On December 19, 1994, scientists at NASA's Goddard Space Flight Center announced that they had obtained the first conclusive evidence that the Earth's protective ozone layer is being depleted by anthropogenic chemical products, and not by natural events such as volcanic eruptions (1). Since the early 1970s there has been a controversial debate as to the source of stratospheric chlorine. One view has held that the major portion of chlorine present in the stratosphere has originated, not from chlorofluorocarbons (CFCs), but from natural processes such as evaporation of seawater and volcanic eruptions. In this view, the chlorine originating from the photochemical breakdown of CFCs represents only a minor fraction of the total chlorine present in the stratosphere. General scientific consensus however holds just the opposite.