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Nitrogen Oxide Emissions Falling: TVA Official Says Statewide Ozone Down Nearly One-Third .

Posted on: Thursday, 18 May 2006, 15:06 CDT

By Ian Berry, Chattanooga Times/Free Press, Tenn.

May 18--OAK RIDGE, Tenn. -- Emissions of a key summertime ozone ingredient will decrease statewide by 29 percent between 1999 and 2007, according to a Tennessee Valley Authority official.

The drop in nitrogen oxide stems largely from a decrease in emissions from the agency's power plants, TVA researcher Cassandra Wylie told a conference on air quality here. She said she's optimistic the decrease is corresponding with a reduction in groundlevel ozone, a pollutant linked to respiratory problems.

But she and other officials from TVA, the National Oceanic and Atmospheric Administration and local governments said it's not proven the efforts are curbing ozone. A cool, wet summer can keep ozone levels down as much as emissions reductions, they said.

"Are things getting better or worse? I think they're getting better," said Richard Artz, acting director of NOAA's Air Resources Laboratory. "But I also think, wait until the next hot summer, and we'll see."

People from across the state and nation have gathered for the East Tennessee Ozone Study workshop, a federally funded project sponsored by NOAA.

In addition to health issues from ozone, several areas in the state including Hamilton County are facing possible economic development restrictions if they don't meet Environmental Protection Agency standards.

Ground-level ozone is caused by a chemical reaction between nitrogen oxide and volatile organic compounds, which mostly are emitted by vegetation. The reaction is triggered by sunlight.

Researchers said ozone levels can fluctuate drastically from place to place based on elevation and weather patterns.

Charts from Ms. Wylie's presentation included ozone levels in Tennessee dating back to 1979. "What you see is a great deal of year-to-year variation," Ms. Wylie said. "There is not an obvious 27-year trend."

During the warm summer months, nitrogen oxide emissions are projected to be 1,439 tons per day in 2007, Ms. Wylie said. That would be down from 2,022 tons per day in 1999. Ms. Wylie noted that for several cities, including Nashville and Memphis, ozone appears to be decreasing since the late 1990s and that hot, dry summers have not been as bad.

A possible exception to that trend, based on TVA's presentation, is Chattanooga. The region had more than 30 days exceeding EPA standards in 2002, more than in any year since 1979. But presenters said there are multiple variables to ozone production, some of which seem counterintuitive. For instance, NOAA air quality program manager Jim Meagher said that as large nitrogen oxide emissions are reduced, the amount of chemicals released into the air actually will combine to produce ozone more efficiently.

Much of Wednesday's discussion centered around Knoxville and the Great Smoky Mountains National Park, which received national attention in the late 1990s for its air quality problems.

E-mail Ian Berry at iberry@timesfreepress.com BY THE NUMBERS Emissions of nitrogen oxide, which chemically reacts with another chemical and sunlight to produce ozone, have decreased in Tennessee. The following figures are for the months of "ozone season" between April and October. 1999 Emissions: 2,022 tons per day Portion from utilities: 25.6 percent Portion from vehicles: 39.6 percent 2007 (projected) Emissions: 1,439 tons per day Portion from utilities: 11.1 percent Portion from vehicles: 36.8 percent Source: Tennessee Valley Authority

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Copyright (c) 2006, Chattanooga Times/Free Press, Tenn.

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Source: Chattanooga Times/Free Press

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