The data reinforces a watchdog report from 2018 that claimed at least 18 companies in China were using the chemical to make foam insulation.

A United Nations-backed report suggests the Earth's protective ozone layer is slowly recovering, due to lower concentrations of harmful greenhouse gases.

Chinese foam-makers appear to be the “mystery” polluters behind the use of a banned, ozone-depleting chemical, an environmental group says.

The Montreal Protocol was an international agreement signed on Sept. 16, 1987.