We present a review of Microsystems-based technologies for the miniaturization of gas detection systems with a focus on air quality monitoring. On one hand, compared to sensors technologies, an approach based on microanalytical instruments can fulfill some of the requirements linked to the detection at the trace level of some pollutants with improved selectivity. On the other hand, the detection system becomes more complex at a higher cost which can result in a limited deployment. Some of the Microsystems components to be highlighted in this communication include micromachined gas preconcentrators, gas chromatographs, and infrared spectrometers. Several performing individual components have been reported in the last decade but several issues still remain at the system integration level to get commercially viable and robust products on the market.