A NASA scientist said yesterday that the concentration of ozone in the upper atmosphere over the South Pole may have fallen to its lowest level since measurements began 13 years ago.
Arlin Krueger, an atmospheric scientist with the NASA's Goddard Space Flight Center in Greenbelt, said satellite data gathered Sunday suggests that "we've got a deeper ozone hole than we've ever seen before."
The data must still be reviewed and verified, he added.
Last week, scientists said the hole failed to shrink, as expected, this year. In the past, its size has varied in a regular pattern.
Sunday's measurement shows that the concentration of ozone inside the hole may have fallen to its lowest recorded level, said Dr. Krueger, principal investigator on the Total Ozone Mapping Spectrometer aboard the Nimbus-7 satellite of the National Aeronautics and Space Administration.
Ozone is a molecule made up of three oxygen atoms. Found in the upper atmosphere, it protects the Earth from the ultraviolet rays.
Scientists believe atmospheric ozone destruction is linked to the release of man-made gases that break down to form chlorine, which dissolves the bonds holding ozone molecules together. Depletion over the Antarctic, which peaks at this time of year, is particularly severe because of weather conditions.
A NASA spokesman said Sunday's measurement means that if the Antarctic's atmospheric ozone could be brought to the Earth's surface and compressed to a layer of pure gas, it would be only 1.1 millimeters thick -- compared to about 3 millimeters 13 years ago.