Chapter 16: Air Pollution
16.2 Natural Sources Of Air Pollution
• Natural Combustion
• Decay
• Biological Emissions
– Chemical
– Particulate (spores, pollen, etc.)
• Wind-blown dust
• Volcanic
16.3 Human-caused Air Pollution
• We categorize pollutants according to their
source
• We also categorize pollutants according to
their content
• Unconventional pollutants also are important
• Indoor air is more dangerous for most of us
than outdoor air
Classification of Pollutants By Source
• Primary: Direct emission
• Secondary: Modified by environment (smog)
• Fugitive: Non-point source (dust)
Classification of Pollutants By Content
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Sulfur emissions
Nitrogen Compounds
Carbon: CO2 and CO
Particulate Matter
Metals (Hg, Cd) and Halogens (Cl, F, Br)
Volatile Organics (gasoline, pesticides)
16.4 Climate, Topography, And
Atmospheric Processes
• Temperature inversions trap pollutants
• Cities create dust domes and heat islands
• Wind currents carry pollutants
intercontinentally
• Stratospheric ozone is destroyed by chlorine
• The Montreal Protocol is a resounding success
Inversion?
• Cold air on ground, warm up above
• Isn’t that normal?
• It’s what buoyancy does, but solar warming of
the surface is stronger
• Reverse of normal state of affairs (that’s why
it’s an “inversion”)
• Stratified air doesn’t circulate vertically, so
pollutants accumulate
Destroying Ozone
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CFCL3 + UV Energy = CFCl2 + Cl
Cl + O3 = ClO + O2
O2 + UV Energy = 2O
ClO + O = Cl + O2
Cl + O3 = ClO + O2 etc.
What about volcanic HCl?
– Most scrubbed out in the eruption cloud
– Very little gets into stratosphere
16.5 Effects Of Air Pollution
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Polluted air causes lung diseases
How does pollution harm us?
Plants are susceptible to pollution damage
Acid deposition has many negative effects
Smog and haze reduce visibility
Smog
Particulate Matter
Particulate Matter
• In pre-industrial days, 100-mile visibility was
normal
• Haze was unusual
– Great Smoky Mountains named because of
natural forest aerosols
– “Dry Fog” – sign of distant volcanic eruptions, was
noted in chronicles
16.6 Air Pollution Control
• Saving Energy and Reducing Pollution
• The most effective strategy for controlling
pollution is to minimize production
• Fuel switching and fuel cleaning also are
effective
• Clean air legislation is controversial
16.7 Current Conditions And Future
Prospects
• Air pollution remains a problem in many
places
• There are signs of hope
Los Angeles
San Francisco, Same Day