Fridge manufacturers in China seem to be using illegal CFCs VCG/VCG via Getty

Who is destroying the ozone layer? In recent decades, concentrations of chlorofluorocarbon gases have been declining in the atmosphere, which is good news for the ozone layer’s recovery and action on climate change.

But levels of the second most abundant of those gases, trichlorofluoromethane (CFC-11), have been rising since 2013, puzzling researchers when they detected the increase last year.

The culprit appears to be illegal production of CFCs in eastern China, in defiance of a 2010 ban on their manufacture.

An international team traced the …