Ultraviolet levels climb in Swiss Alps.

Ultraviolet levels climb in Swiss Alps

Measurements made in the crisp air of the Swiss Alps indicate that levels of ultraviolet-B (UV-B) radiation there have increased during the last decade, apparently due to a thinning of the stratospheric ozone layer. Scientists still cannot say whether UV-B is increasing in urban areas in Europe or the United States. In fact, one study has suggested that ozone pollution in cities may actually overcompensate for ozone loss in the stratosphere.

But at a remote research station high in the Alps, UV-B climbed by 0.5 to 1 percent per year between 1981 and 1989, report Mario Blumthaler and Walter Ambach of Austria's University of Innsbruck. UV-B radiation -- with wavelengths between 290 to 330 nanometers -- causes sunburn and increases the risk of skin cancer and cataracts.

"If this were to continue to rise at this rate, it would become a very serious problem," Blumthaler told SCIENCE NEWS. He and Ambach describe their findings in the April 13 SCIENCE.

Scientists expect increasing UV-B levels to reach Earth's surface as human-made chlorine chemicals thin the stratospheric ozone layer, which normally absorbs most UV-B. Between 1969 and 1986, stratospheric ozone over the northern midlatitudes, including the United States and Europe, dropped by about 3 percent on average. Yet measurements taken two years ago at a network of U.S. stations indicate UV-B decreased between 1974 and 1985 (SN: 2/20/88, p.119).

Experts are unsure how to explain the decrease. Levels of harmful ozone pollution have been rising in many cities, and some researchers suggest such pollution may absorb the extra ultraviolet light streaming down through the thinning stratospheric ozone layer.

Others question the reliability of the Robertson-Berger meters used in both the U.S. and Alps studies. "I don't regard the Robertson-Berger measurements as being necessarily correct," says F. Sherwood Rowland of the University of California, Irvine.

John DeLuisi of the National Oceanic and Atmospheric Administration in Boulder, Colo., contends the meter was not designed to measure long-term trends in UV-B and says those who use it have yet to prove the device can sustain its accuracy over many years. He and his colleagues are now attempting to resolve whether the U.S. network of Robertson-Berger meters has remained accurate.