Environmental Engineering Reference
In-Depth Information
Table 15-1 Science: Types, Sources, and Effects of Major Outdoor Air Pollutants*
C
ARBON MONOXIDE
(CO)
Description:
Colorless, odor-
less gas that is poisonous to
air-breathing animals; forms dur-
ing the incomplete combustion
of carbon-containing fuels
(2 C
increases susceptibility to res-
piratory infections such as the
flu and common colds (espe-
cially in young children and
older adults).
Environmental effects:
Reduces visibility; acid depo-
sition of HNO
3
can damage
trees, soils, and aquatic life in
lakes.
Property damage:
HNO
3
can
corrode metals and eat away
stone on buildings, statues,
and monuments; NO
2
can
damage fabrics.
S
ULFUR DIOXIDE
(SO
2
)
Description:
Colorless, irritat-
ing; forms mostly from the com-
bustion of sulfur-containing
fossil fuels such as coal and oil
(S O
2
SO
2
); in the at-
mosphere can be converted to
sulfuric acid (H
2
SO
4
), a major
component of acid deposition.
Major human sources:
Coal
burning in power plants (88%)
and industrial processes
(10%).
Health effects:
Breathing prob-
lems for healthy people; restric-
tion 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 fos-
sil fuel burning.
Environmental effects:
Re-
duces visibility; acid deposi-
tion of H
2
SO
4
can damage
trees, soils, and aquatic life in
lakes.
Property damage:
SO
2
and
H
2
SO
4
can corrode metals and
eat away stone on buildings,
statues, and monuments; SO
2
can damage paint, paper, and
leather.
in the troposphere as a
major component of photo-
chemical smog.
Major human sources:
Chemical reaction with volatile
organic compounds (VOCs,
emitted mostly by cars and in-
dustries) and nitrogen oxides
to form photochemical smog.
Health effects:
Breathing
problems; coughing; eye,
nose, and throat irritation; ag-
gravates chronic diseases
such as asthma, bronchitis,
emphysema, and heart dis-
ease; 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.
L
EAD
Description:
Solid toxic metal
and its compounds, emitted
into the atmosphere as partic-
ulate matter.
Major human sources:
Paint
(old houses), smelters (metal
refineries), lead manufacture,
storage batteries, leaded gaso-
line (being phased out in devel-
oped 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.
S
USPENDED 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;
cause smoke, dust, and
haze.
Major human sources:
Burn-
ing 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;
aggravates bronchitis and
asthma; shortens life; toxic
particulates (such as lead,
cadmium, PCBs, and dioxins)
can cause mutations, re-
productive problems,
cancer.
Environmental effects:
Re-
duces visibility; acid deposi-
tion of H
2
SO
4
droplets can
damage trees, soils, and
aquatic life in lakes.
Property damage:
Corrodes
metal; soils and discolors
buildings, clothes, fabrics, and
paints.
O
2
2 CO).
Major human sources:
Cigarette smoking, incom-
plete 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 per-
ception and thinking; slows re-
flexes; causes headaches,
drowsiness, dizziness, and
nausea; can trigger heart at-
tacks and angina; damages the
development of fetuses and
young children; and aggra-
vates chronic bronchitis, em-
physema, and anemia. At high
levels it causes collapse, coma,
irreversible brain cell damage,
and death.
N
ITROGEN DIOXIDE
(NO
2
)
Description:
Reddish-brown
irritating gas that gives
photochemical smog its brown-
ish color; in the atmosphere
can be converted to nitric acid
(HNO
3
), a major component of
acid deposition.
Major human sources:
Fossil
fuel burning in motor vehicles
(49%) and power and indus-
trial plants (49%).
Health effects:
Lung irritation
and damage; aggravates
asthma and chronic bronchitis;
O
ZONE
(O
3
)
Description:
Highly reactive,
irritating gas with an un-
pleasant odor that forms
*Data from U.S. Environmental Protection Agency.
The formation of photochemical smog involves a
complex series of chemical reactions. It begins inside
automobile engines and in the boilers of coal-burning
power and industrial plants. At the high temperatures
found there, nitrogen and oxygen in air react to pro-
duce colorless nitric oxide (N
2
choking odor. NO
2
is the cause of the brownish haze
that hangs over many cities during the afternoons of
sunny days, explaining why photochemical smog
sometimes is called
brown-air smog.
When exposed to UV radiation from the sun,
some of the NO
2
engages in a complex series of reac-
tions with hydrocarbons (mostly released by vegeta-
tion, motor vehicles, and other human activities) that
O
2
2 NO). In
the atmosphere, some of the NO is converted to nitro-
gen dioxide (NO
2
), a yellowish-brown gas with a
