Final answer:
A single chlorine atom can persist in the stratosphere for up to two years, destroying many ozone molecules. This atom usually originates from CFCs, which have historically been used in various industrial applications but are now regulated due to their negative environmental impact.
Step-by-step explanation:
A single chlorine atom can last up to two years in the stratosphere, during which time it can destroy numerous ozone molecules. Chlorofluorocarbons (CFCs) release chlorine atoms when they are broken down by ultraviolet light, and these atoms can be incredibly destructive to the ozone layer. Despite the presence of other, less reactive forms of chlorine, such as Cl₂ and ClONO₂, monatomic chlorine primarily derived from CFCs is a significant contributor to ozone depletion. CFCs, once widely used in refrigerants, air conditioning systems, foams, and aerosols, are stable compounds that contribute to this problem for years. The decrease in the use of CFCs has led to a reduction in the size of the ozone hole, showing progress in the global effort to protect the stratosphere's ozone layer.