Unknown sources have released at least 74,000 metric tons of new, man-made gases that are harmful to the ozone layer into the atmosphere, a move that may be illegal per the 1987 Montreal Protocol. 

According to the University of East Anglia's Dr. Johannes Laube and his co-authors, who penned a report on the findings, the gases were discovered in Greenland's ice and Tasmania's air. They write in the paper's abstract: 

We analyzed the composition of unpolluted air samples collected in Tasmania between 1978 and 2012, and extracted from deep firn snow in Greenland in 2008, using gas chromatography with mass spectrometric detection. Using the firn data, we show that all four compounds started to emerge in the atmosphere in the 1960s. Two of the compounds continue to accumulate in the atmosphere. 

Three of these gases are chloroflurocarbons (CFCs) and one is a hydrochlorofluorocarbon (HCFCs), gases that have been strictly regulated by the Montreal Protocol after they were found to have contributed to the development of a massive hole in the ozone layer, which protects us from carcinogenic U.V. rays, in the 1980s. CFCs, commonly known as freons, used to be found in refrigerants, solvents and as propellants in aerosol sprays. HCFCs, similar to CFCs,but slightly less destructive, were used as a replacement for CFCS — but production of both has still been largely phased out thanks to the treaty.  

The Guardian explains that, until Laube's discovery, there were only 13 known chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HFCs), all of them strictly overseen by the Protocol. The discovery of four new ones is, therefore, cause for concern:

"There are definitely more out there," said Dr Johannes Laube, at the University of East Anglia. "We have already picked up dozens more. They might well add up to dangerous levels, especially if we keep finding more." Laube and his colleagues are in the process of fully analyzing the dozens of new compounds, but the work completed on the four new chemicals shows them to be very powerful destroyers of ozone. Laube is particularly concerned that the atmospheric concentrations of two of the new compounds, while low now, are actually accelerating. 

The greenhouse gases could be leaking from industrial plants in the northern hemisphere, but it is not clear if the plant operators are acting illegally. Laube tells Reuters that the Montreal Protocol has some loopholes that could allow for the production of these types of gases. 

Still, Laube says that the current level detected is far, far lower than the level of greenhouse gases emitted in the 1980s, which reached more than one million tons per year. Laube told the BCC that "we're not very worried quite yet, because the concentrations we found are not a threat yet to the ozone layer." He adds that the gases are being used in insecticides and air conditioning, usage not currently covered by the treaty.