Radiation Effects and Sources

What is Radiation? What does Radiation do to us? Where does Radiation come from?

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This publication is based on the major scientific reports of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) published in the last 25 years and aims to expand public knowledge on levels of exposure to ionizing radiation and possible associated effects. This publication does not set, or even recommend, radiation safety standards, rather, it provides information on basic science related to radiation (origin, quantities and units), on radiation effects (on humans and the environment) and on radiation sources (natural and artificial). Helping the public understand what radiation is and how it affects life on this planet lies within the core mandate of UNEP.




Hiroshima, Nagasaki, Three Mile Island, Chernobyl and Fukushima-Daiichi: these names have become associated with the public’s fear of radiation, either from use of nuclear weapons or accidents at nuclear power plants. In fact, people are much more exposed daily to radiation from many other sources, including the atmosphere and the Earth as well as from applications used in medicine and industry.


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