Study confirms increase of ultraviolet radiation in New Zealand
September 10, 1999
Web posted at: 3:49 PM EDT (1949 GMT)
WASHINGTON (AP) -- A decades-long study has confirmed that sunburn-causing ultraviolet radiation in New Zealand has increased by about 12 percent in the last 20 years, probably as the result of a thinning ozone layer in the atmosphere.
The study, to be published Friday in the journal Science, measured the midday level of ultraviolet radiation at Lauder, New Zealand from 1979 to last summer and found a steady increase in the UV rays.
On several occasions last summer, the study found, the UV index in Lauder exceeded 12.5. A UV index level of 10 or more is considered to be very high by the Environmental Protection Agency.
Ultraviolet radiation has been measured at a number of places around the Earth over the last few years because of concern about the thinning ozone layer. The erosion of ozone has been blamed on the decades-long use of industrial gases, such as propellants in hair spray and some refrigerants, that destroy the natural atmospheric gas. Use of the ozone-destroying chemicals has been phased out or curtailed under an international agreement, but the effects are expected to last well into the next century.
Ozone is a natural gas in the atmosphere that blocks some of the ultraviolet radiation from the sun. When ozone is thinned, more UV reaches the Earth. Ultraviolet-B radiation is a primary cause of sunburn and some forms of skin cancer. High levels of UV-B are thought to harm some plants and animals.
Some experts have estimated that a 1 percent reduction in ozone can lead to a 3 percent increase in some types of skin cancer.
UV radiation measurements in New Zealand and other sites in the far South Pacific are of particular interest because they are thought to be influenced by the ozone hole that develops each spring over the South Pole. A thinner ozone layer in the southern hemisphere is thought possibly to be a factor in the high rates of skin cancer in New Zealand.
The study by Richard McKenzie, Brian Connor and Greg Bodeker of the National Institute of Water and Atmospheric Research in New Zealand shows a strong connection between a decrease in ozone and an increase in UV radiation, experts said.
William J. Randel of the National Center for Atmospheric Research in Boulder, Colorado, said there has been about a 10 percent thinning in the stratospheric ozone over the last 30 years, but scientists have had problems in connecting that with actual, dependable measurements of UV radiation increases at the ground level. He said weather and other conditions make the measurements difficult.
The work by McKenzie and his group, said Randel, gives powerful support for the estimates of how ozone thinning affects the increase in UV. The study is important, said Randel, because it gives reliable information for a long period of time and boosts scientific confidence in the theory that links ozone loss to UV increases.
"This is a significant study. It shows there is a good agreement between the calculated UV and the observed UV," said Randel.
Ozone-killing gases in the atmosphere have leveled out in recent years, he said, but it will take decades before the effects of the manmade chemicals disappear altogether.
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