This invention provides systems and methods of supplying oxygen-enriched air to an enclosed space or compartment. The systems and methods may distill oxygen from ambient air by a molecular sieve pressure cycle mechanism, such as a pressure swing absorption, may generate oxygen from water using electricity or may use oxygen enriched air produced by membrane filtration. The invention helps people improve their wellness, productivity and comfort, improve performance of mental and/or physical tasks, increase their alertness, quality of life and pleasure, reduce their drowsiness, and aid in curing and preventing disease by increasing the percentage of oxygen in the enclosed space to a beneficial and safe level.