Carbon dioxide surface, warming the surface and the lower atmosphere. Less energy reaches the upper atmosphere, which is therefore cooler because of this absorption. Increases in atmospheric concentrations of and other long-lived greenhouse gases such as methane, nitrous oxide and ozone have correspondingly strengthened their absorption and emission of infrared radiation, causing the rise in average global temperature since the mid-20th century. Carbon dioxide is of greatest concern because it exerts a larger overall warming influence than all of these other gases combined and because it has a long atmospheric lifetime (hundreds to thousands of years). Not only do increasing carbon dioxide
Nitrous oxide B levels should be checked in people with risk factors for vitamin B deficiency prior to using nitrous oxide anaesthesia. Several experimental studies in rats indicate that chronic exposure of pregnant females to nitrous oxide may have adverse effects on the developing fetus. At room temperature (20 °C (68 °F)) the saturated vapour pressure is 50.525 bar, rising up to 72.45 bar at —the critical temperature. The pressure curve is thus unusually sensitive to temperature. Liquid nitrous oxide acts as a good solvent for many organic compounds; liquid mixtures may form shock sensitive explosives. As with many strong oxidisers, contamination