What Researchers Did
Researchers measured lung function in healthy men before and after they breathed pure oxygen at high pressure for an extended period, to see how much oxygen exposure the lungs could tolerate.
What They Found
In this study of 13 healthy men, breathing 100% oxygen at 3.0 ATA (three times normal atmospheric pressure) continuously for 3.5 hours caused measurable, temporary reductions in some airflow measurements taken afterward. Forced expiratory volume in one second (FEV1) fell by 5.9% and forced expiratory flow at 25-75% of vital capacity (FEF25-75) fell by 11.8% after exposure, while forced vital capacity did not change significantly. A comparison of flow rates using air versus helium-oxygen breathing showed an 18% reduction after exposure, a pattern the researchers said was consistent with narrowing in the small peripheral airways of the lungs. Airway resistance and carbon monoxide diffusing capacity were unchanged. Most participants had mild chest discomfort, cough, or shortness of breath during the exposure, and one man had a seizure at the three-hour mark.
Canadian Relevance
No direct Canadian connection identified.
Study Limitations
The study involved only 13 healthy men, with some measurements based on subgroups as small as 5 to 6 participants, so the findings may not apply to women, older adults, or people with existing lung or health conditions.