Science / Medicine : Ozone Study Questioned

The earth’s protective ozone layer has been thinning out around the world, not just over the South Pole, according to a new analysis of satellite data that was promptly disowned by the government agency that sponsored the study.

Writing in the latest edition of the widely respected Science magazine, Kenneth P. Bowman, an assistant professor of atmospheric sciences at the University of Illinois, said the unexplained depletion appears to have returned the ozone thickness to about where it was at the beginning of the 1960s.

He said the depletion could be the result of natural fluctuations, because the ozone layer was thickening throughout the 1970s. He estimated that the depletion averaged 1% annually from 1979 through 1986.

That estimate was disputed by Robert Hudson, an atmospheric physicist at the National Aeronautics and Space Administration. Hudson said the real decline probably was about half of Bowman’s estimate because Bowman’s data came from an unreliable instrument.

Another NASA official, Michael Prather, said even a decline of one-half of Bowman’s estimate was not certain. “That paper should never have been published,” Prather said.

High-altitude ozone ranging from 15 to 25 miles above Earth makes surface life possible by absorbing the sun’s ultraviolet rays.