A new United Nations report says Earth's protective ozone layer is finally healing from damage caused by aerosol sprays and coolants.

The ozone layer had been thinning since the late 1970s. Scientists raised the alarm and ozone-depleting chemicals were phased out worldwide.

As a result, the upper ozone layer above the Northern Hemisphere should be completely repaired in the 2030s and the gaping Antarctic ozone hole should disappear in the 2060s, according to a scientific assessment released at a conference in Quito, Ecuador.

"It's really good news," said report co-chairman Paul Newman, chief Earth scientist at Nasa's Goddard Space Flight Centre.

"If ozone-depleting substances had continued to increase, we would have seen huge effects. We stopped that."

High in the atmosphere, ozone shields Earth from ultraviolet rays that cause skin cancer, crop damage and other problems.

The ozone layer starts about six miles above Earth and stretches for nearly 40km. Ozone is a colourless combination of three oxygen atoms.

Use of man-made chemicals called chlorofluorocarbons (CFCs), which release chlorine and bromine, began eating away at the ozone.

In 1987, countries around the world agreed in the Montreal Protocol to phase out CFCs and businesses came up with replacements for spray cans and other uses.

At its worst in the late 1990s, about 10 per cent of the upper ozone layer was depleted, said Mr Newman. Since 2000, it has increased by about 1 to 3 per cent per decade, the report said.

This year, the ozone hole over the South Pole peaked at nearly 9.6 million square miles - about 16 per cent smaller than the biggest hole recorded - 11.4 million square miles in 2006.

The hole reaches its peak in September and October and disappears by late December until the next Southern Hemisphere spring, Mr Newman said.

If nothing had been done to stop the thinning, the world would have destroyed two-thirds of its ozone layer by 2065, Mr Newman said.