Oxygen Toxicity: Mechanisms in Humans

This study is investigating the mechanisms of oxygen toxicity in healthy humans — specifically, what happens physiologically when people breathe very high concentrations of oxygen over time. While oxygen is life-giving at normal atmospheric concentrations, breathing pure or near-pure oxygen for extended periods can damage the lungs and other tissues. This is a real clinical concern for patients on mechanical ventilators or undergoing hyperbaric oxygen therapy, but the exact biological mechanisms in humans remain incompletely understood. To be eligible, you must be a non-smoking adult aged 18 to 45, with no cardiorespiratory disease, neuromuscular disease, anemia, or hemoglobin disorders (including sickle cell disease or trait). Males must have a VO2 peak (aerobic fitness measure) of at least 45 mL/kg/min, and females at least 30 mL/kg/min. Pregnancy is an exclusion criterion. The study aims to recruit equal numbers of men and women. Participants will breathe high-concentration oxygen under controlled conditions while researchers measure physiological responses including lung function, blood markers of oxidative stress, and cellular changes. This is foundational mechanistic research that could have significant implications for how intensivists and anesthesiologists set oxygen levels for critically ill and ventilated patients — a field where current evidence for safe oxygen limits remains surprisingly incomplete.