Atmospheric concentrations of five banned ozone-depleting chemicals are on the rise, according to a study published in the journal Nature Geoscience.

These are chlorofluorocarbons (CFCs), chemicals that have been widely used in the manufacture of hundreds of products such as aerosol cans, blowing agents for foam and packaging materials, solvents and refrigeration, and their production for such purposes has been banned by the Montreal Protocol. in 2010 because they destroy the Earth’s protective ozone layer.