Oksygenkonsentrasjon

Oksygenkonsentrasjon, or oxygen concentration, is a measure of how much molecular oxygen is present in a gas mixture or in a liquid. It is commonly expressed as a fraction by volume (FiO2) or as an oxygen partial pressure (P_O2). In Earth's atmosphere the oxygen concentration is about 21 percent by volume, corresponding to a partial pressure of about 160 mmHg at sea level.

In humans, the amount of oxygen delivered to tissues depends on both the arterial oxygen partial pressure (PaO2) and the hemoglobin saturation (SaO2). Normal arterial PaO2 is about 80–100 mmHg, and SaO2 is about 95–100%. A small portion of oxygen is dissolved in plasma (about 0.003 mL O2 per 100 mL blood per mmHg), with the remainder bound to hemoglobin.

Measurement and exposure: FiO2 is set in gas mixtures and is measured with gas sensors. PaO2 and SaO2 are assessed from arterial blood gas analysis, while noninvasive pulse oximetry estimates SpO2. In clinical care, oxygen therapy seeks to maintain adequate oxygen delivery without causing hyperoxia.

Applications and safety: Oxygen concentration is essential in medicine (oxygen therapy, anesthesia), aviation and diving gas planning, and industrial processes. High oxygen levels pose fire and oxidative hazards; prolonged exposure to high FiO2 or high P_O2 can cause oxygen toxicity, so monitoring and limits are used in practice. Hyperbaric oxygen therapy and enclosed spaces with high O2 require strict safety protocols.