air-pressure effects
the adverse mental or physical effects of a significant variation in atmospheric pressure. The effects experienced at high pressures—for example, in diving more than 10 m (33 ft) beneath the surface of the sea—may include difficulty breathing, nitrogen poisoning marked by light-headedness and mental instability, and oxygen poisoning caused by breathing oxygen under extreme pressure. Exposure to low pressures, as in mountain climbing or air travel without oxygen or air-pressure modification, characteristically causes oxygen starvation, with impaired performance and eventual loss of consciousness and death. See also acute mountain sickness; altitude sickness; decompression sickness; grayout.