PbSe is a very important photoconductive material extensively used as IR detector for military applications and may be considered one of the most useful materials for detection in the MIR range. In the last years the opening of its production for wide civil use has allowed the conception of new detection systems based on this semiconductor. Considering some possible applications of it in environmental control, PbSe can provide, for instance, good response band to monitor several gases of major importance (SO2, NO, CO, etc.), especially when their concentrations are high. In this paper, we present applications of this semiconductor for this purpose: the developemnt of a new continuous emission monitoring system (CEMS) using a PbSe detector array in a nondispersive configuration. The basics of this prototype and some experimental results related to the detection of different typical emission gases with this system are presented here.