WASHINGTON – Scientists say warm upper air this September and October helped shrink the man-made ozone hole near the South Pole slightly.
The hole, which is normally at its biggest this time of year, is a part of the atmosphere with low ozone concentrations. The U.S. space agency says on average that it covered 20.9 million sq. km this season, or 6 percent less than the average area since 1990.
High-altitude ozone shields Earth from ultraviolet radiation.
NASA chief atmospheric scientist Paul A. Newman says the main reason for this year’s result is local weather. The upper air has been warmer than normal, which led to fewer polar stratospheric clouds. These clouds are where ozone is destroyed by chlorine and bromine, which come from man-made products such as spray-can propellants and refrigerants, most of which are now outlawed.