Which statement best describes a characteristic of oxygen toxicity caused by prolonged exposure?

• A. Short bursts of high oxygen
• B. Prolonged exposure to high oxygen
• C. No oxygen exposure matters
• D. Reduced oxygen pressure

Answer: (B)

Oxygen toxicity from prolonged exposure happens because breathing high concentrations of oxygen for an extended period causes oxidative stress that damages tissues, especially in the lungs. This is the form of toxicity tied to sustained, not brief, high FiO2 levels; the body’s antioxidant defenses can cope with short spikes, but long-term exposure overwhelms them, leading to pulmonary symptoms and impaired lung function. In contrast, very short bursts of high oxygen can be associated with different, more acute effects (like CNS symptoms under high pressure), and reduced or absent oxygen exposure relates to hypoxia, not oxygen toxicity from hyperoxia. So the best description is the sustained exposure to high oxygen.