Natural Radioactivity in Food: Experts Discuss Harmonizing International Standards | IAEA
Personal radiation|Fukui Prefectural Environmental Radiation Research and Monitoring Center
Background Radiation | US EPA
Hanford Site - Natural background radiation comes from three sources: cosmic, internal and terrestrial. Cosmic radiation comes to Earth in a steady stream from the sun. Differences in elevation, atmospheric conditions, and
Radiation: Effects and Sources
Exposure Dose from Natural and Artificial Radiation [MOE]