Does this help you?: http://www.world-nuclear.org/info/inf05.htm http://www.world-nuclear.org/info/inf05.htm Most radiation exposure is from natural sources. T

Does this help you?: http://www.world-nuclear.org/info/inf05.htm http://www.world-nuclear.org/info/inf05.htm Most radiation exposure is from natural sources. These include: radioactivity in rocks and soil of the earth's crust; radon, a radioactive gas from the earth and present in the air; and cosmic radiation. About one quarter of natural radiation comes from the human body itself. The human environment has always been radioactive and accounts for up to 85% of the annual human radiation dose. Radiation arising from human activities typically accounts for up to 25% of the public's exposure every year. This radiation is no different from natural radiation except that it can be controlled. X-rays and other medical procedures account for most exposure from this quarter. The rest comes from coal burning, appliances, and other industrial and research procedures. Less than 1% of exposure is due to the fallout from past testing of nuclear weapons or the generation of electricity in nuclear, as well as coal and geothermal power plants. That link includes a table of background-radiation by nation in millisieverts (mSv).