Background radiation
Radiation is all around us. Although some radioactive sources are man-made, others occur naturally. The radiation we experience on a day-to-day basis from all sources is called background radiation. Exposure to low levels of radioactivity is part of normal everyday living.
Natural sources
Radioactive sources in nature include the ground (rocks - especially granite) and building materials. Some rocks contain radioactive substances that produce a radioactive gas called radon. This makes the air another source of background radiation.
Plants and animals also absorb radioactive material that is present in the ground and the atmosphere. These plants and animals are part of the food chain.
We are constantly bombarded with cosmic rays from space (especially when going on a long flight).
(Artificial sources of background radiation are discussed on another page.)
Pie chart
The left hand pie chart shows the average contribution of these different sources to our natural background radiation.
[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science
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