Geneva (AP) - The depletion of the ozone layer shielding Earth from damaging ultraviolet rays has reached an unprecedented low over the Arctic this spring because of harmful chemicals and a cold winter, the U.N. weather agency said Tuesday.
The Earth's fragile ozone layer in the Arctic region has suffered a loss of about 40 percent from the start of winter until late March, exceeding the previous seasonal loss of about 30 percent, the World Meteorological Organization said.
The Geneva-based agency blamed the loss on a buildup of ozone-eating chemicals once widely used as coolants and fire retardants in a variety of appliances and on very cold temperatures in the stratosphere, the second major layer of the Earth's atmosphere.
Arctic ozone conditions vary more than the seasonal ozone "hole" that forms high in the stratosphere near the South Pole each winter and spring.
"The Arctic stratosphere continues to be vulnerable to ozone destruction caused by ozone-depleting substances linked to human activities," said WMO secretary-general Michel Jarraud. "The degree of ozone loss experienced in any particular winter depends on the meteorological conditions."
The loss comes despite the U.N. ozone treaty, known as the 1987 Montreal Protocol, which has resulted in cutbacks in the use of ozone-damaging chemicals in the making of refrigerators, air conditioners, fire extinguishers and even hairspray.
The 196-nation ozone treaty encourages industries to use replacement chemicals less damaging to ozone, the atmospheric layer that helps protect against the sun's most harmful rays.