August 20, 2001

Cutting through the Smog

 

The image of Earth from space shows the Northern Hemisphere covered by a shifting, eerie green haze, dotted now and then with sickly red and yellow blotches.

This isn't a cartoon version of a diseased planet. It is the real, real-time portrait of Earth's polluted atmosphere provided by NASA's Terra satellite and its onboard MOPITT instrument.

MOPITT monitors carbon monoxide levels in the troposphere, the part of Earth's atmosphere where pollutants interact with gases to form smog.

These photos reveal a world in which one country's air pollution quickly spreads to other countries. Much of the Northern Hemisphere is suffering permanently from low-level air pollution. Increased levels of carbon monoxide can be seen trailing from factories and fires in Southeast Asia toward North America. In the Southern Hemisphere, spring burning of trees and fields for agriculture appear as large red areas — places where the levels of carbon monoxide (and other pollutants) are very high.

The nations of the world acknowledge that air pollution and related problems are global in nature. For example, the Kyoto Protocol — adopted in Kyoto, Japan, in 1997 — requires countries to reduce their greenhouse gas emissions. Greenhouse gases are considered a major cause of global warming. Greenhouse gases include human-caused emissions of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. These gases, which accumulate in the atmosphere over a long period of time, can contribute to global warming and climate change. In the short term, they lead to severe air pollution that affects people's health.

  • In spring of 2001, President Bush announced that the United States was pulling out of the Kyoto agreement. For more on President Bush's environmental policies, see the Riverdeep article, "Environmental Friend or Foe?"

Earlier this year, the American Lung Association (ALA) released a report, State of the Air 2001 , which provides air pollution data for all states and counties in the United States. Students can read an overview of the report in the CNN.com article, "Report: Polluted Air Reaching More Americans." The report suggests that air pollution remains as big a threat to American health as ever and that things are getting worse, not better. Specific examples from the report include:

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  • The number of Americans living in areas of the United States with levels of air pollution severe enough to cause serious respiratory problems increased from 132 million in the 2000 report (years 1996 to 1998) to 141 million in the 2001 report (years 1997 to 1999).

  • More than 30 million children under the age of 14 were living in areas with "failing" air quality, an increase of nearly 2 million children. Children's lungs are particularly vulnerable to the effects of bad air.

  • One million more elderly were living in areas with unhealthy air.
Only last week, researchers published a report in the journal Science that said more people are killed by air pollution each year than are killed by traffic accidents. In fact, cutting air pollution in four major world cities — Sao Paulo, Brazil; Mexico City; Santiago, Chile; and New York City — could save 64,000 lives over the next 20 years.  

Teaching the Problem

 

(The following SimLibrary activities require Logal Express. Get a free trial subscription.)

Carbon monoxide isn't the only contributor to air pollution. Two other major sources of air pollution include:

  1. PARTICULATES  Suspended particulates are tiny particles of substances hanging in the air. According to the Environmental Protection Agency (EPA), these particulates are associated with reduced lung function and an increase in respiratory illness.
  2. OZONE  Ozone is composed of molecules containing three oxygen atoms. When sunlight acts on hydrocarbons and nitrogen oxide emitted by vehicles and power plants, it causes a reaction between the pollutants and oxygen in the air. The product of this reaction is ground-level ozone. Unlike atmospheric ozone, which is important because it protects Earth from the Sun's radiation, ground-level ozone is harmful because it is a strong respiratory irritant.

     A study published in the summer of 2000 indicated that ozone also affects plants. The researchers discovered that smog makes plants more susceptible to disease, pests, and extreme environmental conditions like drought. In European countries with high ozone levels, the output of some crops has dropped between 5% and 40%.

     Scientists believe that the ozone affects the plants by inhibiting the leaf's pores, called stomates, from opening. Carbon dioxide enters a leaf through the stomates and oxygen is emitted through them. If the stomates cannot open, photosynthesis is disrupted, and the plant produces and stores less food for itself.

     Ironically, trees can also help cause air pollution. In a study released in July 2001, California researchers warned that planting the wrong trees can increase rather than decrease urban air pollution. Trees give off tiny amounts of the hydrocarbons, isoprene and monoterpene. Both compounds are very reactive and can lead to the formation of ground-level ozone. Different kinds of trees release different amounts of these chemicals, so it is important to plant low-emitting trees when attempting to reduce air pollution.

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Analyzing the Problem & Taking Action  

  • Ask your students to look at the ALA report, State of the Air 2001. Have them find and summarize the data for the county in which your school is located to determine how serious air pollution is in your area. Who in your local area is at greater risk of developing health problems from ozone and other ground-level air pollutants?

  • Ask the class to propose five steps the county could enact to reduce local air pollution. They can get some ideas at the sites listed in Extending the Problem #2.

  • Ask students to evaluate the air quality of the school itself. Have them look at things like ventilation, the location of the cafeteria and special classes that might generate fumes and smells (e.g. wood or automotive shops), nearby factories, and wind direction. Encourage them to come up with several action items to improve the air quality of the school grounds.

  • Have students read the article, "Report: Diesel School Buses Loaded with Toxins" from CNN.com. The article presents two sides to the debate over air quality in and near school buses. Have students list arguments from both sides — the Coalition for Clean Air report and the bus-industry reaction. Students may choose to find out the age and condition of their own school district's buses.
 

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Extending the Problem  

  1. Students can learn more about the science behind air pollution in the Why Files unit, The air that we breathe.

  2. Students will find more information about the quality of our air at the following sites:
  3. The Kyoto Protocol was negotiated to deal with the long-term effects of greenhouse gas emissions. Students can learn more about the protocol at the following sites:
  4. As the images from the NASA satellite show, air pollution affecting a community can originate somewhere else. For example, read the article, "Virginia utility agrees to cut pollution; New Jersey breathes easier" from Environmental News Network. Have students discuss whether neighboring counties, states, or countries should be able to impose limits on pollution originating over the border but affecting local residents. Consider the following additional questions:

    • How does the meaning of the expresssion "the air belongs to everyone" change depending on whether a state is a polluter or a downwind victim of another state's pollution?

    • What are the implications of pollution limits or tariffs on states rights or national sovereignty?

    • What are the difficulties in stopping pollution? What if limits to air pollution in a neighboring state comes at the expense of jobs in your own state?
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