Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in scuba divers at depth. It occurs to some small extent at any depth, but in most cases doesn`t become noticeable until deeper depths, usually from 30 to 40 meters. Jacques Cousteau famously described it as the "rapture of the deep". Its precise mechanism is not well understood, but it appears to be a direct effect of nitrogen dissolving into nerve membranes and causing temporary and reversible disruption nerve transmission. While the effect was first observed with nitrogen (in air), other gases including argon, krypton, and hydrogen also cause very similar effects under higher than atmopheric pressure. Nitrous oxide (laughing gas) appears to exert its effect by this mechanism. The noble gases argon, krypton, and xenon are more anesthetic than nitrogen at a given pressure, and xenon has so much anesthetic activity that it is actually a usable anaesthetic at 80% concentration and normal atmospheric pressure. (Xenon has historically been too expensive to be used very much in practice, but xenon has been sucessfully used for surgical operations, and xenon anesthesia systems are still being proposed and designed). Due to its perception-altering effects, the onset of nitrogen narcosis may be hard to recognize, its severity is unpredictable, and in scuba diving it can be fatal, as the result of illogical behaviour in a dangerous environment or in extreme cases. However, the cure for nitrogen narcosis is a simple one, as effects disappear within minutes upon ascending to shallower depths.