System for improving air quality in an aircraft pressure cabin

A system for improving air quality in an aircraft pressure cabin, comprising:

• a recirculation air circuit in which a portion of the cabin air, referred to as recirculation air, is withdrawn from the pressure cabin, is conditioned and then is recirculated into the pressure cabin;
• and
• a nitrogen generator coupled to the recirculation air circuit and through which the quantity of recirculation air is passed wholly or partially so that the nitrogen generator generates nitrogen and an oxygen-containing waste gas from the recirculation air supplied, wherein
• the oxygen-containing waste gas generated by the nitrogen generator, together with any remaining quantity of recirculation air untreated by the nitrogen generator, is recirculated into the pressure cabin at a location downstream of the nitrogen generator,
• only recirculation air is supplied to the nitrogen generator,
• the nitrogen generator utilizes a pressure gradient existing in flight between the pressure cabin and the outside of the aircraft to actuate flow of recirculation air through the nitrogen generator for nitrogen generation, and
• the oxygen-containing waste gas generated by the nitrogen generator is fed back to the recirculation air circuit at a location upstream of the nitrogen generator.