Identify a common radiological dispersal device (RDD).

A common radiological dispersal device (RDD) is known as a dirty bomb. This type of device combines conventional explosives, such as dynamite, with radioactive materials. The primary intent of a dirty bomb is to spread radioactive contamination over a wide area, causing panic and disruption, rather than achieving significant casualties through the explosion itself.

Dirty bombs are significant because they utilize readily available materials, making them a concern for first responders and emergency management personnel. The psychological impact, in addition to the potential for environmental contamination, highlights the importance of their recognition and understanding within the context of radiological threats.

In contrast, a radiation detector is a tool used to identify and measure radiation levels but does not itself disperse radiological materials. Radon gas is a naturally occurring radioactive gas that poses health risks but is not an RDD by itself. A radioactive source is a general term that refers to any material that emits radiation but does not imply that it is used in the context of a dispersal device. Hence, the dirty bomb effectively illustrates the concept of a radiological dispersal device due to its design and intended use.