A new study shows that nitrous oxide, also known as laughing gas, has become the number one ozone depleting substance emitted by humans.

The national oceanic and atmospheric administration's earth system research laboratory, the researchers used mathematical model calculated the human through the use of chemical fertilizer, such as fossil fuel emissions into the atmosphere each year about 10 million tons of nitrous oxide, if human do not take measures to limit its emissions, it will become the 21st century most damaging ozone-depleting substances.

Under the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer, the use of ozone-depleting substances such as chlorofluorocarbons (CFCs) and bromofluorocarbons (BFRCs) has been gradually reduced, but nitrous oxide emissions are not restricted by the protocol and are increasingly damaging the ozone layer, the researchers said.

The research results of the paper will be published in the latest issue of the US journal Science on 28. Restricting future nitrous oxide emissions, a greenhouse gas, would not only speed up the recovery of the Earth's ozone layer, but also slow climate change, the researchers wrote in their paper.

The ozone layer refers to the stratosphere where ozone molecules are relatively enriched 25 to 30 kilometers from the earth. It absorbs more than 99 percent of the sun's harmful ultraviolet rays, protecting life on Earth from short-wave ultraviolet rays, so it is known as the protection umbrella of life on Earth. Human activity has caused a large hole in the ozone layer over Antarctica.

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Nitrous oxide properties:

Nitrous Oxide (Nitrous Oxide), also known as laughing gas, colorless sweet gas, is a kind of oxidant, chemical form N₂O, under certain conditions can support combustion (with oxygen, because laughing gas can be broken down into nitrogen and oxygen at high temperature), but stable at room temperature, has a slight anesthetic effect, and can make people laugh. Its anesthetic effects were first discovered in 1799 by the English chemist Humphrey Davy. Related theory that N₂O and CO₂ molecule has a similar structure (including electronic), then its spatial configuration is linear, N₂O for polar molecules.