Automated SEM/EDS Analysis of Airbag Residue. II: Airbag Residue as a Source of Percussion Primer Residue Particles

• NCJ Number: 225889
• Journal: Journal of Forensic Sciences Volume: 54 Issue: 1 Dated: January 2009 Pages: 69-76
• Author(s): Robert E. Berk M.S.
• Date Published: January 2009
• Length: 8 pages
• Publication Format: Article
• Publication Type: Test/Measurement; Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This study identifies the particles in airbag residue, along with their source, that are the same as those in gunshot residue (GSR) and then identifies the additional particles in airbag residue that clearly distinguish it from GSR.

Abstract

The analysis of airbag residue using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) identified some residue particles that are consistent with GSR, namely, lead, barium, and antimony. The source of these particles was determined to be percussion primers used to initiate the chemical reaction that deploys the airbag in the event of a crash; however, the percussion primer that is used in some airbags is part of a much larger chemical equation than GSR. Squibs, ignition material or boosters, secondary explosives, gas generants, additional oxidizers, or metallic fields may add to the various elements detected in airbag residue by the SEM/EDS technique. High numbers of zirconium or copper/cobalt particles should be present in a sample of airbag residue. Also, airbag particles that may falsely be categorized as GSR should contain either high aluminum levels, elevated levels of allowable elements, or the presence of elements that are rare to GSR. Most particles in airbag residue give some indications that they are not typical GSR particles. Aluminum/silicon micro fibers may be present in the sample. In a traffic accident investigation, test results from the airbags themselves indicate whether percussion primers were used and would identify the main particle types that were produced. This information gives the analyst an idea of what materials to look for on samples from the suspect’s hands or clothing. This study analyzed airbag residue from some passenger side airbags recovered from both foreign and domestic vehicles from the 1991, 1994, and 1996 to 2006 model years. 1 table, 22 figures, and 9 references