Air Pollution

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Air Pollution
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Atmospheric pressure (millibars)
Temperature
Pressure
Thermosphere
Mesopause
Heating via ozone
Mesosphere
Altitude (kilometers)
Altitude (miles)
Stratopause
Stratosphere
Tropopause
Ozone layer
Heating from the earth
Troposphere
Pressure 1,000 millibars at ground level
(Sea level)
Temperature (C)
Fig. 19-2, p. 440
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Layers of the Atmophere

• Thermosphere Closest to the surface of the
  Earth. This is where all weather and air travel
  occurs. Most pollutants affect this layer. Has
  the highest concentration of molecules
• Stratosphere Contains the ozone layer which
  absorbs incoming UV radiation
• Mesosphere temperature decreases with altitude
• Thermosphere Warmed by the sun, lowest air
  pressure of the layers

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Major Air Pollutants

• Nitrogen Oxides
• Carbon Oxides
• Sulfur Oxides
• Particulates
• Ozone
• PANS
• Volatile Organic Compounds (VOCs)
• Radon (Indoor air pollutant)

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Primary Pollutants

• Pollutants that retain the same chemical formula
  from the source to the atmosphere
• methane, SO2, CO, CO2, NO, dust particles,
  microorganisms, and chlorofluorocarbons (CFCs)
• Causes of Primary Pollutants factories, cars,
  wind and soil, volcanoes, forest fires, pollen,
  decaying plants, salt particles from the sea, and
  refrigerants.

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Primary Pollutants
Secondary Pollutants
CO
CO2
SO2
NO
NO2
SO3
Most hydrocarbons
HNO3
H3SO4
Most suspended particles
H2O2
O3
PANs
Most NO3 and SO42 salts
Natural
Stationary
Sources
Mobile
Fig. 19-3, p. 442
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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.

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Sunlight plus Cars Equals Photochemical Smog

• Photochemical smog is a mixture of air pollutants
  formed by the reaction of nitrogen oxides and
  volatile organic hydrocarbons under the influence
  of sunlight.

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Sunlight plus Cars Equals Photochemical Smog

• Mexico City is one of the many cities in sunny,
  warm, dry climates with many motor vehicles that
  suffer from photochemical smog.

Figure 19-4
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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
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Major Air Pollutants

• Suspended particulate matter (SPM)
• Consists of a variety of solid particles and
  liquid droplets small and light enough to remain
  suspended in the air.
• The most harmful forms of SPM are fine particles
  (PM-10, with an average diameter lt 10
  micrometers) and ultrafine particles (PM-2.5).
• According to the EPA, SPM is responsible for
  about 60,000 premature deaths a year in the U.S.

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Major Air Pollutants

• Volatile organic compounds (VOCs)
• Most are hydorcarbons emitted by the leaves of
  many plants and methane.
• About two thirds of global methane emissions
  comes from human sources.
• Other VOCs include industrial solvents such as
  trichlorethylene (TCE), benzene, and vinyl
  chloride.
• Long-term exposure to benzene can cause cancer,
  blood disorders, and immune system damage.

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Major Air Pollutants

• Radon (Rn)
• Is a naturally occurring radioactive gas found in
  some types of soil and rock.
• It can seep into homes and buildings sitting
  above such deposits.

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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.

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Para-dichlorobenzene
Chloroform
Formaldehyde
Tetrachloroethylene
1, 1, 1- Trichloroethane
Styrene
Nitrogen Oxides
Benzo-a-pyrene
Particulates
Radon-222
Tobacco Smoke
Asbestos
Methylene Chloride
Carbon Monoxide
Fig. 19-11, p. 453
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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 some people.

Figure 19-12
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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
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Radon Mitigation

• Vent air

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Mitigation Techniques

• Wet Scrubbers removes particulates Sulfur
  oxides

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Mitigation Techniques

• Electrostatic Precipitators

http//www.bbc.co.uk/schools/gcsebitesize/science/
images/ph_elect28.gif
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Mitigation Techniques

• Mechanical Filters
• Air filters like your furnace filter, car filter
• Remove particulates from the air. Particulates
  removes depends on the quality of the filter.

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Mitigation Techniques

• After-burners used for VOCs and particlute
  pollution control
• Breaks down the molecular structure into CO2 and
  Water Vapor
• Used often for Methane (CH4)
• May be used for energy

http//depts.washington.edu/centc/research_methane
.htm
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Acid Deposition

• Acid Rain caused by sulfur dioxide emissions
• Sulfur dioxide in the atmosphere reacts with
  water vapor to form sulfuric acid
• SO2 H2O -gt H2SO4

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ACID DEPOSITION

• Acid deposition consists of rain, snow, dust, or
  gas with a pH lower than 5.6.

Figure 19-6
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ACID DEPOSITION

• pH measurements in relation to major coal-burning
  and industrial plants.

Figure 19-7
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ACID DEPOSITION

• Environmental Effects
• Erosion
• Leaching of toxic metals (such as lead and
  mercury) from soils and rocks into acidic lakes
  used as sources for drinking water
• Disruption of aquatic ecosystems

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ACID DEPOSITION

• Health effects
• Acid deposition contributes to chronic
  respiratory disease and

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ACID DEPOSITION
Figure 19-8
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ACID DEPOSITION
Figure 19-9
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Mitigation Techniques

• Add neutralizing base to acidic water Lime is a
  good base to use
• Add phosphate fertilizer which raises the pH
  level of the water

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Solutions
Acid Deposition
Prevention
Cleanup
Reduce air pollution by improving energy
efficiency
Add lime to neutralize acidified lakes
Reduce coal use
Add phosphate fertilizer to neutralize acidified
lakes
Increase natural gas use
Increase use of renewable energy resources
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
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Seasons
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OZONE DEPLETION IN THE STRATOSPHERE

• Less ozone in the stratosphere allows for more
  harmful UV radiation to reach the earths
  surface.
• The ozone layer keeps about 95 of the suns
  harmful UV radiation from reaching the earths
  surface.
• Chlorofluorocarbon (CFCs) have lowered the
  average concentrations of ozone in the
  stratosphere.
• In 1988 CFCs were no longer manufactured.

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Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking off a
chlorine atom and leaving CFCl2.
Sun
Cl
Once free, the chlorine atom is off to attack
another ozone molecule and begin the cycle again.

UV radiation
A free oxygen atom pulls the oxygen atom off
the chlorine monoxide molecule to form O2.
The chlorine atom attacks an ozone (O3) molecule,
pulling an oxygen atom off it and leaving an
oxygen molecule (O2).
The chlorine atom and the oxygen atom join to
form a chlorine monoxide molecule (ClO).
Summary of Reactions CCl3F UV Cl CCl2F Cl
O3 ClO O2 Cl O Cl O2
Repeated many times
Fig. 20-18, p. 486
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OZONE DEPLETION IN THE STRATOSPHERE

• During four months of each year up to half of the
  ozone in the stratosphere over Antarctica and a
  smaller amount over the Artic is depleted.

Figure 20-19
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OZONE DEPLETION IN THE STRATOSPHERE

• Since 1976, in Antarctica, ozone levels have
  markedly decreased during October and November.

Figure 20-20
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OZONE DEPLETION IN THE STRATOSPHERE

• Ozone thinning caused by CFCs and other ozone
  depleting chemicals (ODCs).
• Increased UV radiation reaching the earths
  surface from ozone depletion in the stratosphere
  is harmful to human health, crops, forests,
  animals, and materials such as plastic and paints.

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Natural Capital Degradation
Effects of Ozone Depletion
Human Health
Worse sunburn
More eye cataracts
More skin cancers
Immune system suppression
Food and Forests
Reduced yields for some crops
Reduced seafood supplies from reduced
phytoplankton
Decreased forest productivity for UV-sensitive
tree species
Wildlife
Increased eye cataracts in some species
Decreased population of aquatic species
sensitive to UV radiation
Reduced population of surface phytoplankton
Disrupted aquatic food webs from reduced
phytoplankton
Air Pollution and Materials
Increased acid deposition
Increased photochemical smog
Degradation of outdoor paints and plastics
Fig. 20-21, p. 488
Global Warming
Accelerated warming because of decreased ocean
uptake of CO2 from atmosphere by phytoplankton
and CFCs acting as greenhouse gases
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Case Study Skin Cancer

• Structure of the human skin and relationship
  between radiation and skin cancer.

Figure 20-22
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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, more
• Provides pollution credits for industries that
  utilize pollution-control devices
• It established NAAQS and AQI
• Clean Air Act EPA

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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

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Air Quality Index (AQI)

• Measures levels of 5 criteria pollutants
• Forecast of daily air pollution levels
• Purpose to educate and protect public- focuses on
  health effects
• Categories green good, yellow moderate,
  orange unhealthy for sensitive groups, red
  unhealthy, purple very unhealthy

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National Emissions Standards for Hazardous Air
Pollutants

• Regulates emissions (from point sources)
• For specific substances (air toxics w/ known or
  suspected serious health effects (mutagens,
  carcinogens, neurotoxins)
• Tend to be localized, from point sources
• Examples Ammonia, chlorine, asbestos, arsenic,
  mercury, benzene