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Did You Know?

Radiation can be detected and it can be cleaned up.


Radiation in small amounts is safe.


What is radiation?


  • Matter is composed of atoms. Some atoms are unstable. As unstable atoms change and become more stable, they give off invisible energy waves or particles called radiation.

  • There are two types of radiation – ionizing radiation and non-ionizing radiation. Non-ionizing radiation has enough energy to move atoms but not enough to alter them chemically. Examples are microwaves, radio waves and visible light. The more energetic form, ionizing radiation, is capable of removing electrons from atoms and damaging living cells and the DNA of those cells. The rest of this section of the web site refers to ionizing radiation as radiation.

The dose of radiation that a person receives is measured in units called rem.


  • Scientists estimate that the average person in the United States receives a dose of about 360 millirem of radiation per year.

  • Eighty percent of that exposure comes from natural sources – radon gas, the human body, outer space, and rocks and soil.

  • The remaining 20 percent comes from man-made radiation sources, primarily medical x-rays.

    • A chest x-ray gives a dose of 10 millirem per film.

  • For more information on radiation measurement, see the Center for Disease Control and Prevention (CDC) fact sheet Radiation Measurement.


There are three types of ionizing radiation that the public may encounter.


  • Alpha radiation (i.e., natural rock specimens) can be stopped by skin or clothing.

  • Beta radiation (i.e., Iodine-131 treats thyroid cancers) can be stopped by solid material such as wood or glass.

  • Gamma rays (i.e., x-rays, industrial radiography to test metal parts and welds for defects) can be stopped with lead and dirt.


There are specific actions one can take to reduce health effects from a nuclear or radiological bomb. The general guidelines for radiation safety are:


  • Time: Radioactive materials become less radioactive over time. Stay inside until authorities alert you the threat has passed.

  • Distance: The greater the distance between you and the source of the radiation the better. Authorities may call for an evacuation of people from areas close to the release.

  • Shielding: Put as much heavy, dense material between you and the source of the radiation as possible. Authorities may advise you to stay indoors or underground for this reason. Close and seal your windows and turn off any ventilation.



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