In general, these terms relate to a more than a normal amount of Oxygen. Hyperoxic refers to a mixture of gases with higher than normal Oxygen content (above 21%). Hyperoxia is the physiological condition associated with breathing too high of a partial pressure of Oxygen. The human body has a limit on both the partial pressure of Oxygen it can tolerate and the long term dosage of Oxygen. The partial pressure upper limit is generally considered to be approximately 1. 6 ppO2 but most divers leave some margin for error and a more typical upper limit is 1. 4 ppO2. When high partial pressures of Oxygen are inspired, convulsions may occur with little or no warning.