<unk>  occurs when cells, tissues and organs are exposed to an excess supply of oxygen (O2) or higher than normal partial pressure of oxygen. In medicine, it refers to excess oxygen in the lungs or other body tissues, which can be caused by breathing air or oxygen at pressures greater than normal atmospheric pressure. This kind of<unk>  can lead to oxygen toxicity, caused from the harmful effects of breathing molecular oxygen at elevated partial pressures.<unk>  is the opposite of hypoxia;<unk>  refers to a state in which oxygen supply is excessive, and hypoxia refers to a state in which oxygen supply is insufficient. In the environment, it refers to excess oxygen in a body of water or other habitat.
Hyperoxia
Anoxia
Hypoxia 
Pseudohypoxia
Hypoventilation
Hyperventilation
Cerebral hypoxia
Silent hypoxia