Nitrous oxide - better know as laughing gas - is now the 'biggest human-caused ozone-depleting emission', according to US researchers.
The use of and emissions from CFCs or chloroflurocarbons - another ozone depleting group of gases - have been curbed since the Montreal Treaty was signed in 1987.
But nitrous oxide emissions are not regulated by any international treaty.
Writing in the journal Science, researchers from the National Oceanic and Atmospheric Administration (NOAA) say that unless it is regulated, the emissions pose a threat to the successful reversal of the large ozone hole over Antarctica.
Unlike CFCs, nitrous oxide has both natural and anthropogenic sources. Human emissions are a byproduct of agricultural fertiliser use, fossil fuel combustion, industrial processes, and even the combustion of renewable energy sources such as biomass and biofuel.
As well as regulation, US researchers suggest solutions including the more efficient use of fertiliser on cropland and the capture of nitrous oxide produced as a byproduct in chemical processes.
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