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Dirty bomb

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Dirty bomb

In May 2008, officials of the International Atomic Energy Agency, commonly known as the United Nation nuclear watchdog, said to the press that they had been helping China with training exercises to ensure an adequate response in case of a dirty bomb attack during the Beijing Olympics. Do you know what a dirty bomb is, and how it differs from conventional explosives?

What is a dirty bomb?

A dirty bomb contains radioactive materials and conventional explosive. When the explosive is set off, the blast carries radioactive materials into the surroundings. Since a dirty bomb can be made from nuclear wastes, it is a relatively accessible radiological device in terrorist attack.

What are the protential dangers of a dirty bomb?

The radioactive materials used in a dirty bomb will probably not create enough radiation exposure to cause immediate serious illness. The conventional explosive itself would be more harmful to people than the radioactive materials. However, a dirty bomb explosion would create fear and panic, contaminate property, and require potentially costly cleanup.

What protective actions should be done following a dirty bomb explosion?

In the event of a dirty bomb explosion, radiation in the form of alpha particles, beta particles and gamma rays is emitted. The health effects from exposure to radiation can be minimized by (a) keeping away from the source of radiation; (b) staying away from the scene to keep shielding from external shining and inhaling radioactive material; and (c) removing clothes or/and taking a shower to reduce the radioactive contamination on the body.

What is the difference between a dirty bomb and a nuclear bomb?

There is a big difference. A dirty bomb is a conventional explosive device that when set off, contaminates a limited area near the blast. A nuclear bomb sets off huge explosion resulting from nuclear fission or nuclear fusion. In both fission and fusion, a large and highly concentrated amount of energy is released. It will release radioactive fallout and great heat, and cause widespread death, injury and massive damage.

Does the Hong Kong Observatory have an emergency plan to deal with a dirty bomb explosion?

The likelihood of a terrorist attack using a dirty bomb in Hong Kong is low. Nevertheless, the Hong Kong Special Administrative Region Government has a detailed contingency plan for possible terrorist attacks. The Hong Kong Observatory has equipment to monitor ambient radiation levels in Hong Kong and conduct radiological measurements on air, soil, water and food samples. It also provides the emergency departments with weather information to assess the spreading of radioactive materials. Details of the advice provided by the government on terrorist attacks can be obtained here.


  1. World Health Organization, Radiological Dispersion Device (Dirty Bomb), Radiation Fact Sheet, 2003.
  2. Security Bureau, Security Advice and Information, Emergency Response Management website.