Scientists say there's good news on Smokies air quality

I would presume this is also true elsewhere.

Scientists say there's good news on Smokies air quality: "'Since the late 1990's, air quality on all fronts is improving. That's the great news.'
Still, Renfro says the main categories of concern, haze and visibility, obscure distant ridges on hazy summer days for a number of reasons. A big part of it has to do with coal, which creates steam to drive a turbine. That generates electricity at TVA's fossil fuel plants and helps foul the air."