Assessing the Abundance of Pyrotechnic Traces from New Year′s Eve Celebrations in the Netherlands: Implications for Forensic Explosives Investigations

Abstract To ensure a correct interpretation of the presence and abundance of pyrotechnic traces at a crime scene, it is essential to understand reference background levels and the extent to which they are affected by specific activities such as fireworks displays. A total of 112 objects throughout the Netherlands were sampled before and/or after New Year′s Eve 2017, 2018, 2022, and 2023. Sample extracts were analysed with Ion Chromatography ‐ Mass Spectrometry to determine the concentrations of 17 inorganic ions relevant to forensic explosives investigations. The ions SO 4 2− , NO 3 − , Na + , K + , Cl − , PO 4 3− Ca 2+ , Mg 2+ , and NH 4 + were found most often (33–98%) before New Year′s Eve. The maximum amounts recovered ranged from 52.63 to 1071.50 μg for this set of ions. Only 3% of outdoor objects carried detectable levels of ClO 4 − , with a maximum amount of 0.55 μg per 2.3 dm 2 . It appears that NO 2 − , SCN − , ClO 3 − , S 2 O 3 2− , Li + , Sr 2+ , and Ba 2+ are generally absent in the Dutch environment. While fireworks displays do not seem to greatly affect the background levels of inorganic ions related to explosives, mean ClO 4 − levels were increased on January 1 st (p=0.02). Sporadically, high levels of Cl − , SO 4 2− , K + , and even a trace amount of Sr 2+ were observed after New Year′s Eve. These findings are of great forensic relevance for pre‐ and post‐explosion investigations involving trace levels.