Global Air Quality and Pollution

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Global Air Quality and Pollution

• By Hajime Akimoto
• Summary by Ricky Paredes
• Critique by Jesse Kantor
• EE563 Winter 2004

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Summary

• Introduction
• Remote Sensing
• Tropospheric Ozone
• Carbon Monoxide (CO)
• Aerosols
• Intercontinental Transport
• Megacities

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Introduction

• The impact of global air pollution on climate and
  the environment is a new focus in atmospheric
  science
• Air pollution jeopardizes agricultural and
  natural ecosystems
• Air pollution has strong effect on climate change
• Aerosols change global climate through their
  direct and indirect effects on radiative forcing.
• Radiative forcing is the change in the balance
  between radiation coming into the atmosphere and
  radiation going out. A positive radiative forcing
  tends to warm the surface of the Earth, and
  negative forcing tends to cool the surface.
• In the 1990s nitrogen oxide emissions from Asia
  surpassed those from North America and Europe and
  should continue to exceed them for decades.

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Introduction

• Air pollution is international issue
• First became clear when MAPS (1981) measured high
  levels of CO in Asia, Africa, and South America.
• Major contributors
• Fossil fuel combustion
• Biomass burning
• Forest fires
• Agricultural waste burning
• Vegetable fuel combustion

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Introduction
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Remote Sensing

• MAPS (Measurement of Air Pollution from
  Satellite)
• Launched in 1981
• Global distribution of CO
• High concentrations of CO over
• Tropical Asia
• Africa
• South America
• Air pollution as an international issue

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Remote Sensing

• TOMS (Total Ozone Mapping Spectrometer)
• Tropospheric and Stratospheric Ozone measurements
• On Nimbus 7 satellite
• Measurements in Antarctica are shown below
  (notice the growing ozone hole)

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Remote Sensing

• The TOMS is the first instrument to allow
  observation of aerosols as the particles cross
  the land/sea boundary.
• Using this data, it is possible to observe a wide
  range of phenomena such as desert dust storms,
  forest fires and biomass burning.

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Remote Sensing
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Remote Sensing

• MOPITT (Measurement of Pollution in the
  Troposphere)
• Measures carbon monoxide (CO) in the troposphere

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Remote Sensing

• MOPITT in action

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Remote Sensing

• GOME (Global Ozone Monitoring Experiment)
• Measures nitrogen dioxide (NO2) in the troposphere

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Tropospheric Ozone

• Potent greenhouse gas that is toxic to
• Humans
• May cause permanent damage to lungs
• Inhaling it triggers chest pains, coughing,
  nausea, throat irritation, and congestion.
• Animals
• Plant life

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Tropospheric Ozone

• Lifetime of tropospheric ozone
• 1 to 2 weeks in the summer
• 1 to 2 months in the winter
• Hemispherical transport
• Characteristical timescale 1 month
• Occurs in all seasons except summer
• Therefore tropospheric ozone can be transported
  intercontinentally

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Tropospheric Ozone

• Model-Calculated surface O3 during the growing
  season in the Northern Hemisphere in 1860 and 1993

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Tropospheric Ozone

• Spatial extent of global ozone pollution
• The average concentration of ozone in remote
  areas of East Asia is already high enough to
  jeopardize agricultural and natural ecosystems
  there.
• Hence, long range transport of ozone can cause
  the addition of ozone produced locally or
  regionally to exceed critical levels.
• Small increments of ozone concentrations caused
  by contributions from other continents an issue
  of great concern

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Carbon Monoxide (CO)

• Atmospheric lifetime of CO is also long enough to
  allow intercontinental transport and
  hemispherical air pollution
• Significant portion of CO pollution is from
  automobiles and biomass burning
• Global pollution by CO is worrisome because of
  its effect on the oxidizing capacity of the
  atmosphere

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Aerosols

• Aerosols are tiny particles suspended in the air.
• Some occur naturally, originating from volcanoes,
  dust storms, forest and grassland fires, living
  vegetation, and sea spray.
• Human activities, such as the burning of fossil
  fuels and the alteration of natural surface
  cover, also generate aerosols.
• Averaged over the globe, aerosols made by human
  activities currently account for about 10 percent
  of the total amount of aerosols in our
  atmosphere.
• Most of that 10 percent is concentrated in the
  Northern Hemisphere, especially downwind of
  industrial sites, slash-and-burn agricultural
  regions, and overgrazed grasslands.

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Aerosols

• Lifetime of aerosol is about 1 to 2 weeks
• Have a more uneven distribution than ozone
• More concentrated near their source regions over
  continents and in the boundary layer
• The more uneven distribution of tropospheric
  aerosols causes highly heterogeneous radiative
  forcing, which can lead to climate effects
  occurring regionally and globally

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Aerosols
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Intercontinental Transport

• Studies of transboundary air pollution led
• To the investigation of possible intercontinental
  transport and hemispheric air pollution
• Trans-Pacific transport of trace gases from Asia
  to North America has been reported most
  frequently
• This Asian outflow enhances the concentration of
  surface ozone in the US by a few ppbv

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Intercontinental Transport

• Trans-Atlantic transport from North America to
  Europe has been investigated
• North America pollution contributes an average of
  5 ppbv to surface O3 on the west coast of Ireland
• And about 2 to 4 ppbv over Europe in the summer
• The influence of North American pollution on
  European air quality is seen most frequently in
  the free troposphere.

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Intercontinental Transport

• Transport of European outflow across Eurasia to
  Asia has scarcely been studied
• Substantial amount of air travels from Europe to
  East Asia in winter and early Spring.
• Measurements of air pollutants over Eurasia made
  using commercial airlines have revealed high
  concentrations of O3 in the upper troposphere
• Export of nitrogen oxides are the major sources
  over polluted continents and the clean ocean.

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Intercontinental Transport

• Study of the intercontinental transport and
  chemical transformation of O3 between North
  America, Europe, and Asia using a global chemical
  transport model

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Intercontinental Transport
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Intercontinental Transport

• Intercontinental transport of O3 from East Asia
  (to North America and Europe) occurs mostly in
  the middle and upper troposphere.
• Intercontinental Transport of O3 from Europe
  affects mainly near-surface O3 concentrations in
  East Asia.
• The O3 from the US affects Europe in the boundary
  layer and middle and upper troposphere.

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Intercontinental Transport

• NOx emissions from North America and Europe have
  been nearly equal since 1980
• Stringent emission control in western European
  countries after 1990
• Asian emissions have increased rapidly and are
  expected to continue for at least the next couple
  of decades

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Intercontinental Transport

• Future increases of emissions from Africa and
  South America, because of the economic growth
  there, would make global air quality more of an
  issue in the Southern Hemisphere
• Southern Hemisphere is a region where only
  biomass burning has been considered important so
  far.

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Megacities

• Important source of regional and global pollution
• Defined as a metropolitan area with over 10
  million inhabitants
• 17 megacities in 2001
• With rapid growth in developing countries,
  megacities become major contributors of pollution

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Megacities

• Megacities that have three or more pollutants
  that exceed the WHO (World Health Organization)
  health protection guidelines
• Beijing (China)
• Sao Palo (Brazil)
• Moscow (Russia)
• Los Angeles (USA)
• Cairo (Egypt)
• Jakarta (Indonesia)
• Mexico City (Mexico)
• Mexico City was classified as having serious
  problems for sulfur dioxide, carbon monoxide, and
  ozone in addition to heavy pollution for lead and
  nitrogen dioxide. Mexico City suffers in
  particular due to its high altitude and climate
  which results in poor ventilation, in addition to
  the large number of old and poorly maintained
  vehicles.

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Megacities
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Authors Conclusion

• Local, regional, and global air-quality issues,
  and regional and global environmental impacts,
  including climate change, should be viewed in an
  integrated manner.

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Critique

• By Jesse Kantor

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CRITIQUE

• Why should we believe his conclusions about the
  increasing global pollution?
• Does he have enough data to support his
  conclusions?

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Many Satellites

• Air Pollution Measuring Satellites
• MAPS(Measurement of Air Pollution from Satellite)
• MOPITT(Measurement of pollution in Troposphere)
• SCHIAMACHY(Scanning Imaging Absorption
  Spectro-meter for Atmospheric Cartography)
• Ozone Measuring Satellites
• TOMS(Total Ozone Mapping Spectrometer)
• GOME(Global Ozone Monitoring Experiments)
• Aerosol Measuring Satellites
• SEAWIFS(Sea Viewing Wide-Field-of-View Sensor
  Data)
• AVHRR(Advanced Very High Resolution Radiometers)
• MODIS(Moderate Resolution Imaging Spectrometer on
  Terra Satellite)
• SAGE(Stratospheric Aerosol and Gas Experiment on
  Nimbus 7 satellite)
• Total
• 9 Satellites (A large amount of information
  sources)

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References

• 48 sources(A large amount)
• Only 3 written by Akimoto
• This is 6.25 percent
• Many of sources were written in the past 10 years
• The large amount of references gives credibility
  to the paper

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No Old Sources

• Is it good to have only recent sources?
• J. Lelieveld, F. Dentener wrote high-latitude
  Eurasian and North American continents was 15 to
  25 parts per billion by volume (ppbv) in 1860 but
  has increased to 40-50 ppbv even in relatively
  remote areas (2000)
• Brings into doubt their estimation of historical
  information since satellite sensor technology is
  relatively new
• It is excellent to have current sources which
  show that experts currently believe we have
  greatly increasing global pollution
• It is difficult to believe they are entirely
  correct about how fast it is increasing
• They may also not know all the causes
• Many factors contribute to pollution such as
  biomass pollution (forest fires, agricultural
  waste burning)

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Critique of Major Argument

• His major claim is that small concentrations of
  ozone from other continents can push endangered
  regions to a critical mass
• His arguments are very convincing that we have
  pollution problems
• It was not as believable that one continents
  pollution is having a great effect on other
  countries
• Akimoto writes One example of the special extent
  of global ozone pollution is that the average
  concentration of ozone in remote areas of East
  Asia is already high enough to jeopardize
  agriculture and natural ecosystems there
• He assumes that these remote areas are polluted
  by other continents
• It is more likely that pollution in rural Asia
  comes from urban Asia

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Good Point

• The lifetime of these pollutants last long enough
  to spread (1 week-2 months) globally
• We need to be concerned with this possibility
• Some pollutants have more effect globally than
  others
• Tropospheric ozone and CO are more harmful
  globally because their lifetimes are 1-2 months
• Aerosol is not as global
• Its lifetime is 1-2 weeks
• Any global effects are episodic
• It mainly affects local and regional areas

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Same Old Argument

• It is just difficult to prove how much 1
  continent is affected by another
• It is difficult to see the effects of pollution.
• This makes it difficult to motivate people to do
  something about it

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Final Argument Intercontinental Pollution

• He has 11 sources showing some evidence of
  intercontinental transport of gases
• Note These were not harmful gases they tracked
• They have not observed ozone transport, only
  measured increases of ozone in certain areas
• On the other hand, just because we havent
  observed it, it doesnt mean it is not there
• If it is true for other gases, we should be
  concerned about ozone

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Counter Arguments to Intercontinental Pollution

• Trans Atlantic transport of O3 and CO from North
  America to Europe were studied for 6 years but
  few episodes of intercontinental pollution were
  identified
• Transport of European outflow across Eurasia has
  scarcely been studied
• Most of evidence presented by Akimoto that
  supports global pollution more clearly was done
  through modeling
• Hard evidence is more concrete than modeling
• Last page showed more proof of the large amount
  of pollution rather than the intercontinental
  effects of pollution

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Conclusion

• This was a good article
• It may not completely prove all its points but it
  does show we need to be concerned and do more
  studies of intercontinental pollution

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The End

• Questions?
• Comments?