There are unprecedented levels of depletion of the ozone layer, above the Arctic Circle, this spring, according to a NASA-led study. The research was conducted by a team of scientists from 19 institutions across nine countries, including Canada and the United States.

The loss of ozone in the Arctic is, according to NASA, due to the same process as that in the Antarctic - when extremely cold conditions trigger reactions that convert atmospheric chlorine, drawn from man-made chemicals, into forms that destroy ozone. However, the generally warmer stratospheric conditions in the Arctic limit the area affected, as well as the timeframe during which the chemical reactions occur, resulting in far less ozone loss in most years than in the Antarctic.

This time, however, the amount of ozone depletion over the Arctic was comparable to levels in the Antarctic, where a hole has formed every spring since the mid-1980s. The hole over the Arctic is approximately 2 million sq km.

The chemical ozone destruction over the Arctic in early 2011 was, for the first time in the observational record, comparable to that in the Antarctic ozone hole, Gloria Manney, the lead scientist of NASA's Jet Propulsion Laboratory in Pasadena, Calif., told The Guardian.

The scientists also found that at some altitudes the cold period in the Arctic lasted 30 days longer than in any other previously studied Arctic winter; a factor that could also explain the unprecedented ozone loss.

The study was published, on Sunday, in the journal Nature.

As much as 90 percent of Earth's ozone is concentrated in the stratosphere. The stratospheric ozone shields the planet from the damaging effects of Ultra Violet (UV) radiation and any depletion of this layer can result in significant increases in the levels of UV radiation, which affects human beings, animals and entire ecosystems. Specifically, the layer deters UV B-rays that cause skin cancer and other ailments.