The environmental monitoring system EM 27 is an open path Fourier Transform infrared (FT-IR) spectrometer, designed and optimized for remote sensing of chemical substances in the atmosphere. With its high sensitivity, mechanical stability and speed the system is ideally suited for a wide range of applications, from industrial air quality monitoring to academic research in the field. With its proven Bruker RockSolidTM interferometer and the novel design of its sensor module the system is resistant to mechanical shocks and vibrations enabling a long-term alignment of the system under varying temperature conditions. An internal calibration source provides automated radiometric calibration. The system is hardened for field operations in harsh environments and is capable of real-time measurements and analysis on site.