ES 1111

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ES 1111

• Air Pollution and Acid Rain
• Section 11.2 in first text

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Pollutant

• A pollutant is anything that is hazardous to life
  or the environment
• Primary pollutant one that is emitted directly
  into the atmosphere
• Secondary pollutant one that not emitted
  directly, but is generated through chemical
  reactions over time
• Criteria pollutant identified and monitored by
  the US EPA

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Important Criteria Pollutants

• Particulates (can be secondary too)
• Carbon monoxide
• Sulfur Compounds
• Nitric Oxide
• Volatile Organic Compounds
• Lead

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Primary Pollutants and SourcesFigure showing
the primary pollutants and their sources
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Particulates

• Suspended solid or liquid particles (aerosols) in
  the air
• Sizes vary from 0.1 µm to 100 µm
• Sources are fires, volcanic eruptions, breaking
  sea waves, plants (pollen)
• Gravitational settling and precipitation removes
  particulates
• Reduce visibility
• Those smaller than 2.5 µm most readily enter the
  lungs and cause tissue damage

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Carbon Monoxide (CO)

• Colorless and odorless gas
• Most released naturally by volcanic eruptions,
  fires, bacteria, etc.
• Soil microorganisms consume it
• Poorly running automobiles emit large amounts by
  incomplete burning
• Extremely toxic causes heart disease long-term,
  or death within an hour if concentration is 1600
  ppm or more
• Hemoglobin in the blood is 200 times more
  attracted to carbon monoxide than oxygen (leading
  to oxygen starvation of the body)
• Most hazardous to human health of all criteria
  pollutants

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Sulfur Compounds

• 2/3 comes from natural processes (volcanic
  eruptions, bacterial release of hydrogen sulfide
  (H2S), sea spray)
• Sulfur dioxide (SO2) is released by burning
  sulfur-based fossil fuels (coal and oil) and
  other industrial activities
• Sulfur dioxide is colorless but highly corrosive
  and irritates the lungs

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Nitric Oxide (NO)

• Nitric Oxide is toxic, highly reactive,
  colorless, and odorless
• Also considered a pollutant because it readily
  oxidizes into nitrogen dioxide (a toxic secondary
  pollutant)
• Created when high temperature combustion forces
  atmospheric oxygen (O2) and nitrogen (N2) to
  react to form NO

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Volatile Organic Compounds

• Also called hydrocarbons, entirely made of carbon
  and hydrogen atoms
• Examples include methane, butane, propane, and
  octane
• Most emitted naturally by plant and animal
  emissions and decomposition
• Industrial activities/automobiles are a source of
  anthropogenic VOCs
• No direct adverse health effects, but they react
  with other substances to form smog

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Lead

• Was used as a fuel additive to make engines run
  smoother, and for plumbing pipes and in paints
• Can be inhaled or ingested
• Results in brain damage and memory loss, as well
  as low IQ in children

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Secondary Pollutants

• Particulates
• Nitrogen Dioxide
• Ozone

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Particulates

• Secondary particulates can be created by the
  coagulation of gases
• This happens when the humidity is high
• Hygroscopic aerosols are particularly effective
  at being secondary particulate pollutants

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Nitrogen Dioxide (NO2)

• Can be emitted directly as a primary pollutant,
  but most is created by the oxidation of Nitric
  Oxide (NO)
• Toxic gas that has a pungent odor and gives the
  air a yellow to reddish-brown color
• Corrosive and can react with other substances to
  produce other secondary pollutants
• Irritates the lungs and can reduce immunity to
  infection at high levels
• Breaks down readily, so at its highest levels
  when traffic levels are the highest

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Ozone

• At the surface, ozone (O3) is a pollutant - it
  irritates the respiratory system and damages
  plants
• Created differently than it is produced in the
  stratosphere
• Nitrogen dioxide is created when nitrous oxide is
  oxidized. NO2 is broken down by sunlight back
  into NO and O. The loose O reacts with O2 to
  create ozone
• Because it is created by sunlight, ozone is at
  its highest levels in the afternoon

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Smog

• A combination of the words smoke and fog
• Two different types of smog occur
• London Smog original meaning of smog mixture
  of smoke, sulfurous particles and soot with a fog
• Los Angeles Smog Photochemical smog dry air
  smog with ozone, peroxyacyl nitrate (PAN) and
  formaldehyde

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Pollution Meteorology

• Meteorological conditions can make the pollution
  issue better or worse
• The solution to pollution is dilution
• Meteorological conditions that inhibit the
  dispersion of air pollution will create a
  pollution problem
• Pollution can come from a point source (i.e., one
  smoke stack) or a distributed source (i.e., a
  city)

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Atmospheric Stability

• Recall that unstable conditions allow vertical
  motions of the air while stable conditions
  prevent vertical mixing
• Stable conditions will inhibit the pollution from
  dispersing aloft
• Changing profiles of stability with respect to
  the smoke stack can yield different results

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Atmospheric Stability

• Figure 11.8, Page 217
• showing how variations in atmospheric stability
  in reference to smoke stack height will result in
  different dispersions

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Winds

• The stronger the wind, the more diffuse the
  pollution will be
• The more variable the winds (direction), the more
  diffuse the pollution will be
• Wind shear can induce turbulence that can aid in
  the diffusion

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Topography

• At night, cold, dense surface air drains downhill
  into low-lying areas, making them susceptible to
  strong temperature inversions
• Hills and mountains can block flow (like Los
  Angeles)
• Sea breezes can trap pollution in its vertical
  circulation (like Houston)

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Other Meteorological Factors

• For the production of photochemical smog, clear
  skies will allow ample sunlight to begin those
  chemical reactions
• Rain will scrub the atmosphere because many of
  the pollutants are condensation nuclei or
  dissolve easily in water

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Pollution Mitigation Strategies

• Tall smoke stacks
• Catalytic converters on automobiles (can reduce
  by 90 the CO, NO, and hydrocarbon emissions)
• Unleaded gas US has seen a reduction of 90 of
  lead emissions
• Electrostatic precipitators (scrubbers) on power
  smoke stacks
• Using fuels low in sulfur content
• Alternate energy sources
• Mass transit

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Acids

• Acids are substances that, when dissolved in
  water, produce positively charged hydrogen ions
• Bases are substances that, when dissolved in
  water, produce negatively charged hydroxide ions
• Acidity is measured using the pH scale (potenz
  hydrogen)

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pH Scale

• The value of pure distilled water has a pH value
  of exactly 7.0
• Acids will have lower pH values
• Bases will have higher pH values
• Logarithmic scale a decrease of 1 in pH means an
  increase by a factor of 10 in acidity (hydrogen
  ions)

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pH ScaleFigure showing the pH scale and the
values of various substances
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Acid Rain

• Note that clean rain is naturally acidic (pH of
  5.6) due to carbon dioxide in the atmosphere
  dissolving in the water to create carbonic acid
  H2O CO2 gt H2CO3
• Other acids are created when pollution aerosols
  dissolve in water
• Important acids created due to mans activities
  are sulfuric acid and nitric acid

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Sulfuric Acid

• Sulfur dioxide dissolves in water to create a
  weak acid, sulfurous acid SO2 H2O gt
  H2SO3
• Sulfurous acid then can react with oxygen to
  create sulfuric acid H2SO3 O2 gt H2SO4
• Once again, sulfur dioxide is emitted primarily
  by coal-burning power plants

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Nitric Acid

• Nitric acid is created when nitric oxide (NO)
  oxidizes, yielding nitrogen dioxide (NO2). The
  nitrogen dioxide then dissolves in water creating
  nitric acid (HNO3) and nitrous acid (HNO2)
• 2NO2 H2Ogt HNO3 HNO3
• High temperature combustion, such as automobiles,
  produced the nitric oxide that began this process

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Regional Acid RainFigure showing regional pH
values of rain
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Regional Acid Rain

• The northeastern United States has the worst acid
  rain problem
• Midwestern industry located along the Great Lakes
• Prevailing winds blowing eastward
• The southwestern United States has an enhanced
  acidity due to Mexico
• pH values have improved overall in recent
  decades, especially in the northeast
• pH values have worsened slightly in the southwest

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Acid Rain Consequences

• Crop and forest damage was feared
• Increase in acidity for lakes, rivers
• Death of fish and wildlife
• Weathering of monuments and buildings
• Health impacts for those prone to respiratory
  ailments

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Forest Damage

• Fears that forests would die worldwide were
  prevalent in the 80s
• Further studies have shown that the trees in most
  regions are growing better, and studies have
  supported the fact that trees can see an increase
  in growth
• Areas where tree deaths have been observed are a
  result of smoke falling directly on the trees
  from the source

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Damage to Monuments

• Marble structures are especially prone to decay
  due to acid rain
• Marble is made of calcium carbonate (CaCO3), and
  it weathers in sulfuric acid to produce gypsum
  (plaster), carbon dioxide gas, and water
  CaCO3 H2SO4 -gt CaSO4
  H2O CO2
• Cleopatras Needle stood for 3000 years in Egypt,
  but has experienced significant erosion in New
  York over just 100 years (symbols barely visible
  now)

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Cleopatras NeedlePicture of Cleopatras
Needle, showing obvious weathering due to acid
rain in New York
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Acid Rain Mitigation Strategies

• Since acid rain results from pollution, the same
  pollution mitigation strategies will also aid in
  reducing the acid rain problem
• Emissions testing and scrubbing
• Cleaner fuels
• Mass transit
• Alternate Energy

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Indoor Air Pollution

• As bad as the outdoor air pollution can be,
  indoor air pollution is much more harmful to our
  health
• Many of us spend 90 of our time indoors
• Air flow is restricted in our homes and
  businesses, so pollutants can build up

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Oxygen Deficits

• We breathe in 21 oxygen and 0.03 carbon dioxide
• We exhale approximately 16 oxygen and 4 carbon
  dioxide
• About 25 of oxygen has been removed and a
  100-fold increase in carbon dioxide has been
  added in your breath
• Over time, headaches and drowsiness can occur if
  fresh air does not circulate in

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Radon

• Radon is itself harmless
• Results from the radioactive decay of uranium and
  thorium in bedrock
• However, radon is radioactive and the daughter
  products are dangerous
• Estimated that 20,000 lung cancer deaths are due
  to radon decay
• Fresh air circulation is the key to prevention

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Smoking

• Hazards of smoking have been shared with the
  public over the past few decades
• Heart and lung disease results, even with
  second-hand smoke
• Smoking can make individuals 15 x more prone to
  radon-related cancer

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Household Products

• Many of the substances contained in carpet molds,
  paint, insulation, and pressed wood furniture are
  harmful
• Such substances include asbestos, benzine, and
  formaldehyde
• Inefficient stoves and furnaces may emit carbon
  monoxide
• Dispose of harmful materials properly
• Ventilation is vital