New tests show there is no ozone hole over the North Pole, but the ozone layer is seriously depleted and there are worrisome chemical changes in the Arctic atmosphere, scientists said Friday.

"We expect no quick changes over the North Pole, and there is not yet a hole in the ozone layer. But there are strange chemical changes," said Dr. Robert Watson, head of the U.S. National Aeronautics and Space Administration's effort to use a flying laboratory to scan the Arctic skies.Scientists say the hole in the ozone layer at the South Pole may be caused by industrial pollutants, such as chlorine-based compounds used in aerosol spray cans, refrigerators and air conditioners.