Map showing the changes in CFC-11 (trichlorofluoromethane) emissions across Asia from 2008 to 2019. CFC-11 is a greenhouse gas and ozone depleting substance that was once used as a refigerant. In 2018, air pollution tracking stations in South Korea and Japan, part of the Advanced Global Atmospheric Gases Experiment (AGAGE), noticed that there was an increase in CFC-11 emissions (centre map) from northeastern China. The next year, emissions were reduced (right map). AGAGE is a global observing system that monitors global chemical emissions.