Bingo!!
I always remember hearing my grandfather (1899-1980) talk about air pollution in the 1970's and saying that this was "nothing" compared to how it was when they lived in Southern California several times in the 1920-1940 timeframe. Steam engine locomotives, nearly everyone burning coal for home heating, oil refineries openly burning off waste, dust from unpaved streets--he said that there were days, that he could remember, where the sky was black, even in mid-day.
I'm not for going back to the (not so) good ol' days but it needs to be viewed in a historical perspective and context.