NITROUS oxide 鈥� also known as laughing gas 鈥� is the new villain in the fight to save the ozone layer.
Ever since the 1987 Montreal protocol phased out the use of chlorofluorocarbons (CFCs) and other ozone-depleting gases, Earth鈥檚 damaged ozone layer has been on the mend. But nitrous oxide (N2O), whose emissions are not regulated, could reverse those gains, reports of the US National Oceanic and Atmospheric Administration in Boulder, Colorado.
N2O reacts with oxygen atoms in the stratosphere to produce nitric oxide, which in turn destroys ozone. Bacteria release N2O when they consume the nitrogen in soil or water, but human activity now accounts for nearly 40 per cent of N2O emissions (Science, ).
Advertisement
N2O could become 50 per cent more destructive as stratospheric CFCs return to pre-industrial levels. That鈥檚 because nitrogen and chlorine compounds counteract each other鈥檚 effects on ozone: the more chlorine there is, the less destructive nitrogen is, and vice versa. 鈥淣2O is the most important ozone-depleting gas that鈥檚 being emitted,鈥� says Ravishankara.