Ultraviolet radiation strikes a chlorofluorocarbon (CFC) molecule and causes a chlorine atom to break away. The chlorine atom collides with an ozone molecule and steals an oxygen atom to form chlorine monoxide and leave a molecule of ordinary oxygen.
When a free atom of oxygen collides with the chlorine monoxide the two oxygen atoms form a molecule of oxygen. The chlorine atom is thus released and free to destroy more ozone.
Fortunately, chlorine atoms do not remain in the stratosphere forever. Therefore, if humans stop putting CFCs and other ozone-destroying chemicals into the atmosphere, the ozone layer may eventually repair itself.
