Ozone Hole Over City for First Time

W E L L I N G T O N, New Zealand, Oct. 5, 2000 -- The hole in the ozone layer over Antarctica has stretched over a populated city for the first time, after ballooning to a new record size, New Zealand scientists said today.

Previously, the hole had only opened over Antarctica and the surrounding ocean.

Citing data from the U.S. space agency NASA, atmospheric research scientist Stephen Wood said the hole covered 11.4 million square miles — an area more than three times the size of the United States.

Punta Arenas, Chile Exposed

For two days, Sept. 9-10, the hole extended over the southern Chile city of Punta Arenas, exposing residents to very high levels of ultra violet radiation. Too much UV radiation can cause skin cancer and destroy tiny plants at the beginning of the food chain.

Wood is a researcher with New Zealand’s respected National Institute of Water and Atmospheric Research.

Dr. Dean Peterson, science strategy manager of the Antarctica New Zealand research group, said Wood’s findings showed for the first time a city being exposed by the ozone hole.

“The longer it gets, the greater the chances of populated areas being hit by low ozone levels,” said Peterson, who was not involved in the study.

Peterson said segments separating from the hole could affect Argentina and even the tip of South Africa, Australia or New Zealand.

“The hole won’t grow to that size. But as it breaks apart, fingers of low ozone, or filaments as we call them, will go over major land mass areas. Those filaments will be over the land mass for a few weeks.”

Biggest Hole Ever

Last month, scientists expressed surprise when NASA data from Sept. 3 showed the hole at just under 11 million square miles — the biggest it had ever been.

Record-low temperatures in the stratosphere are believed to have helped the expansion of the ozone hole during the southern hemisphere’s spring season.

Antarctic ozone depletion starts in July, when sunlight triggers chemical reactions in cold air trapped over the South Pole during the Antarctic winter. It intensifies during August and September before tailing off as temperatures rise in late November of early December.

Depletion of the ozone layer over Antarctica and the Arctic is being monitored because ozone protects Earth from harmful ultraviolet radiation.

Human-Made Chemicals Deplete Ozone

Human-made chlorine compounds used in refrigerants, aerosol sprays, solvents, foam-blowing agents and bromine compounds used in firefighting halogens cause most ozone depletion.

The temperature over Antarctica also significantly affects the size of each year’s hole. Starting in October, warmer temperatures reduce the ability of chlorine and other gases to destroy ozone.

Experts agree that the man-made chemicals are leveling off thanks to the 1989 Montreal Protocol, which commits countries to eliminating production and use of ozone-depleting substances. But it could be 20 years before ozone levels recover noticeably.

“Although CFC levels will begin to reduce over the next 10 years, variations in the weather pattern will continue,” Peterson said.