities (mostly burning fossil
  fuels).
• It is not regulated as a pollutant under the U.S.
  Clean Air Act.

16
Carbon Dioxide

• CO2 Concentration
• 280 ppm prior to the Industrial Revolution
• (about 275 years ago)
• 384 ppm in 2007
• Increasing exponentially, currently by 2 ppm per
  year

17
Major Air Pollutants

• Nitrogen oxides and nitric acid
• Nitric oxide (NO) forms when nitrogen and oxygen
  gas in air react at the high-combustion
  temperatures in automobile engines and
  coal-burning plants. NO can also form from
  lightning and certain soil bacteria.
• NO reacts with O2 in the air to form NO2.
• NO2 reacts with water vapor in the air to form
  nitric acid (HNO3) and nitrate salts (NO3-) which
  are components of acid deposition.
• Together, NO (primary) and NO2 (secondary) are
  generically labeled as NOx

18
Major Air Pollutants

• Sulfur dioxide (SO2) and sulfuric acid
• About one-third of SO2 in the troposphere occurs
  naturally through the sulfur cycle.
• Two-thirds come from human sources, mostly
  combustion of sulfur-containing coal
• (S O2 ? SO2) and from oil refining and smelting
  of sulfide ores.
• SO2 in the atmosphere can be converted to
  sulfuric acid (H2SO4) and sulfate salts (SO42-)
  that return to earth as a component of acid
  deposition.

19
Major Air Pollutants

• Suspended particulate matter (SPM)
• Consists of a variety of solid particles and
  liquid droplets small and light enough to remain
  suspended in the air.
• The most harmful forms of SPM are fine particles
  (PM-10), with an average diameter lt 10
  micrometers, and ultrafine particles (PM-2.5).

20
Major Air Pollutants

• Suspended particulate matter (SPM)
• According to the EPA, SPM is responsible for
  about 60,000 premature deaths a year in the U.S.
• SPM can irritate nose and throat, damage lungs,
  and aggravate asthma and bronchitis
• Toxic particles of lead, cadmium, and PCBs can
  cause mutations, birth defects, and cancer

21
Major Air Pollutants

• Ozone (O3)
• Is a highly reactive gas that is a major
  component of photochemical smog.
• Ground level ozone is a strong oxidizer and
  damages living tissue when breathed.
• It can
• Cause and aggravate respiratory illness.
• Can aggravate heart disease.
• Damage plants, rubber in tires, fabrics, and
  paints.

22
Major Air Pollutants

• Volatile organic compounds (VOCs)
• Most are hydrocarbons emitted by the leaves of
  many plants, and methane (CH4).
• About two thirds of global methane emissions
  comes from human sources.
• Other VOCs include industrial solvents such as
  trichlorethylene (TCE), benzene, and vinyl
  chloride.
• Long-term exposure to benzene can cause cancer,
  blood disorders, and immune system damage.

23
Major Air Pollutants

• Radon (Rn)
• Radon occurs naturally when Uranium-238 undergoes
  radioactive decay.
• Some types of soil and rock, such as granite, are
  relatively high in U-238
• Radon can seep into homes and buildings sitting
  above these deposits of U-238 containing rocks.

24
URBAN OUTDOOR AIR POLLUTION

• Industrial smog (gray smog) is a mixture of
  sulfur dioxide, droplets of sulfuric acid, and a
  variety of suspended solid particles emitted
  mostly by burning coal.
• In most developed countries where coal and heavy
  oil is burned, industrial smog is not a problem
  due to reasonably good pollution control or with
  tall smokestacks that transfer the pollutant to
  rural areas.

25
Sunlight plus Cars Equals Photochemical Smog

• Photochemical smog is a mixture of air pollutants
  formed by the reaction of nitrogen oxides (NOx)
  and volatile organic hydrocarbons (VOCs) under
  the influence of sunlight.

26
Sunlight plus Cars Equals Photochemical Smog

• Mexico City is one of the many cities in sunny,
  warm, dry climates with many motor vehicles that
  suffer from photochemical smog.

Figure 19-4
27
Factors Influencing Levels of Outdoor Air
Pollution

• Outdoor air pollution can be reduced by
• settling out, precipitation, sea spray, winds,
  and chemical reactions.
• Outdoor air pollution can be increased by
• urban buildings (slow wind dispersal of
  pollutants), mountains (promote temperature
  inversions), and high temperatures (promote
  photochemical reactions).

28
Temperature Inversion
Smoke rising in Lochcarron, Scotland is stopped
by an overlying layer of warmer air.
29
Temperature Inversion
30

Descending cold air mass
Cooler air
Inversion layer
Inversion layer
Sea breeze
Increasing altitude
Decreasing temperature
Denver Cold, cloudy, surrounded by mountains
LA Hot, sunny, ocean on one side, mountains on 3
other sides
Fig. 19-5, p. 447
31
Temperature Inversions

• Cold, cloudy weather in a valley surrounded by
  mountains can trap air pollutants (left).
• Areas with sunny climate, light winds, mountains
  on three sides an ocean on the other (right)
  are also susceptible to inversions.

Figure 19-5
32
ACID DEPOSITION
These trees look bad, but
33
ACID DEPOSITION

• the worst threat of acid deposition is to human
  health, when toxic metals such as lead mercury
  are leached from soils into the water supply,
  where they threaten
• Drinking water
• Food supplies via biomagnification

34
ACID DEPOSITION

• Primary pollutants Sulfur dioxides (SO2),
  nitrogen oxides (NOx), and particulates can react
  in the atmosphere to produce
• Secondary pollutants acidic chemicals that can
  travel long distances before returning to the
  earths surface.
• H2SO4, HNO3, and SO42- and NO3- salts
• Tall smokestacks reduce local air pollution but
  can increase regional air pollution.

35
ACID DEPOSITION

• Acid deposition consists of rain, snow, dust,
  fog, dew, or gas with a pH lower than 5.6.

Figure 19-6
36

Wind
Transformation to sulfuric acid (H2SO4) and
nitric acid (HNO3)
Windborne ammonia gas and particles of cultivated
soil 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
Farm
Lakes in shallow soil low in limestone become
acidic
Ocean
Lakes in deep soil high in limestone are buffered
Fig. 19-6, p. 448
37
ACID DEPOSITION

• pH measurements in relation to major coal-burning
  and industrial plants.

Figure 19-7
38
Effects of Acid Deposition
Dead or Severely Damaged Forests and
Lakes, (especially in the Northeast US and Canada)
39
More Acid Deposition Damage
40
H2SO4
Sulfuric Acid
Nitric Acid
HNO3
SO2
NOx
41
Acid Rain in the US
42
Specific Effects of Acid Deposition in a Vermont
Lake
43
Acid Deposition in Western Europe
44
Effects of Acid Rain on Stone Sculpture
45
This photo, from 1910, shows the effect of 400
years of weathering on a grotesque which
decorates Lincoln Cathedral in England.
In 1984, only 74 years later, acid rain and other
atmospheric pollution have worn the figure to a
barely recognizable remnant.
46
ACID DEPOSITION

• Contributes to chronic respiratory disease
• Can leach toxic metals (such as lead and mercury)
  from soils and rocks into acidic lakes used as
  sources for drinking water.

47
ACID DEPOSITION
Figure 19-8
48
ACID DEPOSITION

• Air pollution is one of several interacting
  stresses that can damage, weaken, or kill trees
  and pollute surface and groundwater.

Figure 19-9
49

Emissions
SO2
NOx
Acid deposition
H2O2
O3
Others
PANs
Susceptibility to drought, extreme cold, insects,
mosses, disease organisms
Reduced photo-synthesis and growth
Direct damage to leaves bark
Soil acidification
Tree death
Root damage
Reduced nutrient water uptake
Leaching of soil nutrients
Release of toxic metal ions
Acids
Lake
Groundwater
Fig. 19-9, p. 451
50

Solutions
Acid Deposition
Prevention
Cleanup
Reduce air pollution by improving energy
efficiency
Add lime to neutralize acidified
lakes !
Reduce coal use
Increase natural gas use
Add phosphate fertilizer to neutralize acidified
lakes !
Increase use of renewable energy resources
Burn low-sulfur coal
Remove SO2 particulates NOx from smokestack
gases (scrubbers)
Remove NOx from motor vehicular exhaust
Tax emissions of SO2
Fig. 19-10, p. 452
51
INDOOR AIR POLLUTION

• Indoor air pollution usually is a greater threat
  to human health than outdoor air pollution.
• According to the EPA, the four most dangerous
  indoor air pollutants in developed countries are
• Tobacco smoke.
• Formaldehyde (upholstery, paneling, particle
  board, carpet, and foam insulation)
• Radioactive radon-222 gas (natural- must be
  vented)
• Very small fine and ultrafine particles.

52
Para-dichlorobenzene
Chloroform
Formaldehyde
Tetrachloroethylene TCE
1, 1, 1- Trichloroethane
Styrene
Nitrogen Oxides
Benzo-a-pyrene
Particulates
Radon-222
Tobacco Smoke
Asbestos
See p. 484
Methylene Chloride
Carbon Monoxide
53
INDOOR AIR POLLUTION

• Household dust mites that feed on human skin and
  dust, live in materials such as bedding and
  furniture fabrics.
• Can cause asthma attacks and allergic reactions
  in some people.

Figure 19-12
54
Case Study Radioactive Radon

• Radon-222, a radioactive, carcinogenic gas found
  in some soils and rocks, can seep into some
  houses and increase the risk of lung cancer.
• Radon comes from the radiactive decay of
  Uranium-238

Sources and paths of entry for indoor radon-222
gas.
Next
55

Outlet vents for furnaces and dryers
Open window
Openings around pipes
Cracks in wall
Slab joints
Wood stove
Cracks in floor
Clothes dryer
Sump pump
Furnace
Slab
Radon-222 gas
Uranium-238
Soil
Fig. 19-13, p. 454
56
HEALTH EFFECTS OF AIR POLLUTION

• Your respiratory system can help protect you from
  air pollution, but some air pollutants can
  overcome these defenses.

Figure 19-14
57

Epithelial cell
Cilia
Goblet cell (secreting mucus)
Nasal cavity
Oral cavity
Pharynx (throat)
Mucus
Trachea (windpipe)
Bronchioles
Bronchus
Alveolar duct
Right lung
Alveoli
Alveolar sac (sectioned)
Bronchioles
Fig. 19-14, p. 455
58
HEALTH EFFECTS OF AIR POLLUTION

• Normal human lungs (left) and the lungs of a
  person who died of emphysema (right).

59
Air Pollution is a Big Killer

• Each year, air pollution prematurely kills about
  3 million people, mostly from indoor air
  pollution in developing countries.
• In the U.S., the EPA estimates that annual deaths
  related to indoor and outdoor air pollution range
  from 150,000 to 350,000.
• According to the EPA, each year more than 125,000
  Americans get cancer from breathing diesel fumes.

60
Air Pollution is a Big Killer

• Spatial distribution of premature deaths from air
  pollution in the United States.

Figure 19-16
61
PREVENTING AND REDUCING AIR POLLUTION

• The Clean Air Act (1970, 77, 90) in the United
  States have greatly reduced outdoor air pollution
  from six major pollutants
• Carbon monoxide CO
• Nitrogen oxides NOx
• Sulfur dioxides SO2
• Suspended particulate matter (less than PM-10)
• Lead Pb
• Ozone O3

62
PREVENTING AND REDUCING AIR POLLUTION

• Environmental scientists point out several
  deficiencies in the Clean Air Act
• The U.S. continues to rely on cleanup rather than
  prevention.
• The U.S. Congress has failed to increase
  fuel-efficiency standards for automobiles.
• Regulation of emissions from motorcycles and
  two-cycle engines remains inadequate.
• There is little or no regulation of air pollution
  from oceangoing ships in American ports.

63
PREVENTING AND REDUCING AIR POLLUTION-
Deficiencies in the Clean Air Act of 1970

• Airports are exempt from many air pollution
  regulations.
• The Act does not regulate the greenhouse gas CO2.
• The Act has failed to deal seriously with indoor
  air pollution.
• There is a need for better enforcement of the
  Clean Air Act.

64
PREVENTING AND REDUCING AIR POLLUTION

• Executives of companies claim that correcting
  these deficiencies would
• cost too much
• harm economic growth
• and cost jobs.

65
Using the Marketplace to Reduce Outdoor Air
Pollution

• To help reduce SO2 emissions, the Clean Air Act
  authorized an emission trading (cap-and-trade)
  program.
• Enables the 110 most polluting power plants to
  buy and sell SO2 pollution rights.
• Between 1990-2002, the emission trading system
  reduced emissions.
• In 2002, the EPA reported the cap-and-trade
  system produced less emission reductions than
  were projected.

66
Solutions Reducing Outdoor Air Pollution

• There are a number of ways to prevent and control
  air pollution from coal-burning facilities.
• Electrostatic precipitator are used to attract
  negatively charged particles in a smokestack into
  a collector.
• Wet scrubber fine mists of water vapor trap
  particulates and convert them to a sludge that is
  collected and disposed of usually in a landfill.

67

Electrostatic Precipitator
Clean gas out
Positively charged precipitator wall
Negatively charged electrode
Dirty gas (smoke) in
Dust falls off into collector
Taken to landfill
Fig. 19-18a, p. 460
68
Electrostatic Precipitator

• Can remove 99 of particulate matter
• Does not remove hazardous ultrafine particles.
• Produces toxic dust that must be safely disposed
  of.
• Uses large amounts of electricity

Figure 19-18
69

Clean gas out
Wet Scrubber
Separator
Liquid water in
Dirty gas (smoke) in
Polluted liquid (sludge) out
Fig. 19-18b, p. 460
70
Wet Scrubber

• Can remove 98 of SO2 and particulate matter.
• Not very effective in removing hazardous fine and
  ultrafine particles.

Figure 19-18
71

Solutions
Stationary Source Air Pollution
Prevention
Dispersion or Cleanup
Burn low-sulfur coal
Disperse emissions above thermal inversion layer
with tall smokestacks
Remove sulfur from coal
Remove pollutants after combustion
Convert coal to a liquid or gaseous fuel
Tax each unit of pollution produced
Shift to less polluting fuels
Fig. 19-17, p. 459
72
Solutions Reducing Outdoor Air Pollution

• In 2003, fourteen states and a number of U.S.
  cities sued the EPA to block new rules that would
  allow older coal-burning power plants to
  modernize without having to install the most
  advanced air pollution controls.

73
Solutions Reducing Outdoor Air Pollution

• There are a number of ways to prevent and control
  air pollution from motor vehicles.
• Because of the Clean Air Act, a new car today in
  the U.S. emits 75 less pollution than did
  pre-1970 cars.
• There is an increase in motor vehicle use in
  developing countries and many have no pollution
  control devices and burn leaded gasoline.

74

Solutions
Motor Vehicle Air Pollution
Prevention
Cleanup
Emission control devices
Mass transit
Bicycles and walking
Less polluting engines
Less polluting fuels
Car exhaust inspections twice a year
Improve fuel efficiency
Get older, polluting cars off the road
Give buyers large tax write-offs or rebates for
buying low-polluting, energy efficient vehicles
Stricter emission standards
Fig. 19-19, p. 460
75
Indoor Air Pollution

• Little effort has been devoted to reducing indoor
  air pollution even though it poses a much greater
  threat to human health than outdoor air
  pollution.
• Environmental and health scientists call for us
  to focus on preventing air pollution (especially
  indoor) in developing countries.

76

Solutions
Indoor Air Pollution
Cleanup or Dilution
Prevention
Use adjustable fresh air vents for work spaces
Cover ceiling tiles lining of AC ducts to
prevent release of mineral fibers
Increase intake of outside air
Ban smoking or limit it to well ventilated areas
Change air more frequently
Set stricter formaldehyde emissions standards for
carpet, furniture, and building materials
Circulate a buildings air through rooftop green
houses
Prevent radon infiltration
Use exhaust hoods for stoves and appliances
burning natural gas
Use office machines in well ventilated areas
Install efficient chimneys for wood-burning stoves
Use less polluting substitutes for harmful
cleaning agents, paints, and other products
Fig. 19-20, p. 461
77

What Can You Do?
Indoor Air Pollution
Test for radon and formaldehyde inside your
home and take corrective measures as needed.
Do not buy furniture and other products
containing formaldehyde.
Remove your shoes before entering your house to
reduce inputs of dust, lead, and pesticides.
Test your house or workplace for asbestos fiber
levels and for any crumbling asbestos materials
if it was built before 1980.
Don't live in a pre-1980 house without having
its indoor air tested for asbestos and lead.
Do not store gasoline, solvents, or other
volatile hazardous chemicals inside a home or
attached garage.
If you smoke, do it outside or in a closed room
vented to the outside.
Make sure that wood-burning stoves, fireplaces,
and kerosene- and gas-burning heaters are
properly installed, vented, and maintained.
Install carbon monoxide detectors in all
sleeping areas.
Fig. 19-21, p. 461
78

Solutions
Air Pollution
Outdoor
Indoor
Improve energy efficiency to reduce fossil fuel
use
Reduce poverty
Distribute cheap 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, solar-produced hydrogen)
Reduce or ban indoor smoking
Transfer technologies for latest energy
efficiency, renewable energy, pollution
prevention to developing countries
Develop simple and cheap tests for indoor
pollutants such as particulates, radon, and
formaldehyde
Fig. 19-22, p. 462
79
Updates Online

• The latest references for topics covered in this
  section can be found at the book companion
  website. Log in to the books e-resources page at
  www.thomsonedu.com to access InfoTrac articles.
• InfoTrac Indoor air pollution. Eva Rehfuess,
  Carlos Corvalan, Maria Neira. Bulletin of the
  World Health Organization, July 2006 v84 i7
  p508(1).
• InfoTrac Risks of cleaning house disclosed. San
  Jose Mercury News (San Jose, CA), May 23, 2006.
• InfoTrac Pollution From Chinese Coal Casts
  Shadow Around Globe. Keith Bradsher, David
  Barboza. The New York Times, June 11, 2006
  pA1(L).
• American Industrial Hygiene Association Do I
  Work in a Sick Building?
• PBS Deadly Smog
• EPA Toxic Air Pollutants

80
Video Air Pollution

• This video clip is available in CNN Today Videos
  for Environmental Science, 2004, Volume VII.
  Instructors, contact your local sales
  representative to order this volume, while
  supplies last.

81
Video Smog Pollution

• This video clip is available in CNN Today Videos
  for Environmental Science, 2004, Volume VII.
  Instructors, contact your local sales
  representative to order this volume, while
  supplies last.

82
How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access JoinIn Clicker
  Content from the PowerLecture main menu for
  Living in the Environment.
• Should carbon dioxide be regulated as an air
  pollutant?
• a. No. Because funds are limited, they should be
  spent on regulating and reducing more toxic air
  pollutants, such as mercury.
• b. Yes. Carbon dioxide is a serious greenhouse
  gas and its emissions must be regulated and
  reduced.

83
How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access the Polls
  Clicker Questions from the PowerLecture main
  menu.
• Should the 1990 U.S. Clean Air Act be
  strengthened?
• a. No. Strengthening the Act would be too
  expensive and would harm the economy.
• b. Yes. Strengthening the Act would improve the
  environment and people's health, save energy, and
  ultimately save money.

84
How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access the Polls
  Clicker Questions from the PowerLecture main
  menu.
• Should emissions trading be used to help control
  emissions of all major air pollutants?
• a. No. Emissions trading has no system for
  verifying compliance and eliminating "hot spots"
  of air pollution.
• b. Yes. Emissions trading is an efficient and
  effective way of reducing air pollution.

85
How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access JoinIn Clicker
  Content from the PowerLecture main menu for
  Living in the Environment.
• Should older coal-burning power and industrial
  plants have to meet the same air pollution
  standards as new facilities?
• a. No. The private sector should not have to
  upgrade existing facilities every time the
  regulations change.
• b. Yes. All facilities should comply with current
  regulations so that the environment and human
  health are effectively protected.