Ozone forms a protective layer that shields the earth from damaging ultraviolet rays.
Any reduction in the ozone layer can let harmful ultraviolet rays from the sun reach the earth's surface. The WMO said last September's ozone hole covered an area 2 times the size of Europe. As in previous years, ozone depletion started in July and intensified during August, Bojkov said. The hole currently covers 3.09 million square miles, close to the size of Europe, and will probably grow to about twice that, Bojkov said. Normal fluctuations in the intensity of atmospheric winds contribute to the hole's size, he added.