Question

Why is there so much ozone?

Answer 1

Well, the amount of ozone actually varies in different parts of the world. Sunnier areas have more ozone than darker areas.

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You are right that there is a process where ozone is consumed. This reaction mechanism is most likely (Physical Chemistry: A Molecular Approach):

`"O"_3(g) + color(red)(cancel(color(black)("Cl"cdot(g)))) => color(red)(cancel(color(black)("ClO"cdot(g)))) + "O"_2(g)`
`ul(color(red)(cancel(color(black)("ClO"cdot(g)))) + "O"cdot(g) => "O"_2(g) + color(red)(cancel(color(black)("Cl"cdot(g)))))`
`"O"_3(g) + "O"cdot(g) -> 2"O"_2(g)`

However, there is also a process that creates ozone from UV light:

`"O"_2(g) stackrel(hnu" ")(=>) color(red)(cancel(color(black)(2"O"cdot(g))))`
`ul(color(red)(cancel(color(black)(2"O"cdot(g)))) + 2"O"_2(g) => 2"O"_3(g))`
`3"O"_2(g) -> 2"O"_3(g)`

These processes usually don't balance each other out, so ozone will remain for quite some time.

However, if as humans we happen to make more gases containing `"Cl"cdot(g)` and `"Br"cdot(g)` as a result of our daily activities, you can see that it does catalyze ozone destruction.

That's not necessarily a good thing, as ozone in the stratosphere (what we call the ozone layer) does help reduce the intensity of the sunlight we get.