Human Presence Detection
Detection of stowaways in shipping containers is important for national security, liability, and for humanitarian reasons. Human breath contains a unique combination of recognizable chemicals; however it requires a sophisticated sensing system such as the C-Scout MAS (Molecular Analysis System) based on our unique Self-Sensing ArrayTM to sense and analyze this combination and discern human presence in a shipping container with a low false-positive rate.
Carbon Dioxide (CO2) detectors are sometimes used to detect human presence, however this method can lead to a high false positive rate. CO2, a heavy colorless gas, is produced by the decomposition of organic substances, and is also a byproduct of many chemical processes.
The chemical analysis capability of the MAS module is well suited to provide a detailed analysis of the air in the container and thus an ability to detect the presence of humans by detecting chemicals indicative of human respiration. The ideal system to detect the presence of people in a container must demonstrate relatively fast detection (alarm within two hours of the container being sealed for shipment), a high probability of detection (Pd) and an extremely low probability of false alarm (Pfa). Pd is of course related to the sensitivity, and Pfa is a function of the selectivity, which for trace detection is the ability to accurately identify chemical signatures and map them to their sources.
There is a substantial body of literature on the chemicals that are produced by humans. Human respiration is a continuous chemical production mechanism and studies have shown it to be a very reliable producer of volatile organic compounds that are ideal for detection with a trace detection system. The chemicals found in human breath are well characterized. The following table shows the compiled results of a chemical analysis of room air for 15 different individuals:
Table 1: Chemicals present in human breath. The individuals tested were in the room, one at a time, for one hour. Acetone, 2-methyl pentane, hexane, isoprene and 2-methyl 1-pentene were the most prevalent chemicals.