Nitrous oxide

Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others,^[4] is a chemical compound, an oxide of nitrogen with the formula N
₂O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste.^[4] At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen.^[4]

Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain-reducing effects,^[5] and it is on the World Health Organization's List of Essential Medicines.^[6] Its colloquial name, "laughing gas", coined by Humphry Davy, describes the euphoric effects upon inhaling it, which cause it to be used as a recreational drug inducing a brief "high".^[5][7] When abused chronically, it may cause neurological damage through inactivation of vitamin B₁₂. It is also used as an oxidiser in rocket propellants and motor racing fuels, and as a frothing gas for whipped cream.

Nitrous oxide is also an atmospheric pollutant, with a concentration of 333 parts per billion (ppb) in 2020, increasing at 1 ppb annually.^[8][9] It is a major scavenger of stratospheric ozone, with an impact comparable to that of CFCs.^[10] About 40% of human-caused emissions are from agriculture,^[11][12] as nitrogen fertilisers are digested into nitrous oxide by soil micro-organisms.^[13] As the third most important greenhouse gas, nitrous oxide substantially contributes to global warming.^[14][15] Reduction of emissions is an important goal in the politics of climate change.^[16]