Abstract: Metal oxide sensors are provided. Systems including the metal oxide sensors and methods for identifying a target gas concentration using the sensors are also provided. A method for increasing the consistency of MOx sensor readings over an in-service interval is provided, comprising: applying a thermal stimulus to a sensor face to reset to a condition substantially devoid of environmental chemical species; a dwell period following the thermal stimulus where the sensor is: (a) held between an ambient temperature and a thermal stimulus temperature, or (b) exposed to temporal patterns of heated and unheated intervals; triggering a reading of electrochemical changes to the sensor caused by chemical species in the environment being sensed, at a consistent time interval after the application of the thermal stimulus; and wherein the application of the thermal stimulus, the dwell period, and the reading of electrochemical changes to the sensor is a thermal stimulus-to-read cycle.

Abstract: A method is provided for separating one or more volatile contaminant components from a gas using a pressure and temperature swing adsorbent filtration filter bed system containing three or more layers of adsorbent materials characterized in that the layers comprise a first layer of adsorbent material, a second layer of dessicant material and a third layer of material capable of adsorbing contaminants that are not retained by the first layer. Preferably the third layer is capable of adsorbing contaminants of relatively low boiling point, e.g. of boiling point less than 50.degree. C., and preferably comprises a microporous adsorbent. The second layer of dessicant material preferably comprises a zeolite.

Abstract: A composite gas filtration system for removal of toxic or harmful agents from a breathable gas supply, wherein a compressor fed pressure swing adsorption unit is placed upstream of an adsorbent carbon filter unit in a gas supply line, characterized in that a plenum chamber is positioned in the gas supply line with one or more inlet orifices supplied by gas treated by the pressure swing adsorption unit, one or more exit orifices leading to the carbon filter unit, and one or more further inlet orifices supplied by gas from upstream of the pressure swing adsorption unit, wherein a device for drawing or propelling breathable gas through the plenum chamber and carbon filter from the further inlet orifices in the event of shut down of the pressure swing adsorption unit and/or compressor is provided.