Air Pollution
G. Tyler Miller’s
Living in the Environment
14th Edition
Chapter 20
Key Concepts
 Structure and composition of the atmosphere
 Types and sources of outdoor air pollution
 Types, formation, and effects of smog
 Sources and effects of acid deposition
 Effects of air pollution
 Prevention and control of air pollution
The Atmosphere
 Troposphere
 78% N, 21% O
 Stratosphere
 Ozone layer
Fig. 20-2 p. 434
40
25
35
25
Stratospheric ozone
15
20
10
15
10
5
Troposphere
5
Photochemical ozone
0
0
5
10
15
Ozone concentration (ppm)
20
0
Altitude (miles)
30
Altitude (kilometers)
20
Stratosphere
Table 20-1 Major Classes of Air Pollutants
Examples
Class
Carbon oxides
Carbon monoxide (CO) and carbon dioxide (CO2)
Sulfur oxides
Sulfur dioxide (SO2) and sulfur trioxide (SO3)
Nitrogen oxides
Nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide
(N2O) (NO and NO2 often are lumped together and labeled
NOx)
Volatile organic compounds (VOCs)
Methane (CH4), propane (C3H8), chlorofluorocarbons (CFCs)
Suspended particulate matter (SPM)
Solid particles (dust, soot, asbestos, lead, nitrate, and sulfate
salts), liquid droplets (sulfuric acid, PCBs, dioxins, and
pesticides)
Photochemical oxidants
Ozone (O3), peroxyacyl nitrates (PANs), hydrogen peroxide
(H2O2), aldehydes
Radon-222, iodine-131, strontium-90, plutonium-239 (Table
3-1, p. 49)
Radioactive substances
Carbon tetrachloride (CCl4), methyl chloride (CH3Cl),
chloroform (CHCl3), benzene (C6H6), ethylene dibromide
Hazardous air pollutants (HAPs), which cause
health effects such as cancer, birth defects, and (C2H2Br2), formaldehyde
nervous system problems
(CH2O2)Table
Primary Pollutants
CO
SO2
CO2
NO
NO2
Most hydrocarbons
Most suspended
particles
Secondary Pollutants
SO3
HNO3
H2O2
H2SO4
O3
PANs
Most NO–3 and SO42
Natural
Sources
Stationary
Mobile
OUTDOOR AIR POLLUTION
–
salts
Table 20-2
Table 20-2 Major Outdoor Air Pollutants
CARBON MONOXIDE (CO)
Description: Colorless, odorless gas that is poisonous to air-breathing animals;
forms during the incomplete combustion of carbon-containing fuels
(2 C + O2
2 CO).
Major human sources: Cigarette smoking incomplete
burning of fossil fuels. About 77% (95% in cities)comes from motor vehicle exhaust.
Health effects: Reacts with hemoglobin in red blood cells and reduces the ability of
blood to bring oxygen to body cells and tissues. This impairs perception and
thinking; slows reflexes; causes headaches, drowsiness, dizziness, and nausea; can
trigger heart attacks and angina; damages the development of fetuses and young
children; and aggravates chronic bronchitis, emphysema, and anemia. At high levels
it causes collapse, coma, irreversible brain cell damage, and death.
Table 20-2
Page 438
NITROGEN DIOXIDE (NO2)
Description: Reddish-brown irritating gas that gives photochemical smog its brownish color;
in the atmosphere can be converted to nitric acid (HNO3), a major component of acid
deposition.
Major human sources: Fossil fuel burning in motor vehicles (49%) and power and industrial
plants (49%).
Health effects: Lung irritation and damage; aggravates asthma and chronic bronchitis;
increases susceptibility to respiratory infections such as the
flu and common colds (especially in young children and older adults).
Environmental effects: Reduces visibility; acid deposition of HNO3 can damage trees, soils,
and aquatic life in lakes.
Property damage: HNO3 can corrode metals and eat away stone on buildings, statues, and
monuments; NO2 can damage fabrics.
Table 20-2
Page 438
Pollutants
SULFUR DIOXIDE (SO2)
Description: Colorless, irritating; forms mostly from the combustion of sulfur containing fossil
fuels such as coal and oil (S + O2
SO2); in the atmosphere
can be converted to sulfuric acid (H2SO4), a major component of acid deposition.
Major human sources: Coal burning in power plants (88%) and industrial processes
(10%).
Health effects: Breathing problems for healthy people; restriction of airways in people with
asthma; chronic exposure can cause a permanent condition similar to bronchitis. According to the
WHO, at least 625 million people are exposed to unsafe levels of sulfur dioxide from fossil fuel
burning.
Environmental effects: Reduces visibility; acid deposition of H2SO4 can damage trees, soils,
and aquatic life in lakes.
Property damage: SO2 and H2SO4 can corrode metals and eat away stone on buildings, statues,
and monuments; SO2 can damage paint, paper, and leather.
Table 20-2
Page 438
Table 20-2 Major Outdoor Air Pollutants
SUSPENDED PARTICULATE MATTER (SPM)
Description: Variety of particles and droplets (aerosols) small and light enough to remain
suspended in atmosphere for short periods (large particles) to long periods
(small particles; Figure 20-6, p. 441); cause smoke, dust, and haze.
Major human sources: Burning coal in power and industrial plants (40%), burning diesel and
other fuels in vehicles (17%), agriculture (plowing, burning off fields), unpaved roads,
construction.
Health effects: Nose and throat irritation, lung damage, and bronchitis; aggravates bronchitis and
asthma; shortens life; toxic particulates (such as lead, cadmium, PCBs, and dioxins) can cause
mutations, reproductive problems, cancer.
Environmental effects: Reduces visibility; acid deposition of H2SO4 droplets can
damage trees, soils, and aquatic life in lakes.
Property damage: Corrodes metal; soils and discolors buildings, clothes, fabrics, and paints.
Table 20-2
Page 438
OZONE (O3)
Description: Highly reactive, irritating gas with an unpleasant odor that forms in the troposphere
as a major component of photochemical smog
Major human sources: Chemical reaction with volatile organic compounds (VOCs, emitted
mostly by cars and industries) and nitrogen oxides to form photochemical smog.
Health effects: Breathing problems; coughing; eye, nose, and throat irritation; aggravates chronic
diseases such as asthma, bronchitis, emphysema, and heart disease; reduces resistance to colds
and pneumonia; may speed up lung tissue aging.
Environmental effects: Ozone can damage plants and trees; smog can reduce visibility.
Property damage: Damages rubber, fabrics, and paints.
Table 20-2
Page 438
Table 20-2 Major Outdoor Air Pollutants
LEAD
Description: Solid toxic metal and its compounds, emitted into the atmosphere as particulate
matter.
Major human sources: Paint old houses), smelters (metal refineries), lead manufacture, storage
batteries, leaded gasoline (being phased out in developed countries).
Health effects: Accumulates in the body; brain and other nervous system damage and mental
retardation (especially in children); digestive and other health problems; some lead-containing
chemicals cause cancer in test animals.
Environmental effects: Can harm wildlife.
Photochemical Smog
 Brown-air
smog
 Photochemical
reaction
 Photochemical
oxidants
Photochemical smog
Solar
radiation
Ultraviolet radiation
NO
Nitric oxide
H2O
Water
NO2
Nitrogen
dioxide
O2
Molecular
oxygen
O
Atomic
oxygen
Hydrocarbons
HNO3
Nitric acid
PANs
Peroxyacyl
nitrates
Aldehydes
(e.g., formaldehyde)
O3
Ozone
Table 1.3: Major Chemical Pollutants in Photochemical Smog:
Sources and Environmental Effects
Table 1.3: Major Chemical
Pollutants in Photochemical
Smog: Sources and
Environmental Effects
Toxic Chemical
Nitrogen Oxides
(NO and NO 2)
Volatile Organic Compounds
(VOCs)
Ozone
(O 3)
Peroxyacetyl Nitrates (PAN)
Sources
Enviromental Effects
Additional Notes
combustion of oil, coal, gas in
decreased visibility due to yellowish
all combustion processes account
both automobiles and industry; color of NO 2; NO 2 contributes to heart
for only 5% of NO 2 in the
bacterial action in soil; forest
and lung problems; NO 2 can suppress atmosphere, most is formed from
fires; volcanic action; lightning
plantgrowth; decreased resistance to
reactions involving NO;
infection; may encourage the spread of concentrations likely to rise in the
cancer
future
evaporation of solvents;
evaporation of fuels; incomplete
combustion of fossil fuels;
naturally occurring compounds
like terpenes from trees
eye irritation; respiratory irritation some are carcinogenic; decreased
visibility due to blue-brown haze
the effects of VOCs are dependent
on the type of chemical; samples
show over 600 different VOCs in
atmosphere; concentrations likely to
continue to rise in future
formed from photolysis of NO 2;
bronchial constriction; coughing,
concentrations of 0.1 parts per
sometimes results from
wheezing; respiratory irritation; eye
million can reduce photosynthesis
stratospheric ozone intrusions irritation; decreased crop yields; retards by 50%; people with asthma and
plant growth; damages plastics; breaks respiratory problems are influenced
down rubber; harsh odour
the most; can only be formed during
daylight hours
formed by the reaction of NO 2
with VOCs (can be formed
naturally in some environments)
eye irritation; high toxicity to plants; was not detected until recognized in
respiratory irritation; damaging to
smog; higher toxicity to plants than
proteins
ozone
Industrial Smog
Industrial smog
Particulates
Sulfur dioxide
Sulfuric acid
Gray-air smog
Fig. 20-6 p. 441
Regional Outdoor Air Pollution from
Acid Deposition
Acid deposition
Wet deposition
Dry deposition
Acid Deposition in the US
Fig. 20-9 p. 445
Water
boatman
Whirligig
Yellow perch
Lake trout
Brown trout
Salamander
(embryonic)
Mayfly
Smallmouth
bass
Mussel
6.5
6.0
5.5
5.0
pH
4.5
4.0
3.5
Figure 17-15
Emission
Page 432
Acid
deposition
SO2
H2 O2
PANs
NOX
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
Leaching of
soil
nutrients
Acid
Tree death
Release of
toxic
metal icons
Root
damage
Reduced
nutrient
and
water
uptake
Acid Deposition and Aquatic Systems
Fish declines
Aluminum toxicity
 Acid shock
Acid Deposition, Plants, and Soil
 Nutrient
leaching
 Heavy metal
release
 Weakens trees
Fig. 20-11 p. 447
Prevention
Reduce air pollution
by improving energy
efficiency
Reduce coal use
Cleanup
Add lime to neutralize
acidified lakes
Add phosphate
fertilizer to neutralize
acidified lakes
Increase natural gas
use
Increase use of
renewable resources
Burn low-sulfur coal
Remove SO2
particulates, and NOx
from smokestack gases
Remove Nox from
motor vehicular exhaust
Tax emissions of SO2
Solutions to
Acid
Deposition
Acid Deposition and Humans
 Respiratory diseases
 Toxic metal leaching
 Damage to structures, especially
containing calcium carbonate
 Decreased visibility
 Decreased productivity and
profitability of fisheries, forests,
and farms
Indoor Air Pollution
Fig. 20-13
p. 450
Radon
 Radioactive radon-222
 Lung cancer threat
 Occurs in certain
areas based on
geology
 Associated with
uranium and organic
material in rock
Fig. 20-14
p. 451
Effects of Air Pollution on People
Respiratory diseases (see Fig. 20-15 p. 452)
Asthma
Lung cancer
Chronic bronchitis
Emphysema
Premature death
Solutions: Preventing and Reducing
Air Pollution
Clean Air Act
National Ambient Air Quality
Standards (NAAQS)
Primary and secondary standards
Emissions trading
Prevention
Reducing
Indoor Air
Pollution
Cleanup or
Dilution
Cover ceiling
tiles and lining
of AC ducts to
prevent release
of mineral fibers
Use adjustable
fresh air vents
for work spaces
Ban smoking or
limit it to wellventilated areas
Increase intake
of outside air
Set stricter
formaldehyde
emissions
standards for
carpet,
furniture,
and building
materials
Change air
more frequently
Prevent radon
infiltration
Use exhaust
hoods for
stoves and
appliances
burning natural
gas
Use office
machines in
well-ventilated
areas
Use less
polluting
substitutes for
harmful
cleaning
agents,
paints, and
other products
Circulate
building’s air
through rooftop
greenhouses
Install efficient
chimneys for
wood-burning
stoves
Prevention
Burn low-sulfur
coal
Remove sulfur
from coal
Convert coal
to a liquid or
gaseous fuel
Shift to less
polluting fuels
Dispersion
or Cleanup
Disperse
emissions above
thermal inversion
layer with tall
smokestacks
Remove
pollutants after
combustion
Tax each unit
of pollution
produced
Emission Reduction - Sulfur
Prevention
Reduce air pollution
by improving energy
efficiency
Reduce coal use
Cleanup
Add lime to neutralize
acidified lakes
Add phosphate
fertilizer to neutralize
acidified lakes
Increase natural gas
use
Increase use of
renewable resources
Burn low-sulfur coal
Remove SO2
particulates, and NOx
from smokestack gases
Remove Nox from
motor vehicular exhaust
Tax emissions of SO2
Reducing Acid
Deposition
Prevention
Mass transit
Cleanup
Emission control
devices
Bicycles and walking
Less polluting engines
Less polluting fuels
Improve fuel efficiency
Get older, polluting
cars off the road
Give buyers tax writeoffs for buying lowpolluting, energyefficient vehicles
Restrict driving in
polluted areas
Car exhaust
Inspections
twice a year
Stricter emission
standards
Reducing Outdoor Air
Temperature Inversions
Subsidence inversion
Figure 17-19 (1)
Page 437
Nasal cavity
Oral cavity
Pharynx (throat)
(see figure 17.18b)
Trachea (windpipe)
Bronchus
Right lung
Bronchioles
(see figure 17.18c)
Figure 17-19 (2)
Page 437
Epithelial cell
Cilia
Mucus
Figure 17-19 (3)
Page 437
Alveolar sac
(sectioned)
Bronchiole
Alveolar duct
Alveoli
Figure 17-21
Page 438
Outdoor Exposure
Developing countries
(urban) 93%
Indoor Exposure
Developed
countries
(urban) 7%
Total deaths 0.2 million
Developing countries
(urban) 23%
Developing
countries
(rural) 67%
Developed countries
(rural) 1%
Developed countries
(urban) 9%
Total deaths 2.8 million
Figure 17-23 (1)
Cleaned gas
Page 442
Electrodes
Dust discharge
Dirty gas
Electrostatic Precipitator
Figure 17-23 (2)
Page 442
Bags
Cleaned gas
Dirty gas
Baghouse Filter
Dust discharge
Figure
17-23
(3)
Cleaned gas
Page 442
Dirty gas
Cyclone Separator
Dust discharge
Cleaned gas
Figure
17-23 (4)
Page 442
Dirty gas
Clean
water
Wet
gas
Dirty water
Wet Scrubber