Oxygen gas (O
2) can be toxic at elevated partial pressures, leading to convulsions and other health problems.[j] Oxygen toxicity usually begins to occur at partial pressures more than 50 kilopascals (kPa), equal to about 50% oxygen composition at standard pressure or 2.5 times the normal sea-level O
2 partial pressure of about 21 kPa. This is not a problem except for patients on mechanical ventilators, since gas supplied through oxygen masks in medical applications is typically composed of only 30%–50% O
2 by volume (about 30 kPa at standard pressure). (although this figure also is subject to wide variation, depending on type of mask).
At what point does oxygen toxicity begin to happen?
50 kilopascals at partial pressures more than 50 kilopascals 50 kilopascals more than 50 kilopascals at partial pressures more than 50 kilopascals