Laughing gas largest threat to Ozone layer: Study


"Although N2O is roughly 160th of Chloro-fluoro carbon (CFC)-11 in terms of ozone depleting potential, it has become the largest ozone depleting substance as Montreal Protocol has considerably reduced emission of others," A R Ravishankara, Director Chemical Sciences Division, National Oceanic and Atmospheric Administration, (NOAA) USA, told PTI over phone.

The research, which will be published in the latest issue of the Science magazine, studied N2O emissions through human activities especially by usage of fertilisers in agriculture.
"Our findings analyse the continuous emissions of N2O compared to that of Chloro fluoro carbon (CFC)-11 from anthropogenic source, especially agriculture, he said.
Speaking about the harmful effects of ozone depletion Ravishankara said, "The phenomenon of ozone depletion will increase the harmful UV radiation on earth, besides damage to infrastructure, plant life, among others."

Using an atmospheric model 'Garcia and Solomon 2 Dimensional model', scientists at Earth System Research Laboratory NOAA, have calculated the ozone depletion potential of Nitrous Oxide as compared to other harmful chemicals at steady state.

The scientist claimed that the emissions of laughing gas are currently present in the atmosphere in such large amounts that it will remain the most abundant ozone-depleting substance throughout the 21st century.

He, however, added that, "Since a large part of India is in the tropics where the overhead stratospheric ozone is already somewhat small, the increase in surface UV levels due to ozone depletion is less than at higher latitudes."

Stratospheric ozone depletion is a matter of concern worldwide because the ozone layer in the upper atmosphere, 10-15 kilometres above surface, keeps 95 to 99 per cent of sun's ultraviolet radiation from striking the earth.

The decrease of stratospheric ozone was first reported in 1974 after which Montreal Protocol was adopted on 16 September, 1987 to prevent ozone layer depletion.
"When Montreal Protocol was signed and amended, N2O was not thought of as an ozone depleting gas," the scientist said.

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