Smog Spreading To South Pacific

DALLAS, March 31 -- Once a stranger in paradise, migrating smog has begun to pollute the skies over oceans in the southern hemisphere, resulting in tropospheric ozone levels near remote islands that would "trigger a first-stage smog alert" in Los Angeles, according to a Nobel laureate in atmospheric chemistry. The report identifying tropospheric ozone as a "major atmospheric problem for the 21st century" came today in Dallas at the national meeting of the American Chemical Society, the world's largest scientific society.

University of California, Irvine, professor F. Sherwood Rowland said today that long-lasting plumes from biomass burnings -- the practice of burning to clear woodland or brush from the land -- travel across Africa and Australia to bring higher smog levels within range of remote locations in the southern oceans, such as Fiji.

Tropospheric ozone is a key, harmful part of the photochemical smog found in major cities throughout the world, often as the result of congested vehicular traffic. However, in some cities such as Mexico City and Santiago, Chile, use of liquefied petroleum gas for heating and cooking also can contribute significantly to ozone formation. At elevated levels, it can cause breathing difficulties, increase the risk of asthma attacks, and adversely affect the growth of trees, shrubs, and cash crops ranging from vegetables to orchids.

Whether you're in a congested city such as Los Angeles or the seemingly pristine environment of the south seas, Rowland said, the chemistry behind tropospheric ozone remains the same: "You need hydrocarbons, nitrogen oxides and sunlight. In the tropics, burning forests give off hydrocarbons and the high temperatures create nitrogen oxides, and there is plenty of sunlight."

The data reported today by Rowland and his University of California, Irvine, colleague Donald Blake stem from a variety of studies, many of which have not yet been published. Some surprising findings have originated from comprehensive NASA aircraft experiments involving a dozen different research groups, including the Blake/Rowland team.

In locations more famous for their isolation than their air pollution -- such as Easter Island, the Galapagos Islands, and Ascension Island -- the NASA researchers detected significant ozone concentrations that can be traced back to biomass burnings on distant continents, indicating that the smog created by the burning is long-lasting and migrates great distances.

In 1996, for example, two research planes flying in the South Pacific encountered ozone from biomass burning on 50 percent of their flights, Rowland said. One airplane flew through a plume of smog about 500 miles north of Fiji in which ozone readings reached 131 parts per billion (ppb). The pollution had traveled over Australia, with the major contributors of ozone likely coming from as far away as Africa. Yet, by the time it reached the south seas, Rowland said, "its ozone concentration was high enough that you would say this is a violation of the EPA regulations," if it occurred in the continental U.S. He noted that harmful ozone levels remain higher in the northern hemisphere around the world, compared to the southern hemisphere.

Rowland shared the 1995 Nobel Prize in Chemistry with Massachusetts Institute of Technology professor Mario J. Molina, Ph.D., for the pair's joint work in the 1970s that revealed the destructive effects of chlorofluorocarbons, or CFCs, on stratospheric ozone, which forms a protective shield against biologically harmful ultraviolet light from the sun in the upper atmosphere. Rowland spoke today at a symposium honoring Molina as the 1998 winner of the American Chemical Society Award for Creative Advances in Environmental Science and Technology.

A nonprofit organization with a membership of more than 155,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.