Harmonized radon data in the European Atlas of Natural Radiation

As the scientific and knowledge service of the European Commission, the mission of the Joint Research Centre (JRC) is to support EU policies with independent evidence throughout the whole policy cycle. In particular, the JRC provides this support to the Directorate General for Energy by collecting, evaluating and reporting artificial environmental radioactivity measurements both for routine (REM database) and emergency preparedness (European Radiological Data Exchange Platform) purposes.
However, with the exception of potential large scale nuclear accidents, natural ionizing radiation is the largest contributor to the collective effective dose received by the world population. To gain a clearer overview of the natural sources of radioactivity, the JRC launched the European Atlas of Natural Radiation with the aim to provide insight into geographical variability of exposure components and their relative importance for total exposure to ionizing radiation.

The Atlas presents contributions from 100 experts in various fields, from 60 institutions such as universities, research centres, national and European authorities, and international organizations. In the first place, this Atlas aims to provide reference values and generate harmonised data for the scientific community and national competent authorities. It also offers an opportunity to the public to become familiar with the radioactive part of its natural environment. Intended as an encyclopaedia on natural radioactivity, the Atlas explains its different sources, i.e. cosmic and terrestrial radiation, and describes the current state-of-the art of knowledge by means of text, graphics and maps.

Being responsible for half of the natural dose, particular attention has been given to indoor radon, of which over one million measurements of long-term indoor radon concentration in ground-floor rooms of dwellings from 36 European countries were collected and aggregated as means within 10 km × 10 km grid cells. The updated version of the European Indoor Radon Map (December 2020) will be presented as well as the statistical analysis of the input data.

Geogenic Radon Potential and Geogenic Radon Hazard Index quantify the contribution of geogenic to indoor radon and are constructed using geogenic quantities, such as uranium concentrations in the ground, geology, soil permeability, soil radon concentration and terrestrial gamma dose rate.
Therefore, it was decided to focus the Atlas on the development of maps that display natural sources of radiation and also serve as quantities which predict geogenic radon. Maps of uranium, thorium and potassium concentrations in soil, covering most European countries, were created, while maps of uranium, thorium and potassium concentrations in bedrock are only available for some countries. A methodology for estimating the terrestrial gamma dose rate (based on ambient dose equivalent rate measurements) has been established, while the European terrestrial gamma dose rate map has been created using uranium, thorium and potassium concentration in soil. The practical use of the maps of the Atlas as geogenic quantities will be illustrated through different examples of scientific studies.

The Atlas is available in digital format and can be ordered as a printed version at https://remon.jrc.ec.europa.eu/ .