Menu:
  • Ozone Destruction
  • Atmospheric Pollution
  • Indoor Pollution

    Links:

  • Atmospheric Greenhouse Gases
  • A History of Climate Change


  • Ozone Destruction

    Goals:
    Students will learn to understand the dynamics involved in destruction of air molecules by CFC (Chlorofluorocarbon) molecules.

    Grades:
    7th - 12th

    Time:
    Short exercise

    Materials:
    strings, cardboard, marker

    Background:
    Though excess ozone at the ground level is harmful, ozone in the stratosphere, between six and thirty miles, is vital to most living things. Stratospheric ozone acts as a shield that absorbs ultraviolet radiation from the sun. Without the ozone layer, more of this radiation will reach the earth's surface, causing rapid sunburn, cataracts, skin cancer, immune system deficiencies in human and animals and cell death, mutation , and growth inhibition in plants.

    Ozone production near the ground does not influence ozone production in the stratosphere. Ozone molecules are too unstable to survive long enough to reach the stratosphere. Chlorofluorocarbons (CFC's), which are extremely stable, do last long enough to reach the stratosphere. There each CFC molecule can destruct many thousands of ozone molecules.

    During the last few decades tens of millions of tons of CFC were manufactured and released into the air. International agreements have already phased out the manufacture of most CFC's, with a worldwide ban by 2006. However, because of their persistence in the atmosphere, the ozone layer is expected to continue to decrease until at least 2050. By then an estimated ten to thirty percent of the ozone layer will be lost above the Southern Appalachian Region. Evidence exists that ultraviolet radiation may have already damaged the leaves of yellow poplars, sycamores, red maples, oaks, hickories, redbuds and white pines in Southern Appalachia.

    Procedure:
    It is probably best to push the desks aside for this activity. If the class is large, this activity should be done in two groups, with one group observing the other. Conversely, this activity can be done outside, if a flat, grassy area is available away from traffic.

    Pick one student to represent the Chlorofluorocarbon. Give him or her a card labeled "CFC" which (s)he can hang around his neck, and blindfold him. Give the rest of the class cards labeled "Ozone." Have the class close their eyes and mill (slowly) around the room Allow the CFC to enter the milieu: whenever he bumps into someone, he must ask them to remove their necklace. He can then put it around his neck. He might announce, "CFC. Your necklace, please" or some other appropriate statement. This person now must sit down, since he represents an ozone molecule which has been destroyed. The group observing (if applicable) should note that at first, many "molecules" are destroyed, but as the atmosphere thins out, the destruction slows down, since the chance of running into a CFC grows slimmer.

    Question:
    Ask the class to imagine what might happen if half of them were allowed to be a CFC, and relate this to reality. Note that one CFC molecule can "wear the necklace" of a thousand ozone molecules and fly around for many years.



    Atmospheric Pollution

    Goals:
    Students will learn to understand the loss of air molecules through the influence of carbon molecules.

    Grades:
    7th - 12th

    Time:
    Short exercise

    Materials:
    none

    Background:
    The Atmosphere is warming for the same reason that a parked automobile gets hot on a sunny day: the heat is trapped by a greenhouse medium. In the case of the car this is glass, but for the atmosphere this is greenhouse gas. The more dense the greenhouse gas, the greater the heating. Carbon dioxides are the most known greenhouse gases. TVA releases over two hundred billion pounds of carbon dioxides annually in air (nearly 0.4 percent of the world's total) in Southern Appalachian annually. Other carbon dioxide emissions come from cars, trucks, furnaces, stoves, etc.

    As a result of the trapping of greenhouse gases, models of TVA predict that the temperature will rise of between 2.7 and 8.1 degrees Fahrenheit by 2050. More violent whether can be expected as well. The severe winters and damaging frosts in 1996 or severe flooding of the 1998 spring in Southern Appalachia are examples of this. Warmer temperature might bring subtropical species to Southern Appalachia, such as malaria, hanta virus, and dengue fever. Growing seasons are likely to change, so that crop varieties now suited to this bioregion may no longer be successful. Furthermore, some tree species may not be able to exist in our region, while weeds, plants and insects may increase in occurrence.

    Procedure:
    Assign one-third of the class as carbon. Explain that they were produced as exhaust from cars driving , smoke from fires, and the smoke from a diesel engine (like a garbage truck). The rest of the class is oxygen. Have them pair up and link arms. Line up the oxygen molecules facing the carbon. Each carbon atom must find an oxygen molecule and link arms, forming a triangle (the carbon must link with both oxygens). They have now formed a carbon dioxide molecule. This is what happens when free carbon is emitted into the atmosphere. Remind the students that we need oxygen to breathe, and by forming carbon dioxide in the atmosphere, those oxygen molecules are no longer available to us. Discuss the principle of a greenhouse, and talk about global warming due to carbon dioxide and other gases trapping heat in the atmosphere.



    Indoor Pollution

    Goals:
    Students will learn to understand the how unventilated air in buildings causes indoor pollution.

    Grades:
    7th - 12th

    Time:
    Short exercise

    Materials:
    soap and waters to make bubbles

    Background:
    The most lethal air pollutant in the bioregion is cigarette smoke. It is not the most toxic, nor the greatest in quantity, but it kills the largest number of people because it is concentrated indoors where people spend most of their times. Second to cigarette smoke is radon, a naturally occurring radioactive gas given off by rocks and soil that seeps into buildings from the ground. Radon is prevalent in the soils of Southern Appalachia--especially in upper East Tennessee and Northwestern Carolina. Simultaneous exposure to radon and cigarette smoke act in "synergy": the multiple effect together are greater than the effects alone by themselves. Other common sources of indoor pollution include wood stoves and fireplaces, mothballs, chlorine bleach, solvents, air fresheners, foam insulation, plastic products, synthetic fibers, adhesives, artificial wood products, polishes, paints, pesticides, photocopiers, dusts and asbestos.

    Because indoor pollutants are trapped and most repeatedly re-circulated, indoor pollution is the most important environmental cause of cancer. The easiest and least expensive way to reduce indoor air pollution is to open the windows. Air conditioning is often used excessively, and can be used less intensively by using appropriate architecture, fans, and proper placements of trees for shade.

    Procedure:
    Bring some bubbles to class. Blow a large bunch inside the classroom (with the door shut), and ask the children to watch the bubbles. See how they float around and remain in the air for quite some time. Then, take the class outside and repeat the exercise. They should note that the bubbles burst, float away, and disperse much more than they did in the room. Explain that the bubbles inside resemble cigarette smoke, which continues to get recirculated when released indoors. (ask them to imagine the bubbles getting sucked into the vent and traveling to the principal's office, for example). Talk about other pollutants such as bleach, Tilex, Formula 409, paint, etc. Explain that this is why it is so important for their parents to open the windows and air out the house after they have been cleaning.