Explosive agents
An explosive substance or agent is a solid or liquid substance (or mixture of substances) which is in itself capable, by chemical reaction, of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings. Pyrotechnic substances and mixtures are included even when they do not evolve gases. Explosions can cause multiple severely injured casualties in a single incident (Adapted from UN 2023 and UK Parliament POSTNOTE 2011).
Primary reference(s)
UN, 2023. Globally Harmonized System of Classification and Labelling of Chemicals (GHS) tenth revised edition United Nations (UN). Accessed 15 March 2025
UK Parliament POSTNOTE Explosive injury Number 395 December 2011. Accessed 14 March 2025
Annotations
Additional scientific description
Explosive substances are commercially used in various industry applications, in ammunition items, and in improvised explosive devices which can be hazardous in storage and non- conflict settings. Ammonium nitrate is an explosive, and its inadequate storage has caused several explosions., As an example, the massive chemical detonation on August 4, 2020 in the Port of Beirut, Lebanon resulted in an uncontrolled fire in an adjacent warehouse which ignited ~2,750 tons of Ammonium Nitrate (AN), The blast supersonic pressure and blast resulted in 220 deaths and injured more than 6,500, with severe damage to the nearby dense residential and commercial areas (Al-Hajj et al., 2021).
Explosive agents are also included as the E of CBRNE which is the abbreviation commonly used to describe the use of Chemical, Biological, Radiological, Nuclear and explosive materials or weapons. The malicious use of such materials could cause significant harm or disruption (Goulart et al., 2022). Explosive agents are a subset of what is commonly referred to as conventional weapons. Technologically, there are many types of explosive materials, including bombs, artillery shells, grenades, missiles, landmines and improvised explosive devices, which are activated by the detonation of a high explosive substance (UNODA no date).
Types of weapons that are particularly problematic in terms of ammunition safety use and indirect fire weapons, such as artillery, rockets and mortars, weapons that fire in salvos, such as multi-launch rocket systems, large air-dropped bombs and surface-to-surface ballistic missiles. Such systems variously involve munitions with a large destructive radius, weapons with inaccurate delivery systems or weapon systems that deliver multiple munitions over a wide area (UNODA no date). A populated area is generally understood as a permanent or temporary concentration of civilians and/or civilian objects. A leading concern is the use of explosive weapons, in particular those with wide-area impacts, in populated areas. Many of these weapons were originally designed for use in open battlefields and are inherently indiscriminate when used in populated areas and therefore result in increased civilian casualties and devastating humanitarian impacts (UNODA no date).
Explosive agents normally carry both the fuel and oxidizer needed for the process. Compounds with high nitrogen and oxygen content are often explosive. Goulart et al (2022) report that there are three necessary components for an explosion to occur:
- The fuel: a flammable substance, that can be oxidised to form highly stable small molecules such as nitrogen gas (N2), carbon dioxide (CO2), or water (H2O). The formation of such stable molecules results in release of large amounts of energy and the rapidly moving small molecules are responsible for the damaging pressure wave(s).
- An oxidant:, often oxygen (O2), or an oxygen-rich species such as nitrate ion, is required in high quantities and in combination with the flammable substance to produce an explosive atmosphere.
- Ignition: Source a spark or high heat must also be present.
In summary, explosives can be described as:
- Primary explosives are substances or mixtures that can easily be detonated by a non-explosive simple initiating impulse such as a flame, impact, friction, heat, electricity or spark etc. They are mainly used in applications where it is desired to produce a shock wave for initiation of a less sensitive secondary explosive or a flame for initiation of propellants. Most of the primary explosives are highly sensitive to mechanical stimuli that make handling them very dangerous (Goulart et al 2022).
- Secondary explosives are individual explosive compounds or formulations that are relatively insensitive to non-explosive stimuli. Secondary explosives are initiated by a detonator. Secondary explosives are used for blasting and to obtain fragmenting and accelerating effects in many industrial and military applications (Goulart et al 2022).
According to Goulart et al (2022) various types of explosives are defined as follows:
- Civilian explosives are explosives that are commercially produced for non-military use. Examples are dynamites, ANFO, and emulsion explosives (Goulart et al 2022);
- Blasting explosives is a term used for explosives in civil use, e.g. in quarrying, road construction, and demolition (Goulart et al 2022);
- Emulsion explosives are explosives in the form of emulsion. They are relatively safe to use and hard to initiate. The primary use for emulsion explosives is for civilian use in the mining industry and during road and tunnel construction work (Goulart et al 2022);
- Energetic materials are defined as a class of compounds, substances and formulations containing a high amount of stored chemical energy, which may be manipulated to be released in a controlled manner. This would include, but is not limited to, materials such as explosives, propellants, pyrotechnics, and their ingredients; and
Binary explosives are two- component explosives which contain two safe-to- handle compounds. The final explosive is prepared by mixing both compounds before use. Home-made explosives (HMEs) are commonly encountered in improvised explosive devices (IED). There are two main categories that prepare and/or use HMEs; HMEs can be made from many different precursors, and some of them may be innocuous in themselves and easily accessible. The threat of improvised explosive device attacks is a global problem. Cheap and relatively easy to construct, IEDs can be made anywhere from a wide range of materials. Categorisation of the harm from the explosive device can be determined through its velocity (high/low). The lack of proper stockpile security for military and commercial explosives - making them susceptible to diversion into illicit hands - also presents a significant security risk (UNODA, 2014)
Metrics and numeric limits
The charge mass for various types of explosives can be expressed in TNT-equivalent (kg). TNT equivalent refers to the amount of energy released by an explosion, measured in terms of the energy released by a specific amount of TNT.
Key relevant UN convention / multilateral treaty
Convention on Certain Conventional Weapons, Amended Protocol II (United Nations, 2008).
In 2015, Afghanistan took the lead within the United Nations General Assembly to develop a resolution focused on the need for an effective global, comprehensive, coordinated approach to counter the proliferation of IEDs in settings of violent extremism and instability. The resolution (70/46), adopted by consensus, included a call for the consistent collection of data, awareness raising, options for the regulation of components, international technical assistance and cooperation, and victim assistance
Examples of drivers, outcomes and risk management
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Drivers
Hazard drivers associated with explosive agents include inappropriate handling, unsafe storage, and unsafe transport (HSE, 2002).
Many types of explosive weapons exist and are currently in use. These include air-delivered bombs, artillery projectiles, missiles and rockets, mortar bombs, and improvised explosive devices (IEDs). Some are launched from the air and others are surface launched. Whilst different technical features dictate their accuracy of delivery and explosive effect, these weapons generally create a zone of blast and fragmentation with the potential to kill, injure or damage anyone or anything within that zone. This makes their use in populated areas - such as towns, cities, markets and camps for refugees and displaced persons or other concentrations of civilians - particularly problematic. The problems increase further if the effects of the weapon extend across a wide area either because of the scale of blast that they produce; their inaccuracy; the use of multiple munitions across an area; or a combination thereof (UNOCHA 2017).
Ammonium nitrate is an explosive and its inadequate storage has caused several explosions (Al-Hajj et al., 2021).
Impacts
The hazard area needs to be assessed whenever an explosive (or potentially explosive) device is found or used. The hazard area depends on the amount of explosive. The hazard area needs to take into account the pure blast effects (shock wave) as well as the effects of a fragmenting charge (shrapnel), fragmenting source, the fireball, the crater volume, and the cratering ejecta. The hazard area is larger for a larger amount of explosive as well as for a fragmenting charge.
Injury depends on the specific location of an explosion can intensify its severity, potentially causing more harm, but injuries from explosions are usually classified as follows:
- Primary: caused by a sudden increase in pressure after an explosion, affecting air-containing organs, such as the lung, ear, eye, etc.
- Secondary: result from bomb fragments and debris being energized by the explosion. These have varying levels of lethality; larger fragments can transfer more energy, increasing the harm caused.
- Tertiary: caused when the casualty is thrown by the explosion and collides with nearby objects. They can have both local and global effects; local deformation of the floor of a protective structure for example, or global acceleration of the structure itself with the casualty inside it.
- Quaternary: related to the thermal effects of the blast, toxic effects, and any risks resulting from the incident, such as drowning (vehicle roll over into river) or freezing (shelter destruction) (UK Parliament POSTNOTE 2011).
The indiscriminate nature of explosions means that both children and women, including pregnant women, can be injured. Disruption of the placenta, and foetal skull fractures can occur as a result of these events in pregnant women. Children suffer a greater proportion of injuries to the head due to its larger size compared with the rest of the body (UK Parliament POSTNOTE 2011).
Multi-hazard context
The figure below summarises common interactions between explosive agents and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.
Multi-hazard diagram
Risk Management
Training on understanding the phenomenon of explosions including their consequences, the prevention techniques available, and the regulatory requirements for a safe and compliant working environment. is provided by many organisations.
Mechanisms exist in many places and as an example the European Explosive Ordnance Disposal Network (EEODN) is a network of law enforcement specialists in explosives and CBRN from the competent authorities of EU MS. Created by EUROPOL in 2008 in order to facilitate cooperation, to share technical and case related information among EU explosives and CBRN specialists and to organise joint trainings and exercises.
As examples of risk management Goulart et al (2022) describe explosives detection systems within aviation security today normally meaning X-ray screening equipment for hold baggage (also called check-in baggage) (Goulart et al 2022).
Explosive Detection Dogs (EDD) are dogs trained for the detection of explosives and are used as a mobile detectors witha unique capacity to find the source, thanks to their strong sensitivity to odours (1,000-10,000,000 times higher than that of human being, is explained by the presence of 300 million olfactory receptors that line their nostrils, against 6 million in human being.) However, canine detection has limitations in terms of not being able to communicate an identification of the substance detected. EDDs are allowed as a screening method for screening persons, cabin baggage and hold baggage and cargo in civil aviation. They are also frequently used in infrastructure protection (Goulart et al 2022). Additionally, strengthening vigilance and national controls: IEDs are often made with military- or commercially-sourced explosives. The UN General Assembly resolution calls for measures to be put in place to establish tighter controls over materials or components used for making IEDs. These controls could encompass national ammunition stockpiles and industrially produced detonators, detonating cords and industrially produced explosives, such as for mining. Relevant industries and corporations could also be encouraged to engage in the regulation of precursor and prefabricated components (UNODA, 2014). Enhancing information sharing: owing to the ad-hoc design of IEDs, there is an overriding need for States to share information on the composition and production methods of captured IEDs, including after IED attacks. The resolution underlines this necessity. Effective information sharing on IED designs and components between Member States has the potential to shorten the learning curve that military and security forces have to go through in order to identify and develop effective counter- measures. Also, civilians will be protected better when effective information sharing on new IED designs leads to quicker neutralisation (UNODA, 2014).
The Secretary-General of the United Nations has highlighted the indiscriminate and severe humanitarian impact of the use of explosive weapons in populated areas since 2009. He has consistently used his reports to the Security Council on the protection of civilians in armed conflict to bring attention to the devastating effects of the use of explosive weapons in populated areas on civilians; and continues to appeal to parties to armed conflict and States to avoid the use of explosive weapons in populated areas, to work to remove conflict from urban areas altogether and to avoid locating military objectives within or near densely populated areas (UNODA no date).
Monitoring
Monitoring and sharing early warning systems in the European Union (EU) is part of the EU action plan on enhancing the security of explosives. The EU EWS is used to exchange information between authorities in different member States, on, for example: immediate threats, theft of explosives,; theft of detonators,; discovery of new modus operandi, etc. (Goulart et al 2022).
References
Al-Hajj, S., Dhaini, H. R., Mondello, S., Kaafarani, H., Kobeissy, F., DePalma R. G., 2021. Beirut Ammonium Nitrate Blast: Analysis, Review, and Recommendations. Frontiers in Public Health, 9, 10.3389/fpubh.2021.657996, https://www.frontiersin.org/journals/public-health/articles/10.3389/fpu… Accessed 12 March 2025.
Goulart De Medeiros, M., Lequarre, A., Geypens, B., Santopolo, D., Daoust-Maleval, I., Brzozowski, K. and Iatan, A., EU CBRNe Glossary, Publications Office of the European Union, Brussels, 2022. ISBN 978-92-76-58865-8, doi:10.2760/0, JRC128863. Accessed 12 March 2025.
Health and Safety Executive (HSE), 2002. Dangerous Substances and Explosive Atmospheres Regulations 2002 SI 2002/2776. Health and Safety Executive (HSE). Accessed 20 May 2025
UK Parliament POSTNOTE Explosive injury Number 395 December 2011. Accessed 14 March 2025.
United Nations, 2008. Convention on Certain Conventional Weapons. Amended Protocol II. Group of Experts. Accessed 14 March 2025.
United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA), 2017. Compilation of Military Policy and Practice: Reducing the humanitarian impact of the use of explosive weapons in populated areas United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA). Accessed 10 March 2025.
United Nations Office for Disarmament Affairs (UNODA), no date. Explosive weapons in populated areas. United Nations Office for Disarmament Affairs (UNODA). Accessed 10 March 2025.
United Nations Office for Disarmament Affairs (UNODA), 2014. Improvised Explosive Devices (IEDs) Publication. United Nations Office for Disarmament Affairs (UNODA). Accessed 14 March 2025.