Ozone Hole Over City for First Time

ByRay Lilley

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

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

Citing data from the U.S. space agency NASA, atmosphericresearch scientist Stephen Wood said the hole covered 11.4 millionsquare miles — an area more than three times the size of the UnitedStates.

Punta Arenas, Chile Exposed

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

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

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

“The longer it gets, the greater the chances of populated areasbeing hit by low ozone levels,” said Peterson, who was notinvolved in the study.

Peterson said segments separating from the hole could affectArgentina and even the tip of South Africa, Australia or NewZealand.

“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 overmajor land mass areas. Those filaments will be over the land massfor a few weeks.”

Biggest Hole Ever

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

Record-low temperatures in the stratosphere are believed to havehelped the expansion of the ozone hole during the southernhemisphere’s spring season.

Antarctic ozone depletion starts in July, when sunlight triggerschemical reactions in cold air trapped over the South Pole duringthe Antarctic winter. It intensifies during August and Septemberbefore tailing off as temperatures rise in late November of earlyDecember.

Depletion of the ozone layer over Antarctica and the Arctic isbeing monitored because ozone protects Earth from harmfulultraviolet radiation.

Human-Made Chemicals Deplete Ozone

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

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

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

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