Misplaced Priority:I don't think, in my edumacated guess, that the nitrogen absorption is an issue. But, I wonder what effect if any breathing compressed air for a week could have on the lungs. Seems as though it could at least be irritating to the tissues.
They put a lot of money into that project... I'll bet that the air was very well cleaned, warmed and humidified (dry, dirty and/or cold air would cause irritation or bronchospasm, especially with long exposures).