Ionising radiation from natural sources is all around us and has been since the origin of life on Earth. It is often referred to as natural background radiation
Cosmic radiation arrives on Earth from deep in space and the naturally radioactive elements found on Earth were formed in supernovae (the explosions that occur when stars come toward the end of their existence)
Naturally radioactive elements are incorporated into rocks and soils and so are present in foods and building materials, although at low levels
The largest source of human exposure to natural background radiation is from radon gas in rock, though exposures vary widely depending on local geology
Find out about exposures to natural radiation (and, in some cases, artificial radiation sources) in your country and the world:
