## 1 Introduction
In the work of [PERSON] et al., it was reported the application of various techniques including Raman spectroscopy, SEM, EDX, and Fourier-Transfer-Infrared-Spectroscopy (FTIR) to determine the physical and chemical analysis of several type of unused confiscated pyrotechnic powders and artifacts (Table 1) [26]. The combination of these various techniques can result in a complementary performance as one technique may not be very suitable to fully characterize or detect certain compounds. The SEM micrographs of this work in one of the analyzed powders showed the presence of irregular-shaped structures referred as \"grains\". Through the application of SEM/EDX mapping and Raman spectroscopy on one the formulations/samples the presence of two layers of materials or \"grains\" intermingled was revealed. A base layer or \"grains\", without physical symmetry, is composed of nitrite compounds with deposited smaller carbon-containing agglomerates on top. The inorganic \"grains\", that are mostly large, have different shapes that are jagged with uneven edges or surfaces. [PERSON] et al. collected various aerosol particulates directly on Cu TEM grids using a single-stage impactor with a 0.5 mm diameter jet nozzle operating under an air flowrate of 1.0 L/min during the Chinese New Year festival [20]. The TEM grids were analyzed using a transmission electron microscope coupled with EDX to determine the elemental compo sition of the particles. The EDX analysis showed that sulfate- and organic-rich particles were dominant in the atmosphere before and after the CNY. In contrast, K-rich sulfates and other metal-rich particles (e.g., Ba, Al, Mg, and Fe) were much more abundant than ammonia-reacted sulfate particles during the CNY. The study also presented a physical view of the morphology of the structures formed in the fireworks. A close inspection of the TEM images showed that the particulates resulting from the fireworks were large in size and irregular in shape. Some of the surfaces of these large particles frequently have condensed or deposited finer structures. TEM images of particles collected from firecracker samples revealed that they were much smaller, more spherical in shape, and aggregated (Table 1). A study by [PERSON] et al. focused on using SEM/EDX to identify and compare the morphology of particles at the microscale--both physically and chemically--that can be generated from gunshot residue (GSR) and those from fireworks (Table 1) [27]. The PM generated from fireworks was collected by placing 12 mm SEM double-sided carbon tapes in a glass Petri dish for SEM/EDX analysis. The sample holders were positioned randomly near the firework discharge to collect fallout particulates during the festivities on the Maltese Islands. Electron microscopy of the fireworks samples revealed large, regular spheroidal-shaped structures, spheroidal structures with smaller condensed particulates, and hollowed spheroidal shapes, depending on the location of the firework discharge. The study concluded that SEM and EDX revealed striking similarities in the physical and chemical characteristics of firework residue and GSR particle formation. [PERSON] et al. conducted SEM/EDX studies in which aerosol samples were collected by trapping them using pump system filters and an Anderson sampler during the Diwal festival in New Delhi [28]. Samples were gathered before, during, and after the event to assess potential changes in the elemental composition of the suspended particulates generated by the fireworks. The SEM/EDX comparative analysis showed that, overall, the particles collected before the event were mostly composed of carbon-rich (organic) material, frequently accompanied by particles rich in Al and Ca (mineral dust). However, the SEM/EDX analysis revealed that the samples collected during and after the fireworks event contained both organic and inorganic particles, including several metallic base elements.