What is the approximate normal range of FIO2 in room air?

The normal range of FIO2 (Fraction of Inspired Oxygen) in room air is approximately 21%. This percentage represents the concentration of oxygen in the atmosphere that humans typically breathe under standard conditions. Room air consists mainly of nitrogen (about 78%) and oxygen, among other gases, with oxygen making up roughly one-fifth of the total composition.

Understanding this value is critical when considering respiratory care and the administration of supplemental oxygen. When someone requires more oxygen than what is present in room air, knowing the baseline concentration allows healthcare providers to calculate the necessary flow rates and concentrations of supplemental oxygen.

The other options represent concentrations that exceed the oxygen levels found in normal atmospheric conditions and would not be found in room air. For instance, higher values like 30% and 50% indicate concentrations typical of supplemental oxygen therapies, while 78% primarily represents nitrogen in the air, not oxygen. Recognizing these standards is essential for effective patient management and treatment planning in medical settings.