By Eric Beech New research on ozone pollution has found that power plants can't be judged by size alone, scientists said Thursday. Tom Ryerson of the National Oceanic and Atmospheric Administration said his research also found that power plants located in forests produce relatively more ozone than ones in more barren areas. Ryerson said his findings should be considered by the Environmental Protection Agency in its efforts to reduce ozone, blamed by health experts and environmental groups for contributing to asthma and other diseases. He said the agency currently focuses on the amount of nitrogen oxide a plant emits.
Ozone is created when nitrogen oxide mixes in the atmosphere with volatile organic compounds.
Volatile organic compounds, or VOCs, come from human sources such as automobile exhaust and petrochemical refining, but also from nature. In the eastern United States, oak trees contribute a substantial amount of VOCs to the atmosphere in the form of the hydrocarbon isoprene, Ryerson said. The study found that plants located near large sources of isoprene result in relatively greater amounts of harmful ozone in the atmosphere, he said. Ryerson said reducing nitrogen oxide emissions in forested rural areas of the eastern United States would result in a relatively greater reduction in ozone than if emissions were lowered by the same amount in the less-forested Midwest. He said large power plants, with their more concentrated plumes of nitrogen oxide, produce relatively less ozone than small plants.