[gwbas1c]

Personally, I think it's some other pollutant.

That being said, there's some remarkable correlations with bans on leaded gasoline.

[olddustytrail]

The man who invented leaded gasoline - Thomas Midgley Jr. - also invented CFCs.

He's been referred to as a "one man environmental disaster".

[SoftTalker]

Two things we know for sure now, and probably knew pretty well even then, chlorinated hydrocarbons and heavy metals are not good for the environment. They have their industrial uses but need to be used with care.