Scientists have detected an unexpected rise in atmospheric levels of CFC-11, a chlorofluorocarbon (CFC) highly damaging to the ozone layer.
Banned by the Montreal Protocol in 1987, CFC-11 was seen to be declining as expected but that fall has slowed down by 50% since 2012.
Researchers say their evidence shows it's likely that new, illegal emissions of CFC-11 are coming from East Asia.
These could hamper the recovery of the ozone hole and worsen climate change.
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