Preface.

Abstract

This special issue of Radiation Protection Dosimetry constitutes the proceedings of the 9th International Symposium on the Natural Radiation Environment (NRE9), organised by Hirosaki University jointly with International Atomic Energy Agency (IAEA). The symposium was held at Hotel New Castle, Hirosaki, Japan, from 22 to 26 September, 2014. The organisation of this symposium was supported by 20 related companies. The first symposium on the Natural Radiation Environment was held at the USA in 1963 as a forum for an international discussion about natural radiation in the environment such as cosmic radiation, radon and terrestrial gamma radiation. Since the first symposium, the NRE symposia have been held, mainly in western countries, at intervals of ∼4–6 years. The NRE symposia have made a huge contribution to our understanding of natural radiation and have helped to stimulate research in this field. Although we were planning to hold this symposium at Nagoya City in May 2012, the organising committee decided on the postponement of the symposium due to the ‘Great East Japan Earthquake’, which occurred in March 2011. It was in the immediate aftermath of this catastrophic event that the organising committee made the decision to suspend the holding in Japan of NRE9 in 2012. The organising committee decided to hold NRE9 in Hirosaki City when more than 3 years have passed since the earthquake.