In the aftermath of the Interstate 75 pileup, Tennessee and the nearby Bowater paper mill faced litigation that went on for years.
Relatives of crash victims and survivors accused Bowater - now AbitibiBowater - of contributing to the deadly fog with its water vapor emissions, and the state faced charges of willful negligence for not responding to the six fog-related accidents that occurred in the years before the 1990 pileup.
Some meteorological experts explained that natural conditions resulted in an unusually thick and unrelenting fog that day: A "temperature inversion," in which the higher-level air is warmer than the lower air, caused the rare fog to be held in place for longer than usual, experts told The Chattanooga Times.
But others argued that artificial contributors worsened the natural fog in the area. Earlier studies had indicated that both industrial emissions and aeration ponds - used by Bowater to treat its water waste before releasing it into the Hiwassee River - contributed to the warm water vapor in the area.
Bowater declined to comment for this story.
More than a decade before the 1990 pileup, in January 1979, University of Tennessee at Knoxville researchers led the first study of fog causes in the area at the request of the state transportation department. The study was based on aerial observation.
One of its authors, Wayne Davis, said the study indicated that Bowater's aeration ponds were potential contributors to the fog cover. But the report emphasized the need for further research.
"We made recommendations to the state at that time about things that should have been done to try to better monitor the situation there," Davis, now dean of the UT College of Engineering, said in a recent interview. "Unfortunately, those kinds of studies were not done at the time."
Some accused Bowater of working to kill a more comprehensive study proposed by the state in 1980.
That study would have evaluated Bowater's role in contributing to the fog and potentially come up with solutions, Steve Hanna, one of the researchers hired to do the follow-up study, said in a recent interview.
"What we were mainly looking for was pollutants released from the paper mill production process," said Hanna, now a professor at the Harvard School of Public Health.
But in 1980, the state cut the study's $100,000 funding. Hanna and others, including those filing suit after the 1990 pileup, believed the state backed away from the study under political pressure from Bowater.
"I think one of the big issues all along, and one of the reasons the initial study didn't go forward, is the fact that this is a very large employer in this whole area," Hanna said.
During litigation after the 1990 crash, an internal Bowater study emerged. Bowater had commissioned it in 1979 to refute the UT report's findings. Instead, the study found Bowater's water vapor emissions did contribute to fog problems, but it did not say to what extent.
The civil lawsuits following the 1990 crash alleged that Bowater had covered up those findings and failed to fix known problems that could have prevented the pileup.
"Instead of doing anything, they kept the study in the hands of their lawyers and did nothing and made no changes and sadly, there was [another] crash involving deaths and injuries," said Douglas Fees, a Huntsville, Ala., attorney who represented most of the plaintiffs. He said he got a copy of the sealed Bowater report in 1993.
Bowater settled its lawsuits for more than $10 million before the case went to trial, according to Chattanooga Times archives. Bowater also had to close one of its aeration ponds, a 235-acre body of water that straddled I-75 at the Hiwassee River, according to the Times.
The state eventually paid about $800,000 to settle lawsuits alleging negligence for failing to respond to known hazards in the fog zone, according to the Tennessee Attorney General's Office.
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