Dirty bombs are what terrorists might build if they have access to radioactive material but lack the technology and other resources required to construct an actual nuclear weapon. Dirty bombs use conventional explosives such as TNT spiked with any available radioactive materials. The destructive power of this weapon would be based on the size of the conventional bomb and the quantity and nature of the radioactive material. The wind speed and direction at the time of and immediately following detonation would play an important role in determining its effects. Because a dirty bomb detonation would sound like any other explosive device, first responders called to the scene might think they were heading into the midst of the effects of a conventional explosive. To understand the nature of the situation and the risk level to those present and close by, first responders must have the tools to quickly and accurately measure the presence and level of radiation. A dosimeter is recommended because it is portable, immediately operational, highly accurate, durable, and easy to use. It requires little maintenance and is highly reliable. There are three basic types of dosimeters: the direct reading dosimeter (or pencil dosimeter), the badge dosimeter, and the electronic dosimeter. Other types of devices, such as Geiger counters and survey meters, are also used to measure the dose rate or the intensity of the radiation at a point in time. But they each have severe shortcomings when used in emergency situations by first responders. The MGPI (Smyrma, Georgia) electronic dosimeter can detect and display radiation dose and dose rate in as little as 2 seconds. In addition to NATO forces, many domestic organizations, including the United States military, use MGPI electronic dosimeters.