a fire susceptible non habitable region of the aircraft where the high concentration nitrogen is reservoired thereby decreasing the capability for the atmosphere therein to support combustion oxygen is also separated from the ambient air thereby establishing a high concentration oxygen supply that is dispensed to an occupant cabin of the aircraft thereby increasing the level of oxygen concentration within the cabin to a level greater than the naturally occurring concentration of oxygen at the experienced internal cabin pressure when it is determined that reduced oxygen concentration is required in the occupant cabin the reservoired high concentration nitrogen is moved into the passenger cabin diluting the oxygen elevated environment application_number US 201113155702 A description fig1 and 2 graphically demonstrate easily monitored physiological reactions to airline flight in the example of fig1 a subject 39 s heart rate 10 linearized 11 is compared to experienced oxygen saturation levels 12 linearized 13 further details of the experienced cabin environment are illustrated in fig2 where temperature 15 pressures 16 and relative humidity 17 linearized 18 are tracked with respect to time for the trip of fig1 the relationship of increasing heart rate to decreasing oxygen saturation levels is readily appreciated this significant bodily reaction however goes substantially unnoticed by the passenger a similar reaction is shown at sea level in fig3 where heart rate 21 clearly tracks oxygen content percentage basis 20 saturation basis 22 in the air therefore as described above in one aspect the present invention constitutes raising the atmospheric concentration of oxygen within aircraft occupant compartments without increasing pressurization several different systems and technology are contemplated as suitable for increasing.