NCJ Number
192032
Journal
Journal of Forensic Sciences Volume: 46 Issue: 6 Dated: November 2001 Pages: 1324-1331
Date Published
November 2001
Length
8 pages
Annotation
An experimental study of the natural sampling of trace signals from explosives concealed on the human body was performed by taking proper account of the thermal behavior of the air surrounding the human body and the particles therein.
Abstract
Experiments were conducted in a dispersal chamber to identify variables that affected the detectibility of concealed RDX (plastic explosive) and TNT patches. Movement by human volunteers was found to enhance the available explosive trace signal above a baseline level. Clothing blocked some of this movement-generated trace signal. The detected signal levels were also found to vary significantly from volunteer to volunteer, indicating that human variability is an issue in explosive trace detection. Further, under the conditions studied here, the detectibility of RDX and TNT was dependent on the efficient sampling of contaminated particulate matter, not the vapor phase. These results thus demonstrate that there is a baseline signal in the plume of a contaminated human subject that is available for detection, and this can be enhanced by agitating the source. Normal movements, walking, and carrying luggage can be expected to agitate the concealed explosive and contaminated clothing, releasing detectable traces into the thermal microenvironment of the body. These results are now being applied in the design of a practical, nonintrusive, trace-detection walk-through portal for aviation-security screening and related applications. This requires that nonideal airflow patterns be considered. Other security applications may include the detection of narcotics and chemical and biological warfare agents. 8 figures and 23 references