Japan's Meteorological Agency says measurements made this year show that the hole in the ozone layer over Antarctica was the smallest one in nearly 30 years.
Chlorofluorocarbons and other man-made gases are blamed for depleting the ozone layer, which shields the Earth from harmful ultraviolet rays. The hole appears annually from August through December.
The agency says analyses of satellite data this year indicate that the hole reached its largest size at 18.78 million square kilometers on September 11th. That was the smallest it had been since 1988.
Agency officials believe that warmer-than-average stratospheric temperatures hindered the production of ozone-depleting chemicals, leading to a reduction in the hole's size.
However, they point out that the hole remains large. It is about 1.4 times the size of Antarctica. Officials also claim that global concentrations of ozone-depleting substances remain high.
A senior agency official says the hole in the ozone layer just happened to be small this year. He adds that continued efforts to preserve the ozone layer are important because it will allegedly take dozens of years for the hole to completely close.