Air Pollution Study Notes

  • Atmospheric Layers
    • 1. Stratosphere: Includes the ozone layer
    • 2. Troposphere: Includes cloud formation and weather
    • 3. Exosphere: Outermost layer (not shown here)
    • 4. Mesosphere: Meteors are found
    • 5. Thermosphere: Location of aurora borealis
  • Temperature Increase in Stratosphere
    • The temperature increases due to:
    • a. A thermal inversion occurs
    • b. The ozone in the stratosphere absorbs UV light as heat
  • Composition of the Atmosphere
    • The atmosphere is primarily composed of Nitrogen (N2).
  • Pollutants
    • Primary pollutants: Pollutants released directly from a source.
    • a. Non-point source pollutants
    • b. Primary pollutants
    • c. Secondary pollutants
    • Secondary pollutants: Pollutants formed from reactions of primary pollutants.
  • Tropospheric Ozone Formation
    • Important pollutants/factors:
    • 1. Volatile Organic Compounds (VOCs)
    • 2. Nitrogen Oxides (NOx)
    • 3. Sunlight (UV light)
    • Reaction steps:
    • a. VOCs react with NO to produce Ozone (O3).
    • b. Light causes NO2 to dissociate into NO and O.
    • c. (O + O2
      ightarrow O3)
  • Ozone Levels
    • Tropospheric ozone levels peak in the afternoon and summer due to increased vehicle emissions and favorable weather conditions (heat and sunlight).
  • Importance of Stratospheric Ozone
    • Protects DNA from UV radiation.
    • Does not contribute to the greenhouse effect.
    • Not used by plants during photosynthesis.
  • Ozone Cycle
    • Breakdown of ozone:
    • (O3 + UV
      ightarrow O + O2)
    • Reformation of ozone:
    • (O + O2
      ightarrow O3)
  • CFCs and Ozone Depletion
    • CFCs prevent ozone from reforming by:
    • a. Dissociation by UV light releases Cl and ClF.
    • b. Chlorine reacts with ozone to produce ClO and O2.
    • Chlorine prevents ozone from reforming by bonding with oxygen atoms instead of allowing ozone to stabilize.
  • Radon
    • Indoor air pollutant from the radioactive decay of uranium.
  • Health Risks
    • Radon is the second leading cause of lung cancer.
  • Other Indoor Air Pollutants
    • Examples:
    • 1. Carbon monoxide: from gas stoves.
    • 2. Formaldehyde: from furniture.
  • Thermal Inversion
    • Occurs when warm air traps cooler air below, preventing pollutant dispersion.
  • Chemical Formulas of Pollutants
    • Nitrogen oxides: NO, NO2
    • Sulfur dioxide: SO2
    • Tropospheric Ozone: O3
    • Lead: Pb
    • Carbon monoxide: CO
    • CFCs: CCl3F
    • Particulate matter: PM10, PM2.5
    • Volatile Organic Compounds: VOCs
  • Characteristics of Air Pollutants
    • Heavy metal (lead): Released as particulate.
    • Nitrogen oxides: Includes NO, NO2, N2O.
    • Organic molecules: Evaporate easily; indoor air pollutants.
    • Hydrocarbons: Contain carbon, chlorine, and fluorine.
    • Carbon monoxide: Poisonous, colorless, odorless gas.
    • Particulate matter: Classified based on size.
    • Ozone: Beneficial in stratosphere, harmful in troposphere.
    • Sulfur dioxide: Colorless gas with a pungent odor.
  • Sources of Air Pollutants
    • Landfills, smelting, vehicle exhaust, burning fossil fuels, cigarettes, CFCs, gas stoves, and coal-burning power plants.
  • Effects of Air Pollution
    • Eye irritation, lung damage, headaches, and respiratory problems.
  • Acid Rain Formation
    • Two reactions:
    • 1. NO2 + H2O
      ightarrow HNO3 (Nitric acid)
    • 2. SO2 + H2O
      ightarrow H2SO4 (Sulfuric acid)
  • Effects of Acid Rain
    • Damage to ecosystems, forest degradation, and harm to water quality.
  • Criteria Pollutants (Clean Air Act 1990)
    • 1. Particulate Matter
    • 2. Nitrogen Dioxides
    • 3. Sulfur Dioxide
    • 4. Carbon Monoxide
    • 5. Lead
    • 6. Ozone
  • Banned Pollutant
    • CFCs were banned under the Montreal Protocol due to their role in ozone depletion.
  • Pollutant Reduction Technologies
    • Wet/Dry Scrubbers: Remove particulate matter/sulfur oxides/nitrogen oxides from emissions.
  • Electrostatic Precipitator
    • Attracts and removes pollutants using electrically charged plates.
  • Catalytic Converters
    • Reduce emissions of nitrogen oxides, carbon monoxide, and hydrocarbons.