<unk>  is a condition resulting from the harmful effects of breathing molecular<unk>  () at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs, and eyes. Historically, the central nervous system condition was called the Paul Bert effect, and the pulmonary condition the Lorrain Smith effect, after the researchers who pioneered the discoveries and descriptions in the late 19th century.<unk>  is a concern for underwater divers, those on high concentrations of supplemental<unk>  (particularly premature babies), and those undergoing hyperbaric<unk>  therapy. The result of breathing increased partial pressures of<unk>  is hyperoxia, an excess of<unk>  in body tissues. The body is affected in different ways depending on the type of exposure. Central nervous system toxicity is caused by short exposure to high partial pressures of<unk>  at greater than atmospheric pressure. Pulmonary and ocular toxicity result from longer exposure to increased<unk>  levels at normal pressure. Symptoms may include disorientation, breathing problems, and vision changes such as myopia. Prolonged exposure to above-normal<unk>  partial pressures, or shorter exposures to very high partial pressures, can cause oxidative damage to cell membranes, collapse of the alveoli in the lungs, retinal detachment, and seizures.<unk>  is managed by reducing the exposure to increased<unk>  levels. Studies show that, in the long term, a robust recovery from most types of<unk>  is possible. Protocols for avoidance of the effects of hyperoxia exist in fields where<unk>  is breathed at higher-than-normal partial pressures, including underwater diving using compressed breathing gases, hyperbaric medicine, neonatal care and human spaceflight. These protocols have resulted in the increasing rarity of seizures due to<unk> , with pulmonary and ocular damage being mainly confined to the problems of managing premature infants. In recent years,<unk>  has become available for recreational use in<unk>  bars. The US Food and Drug Administration has warned those suffering from problems such as heart or lung disease not to use<unk>  bars. Scuba divers use breathing gases containing up to 100%<unk> , and should have specific training in using such gases.
Oxygen toxicity
Cerebral hypoxia
Nitrogen dioxide poisoning
Chromium toxicity
Histotoxic hypoxia
Fluoride toxicity
Chlorine gas poisoning
Silent hypoxia