Groundlevel Ozone

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Ground-level Ozone

• Scott Chao
• Allison Douglas
• Kristin Lee

2
Good Ozone

• Stratospheric or good ozone is located 10-30
  miles above the earths surface
• Protects the planet from harmful UV radiation

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Bad ozone

• Also referred to as tropospheric ozone, urban
  ozone, and smog
• May cause permanent lung damage and harms plants
  and ecosystems
• Caused by nitrous oxide(Nox) and volatile organic
  compounds(VOC).

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Types of Smog

• Gray (London, New York)
• Combustion of coal and fuel oil releases tons of
  ashes, soot, and sulfur compounds.
• Brown (Los Angeles, Denver)
• Caused by automobiles

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Causes of Smog

• NOX is the combination of the concentrations of
  NO and NO2 in the air.
• NOX is a product of combustion
• N2 O2 2NO

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• VOC are reactive hydrocarbons that come from
  incomplete combustion and evaporation of solvents
  and fuels.
• Other sources of VOC are deciduous trees
  (isoprene) and conifer trees (pinene and
  limonene).

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• The formation of ozone is complex and involves
  hundreds of chemical reactions.
• Simplified reaction
• 2NO O2 2NO2
• NO2 h NO O
• O O2 M O3 M

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• h represents short wavelength of light
• M represents a catalyst
• In this case, reactive hydrocarbons (VOC).
• M is a product of the reaction so VOC stay in the
  air to produce more harmful ozone.

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Harmful Effects of Ozone

• Irritates the respiratory system
• Reduces lung function
• Can aggravate asthma
• Can damage and inflame lung tissue
• Similar to sunburn
• Symptoms include wheezing, coughing, and
  difficulty breathing

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• Plant and ecosystem damage
• Interferes with plants ability to produce and
  store food
• Damages leaves of trees and plants
• Reduces crop and forest yields
• Increases plant vulnerability to disease,
  insects, and harsh weather

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Possible Solutions

• Cooler combustion temperatures in cars and power
  plants
• Catalytic converters
• Can reduce NOX, CO, and hydrocarbon emissions up
  to 90

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Scrubbers

• Toxic, corrosive and polluting substances from
  air and gas exhaust systems are absorbed in a
  scrubber solution.
• Absorbed components are rapidly chemically
  reacted into harmless products.
• Products can often be reused.

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Scrubbing Techniques

• Packed Tower
• Can handle fluctuations in vent flows and
  contaminant concentrations
• Recommended tool to handle emergencies
• Ejector Scrubber
• High efficiency
• Used for low volumes with high contaminant
  concentrations

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• Jet Venturi
• For exhaust flows contaminated with dust and
  particles

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Ozone Sensors

• Metal Oxide Semiconductor Sensors
• Clean air low conductivity
• Contact with specific gases increases
  conductivity
• Sensitivity to a particular gas is changed by
  altering the temperature of the sensing element
• Preprogram the sensor

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• Electrochemical Sensors
• Components diffusion barrier, anode, cathode,
  and electrolyte
• Clean air creates stable potential between the
  anode cathode
• Reactive gas passed through is either oxidized or
  reduced causing a current to flow

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• Specifications of various portable sensors
• Range 0-10 ppm of ozone
• Operating temperature 32-104 degrees F
• Size 8- 20 in3
• Weight 6-8 oz
• Power 9 -24 V DC
• Display numerical readout, LED multi-color graph

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Resources

• Mihelcic, James R. Fundamentals of Environmental
  Engineering. John Wiley Sons. New York 1999
• US EPA
• http//www.epa.gov/air/urbanair/ozone/hlth.html 
• http//www.epa.gov/oar/oaqps/gooduphigh/ozone.html
  bad 
• http//www.epa.gov/airnow/health/smog1.html1

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• http//www.appliedozone.com/ozone_sensor_specs.htm
  l
• http//www.appliedozone.com/sensors.html
• http//www.spectrex.com/a_pocket_ozone.htm
• http//www.ozonesensors.com/prodcuts/o3sensorrrep/
  IIozone_detector.htm
• http//www.biosystems.com/appnotes/howoxyge.htm
• http//www.delphian.com/electrochemical20sensors.
  htm
• http//www.freeencyclopedia.com/printable.asp?url
  /ssi/s1/smog.html
• http//www.betescrubbers.com/products/scrubbers-in
  dex.html
• http//www.betescrubbers.com/products/scrubbing-te
  chnique.html