Ozone is created and destroyed by ultraviolet radiation from the Sun that hits the stratosphere. When high energy rays strike ordinary oxygen (O2), they split the molecule into single oxygen atoms, known as atomic oxygen (O). These freed atoms bump O2 and form a molecule of ozone (O3). Ozone is also destroyed when it absorbs low energy rays, which cause a split into O2 and a free O. The threat to the ozone is created by man-produced chemicals called chloroflourocarbons (CFCs), used in plastic foams, air conditioners, and refrigerators. CFCs contain chlorine that breaks down O2 when it reaches the stratosphere and reacts with ultraviolet radiation, destroying large amounts of good ozone. The concern is for increased exposure to harmful ultraviolet rays. Chemicals like CFCs cause the level of ozone protecting us from ultraviolet radiation to decrease. Think of a "leaky bucket." As long as the water flowing into the bucket equals the water leaking out, the water level remains the same. However, adding CFC is like adding more holes to the bucket, disrupting the balance. Research in this area is trying to create models to predict the rate at which ozone is produced and destroyed. The chart below estimates the increases in greenhouse gases.

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