## 1 Introduction
Particularly, a subgroup of halogen (e.g., chlorine, bromine, and iodine)-containing compounds (HCCs) was also identified, including CHOSI, CHOSCI, CHONCI, CHONCI, CHONBr, CHOCIBr, CHOCI, CHOCI, CHOCI, and CHOBr. [PERSON] et al. used an Aethalometer during the Diwali Festival to demonstrate the level of pollution caused by fireworks plumes by measuring the concentration of black carbon particles released into the environment during large-scale firework displays [22]. In addition to particulate matter (PM), several chemical species were also reported, including NO\({}_{2}\), SO\({}_{2}\), PM\({}_{10}\), BC (black carbon), CO, and O\({}_{3}\). These were compared for three periods: pre-fireworks (normal day), during fireworks, and post-fireworks. The study found that PM\({}_{10}\) was the most hazardous pollutant, with concentrations of approximately 90 \(\mu\)g/m\({}^{3}\) on normal days, rising to 1660 \(\mu\)g/m\({}^{3}\) after the fireworks. NO\({}_{2}\) and CO concentrations exceeded the National Ambient Air QualityStandard (NAQS) limits during the three-day festival, whereas they remained well below these limits on normal days. NO\({}_{2}\) levels were three times higher than on normal days, and SO\({}_{2}\) was 10 times greater. Alarmingly, PM\({}_{10}\) levels were found to be 12 times the normal day levels, which is about eight times above the NAAQS limit. BC and surface O\({}_{3}\) concentrations were also elevated during the Diwali period compared to normal days. Additionally, their investigation had a broader scope, examining various meteorological parameters that can affect emissions during the festival. The aforementioned methods are used for bulk sample analysis of pollutant emissions. Researchers have also developed computational models to predict or represent how fine particulate matter (PM\({}_{2.5}\)) from fireworks spreads into the atmosphere. These models can help estimate exposure levels at different distances from the fireworks display and predict the plume trajectory (pollutants) movement based on weather conditions, wind speed, and terrain [23; 24]. As part of ongoing studies on pollutants from fireworks, recent advancements in electron microscopy techniques, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and energy disperse X-ray (EDX) have enabled researchers to focus on the physical and chemical morphology of the particulates formed during fireworks displays. Table 1 lists illustrative works related to the use of electron microscopy in pyrotechnics including as-received (confiscated fireworks), form of collection, chemical analysis, and representative physical morphology. [PERSON] et al. (in 2001) reported that SEM coupled with EDX is the most reliable method for detecting gunpowder residue (Table 1) [25]. Additionally, it was shown in that study that SEM/EDX can be successfully employed to study various pyrotechnic fireworks. Their study served as a proof of concept for using SEM and EDX to identify particulates in pyrotechnic residue. They were able to successfully differentiate between sample origins based on the chemical composition and physical structure of the particulates, confirming that the applied methodology works effectively and can be used on a variety of samples. The SEM micrographs revealed that the pyrotechnic reaction residue (PRR) is composed of spheroidal-shaped particulates with fine condensed particles on their surfaces. The spheroidal particles exhibit a polydisperse diameter, ranging from approximately 10 to 20 microns. Some of the spheroidal structures are smooth, while others appear to have a very coarse surface. The surfaces of these larger irregular particles are covered with smaller aggregates formed of finer shapeless particles. The SEM micrographs also revealed that some of the structures had fractured surfaces and, to some extent, collapsed inward, with the shell appearing compromised and less spheroidal. Micrographs of large structures with irregular shapes were also reported.