An advanced trace gas monitoring system for long duration manned space missions - such as the International Space Station - is discussed. The system proposed is a combination of a Fourier-Transform Infrared Spectrometer (FTIR) and a distributed ‘Smart Gas Sensor system (SGS). In a running multi-phase programme [1,2] the FTIR technology, applying novel analysis methods, has been demonstrated to handle multi-component gas measurements, including identification and quantification of 20 important trace gases in a mixture. In the current phase 3, initiated end of 1997, a fully operational FTIR technology demonstration model will be manufactured and tested. The SGS consists of an array of twenty electrically conductive polymer sensors supplemented with an array of quartz crystal microbalance sensors. The technology has been tested on the Russian MIR space station and is currently miniaturized into a second-generation flight model. Many miniature SGS units with high sensitivity may be distributed in the spacecraft to give very fast detection of any rapid local change in the cabin air quality (‘gas event’). The single FTIR system, with its higher selectivity and stability, can more accurately identify and quantify the polluting contaminants and their development with time in order to determine the needed countermeasures, to check their effect, and to ensure the safety of the crew.