Techniques for monitoring thermal emissivity levels of human traffic within a plurality of sections of a zone of interest are presented. The thermal emissivity levels are monitored using an infrared detector with sensitivity range of less than fifty milliKelvin, and in some variations, about fifteen to thirty milliKelvin, such as a quantum well infrared photodetector (QWIP) equipped camera. Based on differential emissivity calculations, a determination is made whether the monitored emissivity level corresponds to at least one calibrated emissivity level associated with an explosive material. The monitored emissivity levels are calibrated to eliminate the effects of other synthetic objects such as clothing, personal items, and other harmless objects. The monitored emissivity levels are also buffered against changes in environmental factors.