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

• 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• 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

• 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

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