Air Pollution

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Air Pollution

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Exosphere Thermosphere Mesosphere Stratosphere
Troposphere
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Primary pollutants are mixed vertically and
horizontally and are dispersed and diluted by the
churning air in the troposphere. Ex CO, CO2,
SO2, NO, NO2, most hydrocarbons, and most
suspended particles Secondary pollutants while
in the troposphere, some of the primary
pollutants may react with one another or with the
basic compounds of air. Ex SO3, HNO3, H2SO4,
H2O2, O3, and PANs
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Six Principal Pollutants - Carbon Monoxide
(CO) - Lead (Pb) - Nitrogen Dioxide (NO2) - Ozone
(O3) - Particulate Matter (PM-10) - Sulfur
Dioxide (SO2)
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Ozone Ozone is formed by the action of sunlight
on carbon-based chemicals known as hydrocarbons,
acting in combination with a group of air
pollutants called oxides of nitrogen. Ozone
reacts chemically ("oxidizes") with internal body
tissues that it comes in contact with, such as
those in the lung. Ozone (O3) in the troposphere
causes more damage to plants than all other air
pollutants combined.
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SO2 Sulfur dioxide belongs to the family of
gases called sulfur oxides (SOx ). These gases
are formed when fuel containing sulfur (mainly
coal and oil) is burned, and during metal
smelting and other industrial processes. The
major health concerns associated with exposure to
high concentrations of SO2 include effects on
breathing, respiratory illness, alterations in
pulmonary defenses, and aggravation of existing
cardiovascular disease.
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SO2 Emissions
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Lead In the past, motor
vehicles were the biggest
source of lead. But since leaded gasoline has
been phased out, lead emissions have decreased by
about 98 percent. Today, metal processing is the
biggest source of atmospheric lead. Lead can
harm the kidneys, liver, nervous system and other
organs. It may cause neurological impairments
such as seizures, mental retardation and
behavioral disorders. Even at low doses, lead is
associated with damage to the nervous systems of
fetuses and young children, resulting in lowered
IQ and learning problems.
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Particulates Particulates is a general term used
to describe tiny bits of matter floating around
in the atmosphere, such as certain types of smoke
(like diesel smoke), fine ash and dust. Larger
particles are caught by the hairs in your nose
and your breathing tubes, but smaller particles
can get past these defenses and cause lots of
trouble.
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NO2 Nitrogen dioxide belongs to a family of
highly reactive gases called nitrogen oxides
(NOx). These gases form when fuel is burned at
high temperatures, and come principally from
motor vehicle exhaust and stationary sources such
as electric utilities and industrial
boilers. Nitrogen dioxide can irritate the lungs
and lower resistance to respiratory infections
such as influenza.
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Carbon Monoxide
Carbon Monoxide is produced by the
incomplete combustion of the
fossil fuels
gas, oil, coal and wood used in boilers,
engines, oil burners, gas fires,
water heaters, solid fuel appliances and open
fires. When carbon monoxide is present in the air
you breath into your lungs, it attaches itself to
the hemoglobin. The bond between hemoglobin and
carbon monoxide is 250 times stronger than
oxygen. In the lungs carbon monoxide attaches to
red blood cells in place of oxygen.
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Smog (smokefog)
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• The Four Most Dangerous Indoor Air Pollutants
• cigarette smoke
• Formaldehyde
• Asbestos
• radioactive radon-222 gas

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Formaldehyde Formaldehyde is a colorless liquid
or gas with a strong, distinctive odor. It is
found in furniture, new carpets, particle board,
plywood, rubber cement and adhesives. Low levels
of exposure can irritate the eyes, nose and
throat, cause skin problems, serious breathing
problems and can increase your risk of certain
kinds of cancer.
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ASBESTOS Sources Deteriorating of damaged
insulation, fire-proofing, or acoustical
materials. Health Effects No immediate
symptoms. Chest and abdominal cancers and lung
diseases. Smokers are at higher risk of
developing asbestos-induced lung cancer.
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RADON Sources Earth, uranium and rock beneath
home well water building materials. Health
Effects No immediate symptoms. Estimated to
cause about 10 of lung cancer deaths. Smokers
are at higher risk of developing radon-induced
lung cancer.
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Radon-222 can
enter the house by diffusion
from soil and by emanation from building
materials, tap water
and methane gas.Characteristics- an odorless,
tasteless, invisible gas that mixes with air-
chemically inert and essentially non-reactive-
heaviest noble gas with highest melting and
boiling point- highly soluble in non-polar
solvents- moderately soluble in cold water-
able to diffuse through rock and soil- decays by
alpha particle emission (T 1/2 3.8 days)
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The largest source of "indoor air pollution"- in
our homes, our schools or workplaces- is car and
truck pollution. Electric vehicles are sometimes
referred to as "zero-emission vehicles" because
they produce essentially no pollution from the
tailpipe or through fuel evaporation. This is
important, for it means that the use of electric
vehicles could greatly reduce emissions of carbon
monoxide and smog-forming pollutants in cities
with dirty air.
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• Symptoms (IAP)
• As many as 20 million Americans suffer from
• chronic breathing problems
• dizziness
• rash
• headaches
• sore throat
• sinus
• eye irritation

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• Acid Deposition the falling of acids and
  acid-forming compounds from the atmosphere to
  earths surface. Acid deposition is commonly
  known as acid rain, a term that refers only to
  wet deposition of droplets of acids and
  acid-forming compounds
• Effects of Acid rain
• human respiratory disease (bronchitis and
  asthma)
• damages statues, buildings, metals, and car
  finishes
• depletion of calcium and magnesium ions in the
  soil
• damages trees

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How to reduce acid deposition

1. Reduce energy use and thus air pollution by
   improving energy efficiency
2. Switch from coal to cleaner burning natural gas
   and renewable energy resources
3. Remove sulfur from coal before it is burned
4. Burn low-sulfur coal
5. Remove SO2, particulates, and nitrogen oxides
   from smokestack gases
6. Remove nitrogen oxides from motor vehicle exhaust

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Sick Building A building is considered
sick when at least 20 of its occupants suffer
persistent symptoms that disappear when they go
outside At least 17 of the 4 million commercial
buildings in the U.S. are considered sick.
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Ozone Most ozone (about 90) exists in the
stratosphere, in a layer between 10 and 50km
above the surface of the earth. This ozone layer
performs the essential task of filtering out most
of the sun's biologically harmful ultraviolet
(UV-B) radiation.
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Ozone Hole Over Antarctica (and
recently over the Arctic),
stratospheric ozone has been depleted over the
last 15 years at certain times of the
year. This is mainly due to the release of
manmade chemicals containing chlorine such as
CFC's (ChloroFluoroCarbons), but also compounds
containing bromine, other related halogen
compounds and also nitrogen oxides (NOx).
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CFCs CFC's are
chemicals that can be used in
the refrigerator to help keep food
cold. They can
also be used in air-
conditioning and in products in spray cans.
CFC's rise into the air going into a layer called
the stratosphere. When this happens, the CFC's
take part in chemical reactions that can destroy
parts of the ozone which protects us from the
sun's dangerous ultraviolet rays.
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Ozone Hole1979
1998
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Greenhouse Effect
The Earth is kept warm by it's atmosphere, which
acts rather like a woolly coat - without it, the
average surface temperature would be about -18
degrees Centigrade. Heat from the sun passes
through the atmosphere, warming it up. As the
Earth warms up, it emits heat. Some of this heat
is trapped by the atmosphere, but the rest
escapes into space. The so-called "greenhouse
gases" make the atmosphere trap more of this
radiation, so it gradually warms up more than it
should, like a greenhouse.
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Greenhouse Effect
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Greenhouse Effect Ozone Shield
Where in the atmosphere does it occur? Troposphere Stratosphere
What process occurs? Traps heat near the earths surface Filters ultraviolet (UV) radiation from the sun
What natural gases are involved? Water(H2O), carbon dioxide(CO2), methane(CH4) Oxygen(O2), ozone(O3)
What are important human inputs? Carbon dioxide(CO2), methane (CH4), chlorofluorocarbons (CFCs), nitrous oxide(N2O) Chlorofluorocarbons (CFCs), halons, carbon tetrachlorine, methyl choloroform (stable), halogen-containing gases
What problems result? Global warming Ozone depletion
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Carbon Dioxide Carbon dioxide is produced when
any form of carbon or almost any carbon compound
is burned in an excess of oxygen. For example, it
is released into the atmosphere during natural
forest fires and the man-made combustion of
fossil fuels. Other natural sources of carbon
dioxide include volcanic eruptions, decay of dead
plant and animal matter, evaporation from the
oceans and respiration (breathing).
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Methane Methane is a greenhouse gas that is
creating a serious problem for global warming.
Methane gases are very potent when trapping
infrared heat in the atmosphere, because one
molecule of methane can trap infrared heat twenty
times more than carbon dioxide. Methane the
second most importantgreenhouse gas is mostly
produced by the digestive system of cows.
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Asthma
Smog and
particles certainly
trigger attacks
in some people
who already have asthma. For
a long time
it was thought that
air pollution could not cause

asthma to develop in
previously healthy people. Some recent
experiments challenge this belief. Scientists
have shown that people exposed to ozone or
nitrogen dioxide are more likely to react to
allergens such as grass pollens and housedust
mites than those who are not exposed. Thus a
combination of air pollution and allergens could
cause some cases of asthma.
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Lung Cancer Lung cancer is more common in cities
than in the country. We know that over 90 of
lung cancers are caused by smoking cigarettes. A
radioactive gas called radon is thought to cause
about 7 of lung cancers in North America.
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87 of lung cancer cases are caused by smoking.
12 percent of all lung cancer deaths are linked
to radon. Another leading cause of lung cancer is
on-the-job exposure to cancer-causing substances
or carcinogens.
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Air pollution can make you sick. It can cause
burning eyes and nose and an itchy, irritated
throat, as well as trouble in breathing. Some
chemicals found in polluted air cause cancer,
birth defects, brain and nerve damage and
long-term injury to the lungs and breathing
passages. Some air pollutants are so dangerous
that accidental releases can cause serious injury
or even death.
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According to the U.S. Environmental Protection
Agency's (EPA) latest Ten-Year Air Quality and
Emissions Trends report, there have been
significant reductions in all 6 criteria
pollutants and reductions are expected to
continue.
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The 1990 Clean Air Act Under this law, EPA sets
limits on how much of a pollutant can be in the
air anywhere in the United States. This ensures
that all Americans have the same basic health and
environmental protections. The law allows
individual states to have stronger pollution
controls, but states are not allowed to have
weaker pollution controls than those set for the
whole country.
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Chapter 19 Global Warming and Ozone Loss
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The Greenhouse effect

• In the Greenhouse effect, certain gases in the
  atmosphere trap heat in the troposphere (lower
  atmosphere).
• If the atmospheric concentrations of these gases
  rise and arent removed by other processes, the
  average temp of the lower atmosphere will
  gradually increase.

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Greenhouse gases

• The major greenhouse gases are water vapor (H20),
  carbon dioxide (C20), ozone (o3), methane (CH4),
  nitrous oxide (N2O), and chlorofluorocarbons
  (CFCs), and a recently identified
  perfluorocarbons (PFCs)

• These gases remain in the atmosphere for
  2,000-50,000 years.
• The two predominant gases are water vapor
  (hyrologic cycle) and carbon dioxide (global
  carbon cycle)

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Global warming

• Measured atmospheric levels of certain greenhouse
  gases have risen substantially in recent decades
  and are projected to enhance the earths natural
  greenhouse effect, a phenomenon called global
  warming
• Most of the increased levels of these greenhouse
  gases since 1958 have been caused by human
  activities such as burning fossil fuels,
  agricultue, deforestation, and use of CFCs.

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• Carbon dioxide (CO2)
• Responsible for 50-60 of the global warming from
  greenhouse gases produced by human activites
• Main sources are fossil fuel burning (70-75) and
  land clearing and burning (20-25)
• Remains in atmosphere for 50-200 years

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• Chloroflurocarbons (CFCs)
• Contribute to global warming in the troposphere
  and also deplete ozone in the stratosphere
• Main sources are leaking ACs and fridges,
  evaporation of industrial solvents, production of
  plastic foams, and aerosol propellants
• Trap 1,500- 7,000 times as much heat per molecule
  as CO2 while they are in the troposphere.

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• Methane (CH4)
• Accounts for about 20 of the overall warming
  effect
• Produced when anaerobic bacteria break down dead
  organic matter in moist places that lack oxygen.
• Stays in the troposphere for 9-15 years
• Each CH4 molecule traps 20 times as much heat as
  a CO2 molecule

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• Nitrous oxide (N2O)
• Can trap heat in the troposphere and also deplete
  ozone in the stratosphere
• Released from nylon production, burning of
  biomass and nitrogen-rich fuels, smog-fighting
  catalytic converters on motor vehicles, and the
  breakdown of nitrogen fertilizers in soil,
  livestock wastes, and nitrate-contaminated
  groundwater.
• Stays in the troposphere about 120 years.
• About 200 times as much heat per molecule as CO2

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• According to EPA, emission of greenhouse gases by
  the US rose by 20 between 1990 and 1996. Energy
  related activities accounted for about 86 of
  these emissions in 1996, mostly through burning
  fossil fuels.
• The atmospheric concentrations of CO2 and other
  greenhouse gases are projected to double from
  preindustrial levels sometimes during the next
  century and then continue to rise

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The Earths past temperatures

• Since 1860, mean global temperature after
  correcting for excess heating over urban areas
  has risen 0.3-0.6 degrees Celsius.
• Temperature rose about 0.3 degrees between 1846
  and 1997
• Since 1860, the thirteen warmest years occurred
  between 1979 and 1998, with 1990, 1995, 1997, and
  1998 being the four hottest years.

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Future global warming and its effects

• According to the latest climate models, the
  earths mean surface temperature should rise 1-
  3.5 degrees celsius between 1990 and 2100.
• Model projects that once the climate changes, it
  will continue for hundreds of years.

• According to the models, the northern hemisphere
  should warm more and faster than the southern
  hemisphere because the latter has more heat-
  absorbing ocean than land and because water cools
  more slowly than land.

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How Earths climate is affected by various
factors

• Solar output ups and downs in solar output can
  temporarily warm or cool the earth and thus
  affect the projections of climate models.
• Two studies showed that the projected warming
  power of greenhouse gases should outweigh the
  climatic influence of the sun over at least the
  next 50 years.

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• Oceans the oceans might amplify global warming
  by releasing more CO2 into the atmosphere or
  might dampen it by absorbing more heat. The
  oceans currently help moderate tropospheric
  temperature by removing about 29 of the excess
  CO2 pumped into the atmosphere

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• Water vapor content and clouds changes in the
  atmospheres water vapor content and the amount
  and types of cloud cover also affect climate.
  Warmer temperatures would increase evaporation
  and the water-holding capacity of the air and
  create more clouds. Significant increase in the
  water vapor, a potent greenhouse gas, could
  enhance warming (positive feedback).

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• Polar ice the ability of the earths surface to
  reflect light is called its albedo. Because of
  their albedo, light-colored Greenland and
  Antarctic ice sheets act like enormous mirrors,
  reflecting sunlight back into space. If warmer
  temperatures melted some of this ice and exposed
  darker ground or ocean, more sunlight would be
  absorbed and warming would be accelerated.

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• Air pollution pollutants in the lower
  troposphere can either warm or cool the air
  depending on the reflectivity of the underlying
  surface.
• It is hypothesized that SO2 and tiny particles in
  the troposphere attract enough water molecules to
  form condensation nuclei, which leads to
  increased cloud formation

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Some possible effects of a warmer world

• Food production a warmer global climate could
  increase food production in some areas and lower
  it in others, depending on crop- growing capacity
  and climate belts.
• Water supply global warming would reduce water
  supply, shrinking or completely drying up lakes,
  streams, and aquifers.
• Forests and biodiversity global warming would
  change the makeup and location of many of the
  worlds forests

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Continued

• Sea levels in a warmer world, sea levels are
  expected to rise, primarily because ocean water
  expands when heated and because some land-based
  glacial ice will melt
• Weather extremes as more heat is retained in
  the earths climate system, more air will move
  across the earths surface.
• Human health global warming would bring more
  heat waves, which would double or triple
  heat-related deaths among the elderly and people
  with heart disease it would also increase
  suffering from respiratory ailments such as
  asthma and bronchitis.

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Solutions dealing with global warming

• Stabilizing the Co2 levels at the currect level
  would require reducing current global CO2
  emissions by 66-83.
• Increased use of nuclear power to reduce the
  amount of CO2 per unit of electricity as coal
• Using natural gas could help make the 40 to 50
  year transition to an age of energy efficiency
  and renewable energy.

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Ozone depletion

• In a band of the stratosphere 17- 26 kms above
  the earths surface, oxygen is continually
  converted to ozone and back to oxygen by a
  sequence of reactions initiated by UV radiation
  from the sun.
• UV radiation reaching the stratosphere consists
  of three bands A, B, and C. The ozone layer
  blocks out nearly all of the highest- energy and
  biologically damaging UV-B band.
• Ozone depletion by certain chlorine- and bromine-
  containing chemicals emitted into the atmosphere
  by human activities is a serious long-term threat
  to human health, animal life, and the sunlight
  drive promary producers that support the earths
  food chains.

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• CFCs released into the air rise slowly into the
  stratosphere. There, under the influence of high
  energy UV radiation, they break down and release
  highly reactive chlorine atoms, which speed up
  the breakdown of highly reactive ozone into O2
  and O. This causes ozone to be destroyed faster
  than it is formed.

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Solutions protecting the ozone layer

• It will take another 50-60 years for the ozone
  layer to return to 1975 levels and another 100-
  200 years to return to pre- 1950 recovery levels.
  
• Substitutes are already available for most uses
  of CFCs.
• Hydochlorofluorocarbons (HCFCs) contain fewer
  chlorine atoms per molecule than CFCs
• Because of their shorter lifetimes in the
  stratosphere, these compounds should have only
  about 2.5 of the ozone depleting potential of
  CFCs.