[CorrectHorseBat]

Break down into what and where else than down would it go?

[brucethemoose2]

Yeah... Its sulfer dioxide. I am no chemist, but I don't see a safe way that can come down.

[BurningFrog]

Don't know, sorry.

Maybe the main factor is that the SO2 stays up there for 1-2 years, which gives a lot of cooling "bang" for the acid rain "buck".