The atmospheric layer that protects the planet from ultraviolet radiation will fully recover by 2040.

The hole in the ozone layer, once considered the greatest environmental hazard, should disappear completely within the next two decades, concludes a United Nations report.

The ozone layer is slowly but noticeably recovering, and at that rate, the "ozone hole" over Antarctica, where the layer is thinnest, would be completely filled in about 43 years, states a new United Nations report.

A scientific assessment conducted every four years shows that the protective layer is recovering, more than 35 years after a global agreement not to use chemicals that erode the ozone layer, which protects life on Earth from harmful ultraviolet radiation.

Scientists and environmentalists are hailing as one of humanity's greatest environmental victories efforts to reduce the "ozone holes" stemming from a 1987 agreement called the Montreal Protocol that banned certain chemicals.

The ozone layer extends in the lower layer of the stratosphere from about 10 to 50 kilometers above the Earth. Its thickness varies depending on the location and the time of year.

The "ozone holes" that appear in it are caused by the influence of certain gases that people use.

The report says progress is slow and the average concentration of ozone at a height of 30 kilometers in the atmosphere will return to "normal" around 2040, in the Arctic by 2045.

In Antarctica, where the ozone layer is currently thinnest, the layer will not be restored until 2066, the report said.