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Banned trichlorofluoromethane contributed to the rapid growth of Earth’s ozone hole.

TOMS science team & and the Scientific Visualization Studio/NASA/GSFC

Rogue ozone-destroying emissions traced to northeastern China

An international team of researchers has traced the rogue use of a banned, ozone-degrading chemical to a region centered on two provinces in northeastern China. Trichlorofluoromethane (CFC-11), once a common refrigerant also used to produce building insulation, was to be phased out by 2010 under the 1987 Montreal Protocol because of its contribution to a then–rapidly growing hole in Earth’s ozone layer.

As use declined ahead of the ban, atmospheric concentrations of CFC-11 started to drop. Scientists projected a gradual decrease, because CFC-11 would continue to leak from old refrigerators and escape from foam insulation long after production and use stopped.

 But in 2012, levels started to increase in the Northern Hemisphere, with evidence pointing to sources in China. Now, Matthew Rigby of the University of Bristol in the United Kingdom and colleagues have used atmospheric observations and modeling to narrow down both the source and the magnitude of emissions, showing they are coming from Shandong and Hebei provinces and represent new production and use of CFC-11. In addition, amounts have increased since the chemical was banned, the team reports today in Nature.

The paper is “very definitive,” providing “firm evidence” that there is a continuing problem with emissions from China, says Ian Rae, a chemist at the University of Melbourne in Australia who was not involved in the study.

The authors say further investigation is needed to confirm which processes are responsible for the increasing CFC-11 emissions. But, “if consistent with historical usage, it would be expected that emissions have primarily occurred during, or following, [insulation] foam blowing.” That conclusion is in line with previous on-the-ground investigations by the Environmental Investigation Agency, a London- and Washington, D.C.–based environmental group, which singled out the CFC-11 used to create rigid polyurethane insulation in homes and commercial buildings.

“The Chinese have been doing the best they can” to identify and shut down the rogue operations, Rae says. “But regulators have real trouble keeping tabs on what is going on” throughout the country.

Over the past year, China has been bolstering efforts to crack down on the illegal releases, according to plans filed with the United Nations Environment Programme, which monitors compliance with the Montreal Protocol. “We hope that the information that this new study provided helps the Chinese government take steps to address the issue,” says Sunyoung Park, a study co-author who is a geochemist at Kyungpook National University in Daegu, South Korea.