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."