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12/19/1996 08:00:00

Question of the Week: Why Can't We Manufacture Ozone To Be Released Where Needed In the Atmosphere?

Submitted by Ann Marchillo, Glendora, Calif., and answered by Matt Fraser and Patrick Chuang, graduate students in environmental engineering at Caltech.

Ozone is a molecule containing three atoms of oxygen, and is known by the chemical symbol "O3." The stuff we breathe is "O2," which contains two atoms of oxygen. The "ozone hole" is a decrease in the amount of ultraviolet-absorbing ozone in the upper part of the earth's stratosphere, about 10 miles above ground level.

It is helpful to think of the stratosphere as a water tank with a faucet in the bottom. The water level corresponds to the amount of ozone in the stratosphere. Ozone is continuously being created as long as the sun is shining. In our analogy, then, this means that while the sun is up, someone is pouring water into this water tank. However, ozone is easily destroyed by chemical reactions, represented by water flowing out the faucet. At any one time, the amount of ozone in the stratosphere is regulated by the balance beween its generation and destruction (the water pouring into the tank and the water draining from the tank). The ozone hole is mainly due to chlorofluorocarbons, or CFCs, emitted into the atmosphere which cause ozone to be destroyed more quickly (opening the faucet more), thereby causing ozone levels to decrease.

However, unlike a hole in the ground, the ozone hole cannot be filled in once to solve the problem. To fix the ozone hole, we need to constantly pour more ozone into the stratosphere. This is not a reasonable solution, primarily because the amount of energy needed to pump ozone into the stratosphere is overwhelming. It would require over 500 billion watts of power to constantly pour the necessary ozone into the stratosphere to make up for what CFCs destroy. For comparison, Hoover Dam generates about a billion watts. So our "solution" would require 500 Hoover Dams just to pump the ozone into the stratosphere!!

When you think about the pollution from 500 large power plants, such a solution might be worse than the original problem.

Written by Robert Tindol