I have also vaguely noticed that it started being called pollution sometime this century. "Huh, that's new", I thought. Not particularly surprising, though. Of course that timespan is almost 30 years, so my concept of recent change might be getting stretched.

But yeah, more familiar pollutants are dirty or caustic or radioactive, and chew holes in things or give you lung diseases or poison the wildlife, things like that, so it was a little jarring. Though I suppose we had CFCs, they didn't do anything directly harmful either.