Air Quality Issues

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Air Quality Issues
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Outline

• The Atmosphere
• Categories of Air Pollutants
• Control of Air Pollutants
• Acid Deposition
• Ozone Depletion
• Global Warming and Climate Change
• Addressing Climate Change
• Indoor Air Pollution

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The Atmosphere

• The atmosphere is composed of 78.1 N, 20.9 O
  and about 1 of other gases such as argon, carbon
  dioxide, methane, and water vapor.
• Most of the atmosphere is held close to the earth
  by the pull of gravitational force, thus it gets
  thinner with increasing distance from the earth.

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The Atmosphere

• Troposphere extends from the earths surface to
  about 10 km above the earth.
• Stratosphere extends from the top of the
  troposphere to about 50 km above the earth.
• Most ozone located in a band between 15 and 30
  km.
• Mesosphere extends from 50-80 km above the earth.
  
• Thermosphere extends to about 300 km above the
  earth.

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The Atmosphere
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The Atmosphere

• As the atmosphere absorbs heat from the earth, it
  expands and rises.
• When heat is radiated into space, air cools,
  becomes more dense, and flows toward the earth.
• Air quality degraded by multiple sources.
• Air pollution includes both aesthetic and human
  health problems.

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Air Pollution and Population Centers
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Air Pollution and Population Centers

• Many of the mega cities of the developing world
  have extremely poor air quality.
• Increases death rate and lowers general health of
  the population.
• Chronic coughing and susceptibility to infections
  are common.

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Categories of Air Pollutants

• Primary Air Pollutants
• Five major materials released directly into the
  atmosphere in unmodified forms.
• Secondary air pollutants form under reaction of
  primary pollutants and water or sunlight.
• Criteria Air Pollutants are those pollutants for
  which specific air quality standards have been
  set.

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Primary Air Pollutants

• Carbon Monoxide - Produced when organic materials
  are incompletely burned.
• Single largest source is the automobile.
• Not a persistent pollutant.
• Binds to hemoglobin in blood and makes the
  hemoglobin less able to carry oxygen.

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Carbon Monoxide

• Most dangerous in enclosed spaces.
• Cigarette smoking an important source.
• U.S. levels have decreased by about 21 between
  1993 and 2003.
• Increasing number of cars on the road and miles
  driven, can offset savings from catalytic
  converters.

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Primary Air Pollutants

• Particulate Matter - Minute pieces of solid
  materials (lt 10 microns) dispersed into the
  atmosphere.
• PM10 and PM 2.5
• Larger than 2.5 microns are primary pollutants
  Smaller than 2.5 are mostly secondary pollutants.
• Can accumulate in lungs and interfere with the
  ability of lungs to exchange gases.

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Particulate Matter

• Amount of PM10 has decreased 9 between 1996 and
  2002.
• U.S. EPA has been setting PM2.5 standards for a
  shorter period of time.
• Amount decreased 7 between 1996 and 2002.

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Primary Air Pollutants

• Sulfur Dioxide (SO2) - Sulfur and oxygen compound
  produced when sulfur-containing fossil fuels are
  burned.
• Burning coal releases SO2.
• Today over 65 of SO2 released into the
  atmosphere is primarily from coal-burning power
  plants.
• U.S. levels of SO2 decreased 30 between 1993 and
  2002.

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Primary Air Pollutants

• Nitrogen Dioxide
• Oxides of Nitrogen (NOx) - Formed when
  combustion takes place in the air.
• N and O molecules from the air may react with one
  another.
• Nitrogen Monoxide NO
• Nitrogen Dioxide NO2
• Automobile engine is primary source.
• U.S. levels decreased 10 between 1993 and 2002.

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Primary Air Pollutants

• Lead
• Lead (Pb) can enter the body through breathing
  airborne particles or consuming lead deposited on
  surfaces.
• Leaded gasoline was primary source.
• North American lead levels fell 94 between 1982
  and 2002.
• Currently, about 80 of gasoline sold in the
  world is unleaded.

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Lead Emissions
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Primary Air Pollutants

• Volatile Organic Compounds
• Hydrocarbons - Group of organic compounds
  consisting of carbon and hydrogen.
• Evaporated from automobile fuel or remnants of
  fuel incompletely burned.
• Catalytic converters used to burn exhaust gases
  more completely.
• U.S. levels decreased 25 between 1993 and 2002.

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Ground-Level Ozone

• Ozone (O3) is a molecule of three oxygen atoms
  bonded to one another.
• Extremely reactive secondary pollutant.
• Permanent Lung Damage
• Damages Plants
• Destroys Chlorophyll

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Photochemical Smog

• A mixture of primary and secondary pollutants.
  Forms when primary pollutants interact under the
  influence of sunlight.
• Two most destructive components
• Ozone
• Peroxyacetyl Nitrates
• Large cities ringed by mountains tend to have
  trouble with photochemical smog.

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Daily Changes in Photochemical Smog
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Photochemical Smog

• Thermal Inversions - Warm air becomes sandwiched
  between two layers of cold air and acts like a
  lid on the valley.
• Warm air cannot rise, causing smog accumulation.

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Thermal Inversion
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Hazardous Air Pollutants

• Hazardous Air Pollutants (HAP) or Air Toxics are
  compounds that can harm human health or damage
  the environment.
• Some released from consumer activities
• Benzene escapes during automobile refueling.
• Majority released from manufacturing
• Perchloroethylene released from dry cleaning
  processes.

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Control of Air Pollution

• Motor Vehicle Emissions
• U.S. regulations have pressured the automobile
  industry to reduce emissions.
• Positive Crankcase Ventilation Valve (PCV)
• Air Pollution Control Valves (APC)
• Catalytic Converters
• Lead-Free Fuel

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Control of Air Pollution

• Particulate Matter Emissions
• Industrial Activities
• Mining
• Improper Land Use
• Overgrazing
• Fossil Fuel Burning
• Diesel Fuel
• Personal Activities
• Fireplaces and Wood-Burning Stoves

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Control of Air Pollution

• Power Plant Emissions
• Sulfur Removal
• Switch to low-sulfur fuel.
• Remove sulfur from fuel before use.
• Scrubbing gases emitted from smokestack.

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The Clean Air Act

• Clean Air Act
• Series of detailed control requirements the
  federal government implements and states
  administer.
• Emissions of six worst air pollutants dropped 48
  from 1973 to 2002, despite an increase in energy
  consumption of 42.
• EPA estimates benefits have outweighed costs 40
  to 1.

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Acid Deposition

• Acid Deposition is the accumulation of potential
  acid-forming particles on a surface.
• Sulfur Dioxide and Nitrogen oxides are carried
  aloft by wind and form secondary pollutants
  (acids), and then are carried back to earth in
  wet (snow, rain, fog) and dry (particulate) form.
  

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Sources of Acid Deposition
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Acid Deposition - Harmful Effects

• Property / Structural Damage
• Limestone Degradation
• Foliage Damage
• Acidic Soil - Reduced Nutrient Absorption
• Weakened Plant Defenses
• Stressors
• Lake Acidification
• Food Chain Disruption

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Ozone Depletion

• Ozone is formed in the stratosphere when high
  energy ultraviolet radiation splits diatomic
  oxygen into atomic oxygen.
• The atomic oxygen may then combine with another
  diatomic oxygen molecule to form triatomic oxygen
  (Ozone - O3).

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Ozone Depletion

• In the 1970s, it was discovered that CFCs were
  lowering the average concentration of ozone in
  the stratosphere.
• CFCs take 10-20 years to make it into the
  stratosphere.
• Can react with ozone for up to 120 years.

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Ozone Depletion

• In the stratosphere, UV radiation breaks down CFC
  molecules, releasing atomic chlorine. A free
  chlorine atom reacts with an ozone molecule,
  converting it from O3 to O2.
• Montreal Protocol (1987).
• Several industrialized countries agreed to reduce
  CFC production by 50 by 2000.
• As a result, emissions dropped 87 from their
  peak in 1988.

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Global Warming and Climate Change

• Climatic records indicate over past 160,000
  years, a correlation between greenhouse gas
  concentration and global temperatures.
• UN established Intergovernmental Panel on Climate
  Change (IPCC)
• 1996 Assessment - Concluded climate change is
  occurring and it is highly probable human
  activity is importance cause of the change.

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Global Warming and Climate Change

• IPCC Conclusions
• Average temperature of the earth increased .5 to
  1.0 degrees Fahrenheit over the last 100 years.
• Strong correlation between temperature increase
  and amount of greenhouse gases in the atmosphere.
• Human activity greatly increases amounts of
  greenhouse gases in atmosphere.

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Changes in Average Global Temperature
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Causes of Global Warming and Climate Change

• Greenhouse Effect
• Greenhouse gases allow sunlight to penetrate the
  atmosphere.
• Absorbed by earths surface.
• Reradiated as infrared energy (heat).
• Absorbed by gases.

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Greenhouse Effect
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Greenhouse Effect

• Carbon Dioxide
• Fossil fuel burning, deforestation.
• Chlorofluorocarbons
• Refrigerants, cleaning solvents, propellants.
• Methane
• Breakdown of organic material by anaerobic
  material.
• Nitrous Oxide
• Biomass burning - Breakdown of nitrogen-rich
  products.

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Potential Consequences of Global Warming

• Rising Sea Level
• Beach and coastal wetland erosion.
• Disruption of Water Cycle
• Navigation
• Hydropower
• Water Supply and Demand
• Flood Control
• Environmental Quality and Recreation
• Political Issues

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Potential Consequences of Global Warming

• Health Effects
• Most direct effect of climate change would be
  impacts of hotter temperatures.
• Hot temperatures force cardiovascular system to
  work harder to cool the body.
• Heat exhaustion and some respiratory problems
  increase.
• Aggravate air quality problems.
• Ozone

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Potential Consequences of Global Warming

• Changing Forests
• Geographic distributions of vegetation.
• Challenges to Agriculture
• Increased CO2 concentration likely to increase
  crop yields in some areas and decrease yields in
  other areas.
• Pest range expansion could increase
  vulnerability.
• Unanticipated Changes
• Greatest risks may be those yet to be discovered.

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Effects of Global Warming
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Addressing Climate Change

• Energy Efficiency
• Increase efficiency of energy utilization.
• Reduce carbon dioxide production.
• Carbon Tax
• Role of Biomass
• Increase amount of carbon dioxide removed from
  the atmosphere.
• Increased vegetation growth.
• Short-term benefit.

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Addressing Climate Change

• Political and Economic Forces
• Will be difficult to achieve global consensus to
  reduce CO2 emissions, as CO2 is released as a
  result of energy consumption which affects all
  sections of the economy.
• Resources and policies to increase investment in
  renewables and other long-term technologies will
  be needed.

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Indoor Air Pollution

• Growing evidence indicates air within homes and
  other buildings can be more seriously polluted
  than industrialized cities.
• Adverse effects on human health.
• Asbestos
• Formaldehyde
• Airborne Pesticide Residues
• Perchloroethylene
• Paradichlorobenzene

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Indoor Air Pollution

• Smoking most important pollutant.
• Weatherizing to increase efficiency slows air
  exchange and tends to trap pollutants.
• Average person spends almost 90 of time indoors.
• Movements to reduce indoor air pollution lag
  behind regulations governing outdoor air
  pollution.

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Review

• The Atmosphere
• Categories of Air Pollutants
• Control of Air Pollutants
• Acid Deposition
• Ozone Depletion
• Global Warming and Climate Change
• Addressing Climate Change
• Indoor Air Pollution