Air Pollution

1
Air Pollution

• Environmental Science

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What Causes Air Pollution?

• Air Pollution is the contamination of the
  atmosphere by solid, liquid, or gasses
• Most air pollution is the result of human
  activities
• Industrial burning
• Automobile Exhaust
• Some pollutants are
• natural
• Dust
• Pollen and spores
• Volcanic eruptions (sulfur
• dioxide)

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Primary and Secondary Pollutants

• Primary Pollutants a pollutant put directly
  into the atmosphere by humans or nature
• Ex. CO from car exhaust
• Secondary Pollutants a pollutant that is formed
  by a chemical reaction between a primary
  pollutant and another compound in the atmosphere
  (either natural or man-made)
• Ex. Ground level ozone

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Types of Pollutants

• Carbon monoxide (CO)
• mainly comes from car exhaust
• Nitrogen oxides (NOX)
• auto exhaust, power plants and some industrial
  processes
• Sulfur dioxide (SO2)
• burning fossil fuels
• Volatile Organic Compounds (VOCs)
• burning fuel (gasoline vapors)
• Particulate Matter
• tiny particles (can be solids or liquids)
  construction, agriculture, fires, vehicles,
  industry

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Automobile Emissions

• One third (1/3) of air pollution comes from cars
• Americans drove 2.6 trillion miles in 1998
• Only 10 of that was done by busses or trucks

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Clean Air Act of 1970

• Gives the EPA authority to regulate automobile
  emissions
• The EPA required
• Elimination of leaded gasoline
• Lead pollution has decreased 90 as a result
• Catalytic converters had to be installed into
  cars
• Cause a chemical reaction that changes the
  pollutants to less harmful substances
• EPA estimates cars burn fuel 35 more efficiently
  and pollute 95 less now than 30 yrs ago

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Zero-Emission Vehicle

• California began the Zero-Emission Vehicle
  program to encourage the development of
  less-polluting vehicles
• Electric cars are the only true ZEV cars
• 2 types of partial ZEVs
• Gasoline/Electric Hybrids (Toyota Prius)
• Methanol Fuel Cells (all still prototypes)

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Industrial Pollution

• Most power plants generate electricity by burning
  fossil fuels
• Power plants emit at least 2/3 of all sulfur
  dioxide and more than 1/3 of all nitrogen oxides
  that pollute the air.
• Dry cleaning, oil refineries, chemical
  manufacturing plants, furniture refinishers, and
  automobile repair shops all contribute to the
  VOCs in the air.

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Industrial Air Pollution

• Clean Air Act also requires that industries
  remove pollution from their emissions
• Scrubbers remove gasses by spraying water into
  the exhaust to dissolve many soluble pollutants
• Electrostatic Precipitators gasses containing
  dust particles are blown through an electrically
  charged chamber the dust sticks to each other
  and the side of the chamber
• 20 tons of ash generated by coal burning power
  plants each year

10
Smog

• Air pollution that hangs over cities and reduces
  visibility
• Smog is the result of chemical reactions
  involving sunlight, air, car exhaust, and ozone

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Temperature Inversions

• Usually temperature decreases with altitude
• A temperature inversion is when warm air is
  higher and the cold air is trapped beneath
• Sometimes pollution is trapped beneath the warm
  air