I guess that would be nice background, but you can also find the answer in like 5 minutes on Wikipedia. https://en.wikipedia.org/wiki/Chlorofluorocarbon https:

I guess that would be nice background, but you can also find the answer in like 5 minutes on Wikipedia. https://en.wikipedia.org/wiki/Chlorofluorocarbon https://en.wikipedia.org/wiki/Chlorofluorocarbon From the section on Regulation: > It turns out that one of CFCs' most attractive features—their low reactivity—is key to their most destructive effects. CFCs' lack of reactivity gives them a lifespan that can exceed 100 years, giving them time to diffuse into the upper stratosphere. Once in the stratosphere, the sun's ultraviolet radiation is strong enough to cause the homolytic cleavage of the C-Cl bond.