In humans, there are several types of oxygen toxicity:
Central nervous system (CNS) oxygen toxicity is manifested as dizziness, nausea and twitching, especially on the face, leading to convulsions, which although not lethal themselves, can cause drowning of divers or lethal pressure damage during a rapid ascent to the surface.
The likelihood of this type of accident is directly proportional to the partial pressure of oxygen (ppO2) in the breathing gas and to the duration of exposure.
Pulmonary oxygen toxicity is caused by exposure over 16 hours to partial pressures of 0.5 bar or more causing breathing difficulty and pain resulting in lung damage which may be irreversible. This is a rare complication for divers, but may be of concern in intensive care patients needing high inspired oxygen concentrations.
Retinopathic oxygen toxicity causes damage to the retina. Oxygen may be a contributing factor for the disorder called retinopathy of prematurity.
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