An aircraft cabin air treatment system configured in accordance with the invention utilizes oxygen enriched air, which is produced as a byproduct of an onboard inert gas generation system. The oxygen enriched air is released into an environment under ambient pressure conditions, i.e., at a relatively low absolute pressure compared to the cabin pressure. The low pressure oxygen enriched air is compressed with a cabin air compressor, and the outside air is routed back into the cabin. The cabin air compressor functions to generate oxygen enriched outside air and to maintain the desired pressurization of the cabin.