Kyoto Protocol European Union-15, made up of 15 states at the time of the Kyoto negotiations) commit themselves to binding targets for GHG emissions. The targets apply to the four greenhouse gases carbon dioxide (), methane (), nitrous oxide (), sulphur hexafluoride (), and two groups of gases, hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). The six GHG are translated into CO equivalents in determining reductions in emissions. These reduction targets are in addition to the industrial gases, chlorofluorocarbons, or CFCs, which are dealt with under the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. Under the Protocol, only the Annex I
Nitrous oxide used by almost half a million young people at nightspots, festivals, and parties. The legality of that use varies greatly from country to country, and even from city to city in some countries. The major safety hazards of nitrous oxide come from the fact that it is a compressed liquefied gas, an asphyxiation risk, and a dissociative anaesthetic. While relatively non-toxic, nitrous oxide has a number of recognized ill effects on human health, whether through breathing it in or by contact of the liquid with skin or eyes. Nitrous oxide is a significant occupational hazard for surgeons, dentists, and nurses.