[baq]

also pretty much the only... and it was relatively easy as viable replacements were available

[adrianN]

Sulphur dioxide emissions have improved a lot too. Acid rain is no longer an issue afaik.

[esarbe]

That's true.

I am however very pessimistic about our (as a species) ability to deal with something that's even more long-term than i.e. CFCs or SO2.