THE ozone layer is under attack again by the same disastrous chemicals that were outlawed more than 30 years ago.

And it has scientists baffled.

Chlorofluorocarbons, known as CFCs, once kept homes cool and our hair in place. They were used in everything, from hairspray, to refrigerators and airconditioners.

But in 1985, the chemical, which was nonflammable and harmless to humans, was found to be having catastrophic environmental consequences. It was destroying our shield from harmful ultraviolet (UV) radiation — the ozone layer.

This led to the signing of the 1987 Montreal Protocol, which banned global CFC production and in the years since, the world has given itself a pat on the back at news the hole is shrinking.

But an alarming study recently published in Nature Journalhas revealed a surge in the release of the same ozone-destroying substances, and it has Australian scientists worried too.

The study found that atmospheric trichlorofluoromethane — CFC-11 — was on a constant decline from 2002 to 2012.

But since then, about 13 billion gigagrams of the destructive chemical have been recorded in the atmosphere each year despite no reported production, according to the study.

“There’s no question there’s been an upsurge of CFC-11 emissions in recent times,” Dr Paul Fraser from CSIRO’s greenhouse and ozone depleting gases team said.

“And this joins a number of other ozone-depleting chemicals that have also increased.”

Dr Fraser said two other damaging chemicals had only a short life span and were not banned under the Montreal Protocal, but CFC-11 could sit in the atmosphere for a decade.

The mass release has experts bewildered, with some suggesting it could be due to the world’s melting icecaps.

But Dr Fraser dismissed that claim, and instead pointed to illegal use.

“The emerging emissions are coming from East Asia, and largely from China,” he said.

“It would represent a large increase in chemical activity in the Chinese economy, which is probably not unexpected.”

Dr Fraser said continued release could have devastating consequences, including delaying the complete closure of the ozone layer’s hole. This would stymie global efforts to reduce global warming by two degrees by 2100, with the chemicals regarded as “extremely strong” greenhouse gases.

“The question about CFC-11 is whether these emissions will continue. If it continues indefinitely, then it’s a serious problem.”

“Where is it coming from? I do like the suggestion they might be clearing stock (of unused CFC).

“Some companies might have been left with substantial stock, and it’s worth nothing. If they use it illegally, they get some value out of it.”

He said unpublished papers suggested the CFC-11 release had possibly reached its peak.

“We need a few more years of data … in one to two years, we’ll know how serious it is,” Dr Fraser said.

“If it’s a long-term emission process, it’s some sort of illegal new use.”

But Dr Fraser believed the Chinese government would crack down on any companies releasing the damaging gases.

“If any government were to go to town on this sort of stuff, it would be the Chinese government,” he said.

Dr Fraser said the CSIRO were monitoring the issue and actively updating the Australian government.

It’s understood China has not made any public statements on CFCs in recent times.

China banned the production of the ozone-depleting substance in 2007, according to Reuters, to be in line with global agreements.

“Relevant companies must demolish equipment involved in the production of CFC substances by August 15,” a notice said at the time, adding that offenders would be punished according to the law.

Holes in the ozone layer are blamed for increased risk of skin cancer and cataracts in humans. They may also harm crop yields and sea life, according to researchers.