This is actually incorrect. When I was digging through old new york times articles from the 1900s and 1930s (using the online search) I stumbled across numerous articles expressing concern about the pollutants being released by factories and combustion-engine automobiles, and how they not only affect the immediate area but surrounding towns. Don't have links to the sources at the moment, or the time right now to pull it up, will check back later, but if you search on nytimes.com you should be able to pull them up.
I'm thinking an order of magnitude or two farther back. Humanity spent thousands of years making fires, but widespread awareness of how the pollution it emits can hurt people is only a century or two old.
