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Ch 19 Acid Rain
Acid rain
Outdoor/ Indoor Pollution
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).
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 and an ocean on the other (right)
are susceptible to inversions.
Figure 19-5
Descending warm air mass
Warmer air
Inversion layer
Inversion layer
Sea breeze
Increasing
altitude
Decreasing
temperature
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VIDEO
Fig. 19-5, p. 447
ACID DEPOSITION
• Sulfur dioxides, nitrogen oxides, and
particulates can react in the atmosphere to
produce acidic chemicals that can travel long
distances before returning to the earth’s
surface.
– Tall smokestacks reduce local air pollution but can
increase regional air pollution.
Animation: Acid Deposition
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ANIMATION
ACID DEPOSITION
• Acid deposition consists of rain, snow, dust, or
gas with a pH lower than 5.6.
Figure 19-6
Wind
Transformation to
sulfuric acid (H2SO4)
and nitric acid
(HNO3)
Nitric oxide (NO)
Windborne ammonia gas and
particles of cultivated soil partially
neutralize acids and form dry
sulfate and nitrate salts
Sulfur dioxide
(SO2) and NO
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)
Acid fog
Farm
Ocean
Lakes in deep soil
high in limestone
are buffered
Lakes in shallow soil
low in limestone
become acidic
Fig. 19-6, p. 448
ACID DEPOSITION
• pH measurements in relation to major coalburning and industrial plants.
Figure 19-7
ACID DEPOSITION
• Acid deposition contributes to chronic
respiratory disease and can leach toxic metals
(such as lead and mercury) from soils and
rocks into acidic lakes used as sources for
drinking water.
ACID DEPOSITION
Figure 19-8
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
Emissions
SO2
Acid H O
2 2
deposition
PANs
NOx
O3
Others
Reduced
photosynthesis and
growth
Direct damage to
leaves & bark
Tree death
Soil acidification
Leaching
of soil
nutrients
Acids
Susceptibility
to drought,
extreme cold,
insects,
mosses, &
disease
organisms
Release of
toxic metal
ions
Root
damage
Reduced nutrient &
water uptake
Lake
Groundwater
Fig. 19-9, p. 451
Animation: Effects of Air Pollution in Forests
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ANIMATION
Solutions
Acid Deposition
Prevention
Reduce air pollution by
improving energy
efficiency
Cleanup
Add lime to
neutralize acidified
lakes
Reduce coal use
Increase natural gas
use
Increase use of renewable
energy resources
Add phosphate
fertilizer to
neutralize acidified
lakes
Burn low-sulfur coal
Remove SO2 particulates
& NOx from smokestack
gases
Remove NOx from motor
vehicular exhaust
Tax emissions of SO2
Fig. 19-10, p. 452
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.
– Radioactive radon-222 gas.
– Very small fine and ultrafine particles.
Chloroform
Para-dichlorobenzene
Tetrachloroethylene
Formaldehyde
1, 1, 1Trichloroethane
Styrene
Nitrogen
Oxides
Benzo-a-pyrene
Particulates
Tobacco
Smoke
Asbestos
Carbon Monoxide
Radon-222
Methylene Chloride
Fig. 19-11, p. 453
Interactive Home
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ANIMATION
PVC Exposure
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VIDEO
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
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VIDEO some people.
Figure 19-12
Case Study: Radioactive Radon
• Radon-222, a
radioactive gas
found in some soils
and rocks, can seep
into some houses
and increase the risk
of lung cancer.
Sources and paths of entry
for indoor radon-222 gas.
Figure 19-13
Outlet vents for furnaces and dryers
Open
window
Openings
Cracks in
around
wall
pipes
Slab joints
Wood stove
Clothes
dryer
Furnace
Radon-222
gas
Cracks in floor
Sump
pump
Uranium-238
Soil
Fig. 19-13, p. 454
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
Epithelial cell
Cilia
Goblet cell
(secreting
mucus)
Nasal cavity
Oral cavity
Pharynx (throat)
Mucus
Trachea (windpipe)
Bronchioles
Bronchus
Alveolar
duct
Right lung
Alveolar sac
(sectioned)
Alveoli
Bronchioles
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VIDEO
Fig. 19-14, p. 455
HEALTH EFFECTS OF AIR POLLUTION
Normal human lungs (left) and the lungs of a
person who died of emphysema (right).
Figure 19-15
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.
Air Pollution is a Big Killer
• Spatial distribution of premature deaths from air
pollution in the United States.
Figure 19-16
Video: Air Pollution in China
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VIDEO
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