Nitrous oxide is a colourless, non-flammable, relatively inert gas at room temperature and has a slightly sweet odour.
Nitrous oxide, when inhaled at high concentrations (70% by volume) has an anaesthetic effect and at lower concentrations, an analgesic effect. Long term exposure has been shown to have neurotoxic effects and has also been attributed to the increased incidence of foetal abnormalities and spontaneous abortion.
It is also a strong absorber of infra-red radiation and is therefore a powerful greenhouse gas.
Nitrous oxide has been used as an anaesthetic since 1844 and is still used clinically for both anaesthesia and analgesia.
It occurs naturally due to the decomposition of organic nitrogen compounds in the soil.
It is also used as an aerosol spray propellant, particularly for foods such as whipped cream and cooking oils.