Threshold concentration of nitrous oxide affecting psychomotor performance.

Using audiovisual reaction times, no effects were found in 12 subjects exposed to 1, 2, 4, or 8% nitrous oxide. In subsequent studies on 30 subjects, a positive effect on performance was found at a concentration of between 8 and 12% nitrous oxide. In addition, there was no difference in mean reaction time in 12 subjects exposed to air or 8% nitrous oxide. It is concluded that the threshold concentration of nitrous oxide for an effect on psychomotor performance as assessed by choice reaction times probably lies between 8 and 12%.