Carbon dioxide equivalent of "emissions" or rate of greenhouse gas emission—a "flow" into the atmosphere—rather than the instantaneous value of the radiative forcing of the "stock" (concentration) of greenhouse gases "in the atmosphere" described by e. The carbon dioxide equivalency for a gas is obtained by multiplying the mass and the GWP of the gas. The following units are commonly used: For example, the GWP for methane over 100 years is 34 and for nitrous oxide 298. This means that emissions of 1 million metric tonnes of methane and nitrous oxide respectively is equivalent to emissions of 34 and 298 million metric tonnes
Nitrous oxide aid responders in prehospital settings, given the relative ease and safety of administering 50% nitrous oxide as an analgesic. The rapid reversibility of its effect would also prevent it from precluding diagnosis. Recreational inhalation of nitrous oxide, with the purpose of causing euphoria and/or slight hallucinations, began as a phenomenon for the British upper class in 1799, known as "laughing gas parties". Starting in the nineteenth century, widespread availability of the gas for medical and culinary purposes allowed the recreational use to expand greatly, throughout the world. In the United Kingdom, as of 2014, nitrous oxide was estimated to be