Air Pollution

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					Chapter 20
Air Pollution
The Atmosphere as a Resource
Atmospheric composition:
Nitrogen = 78%
Oxygen = 21%
Argon = 0.93%
Carbon dioxide = 0.04%
              Air Pollution
What do you know?
1. What is outdoor air pollution?
2. What do you think causes outdoor air
3. Where does air pollution come from?
4. Have you ever seen air pollution? How
   do you know?
5. Is air pollution a solid, liquid or a gas?
6. Do you think humans are affected by air
   pollution? How?
              Air Pollution
7. What else do you think might be affected
    by air pollution?
8. How do we get rid of air pollution?
9. Have you heard of ozone? Is it good or
    bad? Explain.
10. Have you heard about particle pollution
11. Do you think particles floating in the air
    affect humans? How?
12. How do particles get into the air?
       Types of Air Pollution
Air Pollution – various substances added to the
 atmosphere by natural events and human
 activities in high enough concentrations to
 cause harm to humans, other organisms, or
Primary air pollutant – a substance emitted
 directly to the atmosphere
Secondary Air Pollutant – a substance formed
 in the atmosphere as a result of reactions
 involving primary pollutants
Types and Sources of Air Pollution
Primary and Secondary Air Pollutants
Types and Sources of Air Pollution
Major Classes of Air Pollutants
• Particulate matter
• Nitrogen oxides
                     Ozone damage
• Sulfur oxides
• Carbon oxides
• Hydrocarbons
• Ozone
• Lead
Types and Sources of Air Pollution
Major Air Pollutants
         Types of Air Pollution
Particulate Matter – solid
  and liquids suspended
  in the atmosphere.
• Soil, Soot, lead,
  asbestos, sea salt,
  sulfuric acid droplets
• Reduces visibility
• Corrodes structures
• Leaves residue on
• Can absorb other toxic
      Types of Air Pollution
Nitrogen oxides- NO, NO2, N2O
• Produced by the reaction at high
  temperatures between N2 and O2
• Inhibit plant growth
• Aggravate respiratory conditions
• Involved in the production of
  photochemical smog
• N2O is a greenhouse gas and is involved in
  ozone depletion
• Corrode metals and textiles
         Types of Pollution
Sulfur oxides – SO2, SO3
• formed mainly when sulfur containing fuels
  are burned (mainly coal)
• Dissolve in water to form sulfuric acid (acid
  rain), which damages plants and structures
• Damage plants
• Respiratory irritants
        Types of Pollution
Carbon Monoxide – CO
• Produced by the incomplete combustion of
• Poisonous gas
         Types of Pollution
Hydrocarbons-compounds containing H and C
• Wide variety of compounds
• Involved in the production of
  photochemical smog.
• Some are toxic (respiratory irritants,
• Some are involved in ozone depletion
• Methane (CH4) is a potent greenhouse gas.
         Types of Pollution
Ozone – O3
• Essential component of the stratosphere
  that blocks UV light waves from the sun
• Harmful component of photochemical
  smog in the troposphere.
• A secondary pollutant formed by reactions
  between nitrogen oxides and
  hydrocarbons, initiated by sunlight
• Reduces visibility and causes health
  problems; damage to plants
        Effects of Air Pollution
•   Damages organisms
•   Reduced visibility
•   Corrodes materials
•   Especially harmful to the respiratory
    systems of humans
•   Reduction in crop productivity
•   Leads to acid deposition
•   Global climate change
•   Stratospheric ozone depletion
        Effects of Air Pollution
Air Pollution and Human Health

Air Toxics – a variety of hazardous air pollutants; it is
estimated that 360 out of 1 million Americans die of cancer
every year as a result of air toxics.
      Effects of Air Pollution
Effects of air pollution on children:

• Air pollution can restrict lung development
  in children making them more susceptible
  to respiratory and heart problems later in
• Children have a higher metabolic rate,
  meaning they breathe in more air than
  Controlling Air Pollution in the
           United States
Clean Air Act
 Emissions in the US, 1970 vs. 2000
     Controlling Air Pollution
• Energy efficiency and conservation are important
• Smokestacks are equipped with electrostatic
  precipitators, scrubbers, filters, etc. to remove
  particulates, sulfur oxides, and nitrogen oxides
• Controlling the fuel/air ratio and lowering
  combustion temperatures leads to the
  production of less nitrogen oxides
• Modifications to furnaces and combustion
  engines to provide more complete combustion
  eliminates carbon monoxide and hydrocarbon
   Controlling Air Pollution in the
            United States
Controlling Air Pollutants
Electrostatic precipitator

                               Turned ON
                             Turned OFF
   Controlling Air Pollution in the
            United States
Controlling Air Pollutants
Electrostatic precipitator

                               Turned ON
                             Turned OFF
     Controlling Air Pollution
Clean Air Act
• passed in 1970; amended in 1977 and
• Administered by the EPA
• States pass laws which must be as
   stringent as the federal law
• Focuses on six air pollutants (lead,
   particulates, sulfur dioxide, carbon
   monoxide, nitrogen oxides, ozone)
  Controlling Air Pollution in the
           United States
US Urban Areas with Worst Air Quality, 2002
     Controlling Air Pollution
Clean Air Act
• Areas which do not meet regulatory
  requirements for the six pollutants are
  designated as nonattainment areas
• 1977 and 1990 amendments required
  stricter controls on automobile emissions.
• 1990 amendments also focused on
  regulation of air toxics; required a 90 %
  reduction in emissions of 189 toxic

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