Dirty Bomb - programme summary
Bomb technology - page 1 of 4
A dirty bomb is a radiological weapon but unlike a nuclear bomb, its purpose is to contaminate rather than destroy. It uses normal explosives to disperse radioactive materials in the local environment, creating a hazard to health that could last for years unless cleaned up.
The relative ease of making such a bomb means it is a potent terrorist weapon but Horizon's investigation shows that the risk to health from most such devices need not be great. It also underlines the need for governments to act to secure radioactive sources from falling into criminal hands. Horizon deliberately avoids outlining the production process in any detail.
"A very small amount of material turns into a weapon with psychological and economic impact"
Dr Michael Levi, Defence expert, Federation of American Scientists
Horizon publishes the results of specially commissioned research, modelling two possible dirty bomb scenarios: attacks on either London or Washington DC. The main conclusion is that the health risks from a dirty bomb explosion are localised to people who are close to the incident or are in contact with the contamination. Although the modelled attack scenarios could have wide-ranging economic repercussions, the majority of the population of either capital city would have only a negligible increase in their risk of developing cancer.
No one has ever exploded a dirty bomb in anger, but there has been at least one close call. In November 1995, a security alert in Moscow eventually unearthed a package of radioactive material, wired with explosives. The Russian authorities kept the incident from the public; a warning to the world about the risk of so called 'radiological dispersion devices' went unannounced. More recently, documents found in Afghanistan as well the FBI's arrest of Jose Padilla en route to Chicago have made security services the world over take seriously the risk of an attack.
"Low levels of radiation over time can cause cell mutations"
Prof Steve Jackson, Cambridge University
A dirty bomb is a small and relatively simple device, sometimes inaccurately called a poor man's nuclear weapon. The radioactive material it contains is unrefined and plays no part in detonating the bomb. The amount of conventional explosive need not be large and may not kill anyone. Its power lies in the cloud of dust released at the same time, producing a nuclear fallout that has a range of health effects. All assessments of likely results make assumptions about the size of the dirty bomb (how much radioactivity it disperses), the type of radiation and the environment in which it explodes.
Anyone who comes into contact with radiation increases their risk of cancer. In a dirty bomb attack, only those who receive the very largest doses - perhaps if injuries prevent their immediate decontamination - could potentially suffer mild radiation sickness. Its symptoms include hair loss and vomiting. (At exposure levels far beyond any dirty bomb, radiation sickness can kill.)