U.S. Warns of Arctic Ozone HoleBy Rudy Abramson
Los Angeles Times
Conditions over the Arctic are ripe for the development of an ozone "hole" comparable to the one discovered over the opposite pole five years ago, government scientists said Monday.
The possibility of severe depletion of the ozone layer over the Arctic, in addition to the already-reported thinning of the layer elsewhere, has heightened concerns among medical experts about the potential for higher levels of skin cancer, cataracts, and immune-system damage that result from exposure to the sun's rays.
Considering their findings alarming enough to release them in the middle of a study that is still under way, the scientists said they have recorded the highest levels of ozone-damaging chemicals ever detected -- some over heavily populated areas of New England and Canada.
In addition, they have found diminished levels of nitrogen oxides, which act to protect the ozone layer in the atmosphere.
Whether the depletion in the north follows the pattern over the Antarctic depends on what happens to a huge, shifting mass of cold air in the region.
But one researcher said existing conditions suggest an ozone loss in the northnermost latitudes of 30 percent to 40 percent.
"We are going to be extremely surprised if we go up there and do not see measureable ozone loss," said Michael J. Kurylo, manager of the National Aeronautics and Space Administration's upper atmosphere research program.
The latest evidence of ozone destruction produced new calls for faster action to ban chlorofluorocarbons, commonly called CFC's, halons and other chlorine-based industrial chemicals blamed for damage to the protective blanket of ozone in the earth's upper atmosphere.
Since discovery of the Antarctic Ozone "hole" more than five years ago, scientists also have found thinning of the layer in the middle latitudes. That development led the Environmental Protection Agency to estimate last year that the next half century will see as many as 12 million additional skin cancer cases and perhaps 200,000 additional deaths.
Scientists conducting the Arctic observations -- sponsored by NASA, the National Oceanic and Atmospheric Administration, and the National Science Foundation -- based their grim forecast on the discovery of surprisingly high levels of ozone-killing chemicals.
Flights by modified U-2 reconnaissance planes last month detected the highest levels of chlorine monoxide ever recorded in the atmosphere, reaching as far south as New England and eastern Canada, according to Harvard chemist James G. Anderson.
Flights originating in Bangor, Maine, encountered dramatically increased levels of chlorine north of the city before even reaching their planned altitude above 60,000 feet.
At the same time, instruments recorded lower than expected levels of nitrogen oxides, which serve to slow chemical process of ozone destruction.
Both ozone and nitrogen oxides are key pollutants in urban smog. But in the stratosphere, ozone blocks the ultra violet radiation that causes skin cancer. Nitrogen oxides serve to fight off the buildup to chlorine and bromines which cause ozone to break up.
The results show that CFC's are even more efficient at destroying the ozone than scientists had believed. It is now clear, Anderson said, that pervasive high levels of chlorine compounds exist in the stratosphere from the mid-Caribbean to the Arctic, with the more benign forms constantly being transformed into the more destructive.
Use of CFC's, long employed in chemicals such as the freon used in refrigerators and air conditioners, has dropped dramatically, and they are no longer used as propellants for hair spray and deodorant cans.
But pressure to continue their use comes mainly in developing countries where refrigeration and air conditioning is just beginning to be used on a massive scale.