DUKE ENVIRONMENTAL SCIENTIST SUPPORTS CLEAN AIR ACT REVISIONS

WASHINGTON -- William Schlesinger, a Duke University environmental chemist, Wednesday urged Congress to support the tougher ozone and nitrogen standards in proposed revisions to the Clean Air Act.

Schlesinger said in testimony prepared for the House Subcommittee on Economic Growth, Natural Resources and Regulatory Affairs that the Environmental Protection Agency's own regulatory impact statements on the Clean Air Act revisions "provide a careful, quantitative analysis of the human health effects of these pollutants ..."

But "these documents significantly understate the benefits of tighter emissions standards as far as natural ecosystems are concerned -- that is, on the ecology of our environment," he said.

In addition to causing health effects, studies suggest that current concentrations of ground level ozone are "enough to reduce agricultural production over much of the Midwest and eastern U.S.," Schlesinger said in his testimony. And atmospheric nitrogen pollution also finds its way to rivers and estuaries, where it supports the growth of "unnatural levels" of algae blooms, which can lead to fish kills.

Existing Clean Air Act restrictions on sulfur dioxide, another industrial pollutant, have resulted in "substantial reductions in the acidity of rain," he said. "However, continuing emissions of nitrogen compounds also contribute to acid rain, to the formation of tropospheric (ground level) ozone, and to the eutrophication (over enrichment) of natural waters."

According to Schlesinger's own calculations, the tighter restrictions proposed in the Clean Air Act revisions would reduce the global release of nitric oxide by 20 percent by the year 2007.

A James B. Duke professor at Duke's department of botany and Nicholas School of the Environment, Schlesinger is a coauthor of a recent Ecological Society of America report that warns of "serious impacts" stemming from rapid worldwide nitrogen releases due to human activities. Those activities include actions such as fertilizer production and vehicular emissions.

Among the impacts is increased levels of ozone, a powerful oxidant produced near the ground during reactions between sunlight, oxides of nitrogen and other chemicals known as volatile organic carbon molecules.

Oxides of nitrogen are emitted by industries and automobiles, while trees are the major sources of volatile organic carbons in the eastern United States, Schlesinger said in an interview.

Ground level ozone -- which is distinct from the natural upper-atmospheric ozone layer that protects life from harmful solar ultraviolet radiation -- can harm cells in the lungs of humans as well as on the leaves of plants, he said.
Oxides of nitrogen also are acid rain precursors, and can they lead to an over-fertilization of plant ecosystems as well as to water pollution, according to his testimony.

For additional information, contact Tim Lucas at the Nicholas School’s Office of Communications, at (919) 613-8084 or tdlucas@duke.edu.