Atmospheric monitoring has tracked rogue emissions of ozone-destroying chlorofluorocarbons to northeast China (Nature 2019, DOI: 10.1038/s41586-019-1193-4). Trichlorofluoromethane, or CFC-11, is controlled under the Montreal protocol, and its production was meant to cease by 2010. Before then, CFC-11 was widely used for blowing foams, and it is still leaking from insulating foam in buildings, refrigerators, and other products. Although that reservoir should decline over time, researchers reported last year that global CFC-11 emissions had actually risen between 2014 and 2016, potentially delaying ozone-layer recovery by a decade. Atmospheric modeling suggested that new production and use of the chemical in east Asia was responsible. Members of the same team have now gathered additional data from monitoring stations in South Korea and Japan that show that emissions from eastern mainland China—particularly the provinces of Shandong and Hebei—more than doubled from 2008–12 to 2014–17, an increase of 7,000 metric tons. That accounts for roughly half of the global rise in CFC-11 emissions since 2013. “They’re producing this in serious quantities,” says team member Matt Rigby of the University of Bristol. China’s government has been clamping down on companies using ozone-destroying chemicals. “We hope this provides another piece of information they can use to tackle this problem,” Rigby says.