hydrogen narcosis

{{short description|Psychotropic state induced by breathing hydrogen at high partial pressures}}

Hydrogen narcosis (also known as the hydrogen effect) is the psychotropic state induced by breathing hydrogen at high pressures. Hydrogen narcosis produces symptoms such as hallucinations, disorientation, and confusion, which are similar to hallucinogenic drugs. It can be experienced by deep-sea divers who dive to {{convert|300|m|ft|abbr=on|sigfig=1}} below sea level breathing hydrogen mixtures.{{cite web|url=http://www.mejeme.com/dive/articles/mixhistory.htm|title=Diving With Gas Mixes Other Than Air|last=Taylor|first=Larry "Harris"|access-date=2009-03-02}} However, hydrogen has far less narcotic effect than nitrogen (which causes the better known nitrogen narcosis) and is very rarely used in diving. In tests of the effect of hydrogen narcosis, where divers dived to {{convert|500|m|ft|abbr=on|sigfig=2}} with a hydrogen–helium–oxygen (hydreliox) mixture containing 49% hydrogen, it was found that while the narcotic effect of hydrogen was detectable, the neurological symptoms of high-pressure nervous syndrome were only moderate.{{cite journal |last=Abraini |first=JH |author2=Gardette-Chauffour, MC |author3=Martinez, E |author4=Rostain, JC |author5= Lemaire, C |date=1994 |title=Psychophysiological reactions in humans during an open sea dive to 500 m with a hydrogen-helium-oxygen mixture |journal=Journal of Applied Physiology |publisher=American Physiological Society |volume=76 |issue=3 |pages=1113–8 |issn=8750-7587|url=http://jap.physiology.org/cgi/content/abstract/76/3/1113 |access-date=2009-03-01 |pmid=8005852 |doi=10.1152/jappl.1994.76.3.1113}}{{cite journal |last=Rostain |first=JC |author2=Gardette-Chauffour, MC |author3=Lemaire, C |author4= Naquet, R |title=Effects of a H2-He-O2 mixture on the HPNS up to 450 msw. |journal=Undersea Biomedical Research |volume=15 |issue=4 |pages=257–70 |date=1988 |issn=0093-5387 |oclc=2068005 |pmid=3212843 }}