Air Pollution

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Traditional Aboriginal Knowledge

Air Pollution

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Smog
Control of Air Pollution
Air Inversion
Global Warming
Greenhouse Gases
External Links

adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane University


Smog
Smoke plus Fog (based on Britain's experience) (Grey smog)

Control of Air Pollution Automobiles


  • Catlytic converter converts carbon monoxide, nitrous oxides and hydrocarbons into carbon dioxide, nitrogen and water.
  • Recirculating exhaust gas along with a catlytic converter greatly reduces emissions.
    • Coal Main problem is the sulfur dioxide it produces upon burning. Solutions:
  • Burn only low sulfur coal.
  • Wash coal to remove pyrite.
  • Convert coal to gas (called Gasification)
  • Fluidized Bed Combustion (or Limestone Injection): Mix coal with limestone, to form calcium sulfides or sulfates, which are prevent sulfur from forming sulfur dioxide.
  • Scrubbing - slurries of lime or limestone.


    • Air Inversion

      In valleys or on the lee side of mountains, air inversion may occur. A warmer air mass moves above cooler air, trapping the cooler, denser air underneath and increasing the severity of air pollution. Los Angeles is a good example of this, where warm desert air from the east comes over the mountains to the east of Los Angeles and lies over the cooler Pacific Ocean air. The cooler air is trapped because it cannot rise through the less dense warm air above it, and the pollution in the cold air accumulates.
     


    A similar situation arises in mountain valleys where warm air overlies the colder air which accumulates in the valleys.



    Also, cities tend to form featuers known as heat islands or dust domes, which tend to collect warm air filled with pollutants, and help spread it out over nearby suburbs.




    Global Warming


    solar-radiation.gif><br><ul> <li>If there were no greenhouse effect, the average temperature on the earth would be 0°F with huge fluctuations in a 24 hour period.</li> <li>When visible light from the sun hits the earth some is absorbed, heating the earth.   The heated earth gives off infrared radiation characteristic of the 60o F temperature. This longer wavelength infrared radiation  is then reradiated back into space. Some of the  infrared radiation, however, is  trapped (absorbed) by greenhouse gases. This is known as The Greenhouse Effect. See Blatt pg. 491 for a more detailed explanation.</li> <li>There are several gases which cause the greenhouse effect, and whose concentrations determine the amount of heat retained by the earth. Primary among these are water vapor, carbon-dioxide and methane. The chart below shows how the concentration of CO2 in the atmosphere has changed in the last 40 years:</li><ul> <br> <img src=