Four new manmade gasses are threatening the Earth's ozone layer and two of them have given scientists an elevated cause for concern.

According to BBC News, scientists are unsure of the origin of these substances akin to chlorofluorocarbon (CFC) gases that were restricted in the 1980s. Three new gasses have been identified as "new" CFCs and one has been named a new hydrochlorofluorocarbon (HCFC).

The ozone layer shields the Earth from harmful UV rays from the sun. Scientists from the British Antarctic Survey were the first to discover a "hole" in the ozone in 1985 lying right over Antarctica.

The researchers' work has been published in the journal Nature Geoscience.

"Our research has shown four gases that were not around in the atmosphere at all until the 1960s which suggests they are man-made," lead researcher Dr. Johannes Laube, of the University of East Anglia's School of Environmental Sciences, said in a press release.

"CFCs are the main cause of the hole in the ozone layer over Antarctica. Laws to reduce and phase out CFCs came into force in 1989, followed by a total ban in 2010. This has resulted in successfully reducing the production of many of these compounds on a global scale. However, legislation loopholes still allow some usage for exempted purposes."

By extracting air from a perennial snow in the Antarctic, the researchers were able to look back 100 years at various atmosphere changes. Two of the newly discovered gasses are particularly troublesome, but all four have been released in an estimated total of 74,000 tons.

"The identification of these four new gases is very worrying as they will contribute to the destruction of the ozone layer," Laube said in the release. "We don't know where the new gases are being emitted from and this should be investigated. Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components.

"What's more, the three CFCs are being destroyed very slowly in the atmosphere - so even if emissions were to stop immediately, they will still be around for many decades to come."