A new generation of ion mobility spectrometers has been designed especially for the environmental monitoring due to toxic compounds in ambient air: phosgene, halocarbons, isofluorane, halothane, formaldehyde, ethylenoxide, acrolein, chemical warfares and many others. The IMS is equipped by means of tritium ionization sources, which have lower radiation hazards than nickel-63 sources. Aromatics are monitored by means of a special version using photoionization. Minimal detectable concentrations are in the ppb-range, mostly even below.