An explosion is a sudden, fast increase in pressure between two different areas that results in the rapid unplanned disassembly of buildings, vehicles and other things in the immediate vicinity.

Although an explosion can have many causes, most are related to human activity, such as fires, containment system failures, and intentional explosions, including demolition and terrorism. Whatever the motivation or cause behind the explosion, the consequences and effects remain the same.

When there is a quick increase in pressure in a contained area, it can rapidly exceed the capacity of the container – whether a building, a tank or other container – to adapt to the pressure and safely dissipate it. When this occurs, it begins a rapid unplanned disassembly that we see as an explosion. Some containers, particularly those containing flammable materials such as gasoline, propane, oil and compressed gasses, are designed with relief valves to prevent an explosion. In this situation, the container itself fails safely at or through the relief valve when the pressure difference inside and outside reaches a certain point. This is the reason why rail cars and propane tanks do not generally explode during a fire.

A fire causes an explosion by the transfer of heat. The fire’s radiant heat causes a substance to expand and increases surrounding pressure until the container fails, either through a pressure relief valve or by rapid unplanned disassembly. When a containment system, such as a tank, pipeline or hazardous materials vessel fails, an explosion can happen when two substances mix and have a highly volatile reaction.

For example, when a pipeline fails and the fumes within it are mixed with oxygen, the combined substances become more volatile, allowing a simple spark to ignite an explosion. Or, if a hazardous materials containment system (such as a wall, ventilation process or tank) fails and allows two substances to mix, those substances may react violently, increasing the pressure inside quickly enough to cause an explosion.

An intentional explosion uses a reaction between volatile compounds to create a rapid increase in pressure. Demolition experts often use “plastic” explosives that have been manufactured to strict quality standards and will only react to a specific input, such as an electrical current. Improvised explosive devices (IEDs), like pipe bombs, car bombs and other similar devices, often use re-purposed military munitions and explosives or homemade combinations of volatile substances such as ammonium nitrate and fuel oil.

Key Facts

  • Unsafe storage of agricultural fertilizer is one of the largest causes of explosions. Ammonium nitrate has been used as an agricultural fertilizer for decades, enhancing crop yields and increasing food security. However, since 2013 unsafe storage of ammonium nitrate has been directly tied to three major explosions. That year, a blast at the West Texas Fertilizer Company killed 15 people – mostly firefighters who had responded to the plant’s initial fire. In 2015, a fire at the Port of Tianjin in China spread to a warehouse containing hazardous materials, including 800 tonnes (1.76 million pounds) of ammonium nitrate. The resulting explosion, which was visible from space, killed 173 people – including eight whose bodies were never recovered. The August 2020 explosion at the Port of Beirut (Lebanon) was caused by the explosion of 500 tonnes (1.1 million pounds) of ammonium nitrate.
  • Countries without strict safety standards are at higher risk of explosion-related disasters. Almost any substance can explode when mixed with the appropriate amount of air and heat. Countries without strict safety standards are less likely to have appropriate precautions to prevent dust explosions from grain or wood processing. These explosions can not only kill or injure people working in industrial facilities, they can also destroy those facilities and leave an entire region without an essential source of economic activity.
  • Because most explosions happen as a result of human activity, they can have a disproportionate effect on critical infrastructure and systems. Human activity is the leading cause of non-natural explosions, whether intentional or accidental. Often, this is due to transportation-related incidents and occurs in or near places where critical infrastructure is located. In 2008, a series of explosions at a propane storage facility in Toronto, Ontario, closed down the busiest highway in North America.

How to Help

  • Fund and support advocacy for stronger building and life safety codes. In North America and Europe, there are extensive building and life safety codes that help limit the occurrence of explosions and minimize the damage from them when they happen. Stronger codes will reduce the potential for improper and unsafe storage and transportation of explosive materials.
  • Support the development of sustainable and resilient infrastructure. By necessity, many components of critical infrastructure and systems are located in or adjacent to places where there is a higher risk of explosion. Building infrastructure that is better able to resist the effects of an explosion and has redundancy built into it will help minimize infrastructure outages.
  • Fund research into more resilient building materials and methods. Some of the damage associated with explosions occurs because of the expanding pressure wave. However, much more of the destruction occurs because of shrapnel and debris. Buildings, containers and systems that better resist rapid unplanned disassembly will reduce the amount of damage, injuries and deaths associated with an explosion.
  • Support rebuilding and redevelopment post-explosion. Unfortunately, we cannot prevent all explosions. Funders must be ready to move quickly, like any other disaster, to provide relief and response funding and be prepared to invest in long-term recovery.

What Funders Are Doing

The Center for Disaster Philanthropy (CDP) made two donations to support recovery from the Beirut Explosion in 2020 from our Global Recovery Fund with support from a partner who wishes to remain anonymous.

  • Miyamoto Global Disaster Relief received a $50,000 grant to repair housing units damaged by the devastating explosion. The program will leverage Miyamoto Relief’s engineering expertise to focus on homes of historical or cultural significance that suffered structural damages (instead of buildings that require lighter repairs, such as replacing doors and windows).
  • Cooperative Assistance for Relief Everywhere (CARE) also received a $50,000 grant. CARE will be using cash and vouchers to address food security and livelihood, repairs and rehabilitation to homes with a particular focus on safe shelter and protection for vulnerable individuals and gender-based activities, including counseling.

Additionally, The Charles Stewart Mott Foundation provided a $100,000 grant to the American Near East Refugee Aid organization, which facilitated and supplied critical shipments of medical equipment as well as capacity-building support to the hospitals and health centers in Beirut.

Other grants related to explosions include:

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(Photo: Port of Beirut a few days after the explosion in August 2020. Source: rashid khreiss on Unsplash)