Glenn Reynolds blames TVA dirt-burners for the allergies found in Knoxville. I don't know if there's any science behind this, and he himself notes that the air looks clearer.
But then I know a little about TVA. Back in the 80's people I knew who had worked at the dirt-burners such as Widows Creek said that things were done a little differently at night when the smoke wasn't visible. And plant workers knew better than to drive presentable vehicles to work, because the atmosphere in the immediate vicinity would eat the paint off the vehicles eventually.
Mind you, this was 20 years ago and much could have changed in their attitudes in addition to forced changes via regulations. But the best thing they might have done for the local environment would have been to complete their nuclear power fleet.
It's not as if TVA doesn't have any nukes - they completed 3 at Browns Ferry (west of Huntsville, AL), 2 at Sequoyah (Soddy-Daisy, TN, just northeast of Chattanooga), and I hear that they finally finished 2 at Watts Bar (near Maryville, TN between Chattanooga and Knoxville). But that's less than half of what was originally planned back in the 60's. I'm working from memory here, but IIRC TVA has 10 partially completed nuclear power plants at 4 sites. The ones closest to completion are Bellefonte 1 and 2 (near Scottsboro, AL between Huntville and Chattanooga), which were something like 80% complete on unit 1 and 50% complete on unit 2 as of about 1985 when work was stopped. Other sites include Yellow Creek (2 units near Corinth in extreme NE MS); Hartsville A and B (4 units at Hartsville, TN east of Nashville), and Phipps Bend (2 units near Surgoinsville, TN ENE of Knoxville in the Bristol/Kingsport/Johnson City area).
(You might recall Browns Ferry. An event occurred there in the 70's which at the time was the scariest ever at a commercial nuclear power plant in the US. Nothing was released to the environment and no one was hurt, but with less fortuitous circumstances things could have been much uglier. Analysis of the event caused a number of regulatory changes that were incorporated at BF and also propagated through the rest of the nuclear power industry).
Why did TVA back off? Well, for one the financial burden of trying to build so many plants was incredible. Under ideal circumstances it would have been difficult, but this was in the post Jimmy Carter stagflation economy which had caused future energy consumption projections to fall, which led decision makers to believe that the plants would not be needed at their planned times of completion.
Also, many other sites were under construction at the same time, so experienced engineering and craft personnel were stretched very thin. Here TVA had unique problems due to its quasi-govt status, because their pay rates were constrained by govt regulations. IIRC no employee could make any more than the $65K or so a Congressman made at the time, including the CEO of the organization. CEOs with less responsibility at other electric utilities at the time (and TVA was about more than just electric power) made 4 or more times that. So it was difficult to keep enough talented upper management or technical people on staff to get the plants built - someone else was always hiring and offering more money.
But Jimmy Carter probably did the worst by appointing S. David Freeman to the board that ran TVA. Freeman was and is an opponent of nuclear power, and even one as self-absorbed as Carter had to have known this. Thus Carter's intent was clear. May they both freeze in the dark.
Can TVA revive their program? Energy use predictions certainly have changed since the Carter dark ages. Money is cheaper. The nuclear power industry has been moribund for some time, driving many like experienced professionals like me to alternate careers - some of us might be able to be seduced back into the business. Regulation has stabilized, and entire new inherently safer technologies are available now. I'm sure TN and adjacent states would welcome several $billion in spending over the next half-decade or so.
But politics always seems to intrude. I haven't been in a position to know anything useful internal to TVA for some time, and it wouldn't surprise me to see that they had built dirt-burners at some of the original nuclear sites. And nearby utilities will complain justifiably about TVA's unique status wrt the govt, just as other mortgage industry players complain about Fannie and Ginnie Mae and Freddie Mac.
Whatever the current situation, President Bush might be in position to jump-start TVA via the right appointments. Frist, Lamar! - get to work!