Radon

Natural ionising radiation is considered the largest contributor to the collective effective dose received by the world’s population. Man is continuously exposed to ionising radiation from several sources that can be grouped into two categories: first, high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and, second, radioactive nuclides generated when the Earth was formed and still present in its crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium (U) and thorium (Th) radioactive families together with potassium (40K), a long-lived radioactive isotope of the elemental potassium. In most cases, radon (222Rn), a noble gas produced by radioactive decay of the 238U progeny, is the major contributor to the total dose. This European Atlas of Natural Radiation has been conceived and developed as a tool for the public to become familiar with natural radioactivity; be informed about the levels of such radioactivity caused by different sources; and have a more balanced view of the annual dose received by the world’s population, to which natural radioactivity is the largest contributor. At the same time, it provides reference material and generates harmonised data, both for the scientific community and national competent authorities. Intended as an encyclopaedia of natural radioactivity, the Atlas describes the different sources of such radioactivity, cosmic and terrestrial, and represents the state-of-the art of this topic. In parallel, it contains a collection of maps of Europe showing the levels of natural sources of radiation. This work unfolds as a sequence of chapters: the rationale behind; some necessary background information; terrestrial radionuclides; radon; radionuclides in water and river sediments; radionuclides in food; cosmic radiation and cosmogenic radionuclides. The final chapter delivers the overall goal of the Atlas: a population-weighted average of the annual effective dose due to natural sources of radon, estimated for each European country as well as for all of them together, giving, therefore, an overall European estimate. As a complement, this introductory chapter offers an overview of the legal basis and requirements on protecting the public from exposure to natural radiation sources. In Europe, radiation has a long tradition. Based on the Euratom Treaty, the European Atomic Energy Community early established a set of legislation for protecting the public against dangers arising from artificial ('man-made') ionising radiation, but this scope has since been extended to include natural radiation. Indeed, the recently modernised and consolidated Basic Safety Standards Directive from 2013 contains detailed provisions on the protection from all natural radiation sources, including radon, cosmic rays, natural radionuclides in building material, and naturally occurring radioactive material.