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									Chapter 19

Air Pollution
     Chapter Overview Questions
 What   layers are found in the atmosphere?
 What are the major outdoor air pollutants,
  and where do they come from?
 What are two types of smog?
 What is acid deposition, and how can it be
 What are the harmful effects of air pollutants?
 How can we prevent and control air
      Core Case Study:
When Is a Lichen Like a Canary?
                  Lichens  can warn
                   us of bad air
                   because they
                   absorb it as a
                   source of

                               Figure 19-1
         Core Case Study:
   When Is a Lichen Like a Canary?
 Some   lichen species are sensitive to specific
  air-polluting chemicals.
 After Chernobyl, more than 70,000 reindeer
  had to be killed because they ate highly
  radioactive lichens.
 Because lichens are widespread, long-lived,
  and anchored in place, they can help track
  pollution to its source.
            Theatmosphere
            consists of several
            layers with different
            pressures, and

                             Figure 19-2
                          Atmospheric pressure (millibars)


  Altitude (kilometers)
                                    Heating via ozone

                                                               Altitude (miles)



                                              Ozone “layer”
                                   Heating from the earth
 (Sea                                                         Pressure = 1,000
level)                                                        millibars at ground
                                    Temperature (˚C)          level
                                                                                  Fig. 19-2, p. 440
 The  atmosphere’s innermost layer
  (troposphere) is made up mostly of nitrogen
  and oxygen, with smaller amounts of water
  vapor and CO2.
 Ozone in the atmosphere’s second layer
  (stratosphere) filters out most of the sun’s
  UV radiation that is harmful to us and most
  other species.
        Processes of Air Pollution
 Attrition
 Vaporization
 Combustion
 Natural Fires - Smoke
 Volcanoes - Ash and acidic components
 Sea Spray - Sulfur
 Vegetation - Volatile organic compounds
 Bacterial Metabolism - Methane
 Dust
     Pollen
 Viruses      and Bacteria
  Cultural Processes of Air Pollution
 Continuous   rather than sporadic emissions
 Local concentrations in small areas
 Combinations of cultural pollutants are
  potentially bad
 Local discharges can overwhelm natural
 Primary Pollutants - Released directly from
  the source.
 Secondary Pollutants - Modified to a
  hazardous form after entering the air and
  mixing with other environmental components.
     Fugitive Emissions - Do not go through
       • Dust from human-activities.
                 AIR POLLUTION

   Some primary air pollutants may react with one
    another or with other chemicals in the air to form
    secondary air pollutants.
                                                  Figure 19-3
                        Primary Pollutants

                          CO CO2                    Secondary Pollutants
                        SO2 NO NO2
                        Most hydrocarbons                 SO3
                     Most suspended particles         HNO3 H3SO4
                                                     H2O2 O3 PANs
                                                Most NO3– and SO42– salts
Sources    Natural          Stationary


                                                               Fig. 19-3, p. 442
                Major Air Pollutants
 Carbon      oxides:
     Carbon monoxide (CO) is a highly toxic gas that
      forms during the incomplete combustion of
      carbon-containing materials.
     93% of carbon dioxide (CO2) in the troposphere
      occurs as a result of the carbon cycle.
     7% of CO2 in the troposphere occurs as a result
      of human activities (mostly burning fossil fuels).
       • It is not regulated as a pollutant under the U.S. Clean
         Air Act.
            Conventional Pollutants
 Carbon     Oxides
     Predominant form of carbon in the air is carbon
       • Increasing levels due to human activities.
       • Annual Emissions: 7-8 billion metric tons
     Carbon monoxide is a colorless, odorless, toxic
      gas produced by incomplete fuel combustion.
       • Annual Emissions: 1 billion metric tons
                Major Air Pollutants
 Nitrogen      oxides and nitric acid:
     Nitrogen oxide (NO) forms when nitrogen and
      oxygen gas in air react at the high-combustion
      temperatures in automobile engines and coal-
      burning plants. NO can also form from lightening
      and certain soil bacteria.
       • NO reacts with air to form NO2.
       • NO2 reacts with water vapor in the air to form nitric
         acid (HNO3) and nitrate salts (NO3-) which are
         components of acid deposition.
            Conventional Pollutants
 Nitrogen    Compounds
     Nitrogen oxides are reactive gases formed when
      nitrogen is heated above 650o C in the presence
      of oxygen, or when nitrogen compounds are
       • Annual Emissions: 230 million metric tons
              Major Air Pollutants
 Sulfur   dioxide (SO2) and sulfuric acid:
     About one-third of SO2 in the troposphere occurs
      naturally through the sulfur cycle.
     Two-thirds come from human sources, mostly
      combustion (S+ O2  SO2) of sulfur-containing
      coal and from oil refining and smelting of sulfide
     SO2 in the atmosphere can be converted to
      sulfuric acid (H2SO4) and sulfate salts (SO42-) that
      return to earth as a component of acid
            Conventional Pollutants
 Sulfur   Compounds
     Natural sources of sulfur in the atmosphere
      include evaporation from sea spray, volcanic
      fumes, and organic compounds.
     Predominant form of anthropogenic sulfur is
      sulfur-dioxide from fossil-fuel combustion.
       • Annual Emissions: 114 million metric tons
             Major Air Pollutants
 Suspended      particulate matter (SPM):
    Consists of a variety of solid particles and liquid
     droplets small and light enough to remain
     suspended in the air.
    The most harmful forms of SPM are fine particles
     (PM-10, with an average diameter < 10
     micrometers) and ultrafine particles (PM-2.5).
    According to the EPA, SPM is responsible for
     about 60,000 premature deaths a year in the
            Conventional Pollutants
 Particulate    Matter
     Atmospheric aerosols (solid or liquid)
       • Respirable particles smaller than 2.5 micrometers are
         among most dangerous.
     Anthropogenic particulate emissions amount to
      about 362 million metric tons annually.
                Major Air Pollutants
 Ozone     (O3):
     Is a highly reactive gas that is a major
      component of photochemical smog.
     It can
       • Cause and aggravate respiratory illness.
       • Can aggravate heart disease.
       • Damage plants, rubber in tires, fabrics, and paints.
 Strong   oxidant-tires and cracks
 6-7% of U.S. agricultural production lost due
  to ozone pollution.
 Irritant of sensitive tissues-eyes & throat
               Major Air Pollutants
 Volatile   organic compounds (VOCs):
     Most are hydorcarbons emitted by the leaves of
      many plants and methane.
     About two thirds of global methane emissions
      comes from human sources.
     Other VOCs include industrial solvents such as
      trichlorethylene (TCE), benzene, and vinyl
       • Long-term exposure to benzene can cause cancer,
         blood disorders, and immune system damage.
             Major Air Pollutants
 Radon    (Rn):
    Is a naturally occurring radioactive gas found in
     some types of soil and rock.
    It can seep into homes and buildings sitting
     above such deposits.

 Industrialsmog is a mixture of sulfur dioxide,
  droplets of sulfuric acid, and a variety of
  suspended solid particles emitted mostly by
  burning coal.
     In most developed countries where coal and
      heavy oil is burned, industrial smog is not a
      problem due to reasonably good pollution control
      or with tall smokestacks that transfer the pollutant
      to rural areas.
            Case Study:
 South Asia’s Massive Brown Cloud
A huge dark brown cloud of industrial smog,
 caused by coal-burning in countries such as
 China and India, stretches over much of
 southeastern Asia.
    In areas beneath the cloud, photosynthesis is
     reduced interfering with crop development.
    Fine particles and droplets in the cloud appear to
     be changing regional climates (including rainfall).
      • May have contributed to floods in 2002 and 2005
        which killed thousands of people.
       Sunlight plus Cars Equals
         Photochemical Smog

 Photochemical  smog is a mixture of air
 pollutants formed by the reaction of nitrogen
 oxides and volatile organic hydrocarbons
 under the influence of sunlight.
      Photochemical Oxidants
• Products of secondary atmospheric
  reactions driven by the sun’s energy
   O2 + UV ==> O + O (oxygen free radical)
   NO2 +UV ==>NO + O

   O + O2 ==> O3 (ozone)

   O2 + NO ==> O2 + NO2

   NO + VOC ==> NO2 + PAN (peroxy-

    acetylnitrate) + aldehydes
• NO2+UV+VOC+O2==>NO2+O3+PAN+
Sunlight plus Cars Equals
  Photochemical Smog
              Mexico   City is one
               of the many cities
               in sunny, warm, dry
               climates with many
               motor vehicles that
               suffer from

                             Figure 19-4
        Factors Influencing Levels of
           Outdoor Air Pollution
 Outdoor    air pollution can be reduced by:
     settling out, precipitation, sea spray, winds, and
      chemical reactions.
 Outdoor    air pollution can be increased by:
     urban buildings (slow wind dispersal of
      pollutants), mountains (promote temperature
      inversions), and high temperatures (promote
      photochemical reactions).
 Inversions
     Temperature inversions occur when a stable
      layer of warm air overlays cooler air, reversing
      the normal temperature decline with increasing
      height, and preventing convection currents from
      dispersing pollutants.
       • Cold front slides under warm air mass.
       • Cool air subsides down slope.
             Rapid nighttime cooling in a basin.
          Temperature Inversions

 Cold, cloudy weather in a valley surrounded
  by mountains can trap air pollutants (left).
 Areas with sunny climate, light winds,
  mountains on three sides and an ocean on
  the other (right) are susceptible to inversions.
                                           Figure 19-5
                                 Descending warm air mass
 Warmer air
Inversion layer                        Inversion layer

                                Sea breeze


                                                 Fig. 19-5, p. 447
              ACID DEPOSITION
 Sulfurdioxides, nitrogen oxides, and
 particulates can react in the atmosphere to
 produce acidic chemicals that can travel long
 distances before returning to the earth’s
     Tall smokestacks reduce local air pollution but
      can increase regional air pollution.

 Aciddeposition consists of rain, snow, dust,
 or gas with a pH lower than 5.6.
                                         Figure 19-6
Transformation to
sulfuric acid
(H2SO4) and nitric            Windborne ammonia gas and
acid (HNO3)                   particles of cultivated soil
                              partially neutralize acids and             Wet acid depostion
                              form dry sulfate and nitrate               (droplets of H2SO4
                              salts                                      and HNO3 dissolved
  Nitric oxide (NO)                                                      in rain and snow)
                      Sulfur dioxide         Dry acid deposition
                      (SO2) and NO           (sulfur dioxide gas and
                                             particles of sulfate and
                                             nitrate salts)
          Acid fog
                                                                         Lakes in shallow soil
Ocean                                                                        low in limestone
                                                        Lakes in deep          become acidic
                                                          soil high in
                                                        limestone are

                                                                                Fig. 19-6, p. 448

 pHmeasurements in relation to major coal-
 burning and industrial plants.
                                       Figure 19-7
 Acid deposition contributes to chronic
 respiratory disease and can leach toxic
 metals (such as lead and mercury) from soils
 and rocks into acidic lakes used as sources
 for drinking water.

                  Figure 19-8

           Air pollution is
            one of several
            stresses that can
            weaken, or kill
            trees and pollute
            surface and

                      Figure 19-9

            SO2      NOx
     Acid H O        O3
             2 2
deposition           Others
                                                                 to drought,
                                                                 extreme cold,
           Direct damage to                     Reduced          insects,
           leaves & bark                        photo-           mosses, &
                                                synthesis        disease
                                                and growth       organisms

                           Soil acidification                                     Tree death

                   Leaching               Release of    Root     Reduced nutrient
                   of soil      Acids     toxic metal   damage   & water uptake
                   nutrients              ions

                                                                                    Fig. 19-9, p. 451
                   Acid Deposition
      Prevention                     Cleanup
Reduce air pollution                 Add lime to
by improving                         neutralize
energy efficiency                    acidified lakes
Reduce coal use
                                     Add phosphate
Increase natural
gas use                              fertilizer to
Increase use of                      acidified lakes
renewable energy

Burn low-sulfur coal

Remove SO2
particulates & NOx
from smokestack

Remove NOx from
motor vehicular

Tax emissions of SO2
                                                       Fig. 19-10, p. 452
 Indoor air pollution usually is a greater threat
  to human health than outdoor air pollution.
 According to the EPA, the four most
  dangerous indoor air pollutants in developed
  countries are:
     Tobacco smoke.
     Formaldehyde.
     Radioactive radon-222 gas.
     Very small fine and ultrafine particles.
                                         Tetrachloroethylene       Formaldehyde

1, 1, 1-




                                                      Tobacco      Radon-222
Asbestos                                               Smoke

                  Carbon Monoxide            Methylene Chloride
                                                                         Fig. 19-11, p. 453
         Household  dust mites
         that feed on human skin
         and dust, live in
         materials such as
         bedding and furniture
             Can cause asthma
              attacks and allergic
              reactions in some
                                Figure 19-12
  Case Study: Radioactive Radon

                              Radon-222,  a
                              radioactive gas
                              found in some
                              soils and rocks,
                              can seep into
                              some houses and
                              increase the risk of
                              lung cancer.

Sources and paths of entry
for indoor radon-222 gas.
                                            Figure 19-13
              Outlet vents for furnaces and dryers

                  Openings         Cracks
                  around           in wall
                         Slab joints

                   Wood stove
                    Cracks in floor
        Clothes                       Sump
Furnace dryer                         pump

          gas          Uranium-238


                                             Fig. 19-13, p. 454

 Yourrespiratory system can help protect you
 from air pollution, but some air pollutants can
 overcome these defenses.                 Figure 19-14
                                                 Epithelial cell

                                   Goblet cell
Nasal cavity                       mucus)
Oral cavity
Pharynx (throat)
Trachea (windpipe)
Right                                                                       duct

                                    Alveolar sac

                                                                   Fig. 19-14, p. 455

Normal human lungs (left) and the lungs of a
 person who died of emphysema (right).
                                        Figure 19-15
          Air Pollution is a Big Killer
 Each  year, air pollution prematurely kills
 about 3 million people, mostly from indoor air
 pollution in developing countries.
     In the U.S., the EPA estimates that annual
      deaths related to indoor and outdoor air pollution
      range from 150,000 to 350,000.
     According to the EPA, each year more than
      125,000 Americans get cancer from breathing
      diesel fumes.
       Air Pollution is a Big Killer

 Spatial distribution of premature deaths from
 air pollution in the United States.
                                         Figure 19-16
 TheClean Air Acts in the United States have
 greatly reduced outdoor air pollution from six
 major pollutants:
     Carbon monoxide
     Nitrogen oxides
     Sulfur dioxides
     Suspended particulate matter (less than PM-10)
 Environmental  scientists point out several
 deficiencies in the Clean Air Act:
     The U.S. continues to rely on cleanup rather than
     The U.S. Congress has failed to increase fuel-
      efficiency standards for automobiles.
     Regulation of emissions from motorcycles and
      two-cycle engines remains inadequate.
     There is little or no regulation of air pollution from
      oceangoing ships in American ports.
    Airports are exempt from many air pollution
    The Act does not regulate the greenhouse gas
    The Act has failed to deal seriously with indoor
     air pollution.
    There is a need for better enforcement of the
     Clean Air Act.
 Executives of companies claim that
 correcting these deficiencies would cost too
 much, harm economic growth, and cost jobs.
  Using the Marketplace to Reduce
        Outdoor Air Pollution
 Tohelp reduce SO2 emissions, the Clean Air
 Act authorized and emission trading (cap-
 and-trade) program.
     Enables the 110 most polluting power plants to
      buy and sell SO2 pollution rights.
     Between 1990-2002, the emission trading system
      reduced emissions.
     In 2002, the EPA reported the cap-and-trade
      system produced less emission reductions than
      were projected.
      Reducing Outdoor Air Pollution
 There are a of ways to prevent and control air
 pollution from coal-burning facilities.
     Electrostatic precipitator: are used to attract
      negatively charged particles in a smokestack into
      a collector.
     Wet scrubber: fine mists of water vapor trap
      particulates and convert them to a sludge that is
      collected and disposed of usually in a landfill.
Electrostatic Precipitator
              Can  remove 99% of
               particulate matter
              Does not remove
               hazardous ultrafine
              Produces toxic dust
               that must be safely
               disposed of.
              Uses large amounts
               of electricity
                             Figure 19-18
                            Clean gas out

Negatively charged         Positively charged
          electrode        precipitator wall

  Dirty gas
  (smoke) in

                           Dust falls off into

                      Taken to landfill

                                                 Fig. 19-18a, p. 460
Wet Scrubber
       Can  remove 98% of
        SO2 and particulate
       Not very effective in
        removing hazardous
        fine and ultrafine

                      Figure 19-18
             Clean gas out


                                   water in

Dirty gas
(smoke) in

                         Polluted liquid
                         (sludge) out

                                              Fig. 19-18b, p. 460

          Stationary Source Air Pollution

Prevention                        Dispersion or

Burn low-sulfur                   Disperse emissions
coal                              above thermal
                                  inversion layer with
                                  tall smokestacks
Remove sulfur
from coal

                                  Remove pollutants
Convert coal to a                 after combustion
liquid or gaseous

                                  Tax each unit of
Shift to less                     pollution produced
polluting fuels

                                                       Fig. 19-17, p. 459
       Reducing Outdoor Air Pollution
 In 2003, fourteen states and a number of
  U.S. cities sued the EPA to block new rules
  that would allow older coal-burning power
  plants to modernize without having to install
  the most advanced air pollution controls.
      Reducing Outdoor Air Pollution
 There are a of ways to prevent and control air
 pollution from motor vehicles.
     Because of the Clean Air Act, a new car today in
      the U.S. emits 75% less pollution than did pre-
      1970 cars.
     There is and increase in motor vehicle use in
      developing countries and many have no pollution
      control devices and burn leaded gasoline.

            Motor Vehicle Air Pollution

Prevention                         Cleanup
Mass transit                       Emission
                                   control devices
Bicycles and

Less polluting
Less polluting fuels               Car exhaust
Improve fuel efficiency            twice a year

Get older, polluting
cars off the road

Give buyers large tax
write-offs or rebates for
buying low-polluting,              Stricter
energy efficient                   emission
vehicles                           standards
                                                     Fig. 19-19, p. 460
            Indoor Air Pollution
 Littleeffort has been devoted to reducing
  indoor air pollution even though it poses a
  much greater threat to human health than
  outdoor air pollution.
 Environmental and health scientists call for
  us to focus on preventing air pollution
  (especially indoor) in developing countries.
                New Flash!!
 B-727  Stretches falling from the sky @ the
  rate of 5.3 per day!!
 The math: 400,000 / 207 passengers / 365
  days = 5.3 full planes crashing per day!
 WHO est. that tobacco kills 3 million deaths
  per year.
 What should society do??
              Signs of Hope
 Sweden    and West Germany cut their sulfur
  emission by two-thirds between 1970 and
 Australia and Switzerland even regulate
  motorcycle emissions.
 South Coast Air Quality Management District
  in California has adopted rules to clean the
  air in the Los Angeles Basin.
 Clean  Air Act (1963) - First national air
  pollution control.
 Clean Air Act (1970) rewrote original.
     Identified critical pollutants.
     Established ambient air quality standards.
       • Primary Standards - Human health
       • Secondary Standards - Materials, environment,
         aesthetic and comfort.
                 Clean Air Act
 Revision   (1990) - Included provision for:
     Acid Rain
     Urban Smog
     Toxic Air Pollutants
     Ozone Protection
     Marketing Pollution Rights
     Volatile Organic Compounds
     Ambient Ozone
     Nox Emissions
 Revision   (1997) - Stricter standards
            Clear Skies Initiative
 On February 14, 2002 President George W. Bush
  announced the Clear Skies Initiative.
 The Initiative based on central idea: "that economic
  growth is key to environmental progress, because it
  is growth that provides the resources for investment
  in clean technologies."
 The resulting proposal was a market-based cap-
  and-trade approach which intends to legislate
  power plant emissions caps without specifying the
  specific methods used to reach those caps. The
  Initiative would reduce the cost and complexity of
  compliance and the need for litigation.
            Clear Skies Initiative
 Current power plant emissions amounted to
  67% of all sulfur dioxide (SO2) emissions (in
  the United States), 37% of mercury
  emissions, and 25% of all nitrogen oxide
  (NOx) emissions.
 Only SO2 has been administered under a
  cap-and-trade program.
                   Clear Skies Initiative
   The goals of the Initiative are three-fold:
       Cut SO2 emissions by 73%, from emissions of 11 million tons to a
        cap of 4.5 million tons in 2010, and 3 million tons in 2018.
       Cut NOx emissions by 67%, from emissions of 5 million tons to a cap
        of 2.1 million tons in 2008, and to 1.7 million tons in 2018.
       Cut mercury emissions by 69%, from emissions of 48 tons to a cap of
        26 tons in 2010, and 15 tons in 2018.
       Actual emissions caps would be set to account for different air quality
        needs in the East and West.
   Through the use of a market-based cap-and-trade program,
    the intent of the Initiative was to reward innovation, reduce
    costs, and guarantee results.
   Each power plant facility would be required to have a permit
    for each ton of pollution emitted.
   Because permits are tradeable, companies would have a
    financial incentive to cut back their emissions using newer
            Clear Skies Initiative
 The law reduces air pollution controls, including
  those environmental protections of the Clean Air
  Act, including caps on toxins in the air and budget
  cuts for enforcement.
 The Act is opposed by conservationist groups such
  as the Sierra Club with Henry A. Waxman, a
  Democratic congressman of California, describing
  its title as "clear propaganda."
 In some cases, the difference between existing
  laws and the Clear Skies Act is as little as 3%.
                 Clear Skies Initiative
   Among other things, the Clear Skies Act:
       Allows 42 million more tons of pollution emitted than the
        EPA proposal.
       Weakens controls on mercury pollution levels compared
        to what would be achieved by enforcing the Clean Air Act
       Weakens the current cap on nitrogen oxide pollution
        levels from 1.25 million tons to 2.1 million tons, allowing
        Delays the improvement of sulfur dioxide (SO2) pollution
        levels compared to the Clean Air Act requirements.
       Delays enforcement of smog-and-soot pollution
        standards until 2015.
                 Blue Skies Initiative
   The Clear Skies Act will supposedly allow:
       3 million tons more NOx through 2012 and 8 million more
        by 2020,
       SO2, 18 million tons more through 2012 and 34 million
        tons more through 2020,
       and 58 tons more mercury through 2012 and 163 tons
        more through 2020 would be released into the
        environment than what would be allowed by enforcement
        of the Clean Air Act.
   In August 2001, the EPA proposed a version of the
    Clear Skies Act that contained short timetables and
    lower emissions caps. It is unknown why this
    proposal was withdrawn and replaced with the more
    industry-friendly Bush Administration proposal.
         Sierra Club Web Page
 Inthe United States, air quality has improved
  dramatically in the last decade in terms of
  major large-volume pollutants.
      Cities where pollution is largely from traffic still
       have serious air quality problems.
 Major metropolitan areas of many developing
  countries are growing at explosive rates, and
  environmental quality is very poor.
Air Pollution in Developing Countries
  “Where you shouldn’t spend your
 Many metropolitan areas of developing
 countries are growing at explosive rates.
     Mexico City
       • Pollution levels exceed WHO health standards 350
         days per year.
     China’s 400,000 factories have no air pollution
    Scorecard: The Pollution
        Information Site
                                  Indoor Air Pollution
                       Prevention                 Cleanup or

Cover ceiling tiles & lining of AC                Use adjustable fresh air
ducts to prevent release of mineral               vents for work spaces
                                                  Increase intake of outside air
Ban smoking or limit it to well
ventilated areas
                                                  Change air more frequently
Set stricter formaldehyde
emissions standards for carpet,                   Circulate a building’s air
furniture, and building materials                 through rooftop green houses

Prevent radon infiltration                        Use exhaust hoods for stoves
                                                  and appliances burning
Use office machines in well                       natural gas
ventilated areas
Use less polluting substitutes for                Install efficient chimneys for
harmful cleaning agents, paints,                  wood-burning stoves
and other products
                                                                         Fig. 19-20, p. 461
                         What Can You Do?
                        Indoor Air Pollution

• Test for radon and formaldehyde inside your home and take
  corrective measures as needed.
• Do not buy furniture and other products containing formaldehyde.
• Remove your shoes before entering your house to reduce inputs
  of dust, lead, and pesticides.
• Test your house or workplace for asbestos fiber levels and for
  any crumbling asbestos materials if it was built before 1980.
• Don't live in a pre-1980 house without having its indoor air
  tested for asbestos and lead.
• Do not store gasoline, solvents, or other volatile hazardous
  chemicals inside a home or attached garage.
• If you smoke, do it outside or in a closed room vented to the outside.
• Make sure that wood-burning stoves, fireplaces, and kerosene-
  and gas-burning heaters are properly installed, vented, and
• Install carbon monoxide detectors in all sleeping areas.
                                                                 Fig. 19-21, p. 461
                                   Air Pollution
                    Outdoor                    Indoor

Improve energy efficiency to                   Reduce poverty
reduce fossil fuel use

                                               Distribute cheap &
Rely more on lower-polluting                   efficient cookstoves or
natural gas                                    solar cookers to poor
                                               families in developing
Rely more on renewable energy
(especially solar cells, wind, &
solar-produced hydrogen)                       Reduce or ban indoor

Transfer technologies for
latest energy efficiency,                      Develop simple and cheap
renewable energy, & pollution                  tests for indoor pollutants
prevention to developing                       such as particulates, radon,
countries                                      and formaldehyde

                                                                  Fig. 19-22, p. 462
              Stratospheric Ozone
 Discovered in 1985 that stratospheric ozone
 levels were dropping rapidly during
 September and October.
      Occurring since at least 1960.
 Atground-level, ozone is a pollutant, but in
 the stratosphere it screens UV radiation.
      A 1% decrease in ozone results in a 2% increase
       in UV rays reaching the earth.
                 Stratospheric Ozone
 Circumpolar vortex isolates Antarctic air and
 allows stratospheric temperatures to drop
 and create ice crystals at high altitudes.
     Absorb ozone and chlorine molecules.
       • When sun returns in the spring, energy liberates the
         chlorine allowing the depletion process to proceed
             CFCs believed to be main culprit.
               • Persist for decades.
               • Production eliminated in 1996.
Destruction of Stratospheric Ozone

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