a record eight straight days, but pollution levels really may not have increased
much, a UT engineer said recently.
Wayne Davis, professor of Civil and Environmental Engineering, said stricter
air quality standards set last year by the U.S. Environmental Protection
Agency caused more unhealthy air days to be reported.
Davis said ozone in the Smokies exceeded the new standard of 85 parts
per billion in an eight hour period each of the eight days but probably
did not exceed the old mark of 120 ppb for one hour.
"There's much more tendency to exceed the eight-hour standard than
there was the one-hour standard," Davis said. "I'm not sure these
days exceeded the old standard."
"It (overall ozone) may not be that different than it was in previous
years. But now we have a new standard in place which is going to cause a
lot more concern."
Between May 13-21, the Smokies recorded 89 to 99 ppb. Natural ozone levels
range from 20 to 40 ppb.
Ground-level ozone, which is different from atmospheric ozone that protects
Earth from ultraviolet radiation, is formed when sunlight reacts with pollutants
such as nitrogen oxides and hydrocarbons from coal-fired power plants, automobiles
and industrial emissions.
The Smokies had only 19 unhealthy ozone days in 1997 under the new standards.
Davis said high pressure weather systems and hot temperatures helped
push the park's ozone levels higher this year, but probably not often beyond
the old standard, he said.
"This may be a worse year than previous years. The eight days in
May would suggest that it might be a lot worse this year," he said.
"But I do not think ozone concentrations rose above the 120 ppb, one-hour
standard. This new standard is tougher to meet and is drawing more attention
Davis said the new attainment levels are a better mark for protecting
humans from lung and respiratory problems caused by ozone.
"The newer standard gives a more accurate characterization of air
pollution problems and health effects," Davis said. "Current scientific
data show that a longer exposure at a lower concentration is more important
than a one-time peek at a one hour base, and is more representative of an
air pollution problem."
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