How do chlorofluorocarbons (CFCs) affect the ozone layer?

CFCs are hydrocarbons in which some or all of the hydrogen atoms have been replaced by fluorine atoms. They are often used as refrigerants, solvents and until recently as propellants in aerosol cans. When released, they rise high into the Earth’s atmosphere where they interact with the Sun’s ultraviolet rays.

This interaction causes them to breakdown into molecular fragments that act as catalysts that greatly speed up the processes by which ozone breaks down in the atmosphere. The chlorine atoms undergo a series of reactions that convert two molecules of ozone into three molecules of hydrogen, thus further depleting the ozone in the atmosphere.

Why is this such a big deal? Well, since ozone filters out a lot of the sun’s ultraviolet radiation, less ozone means more ultraviolet rays will reach the Earth’s surface. This eventually leads to more dangers such as skin cancer, damage to crops, damage to sea life and even materials like plastics.

Bradford DeLong, bulletin board.
Wikipedia, Ozone Depletion.