The atmospheric concentration of five chemicals that destroy the ozone and whose use has been banned, is increased, according to research published in the journal “Nature Geoscience”.

It’s about them chlorofluorocarbons (CFCs), chemicals widely used in the production of hundreds of products such as aerosol sprays, blowing agents for foams and packaging materials, solvents, as well as in refrigeration, and their production for such uses was banned under the Montreal Protocol in 2010 because they destroy the protective layer of the Earth’s ozone. However, these substances can still be released as raw materials, which are used to make other compounds, intermediates and by-products in the production of other chemicals, such as hydrofluorocarbons (HFCs), which were developed as replacements for CFCs in refrigeration and the air conditioning. This is a permissible exception to the Montreal Protocol, however it is contrary to its broader objectives.

The research, led by the University of Bristol and the US National Oceanic and Atmospheric Administration (NOAA), was carried out by a team of scientists from Britain, the US, Switzerland, Australia and Germany. The researchers focused on five CFCs with few or no known current uses, which have atmospheric lifetimes ranging from 52 to 640 years. After measurements taken at 14 locations around the world, it was found that the atmospheric concentration of five CFCs has increased since their production was phased out for most uses in 2010 and reached a record concentration in 2020.

For three of these CFCs, the increased emissions may be due in part to their use in the production of two common HFCs, used primarily in refrigeration and air conditioning. The reasons behind the increasing emissions of the other two CFCs are less clear, as there are no known current uses for them.

“The bottom line is that the manufacturing process for some of the chemicals that replace CFCs may not be completely ozone-friendly, even if the replacement chemicals themselves are,” says the study’s lead author, Luke Western, a researcher at the University of Bristol and the National Oceanic and Atmospheric Administration.

According to the researchers, emissions from these CFCs do not currently pose a significant threat to ozone recovery; but as they are potent greenhouse gases, they still affect the climate. Also, if emissions of these five CFCs continue to increase, their impact may negate some of the benefits gained from the Montreal Protocol.

“Given the continued increase of these chemicals in the atmosphere, it may be time to consider improving the Montreal Protocol a bit more”said study co-author Johannes Laube from the Institute for Energy and Climate Research at Forschungszentrum Jülich.