An air treatment system (100) for treating air of an inhabited space (1). The air treatment system has an air preparation module (3) and a cryogenic module (5). The air preparation module (3) is configured to receive air extracted from the inhabited space (1) and is configured to increase the pressure of the extracted air so as to increase the density and decrease the moisture content of the extracted air, thereby converting the extracted air into dry air. The cryogenic module (5) is coupled to the air preparation module (3) to receive the dry air and is configured to decrease a temperature of the dry air such that at least part of at least one component of the dry air is separated and removed from the dry air thereby converting the dry air into treated air for delivery into the inhabited space (1).