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Background Radiation

Discusses radiation in the environment, its sources and the side effects of exposure.

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Background Radiation

People relaxing in a hot pool

Credit: Ken Thomas
Source: http://commons.wikimedia.org/wiki/File:Radium_Hot_Springs-27527.jpg
License: CC BY-NC 3.0

Easing Aches and Pains

Sitting in a hot bath or spa has always been a great prescription for dealing with sore muscles. People used to believe that it was even more beneficial to immerse themselves in radioactive hot springs and drink water containing radioactive materials (some still do). In the early 1900s, people spent millions of dollars on treatments and “radioactive water” with the belief that all of their ills would be taken care of. Radioactivity in the water was usually due to radon gas that leaked up from deep underground, formed by decay of other radioisotopes. If you're feeling sore, find a hot pool and sit back and relax.

Background Radiation

We are all exposed to a small amount of radiation in our daily lives. This background radiation comes from naturally occurring sources and from human-produced radiation. Exposure to X-rays and nuclear medicine isotopes, ground sources, and cosmic radiation account for almost half of the background exposure of the average American. Radon gas, formed from the decay of uranium and thorium isotopes, is responsible for a little over half the total amount of background radiation. See Table below for background sources.

Sources of Background Radiation
radon 54%
consumer products 3%
nuclear medicine 4%
cosmic radiation 8%
terrestrial 8%
internal 11%
X-rays 11%
other 1%

The Problem of Radon

Small amounts of uranium and thorium are found in the soil of a large number of areas in the U.S. When radioactive isotopes of these elements decay, radon is one of the products formed. Radon is a colorless, odorless gas and is chemically inert, as it is one of the noble gases.

Radon is also radioactive and can easily be inhaled into the lungs. Over time, this internal radon exposure can lead to the development of lung cancer. The incidence of lung cancer in smokers exposed to radon is much higher than that in non-smokers exposed to radon since smoking has already produced some lung damage, and the radon simply makes the damage worse. Radon exposure is highest in homes lacking good air circulation to move the gas out of the residence. There are a number of inexpensive approaches to decreasing your exposure to radon. A good start is to test your living area for radon with a radon test kit.

Radon test kit

Credit: Courtesy of the National Cancer Institute
Source: http://commons.wikimedia.org/wiki/File:Radon_test_kit.jpg
License: CC BY-NC 3.0

Radon test kit. [Figure2]


  • Background radiation is defined.
  • Sources of background radiation are listed.



Read the material at the link below and answer the following questions:


  1. Where does radon come from?
  2. What are the health hazards of radon?
  3. How can you lower radon exposure indoors at home?



  1. What is background radiation?
  2. What are some naturally-occurring sources of background radiation?
  3. What is the major source of background radiation?

Image Attributions

  1. [1]^ Credit: Ken Thomas; Source: http://commons.wikimedia.org/wiki/File:Radium_Hot_Springs-27527.jpg; License: CC BY-NC 3.0
  2. [2]^ Credit: Courtesy of the National Cancer Institute; Source: http://commons.wikimedia.org/wiki/File:Radon_test_kit.jpg; License: CC BY-NC 3.0

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