The Great Smoky Mountains are part of the Appalachian chain, between Tennessee and North Carolina, across the country from the Sierra Nevada. I imagine that the latter might also experience haze from the same cause (terpenes emitted by living trees), but given that a large part of the current problem is the suppression of natural wildfires, it would not be surprising for there to be actual smoke despite there being few European settlers. Native Americans in the region also used fire to manage their environment, e.g. to create meadows, as in Yosemite.