BEIJING, Oct. 22 (Xinhuanet) -- The Antarctic ozone hole has regained it's average size, about the size of North America, shrinking nearly 16 percent from last year's record high, a NASA expert said Friday.
Warmer weather and more storms this year are the reason the hole is slightly smaller, said NASA atmospheric scientist Paul Newman.
"There's no way we could say we're seeing real improvement, but it's smaller because of the weather situation,ˇ§ Newman said.
The ozone hole in mid-September reached a maximum size of 9.7 million square miles, down from its peak of 11.5 million square miles last year, said Newman.
Human produced gases, containing chlorine and bromine, damage the Earth's protective ozone layer, forming a hole over the South Pole and into the Southern hemisphere. Because the ozone layer protects life on Earth by blocking ultraviolet rays, countries across the world 20 years ago agreed to ban many compounds such as spray-can propellants.
The ozone hole is man-made and was first discovered in 1985. At the current rate it should be closed up by 2070, Newman said. Nearly 80 percent of the ozone-depleting chemicals in the atmosphere are man-made.
But those compounds stay in the atmosphere 40 to 100 years and the total amount of chlorine compounds in the air is only down 3.1 percent since 2001, Newman said. For the past 15 years or so, the ozone hole has been about the same size, going up slightly and down slightly, mostly based on the weather, he said. It appears from July to October.