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24 September 2014
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First shown: BBC Two, Thursday 30 January 2003
Dirty Bomb

Dirty Bomb - questions and answers

What's the difference between a dirty bomb and a nuclear bomb?

Dirty bombs and nuclear weapons explode in totally different ways. A dirty bomb is likely to be a primitive device composed of high explosives (such as dynamite or Semtex) and radioactive materials. The bomb blast rapidly disperses the radioactive particles, creating a radioactive contamination hazard. The blast itself of a dirty bomb is no more forceful than any other type of high explosive bomb.

A nuclear bomb is far more sophisticated and relies on the generation of a runaway nuclear fission reaction. Highly refined 'fissile' material (either uranium-235 or plutonium-239) is needed. When the bomb detonates, explosives start a nuclear reaction that releases enormous amounts of energy. One nuclear bomb could destroy an entire city.

How difficult and dangerous is the production process?

The technology of a dirty bomb is relatively simple in principle. The key components are conventional plastic explosives and radioactive material. There are many complexities in the actual process of making a functional dirty bomb. The process could be potentially fatal in the long term, but a bombmaker could protect themselves for long enough to build the device. Neither the Horizon programme nor website discuss methods or precautions in any way.

Were dirty bombs ever part of official war strategies?

Both the UK and USA are cagey about the possibility that the military may have discussed the use of these devices for combat purposes. There are persistent rumours that they carried out some research during the Cold War. Dirty bombs have never actually been used, perhaps because they have been considered inappropriate for military purposes; their effect is too delayed and unpredictable to sway a battle.

Can dirty bombs be transported?

A dirty bomb could potentially be transported across borders although this would increase the chance that the material would be detected. It is more likely that terrorists would use material obtainable within the target country and construct the bomb as close to the target as possible.

How difficult is to model the effect of a dirty bomb?

There are many variables when considering the effects of a dirty bomb scenario. The most apparent are the weather, the amount and type of radioactivity dispersed and the location in question. However, there are a number of fundamental principles that lie behind any dispersion of this kind.

Who is equipped to recognise that a bomb is dirty?

The emergency services would be the first people on the scene. Radiation detectors on fire engines might well indicate that there is radiological contamination present. Once this has been established, hazardous materials emergency response staff would be called to the scene to try to identify the scope of the contamination. They would be equipped with protective clothing, breathing apparatus and geiger counters to protect themselves and ascertain the levels of radioactive contamination.

Is anyone actually at risk of acute radiation exposure?

Every scenario is dependent on the amount of radioactivity dispersed by the bomb itself. It is accurate to assume that near the epicentre of the bomb the levels of radiation might be high and could cause acute radiation exposure if anyone was exposed to the material for long enough. This is unlikely as rescue workers would be aware of the levels of radiation they were being exposed to (by radiation level detectors) and would (most likely) work for short time intervals on a rotation basis. We can assume that all members of the public would be evacuated immediately. The real risk is that a person injured by the blast was then contaminated by the radiation - this might lead to acute radiation exposure if decontaminating them was delayed.

What's the first thing to do if there's a dirty bomb attack in my town?

If you are inside, then close your windows and turn off any external ventilation. This will stop radioactive particles getting inside. If you are outside, then get inside, wash yourself down (in a shower) and discard your clothes. You should then stay inside until you are advised to do otherwise by law enforcement officials or emergency personnel. If people start fleeing the scene it will be harder to contain the contamination and allow emergency workers to carry out their job effectively. It is envisaged that more people are likely to die in the panic that may follow an incident (car accidents etc) than as a direct result of the bomb itself.

Would movement restrictions be imposed after an attack?

This is an issue that both the UK and USA governments are looking at closely. People's instinct may be to leave the area immediately. They may just panic and run. However, staying indoors is the most sensible option to reduce exposure to the radiation.

Are dirty bombs weapons of fear rather than actual harm?

Fear and intimidation are key aspects of the threat of the dirty bomb. The anthrax attacks in the USA in 2001 outlined just how effective biological attacks can be as weapons of terrorism. It would be possible to construct a dirty bomb that could cause real harm and serious health consequences. However a smaller dirty bomb may be the more plausible threat with the primary motive of generating fear and panic. The anthrax scares showed just how potent fear can be with real consequences for the economy, the running of government and the national psyche.

But the dirty bomb's strength is also its weakness. The more we understand that the dirty bomb is a weapon of fear, the more we can control the outcome of such an attack. Understanding the risks and reacting to them in a sensible manner will allow us to cope should we ever need to.

To what extent are dirty bombs economic weapons?

As ever, the size of a dirty bomb and its target greatly affect its impact. The decontamination costs and the potential long and short term health costs could run into millions of pounds. The potential to wreak economic harm is genuinely significant, with substantial knock-on effects on tourism, trade, businesses, property values and agriculture.

What are governments doing to tighten radiological security?

The USA has now realised that this is an issue that they have been lax over. In the past, radioactive materials were seen to raise safety issues, not security issues. Senator Hillary Clinton has sponsored a dirty bomb prevention bill which outlines the need to better track, secure, and dispose of radiological materials. The US government is now pouring a lot of money into International Atomic Energy Agency programmes designed to tackle the very serious problem of 'orphan sources' in the former Soviet Union. (Orphan sources are radioactive materials that are left unguarded, with no security.) The British government is also contributing to efforts to tackle this serious problem.

What kind of security measures in public spaces might help?

The USA is putting money and research into the development of radiation detection devices. The intention is to install these in airports, ports and other locations to help track the movement of any potentially harmful radioactive materials. Some of these detection devices are currently being installed covertly at strategic locations.

Monterey Institute of International Studies
Center for Nonproliferation Studies
BBC News Online
Analysis: making a 'dirty bomb'
Council on Foreign Relations
What is a dirty bomb?
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