Protecting against the risk of blast or explosions

A risk assessment is something that should be undertaken at regular intervals to identify new threats, risks and vulnerabilities. Protecting against blast attacks is only one element of mitigation strategies, but potentially the most severe risk a property can encounter.

For buildings that are either culturally significant, contain assets of high value or that experience high volumes of people, there is an unprecedented risk of explosion.

As stated on the MI5 website, the UK currently faces a ‘Substantial’ national threat from terrorism.

In place through-out the UK, specialist task forces are constantly prepared to tackle imminent danger.

The National Counter Terrorism Security Office (NaCTSO) police unit in particular continually identifies and eliminates terror threats both within the UK and beyond its borders.

Protecting against blast attacks is a high priority, especially as terrorism is, unfortunately, the main concern.

In cases of terror attacks, an attacker will intend to cause as much havoc and fear without a thought for the casualties and loss of life that are the result of an explosion.

For sites and facilities that store, or play a large part in the life-cycle of, flammable materials such as fuel, must also protect their facilities against blasts that are considered accidental.

Whilst protecting the people is not to be overlooked, sites that are identified as Critical National Infrastructure (CNI) – for example Energy facilities – protecting the property from destruction is a much bigger concern.

Download our guide: Protecting Against Blast 

Why is it important to protect against a blast attack?

Fuelled by extremist views, emotion or a whole manner of other things, terrorists are defined as those who intend to cause harm against civilians in the pursuit of political or religious aims. A terrorist attack can come in many forms but as we have seen in news cycles across the world, bombs detonated in widely-populated public spaces have a more dangerous impact and garner a lot more attention.

A property that has identified blast a potential threat, whether it is a commercial space or a building on a Military Defence site, must be reinforced to withstand extreme conditions. Understanding what a blast will do to a property is a large part of this.

When a bomb is detonated, the initial explosion will create an enormous amount of pressure (referred to as incident pressure) which is then projected onto everything surrounding it causing massive destruction. This initial blast will effectively bounce off the objects around it, whether it be a vehicle, doorway or person, subsequently creating a negative pressure force. This pressure will then bounce back, causing further damage to the weakened building structure and its fixtures and fittings.

One of the biggest concern when protecting against blast attacks is debris. Whether it be dislodged brick from three floors up, glass shattering from initial pressure or other materials splintering, a close explosion will cause significant damage to the building structure.

Buildings are much more capable to withstand a blast, so it is important to remember that anything placed in-between bomb and civilian is a measure in itself. Physical reinforcement through tried and tested products designed to counter attacks of this kind is vital; the worst possible action is to do nothing at all.

Common challenges when protecting against blast risk

Securing any property against explosion is a complicated task; there must be some acknowledgement of the severity of risk being posed. A commercial building in a well-populated area will have a higher percentile blast risk compared to a commercial building in suburban areas, however, the likelihood of it being targeted over a nearby government building is small.

Securing a property against a targeted attack rather than reinforcing it to protect the people inside may therefore be misapplication of resources.

For buildings in widely-populated areas, explosives will be transported either via vehicle or person. Vehicle mitigation including bollards, fences and gates are not only a deterrence but a strong tactic in keeping vehicle-borne improvised explosive devices (VBIED) as far away from a structure as possible. Automated detection technology integrated within security procedures will also identify suspicious behaviour, not only playing a much larger role within the overall security strategy but also acting as an effective measure of mitigation against person-borne improvised explosive devices (PBIED).

With cases of PBIED, the concern will not be for massive loss of life; smaller explosives can be used to as a means of breaching a secured building or enclosure. The challenge here is to find a balance of protective, counter-terror security measures with urban design principles more effective entrance arrangement to rest hostile entry.

One solution is the Obexion Blast Blind which provides an interior shield to window aperture. An effective barrier between glass and interior space, the Obexion Blast Blind absorbs the initial pressure wave through automatic closing then later reflects of further pressure such as force or falling debris. Another blast mitigation product available from Charter Global is the Obexion Blast Door, which has been independently tested to withstand 100kg of TNT at a distance of both 25 and 15 metres. 

How much damage incurred will depend on the size of the explosive charge, how close the building, vehicle or person is to the explosion on detonation and the duration of the pressure wave. Worst-case scenarios are almost impossible to protect against.

From the point of view of the emergency services, the most common cause of death from an explosive are not primary blast injuries (been directly hit by the initial pressure wave) but rather secondary blast injuries (those inflicted by flying debris). Enveloping a building with reinforced physical security measures will never 100% mitigate destruction following a large blast, but it will massively reduce casualties from the destruction thereafter.

From a basic security understanding, blast resistance products provide an excellent side benefit of protecting a property against most other threats. Blast resistance entry points such as reinforced doors will at the very least delay an experienced criminal. 


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