Abstract: An air treatment system includes a recirculation line (24) through which air from the enclosed space can be recirculated, and a contaminant adsorption assembly (36) is provided in an auxiliary supply conduit (31). In the event that contaminants are detected in atmospheric air, air from the enclosed space can be recirculated for conditioning and then readmitted to the enclosed space. Oxygen that is breathed by occupants of the enclosed space can be replenished by admitting air from atmosphere, which is treated using the adsorption assembly and then mixed with air that is in the enclosed space or being recirculated for admission to the enclosed space.

Abstract: A method of removing individual gas components of a mixture of gases within a controlled environment container uses apparatus which comprises first and second chambers which are arranged in parallel for the gas mixture to flow through them from their inlet ends to their outlet ends. The chambers contain adsorbent material with different affinities for the gas components of the mixture. The method comprises supplying the gas mixture to the first chamber so as to pressurize it while allowing a purge stream to flow from the outlet end of the first chamber to the second chamber to purge adsorbed gas from the adsorbent material in the second chamber. A purge pulse of gas is then supplied from the outlet end of the first chamber to the second chamber to purge adsorbed gas from the adsorbent material in the second chamber, the rate of flow of the purge stream being less than that of the purge pulse.