Background radiation

Background radiation is the natural radiation we get by living on Earth. There are many naturally occurring radioactive isotopes which decay over time. They release radioactive particles or radiation into the surroundings. We call this "background radiation".

The biggest source of natural background radiation is radon in the air. This radioactive gas comes from the ground. Radon and its isotopes, parent radionuclides, and decay products make up most of the radiation we get.

Radioactive material is found throughout nature. It occurs naturally in soil, rocks, water, air, and vegetation, from which it is taken into the body. Humans also get radiation from radioactive materials outside the body and from cosmic radiation from space.

The worldwide average natural dose to humans is about 2.4 millisievert (mSv) per year. This is four times the worldwide average artificial radiation exposure, which in 2008 amounted to about 0.6 mSv per year. In addition there are X-rays and other forms of medical imaging. In Europe, average natural background exposure by country ranges from under 2 mSv annually in the United Kingdom to more than 7 mSv annually for some groups of people in Finland.

Background Radiation Media

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  The weather station outside of the Atomic Testing Museum on a hot summer day. Displayed background gamma radiation level is 9.8 μR/h (0.82 mSv/a) This is very close to the world average background radiation of 0.87 mSv/a from cosmic and terrestrial sources.

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  Cloud chambers used by early researchers first detected cosmic rays and other background radiation. They can be used to visualize the background radiation

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  Estimate of the maximum dose of radiation received at an altitude of 12 km 20 January 2005, following a violent solar flare. The doses are expressed in microsieverts per hour.

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  Displays showing ambient radiation fields of 0.120–0.130 μSv/h (1.05–1.14 mSv/a) in a nuclear power plant. This reading includes natural background from cosmic and terrestrial sources.

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  Per capita thyroid doses in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site from 1951 to 1962.

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  Atmospheric 14C, New Zealand and Austria. The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. Atmospheric nuclear weapon tests almost doubled the concentration of 14C in the Northern Hemisphere.

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  Radiation level in a range of situations, from normal activities up to the nuclear accidents. Each step up the scale indicates a tenfold increase in radiation level.