Air Pollution
The Atmosphere
• This is our protective blanket of gasses.
– 78% Nitrogen
– 21% Oxygen
– .03% Carbon Dioxide CO2
– .01% Ozone 03
Atmospheric Gases
Atmospheric pressure (millibars)
Temperature
Pressure
Thermosphere
Heating via ozone
Mesosphere
Stratopause
Stratosphere
Altitude (miles)
Altitude (kilometers)
Mesopause
Tropopause
Ozone “layer”
Heating from the earth
Troposphere
(Sea
level)
Temperature (˚C)
Pressure = 1,000
millibars at ground
level
Fig. 19-2, p. 440
The Atmosphere - Layers
• Troposphere
–
–
–
–
–
Layer in which we live
Most weather occurs here
90% of the gasses are here
78% nitrogen, 21% oxygen
0-6 mile above N and S Pole
• Mount Everest is 5.3 miles
tall
– 0-10 miles above equator
– Temperature decreases with
altitude until the next layer is
reached
• Stratosphere
– 6-31 miles in altitude
– Calm
– Air traffic due to lack of
weather
– Temperature increases with
altitude
– Ozone layer (oxygen is
converted to O3 by lightning
and/or sunlight)
– 99% of ultraviolet radiation
(especially UV-B) is absorbed
by the stratosphere
The Atmosphere - Layers
• Mesosphere
– 30 to 50 miles in altitude
– Temperature decreases
with increasing altitude
– Temperatures in the
mesopause (top of the
mesosphere) are the
coldest on Earth – approx.
-100˚C (-148˚F)
– Above airplane heights and
below orbital heights, thus
it is poorly understood
• Thermosphere
– 50 to 310 miles in altitude
– Biggest of all layers
– Temperature increases
with altitude
– Very high temperatures
1,500 °C (2,730 °F) to
2,500 °C (4,530 °F) but
little heat is transferred
because of the space
between the gas particles
– International Space Station
flies in this layer
The Atmosphere - Layers
• Exosphere
– 310 miles to space
– Upper most layer of the
atmosphere
– Only light elements exist
here, mainly Hydrogen
To the right is a scale
representation of the
atmospheric layers:
•
•
•
•
•
Purple = Exosphere
Blue = Thermosphere
Green = Mesosphere
Yellow = Stratosphere
Red = Troposphere
Ozone
• How much of our atmosphere is ozone?
• Ozone that surrounds the earth 12-35
miles above the earth is our first line of
defense of the sun’s ultraviolet radiation.
– This radiation can cause sunburn, skin
cancer, cataracts, …
• Ozone is constantly created and destroyed
What Happens to Solar Energy
Reaching the Earth?
• Solar energy
flowing through
the biosphere
warms the
atmosphere,
evaporates and
recycles water,
generates winds
and supports
plant growth.
Figure 3-8
The Natural Greenhouse Effect
• Three major factors shape the earth’s
climate:
– The sun.
– Greenhouse effect that warms the earth’s lower
troposphere and surface because of the
presence of greenhouse gases.
– Oceans store CO2 and heat, evaporate and
receive water, move stored heat to other parts of
the world.
– Natural cooling process through water vapor in
the troposphere (heat rises).
Greenhouse Effect
• This “greenhouse
effect” is vital for our
survival. Without heat
trapping gasses our
planet would be cold
and lifeless.
• The gasses act like a
car that gets hot
inside.
Major Greenhouse Gases
• The major greenhouse gases in the lower
atmosphere are water vapor, carbon
dioxide, methane, nitrous oxide, ozone,
and CFCs.
– These gases have always been present in
the earth’s troposphere in varying
concentrations.
– Fluctuations in these gases, plus changes in
solar output are the major factors causing the
changes in tropospheric temperature over
the past 400,000 years.
Major Greenhouse
Gases
• Increases in average
concentrations of three
greenhouse gases in the
troposphere between
1860 and 2004, mostly
due to fossil fuel burning,
deforestation, and
agriculture.
Figure 20-5
PAST CLIMATE AND THE
GREENHOUSE EFFECT
• Over the past 900,000 years, the
troposphere has experienced prolonged
periods of global cooling and global
warming.
• For the past 1,000 years, temperatures
have remained fairly stable but began to
rise during the last century.
PAST CLIMATE AND THE
GREENHOUSE EFFECT
Figure 20-2
How Do We Know What
Temperatures Were in the Past?
• Scientists analyze tiny
air bubbles trapped in
ice cores learn about
past:
– troposphere
composition.
– temperature trends.
– greenhouse gas
concentrations.
– Solar output,
snowfall, and forest
fire activity. Figure 20-3
How Do We Know What
Temperatures Were in the Past?
• In 2005, an ice
core showed that
CO2 levels in the
troposphere are
the highest they
have been in
650,000 years.
Figure 20-4
Greenhouse Effect
• If the gasses in the atmosphere become
increased beyond “normal” the
temperature of the earth can increase.
• An increase in temperature can change
the climate cycles.
– Ice caps melt, drought, floods, change in
temperature…
– Effects the environment as well
• What are some effects if the above happens?
Controversy
• CO2 levels are increasing due to human
activity – no controversy
• What does that mean? - controversy
– 97% of climate scientists agree that this leads
to global warming
– 53% of Americans believe global warming is
real
– 87% of Europeans believe global warming is
a serious concern
Data can be manipulated
From NOAA
EFFECTS OF GLOBAL
WARMING
• Between 1979 and 2005, average Arctic sea
ice dropped 20% (as shown in blue hues
above).
Figure 20-8
Rising Sea Levels
• During this century
rising seas levels
are projected to
flood low-lying
urban areas,
coastal estuaries,
wetlands, coral
reefs, and barrier
islands and
beaches.
Figure 20-10
Rising Sea Levels
• If seas levels
rise by 9-88cm
during this
century, most
of the Maldives
islands and
their coral reefs
will be flooded.
Figure 20-11
Changing Ocean Currents
• Global warming could alter ocean currents
and cause both excessive warming and
severe cooling.
Figure 20-12
CLIMATE CHANGE AND HUMAN
ACTIVITIES
• Evidence that the earth’s troposphere is
warming, mostly because of human
actions:
– The 20th century was the hottest century in the
past 1000 years.
– Since 1900, the earth’s average tropospheric
temperature has risen 0.6 C°.
– Over the past 50 years, Arctic temperatures
have risen almost twice as fast as those in the
rest of the world.
– Glaciers and floating sea ice are melting and
shrinking at increasing rates.
EFFECTS OF GLOBAL
WARMING
• A warmer troposphere can decrease the
ability of the ocean to remove and store
CO2 by decreasing the nutrient supply for
phytoplankton and increasing the acidity of
ocean water.
• Global warming will lead to prolonged heat
waves and droughts in some areas and
prolonged heavy rains and increased
flooding in other areas.
EFFECTS OF GLOBAL
WARMING
• In a warmer world, agricultural productivity may
increase in some areas and decrease in others.
• Crop and fish production in some areas could be
reduced by rising sea levels that would flood river
deltas.
• Global warming will increase deaths from:
– Heat and disruption of food supply.
– Spread of tropical diseases to temperate regions.
– Increase the number of environmental refugees.
DEALING WITH GLOBAL
WARMING
• Climate change is such a difficult problem to
deal with because:
– The problem is global.
– The effects will last a long time.
– The problem is a long-term political issue.
– The harmful and beneficial impacts of climate
change are not spread evenly.
– Many actions that might reduce the threat are
controversial because they can impact
economies and lifestyles.
Air Pollution
• Air Pollutant is defined as any substance
in the air that is concentrated enough to
harm living things or do damage to manmade objects.
• The EPA regulates (tries) pollution
emissions from combustion by factories
and machines.
Human Actions and Our
Environment
• When the human population was low,
there was very little impact to the
environment.
– Wind, rain, and time were the natural air
cleaners.
• As the human population increased, time
could not clean the air fast enough.
Human Actions and Our
Environment
•
The human impact has changed three
major ecosystem cycles.
1.
–
–
–
The chemical cycles
Carbon Cycle
Nitrogen Cycle
Sulfur Cycle
– By adding more chemicals we slow down
the cycle
Human Actions and Our
Environment
2. The energy cycles
•
•
Conservation of energy
Energy from fossil fuels is used faster that
replaced
3. Biodiversity is reduced
•
Farms reduce the plant biodiversity with a single
crop, and kill animals with chemicals
Air Pollution
• Primary pollutants – released directly into
the atmosphere
– Ex) nitrogen oxides (NOx), sulfur oxides (SOx),
methane (CH4), dust, Chlorofluorocarbons
(CFCs)
• Causes of Primary Pollutants – factories,
cars, wind and soil, volcanoes, forest fires,
pollen, decaying plants, salt particles from the
sea, and refrigerants.
Air Pollution
• Secondary pollutants – Form when
primary pollutants react.
– Ex) ozone, smog, and acid rain
Air Pollutants – Carbon Oxides
• Carbon monoxide (CO) is a highly toxic gas that
forms during the incomplete combustion of
carbon-containing materials.
• 93% of carbon dioxide (CO2) in the troposphere
occurs as a result of the 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.
Carbon Cycle
• The ocean is the largest carbon sink.
• The process of CO2 being removed from
the atmosphere and stored by a sink is
called sequestration.
Ocean Acidification
• Dissolving CO2 in seawater increases
the hydrogen ion (H+) concentration in the
ocean, and thus decreases ocean pH.
• Between 1751 and 1994 surface ocean pH
is estimated to have decreased from
approximately 8.25 to 8.14, representing
an increase of approaching 30% in acidity.
The Nitrogen Cycle:
Steps in Nitrogen Cycle
• Nitrogen Fixation
– Lightning (N2  NO3)
– Bacteria (N2  NH4+)
• Nitrification (NH4+  NO2- (nitrite)  NO3-(nitrates))
• Assimilation (NO3-(nitrates) converted to amino
acids, DNA, chlorophyll)
• Ammoniafication (wastes and decaying organisms
broken down into NH4+)
• Denitrification (nitrites are changed to N2 by
anaerobic bacteria)
Air Pollutants – Nitrogen Oxides
• The atmosphere is the largest nitrogen
sink, storing nitrogen in the form of N2.
• NO2 reacts with water vapor in the air to
form nitric acid (HNO3) and nitrate salts
(NO3-) which are components of acid
deposition.
Human Influence on Nitrogen
Cycle
• Fossil fuel
combustion,
• Use of artificial
nitrogen fertilizers,
• Release of nitrogen in
wastewater
• At high temps, N2
reacts with O2 to form
NOx.
• Gives brown color to
smog
• Photochemical smog
– nitrogen and light
form “bad” ozone.
Air Pollutants – Sulfur Oxides
• Naturally occurring
– Volcanoes
• Burning of coal, oil, gasoline
• Cause Lung damage, asthma, and
bronchitis
• Sulfur can be removed from smoke by wet
scrubbers in factories
• Largest sulfur sink is sedimentary rocks
Air Pollutants – Sulfur Oxides
• 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 (S+ O2  SO2) of sulfurcontaining coal 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.
The Sulfur Cycle
Figure 3-32
Air Pollutants - VOCs
• Volatile organic compounds (VOCs):
– Organic compounds (mostly hydrocarbons) that
exist as gases in the air
– Ex) incomplete combustion of gasoline, methane
– About two thirds of global methane emissions
comes from human sources.
– Can be natural (methane and terpenes) or manmade (trichlorethylene (TCE), benzene, CFCs and
vinyl chloride).
• Long-term exposure to benzene can cause cancer,
blood disorders, and immune system damage.
Air Pollutants - Ozone
• VOC + NOx + Sunlight = Ozone (O3)
– It can
• Cause and aggravate respiratory illness.
• Can aggravate heart disease.
• Damage plants, rubber in tires, fabrics, and paints.
• Ozone (O3):
– “bad” ozone - found in troposphere
– Is a highly reactive gas that is a major
component of photochemical smog.
Atmospheric Ozone
• Lightning and Ultraviolet light creates ozone, but
there are a variety of things that can destroy it
faster. THEY STAY AROUND LONGTERM
• CFC – Chlorofluorocarbons react with an
oxygen atom to break down O3 to O2.
• 1 chlorine can destroy 100,000 ozone molecules
• CFC’s come from refrigeration and aerosol cans.
• As ozone is broken down, the ozone layer gets
thinner.
– This radiation that gets through can cause sunburn,
skin cancer, cataracts, …
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and
leaving CFCl2.
Sun
Cl
UV radiation
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom off
it and leaving an oxygen
molecule (O2).
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
The chlorine atom
and the oxygen atom
join to form a chlorine
monoxide molecule
(ClO).
Fig. 20-18, p. 486
Atmospheric Ozone
• Where is the ozone the
thinnest?
New Index
Air Pollutants – Particulates
• Suspended particulate matter (SPM):
– Consists of a variety of solid particles and
liquid droplets small and light enough to
remain suspended in the air.
• Light enough to float in air
• Dust, lead, mercury, radon
• Get in lungs, stain buildings, reduce
visibility
URBAN OUTDOOR AIR
POLLUTION
• Industrial 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.
Primary Pollutants
CO CO2
SO2 NO NO2
Most hydrocarbons
Most suspended particles
Sources
Natural
Secondary Pollutants
SO3
HNO3 H3SO4
H2O2 O3 PANs
Most NO3– and SO42– salts
Stationary
Mobile
Fig. 19-3, p. 442
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.
Acid Deposition
• AKA Acid Rain
• Rain cleans the air,
but pollutes the water.
• Normal pH is 6.6
Acid Rain is about 4.3
• Plants like to grown in
soil with a pH of 6-7
• What happens to the
plants?
ACID RAIN
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
Acid fog
Dry acid deposition
(sulfur dioxide gas and
particles of sulfate and
nitrate salts)
Farm
Ocean
Lakes in deep
soil high in
limestone are
buffered
Wet acid depostion
(droplets of H2SO4
and HNO3 dissolved
in rain and snow)
Lakes in shallow soil
low in limestone
become acidic
Fig. 19-6, p. 448
ACID DEPOSITION
• pH measurements in relation to major
coal-burning and industrial plants.
Figure 19-7
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
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).
Geography can effect pollution
concentrations.
Topography and Pollution
• Mountainous areas tend to trap
pollution
• Flat areas tend to allow pollution
to disperse
• Forest Fires in the
Los Angeles area.
• Winds carry the
smoke across the
ocean.
• Wind can clean the
air, but it can also
spread it
somewhere else.
Geography can effect air pollution.
Temperature Inversion
• Cold air is more
dense. Sometimes
when it sinks below
the warm air, it
brings the pollution
with it.
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
• Rising smoke in Lochcarron, Scotland
forms a ceiling over the valley due to a
temperature inversion
Great Smog of 1952
• London
• Thousands died b/c of smog
(respiratory illness)
• Results:
– Caused evaluation of smog
effects of health
– Passed the Clean Air Act of
1956 (UK)
How does air quality effect me?
•
•
•
•
•
•
•
Asthma
Emphysema
Allergies
Heart disease
Drink polluted water
Colds
Pneumonia
Law – Clean Air Act
•
•
•
•
1963 - first passage
1970, 1977 and 1990 - amended
Involves EPA
Sets standards for acceptable levels of
sulfur oxides, nitrogen oxides, ozone,
carbon monoxide, hydrocarbons, lead, &
cut out CFCs
• Provides pollution credits for industries
that utilize pollution-control devices+
• Bush administration relaxed rules
PREVENTING AND REDUCING
AIR POLLUTION
• The Clean Air Acts in the United States
have greatly reduced outdoor air pollution
from major pollutants:
– Carbon monoxide
– Nitrogen oxides
– Sulfur dioxides
– Suspended particulate matter
PREVENTING AND REDUCING
AIR POLLUTION
• 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 fuelefficiency 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.
PREVENTING AND REDUCING
AIR POLLUTION
– 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.
National Ambient Air Quality
Standards (NAAQS)
• Sets acceptable concentrations for 6
“criteria” pollutants that:
– Threaten public health/the environment
over broad areas (non-point)
– Are emitted in large quantities
– CO, Pb, Nitrogen Oxides, Ozone,
Particulate Matter and Sulfur Dioxides
What kind of things are being done to
control the pollution internationally?
• Kyoto Protocol
• is a protocol to the United Nations Framework
Convention on Climate Change (UNFCCC), aimed at
fighting global warming
• The United Nations Framework Convention on
Climate Change (UNFCCC) is an international
environmental treaty with the goal of achieving the
"stabilization of greenhouse gas concentrations in
the atmosphere at a level that would prevent
dangerous anthropogenic interference with the climate
system.“
National Participation
Solutions:
Reducing Outdoor Air Pollution
• There are a 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.
Solutions:
Reducing Outdoor Air Pollution
• There are a couple 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.
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
Wet Scrubber
• Can remove 98%
of SO2 and
particulate matter.
• Not very effective
in removing
hazardous fine and
ultrafine particles.
Figure 19-18
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.
Indoor Pollution
Pollutant
• Ammonia
• Arsenic
Where Found
Health Effect
• Cleaning Products • Respiratory Irritant
• Smoking/pesticides • Toxic / carcinogen
/rodent poison
• Lung diseases
• Insulation
• Asbestos
• Bacterial infections
• Damp building
• Bacteria
• Respiratory irritant
• Benzene/Gasoline • Gasoline
• Headaches,
• Carbon Monoxide • Wood burning
drowsiness,
fireplace, tobacco
dizziness,
smoke, kerosene,
confusion, nausea,
automobiles,
death
natural gas
Pollutant
• Chloroform
• Fiberglass
• Formaldehyde
• Fungus/Mold
• Lead particulate
Where Found
• Chlorine treated
water
• Tables, insulation,
skateboards
• Furniture stuffing,
particle board, fiber
board, foam
insulation,
carpeting
• Air systems, damp
buildings
• Paint particulates,
exhaust from
leaded gasoline
Health Effect
• Cancer
• Respiratory and
skin irritant
• Nasal/lung cancer,
asthma, eye/nose/
throat irritant
• Respiratory irritant
• Impaired development,
clumsiness, memory
loss, anemia
Pollutant
• Mercury
Where Found
• Fungicides, old
thermometers/
thermostats
• Methane/Propane • Natural gas leaks /
sewer backup
• Tobacco Smoke • Cigarettes, cigars,
pipes
• Pesticides
• Sprays, strips,
outdoor air
Health Effect
• Damages nervous
system, Cancer
• Headaches, fatigue,
nausea, confusion,
• Cancer, heart
disease, respiratory
disease, ear
infections
• Central nervous
system/ Kidney /
liver damage
Pollutant
• Radon
• Trichloroethane
• VOCs
Where Found
Health Effect
• Radioactive
• Lung cancer, lung
soil/foundations,
tissue damage
Uranium deposits,
radioactive well
water
• Dizziness, irregular
• Aerosol sprays
breathing
• Respiratory irritant,
• Tobacco
combustion, burned weakened immune
system
food, paints,
varnishes, cleaning
products
Methods of prevention or clean-up
•
•
•
•
•
•
•
Improved Ventilation
Tobacco smoke reduction methods
Legislative measures
Alternative materials
Control temperature and humidity
Alternative pest control
Maintenance of appliances and filtering
systems
Case Study: Radioactive Radon
Sources and paths of entry
for indoor radon-222 gas.
• Radon-222, a
radioactive gas
found in some
soils and rocks,
can seep into
some houses
and increase the
risk of lung
cancer.
Figure 19-13
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