Passive remote sensing addresses the problem of remotely monitoring, i.e. detecting the presence of, specific chemicals by the analysis of the radiative infrared signature of the material in the line-of-sight (LOS). Development of processing techniques for detecting the presence of the target chemical with a low enough false alarm rate in real time is the essence of the signal processing requirement for remote sensing. The aspects of data simulation and signal processing to achieve the passive remote monitoring objective are discussed. Application to environmental pollution monitoring is suggested.