Calvert County Health Department

Dirty Bomb Facts

Because of recent terrorist events, people have expressed concern about the possibility of a terrorist attack involving radioactive materials, possibly through the use of a "dirty bomb", and the harmful effects of radiation from such an event.

What a Dirty Bomb is...
A dirty bomb, or radiological dispersion device, is a bomb that combines conventional explosives, such as dynamite, with radioactive materials in the form of powder or pellets. The idea behind a dirty bomb is to blast radioactive material into the area around the explosion. This could possibly cause buildings and people to be exposed to radioactive material. The main purpose of a dirty bomb is to frighten people and make buildings or land unusable for a long period of time.

Dangers of a Dirty Bomb
If low-level radioactive sources were to be used, the primary danger from a dirty bomb would be the blast itself. Gauging how much radiation might be present is difficult when the source of radiation is unknown. However, at the levels created by most probable sources, not enough radiation would be present in a dirty bomb to cause severe illness from exposure to radiation.

What People Should Do Following an Explosion
Radiation cannot be seen, smelled, felt, or tasted by humans. Therefore, if people are present at the scene of an explosion, they will not know whether radioactive materials were involved at the time of the explosion.

If people are not too severely injured by the initial blast, they should:

• Leave the immediate area on foot. Do not panic. Do not take public or private transportation such as buses, subways, or cars because if radioactive materials were involved, they may contaminate cars or the public transportation system.
• Go inside the nearest building. Staying inside will reduce exposure to any radioactive material that may be on dust at the scene.
• Remove clothes as soon as possible, place the removed clothes in a plastic bag, and seal the bag. Removing clothing will remove most of the contamination caused by external exposure to radioactive materials. Saving clothing would allow for testing for exposure without invasive sampling.
• Take a shower or wash as best as possible. Washing will reduce the amount of radioactive contamination on the body and will effectively reduce total exposure.
• Be on the lookout for information. Once emergency personnel can assess the scene and the damage, they will be able to tell people whether radiation was involved.

Even if people do not know whether radioactive materials were present, following these simple steps can help reduce their injury from other chemicals that might have been present in the blast.

Taking Potassium Iodide (KI)
Potassium Iodide only protects a person's thyroid gland from exposure to radioactive iodine. KI will not protect a person from other radioactive materials or protect other parts of the body from exposure to radiation. It must be taken prior to exposure (for example when people hear a radioactive cloud is coming their way) or immediately after exposure to be effective. Since there is no way of knowing whether radioactive iodine was used in the explosive device, taking KI would probably not be beneficial. Also, KI can be dangerous to some people. Taking KI is not recommended unless there is a risk to exposure to radioactive iodine.

Resources: Centers for Disease Control and Prevention; Fact Sheet on Dirty Bombs; December 6, 2002.

For more information about dirty bombs and bioterrorism browse to or call:

• Calvert County Health Department - 410-535-5400
• Calvert County Emergency Management - 410-535-1600
• Department of Mental Health and Hygiene
• Centers for Disease Control and Prevention
• Federal Emergency Management Agency
• Nuclear Regulatory Commission
• CDC Public Response Service
• 888-246-2675
• 888-246-2857 (Español)
• 866-874-2646 (TTY Service