AIR POLLUTION

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AIR POLLUTION

• Chapter 17

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The Atmosphere

• Two lowest layers figure 17.1
• Troposphere
• Stratosphere

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Troposphere

• Surface gt 7 or 8 miles
• Contains 75 of mass of Es air
• 78 N2, 21 O2, lt1 Ar
• Convection or turning
• Where almost all weather occurs
• Temperature decreases w/ altitude
• Ozone is a pollutant here!
• Bad ozone

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Stratosphere

• From top of troposphere gt 30 miles
• Lower over poles, higher in tropics
• Much lower pressure
• Contains ozone layer gt
• Temp slightly increases w/ altitude
• This is the good ozone
• Very stable - hardly any weather, pilots like to
  fly here

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Outdoor Air Pollution

• Pollutants, smog, acid deposition

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Air Pollution Types

• Primary pollutants
• Secondary pollutants

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Primary Pollutants

• Put in air directly by human or natural activities

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Primary Pollutants

• Carbon oxides (CO and CO2)
• Nitrogen oxides (NOx)
• Sulfur oxides (SO2 and SO3)
• Volatile organic compounds (VOCs)
• Smelly stuff in car exhaust unburned
  hydrocarbons (HC)
• Evaporated fuel
• Particulates (solid or liquid)

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Secondary

• Products of chemical reaction of primary
  pollutants with other air components and sunlight
• Photochemical smog is a mixture of primary and
  secondary pollutants reacted with sunlight

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Photochemical Smog

• Nitrogen oxides VOCs sunlight
• gt bad ozone lots of chemicals
• More common in cities with sunny, warm, dry
  climates and lots of motor vehicles
• Can occur naturally Blue Ridge Mts
• E.g., Los Angeles Air pollution capital of U.S.

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Industrial Smog

• Traditional smog smoke fog
• Fog sulfur oxides sulfuric acid particulate
  matter
• Coal and heavy oil burning
• Mostly in winter
• Almost nonexistent in MDCs today due to pollution
  controls
• Still occurs in China, E. Europe

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Thermal Inversion

• Worsens smog conditions (photochemical or
  industrial)
• Happens mostly in valleys, fig 17-4 Warm air
  forms a lid over cooler air (inversion)
• Air pollutants trapped in valley

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Figure 17.4 Donora, PA 1948, Coal burning
thermal inversion
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Acid Deposition

• Some fossil fuels (mainly coal) can contain
  significant amounts of sulfur (also some nitrogen
  cmps)
• When burned, SO2 and NOx are released and
• Dissolve in H2O to form acids (lower pH)
• gt Acid rain

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Acid rain

• Downwind of industrial areas
• E.g., Industrial midwest prevailing westerlies
  gt
• Causes acid rain in, for example, Ontario and
  Upstate New York

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Acid rain

• Kills trees, aquatic life (over 10 of lakes in
  the Adirondacks are too acidic to support fish)
• European countries also affected

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SOLUTIONS
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Clean Air Acts

• 1970, 1977, 1990
• Require EPA to establish national ambient air
  quality standards (NAAQS) for 6 outdoor
  pollutants
• Maximum allowable levels of each
• Worked U.S. reduced levels of 5 pollutants from
  1970 94 (all but NOx)
• 2000 EPA Study on effectiveness of CAA p. 397
  Overall fairly effective

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PREVENTION !

• Improved energy efficiency
• Reduce fossil fuel use
• Slow population growth
• Incentives like full-cost pricing
• Internalize externalities
• National (rather than state) air quality
  standards (Why?)
• Export appropriate tech. to LDCs