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Radiation Safety

The guiding principle of radiation safety is “ALARA”. ALARA stands for “as low as reasonably achievable”. This principle means that even if it is a small dose, if receiving that dose has no direct benefit, you should try to avoid it. To do this, you can use three basic protective measures in radiation safety: time, distance, and shielding.

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  • Time refers to the amount of time you spend near a radiation source.
  • Minimize your time near a radiation source to only as long as it takes to accomplish a task.
  • First responders can use alarming dosimeters to help them minimize the amount of time they are in an area with elevated radiation levels.

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  • Distance refers to how close you are to a radiation source.
  • Maximize your distance from a radioactive source as much as possible.
  • If you increase your distance from a radiation source, you will decrease your dose.

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illustration of white shield against black background


In a radiation emergency you may be asked to get inside a building and take shelter for a period of time.

  • To shield yourself from a radiation source, put something between you and the source.
  • In a radiation emergency, officials may instruct you to get inside and put as many walls between you and the outside as possible. This is another way to use shielding.
  • Protective clothing can shield first responders from alpha and beta particles, but will not protect them from gamma rays. Standing behind a wall or a fire truck can also serve as a shield.

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