A Preliminary Study of Radon Equilibrium Factor at a Tourist Cave in Okinawa, Japan

Abstract

The International Commission on Radiological Protection (ICRP) issued its Publication 137, Occupational Intakes of Radionuclides: Part 3 in which the radon equilibrium factor is fixed as 0.4 for tourist caves; however, several studies have reported a different value for the factor and its seasonal variation has also been observed. In this study, the radon concentration, equilibrium equivalent radon concentration and meteorological data were measured, and the equilibrium factor was evaluated in a tourist cave, Gyokusen-do Cave located in the southern part of Okinawa Island in southwestern Japan. Radon concentrations were measured with an AlphaGUARD and their corresponding meteorological data were measured with integrated sensors. Equilibrium equivalent radon concentration was measured with a continuous air monitor. The measured radon concentrations tended to be low in winter and high in summer, which is similar to previously obtained results. By contrast, the equilibrium factor tended to be high in winter (0.55 ± 0.09) and low in summer (0.24 ± 0.15), with a particularly large fluctuation in summer. It was concluded that measurements in different seasons are necessary for proper evaluation of radon equilibrium factor.

Radon Dynamics and Effective Dose Estimation in a Touristic Volcanic Cave: La Cueva del Viento, Tenerife (Canary Islands, Spain)

“…Therefore, such values could have been over or underestimated due to seasonal fluctuations and were not suitable for dosimetry studies for guides and tourists. In addition, and compared to other geological settings (i.e., karstic caves) reported in other Spanish territories (Alvarez-Gallego et al, 2015;Dumitru et al, 2015;Lario et al, 2005), and around the world (Alberigi et al, 2011;Wang et al, 2019;Yamada et al, 2021), the volcanic nature and activity of the Canary Islands may impact the radon-level of different touristic caves situated in this archipelago (López et al, 2012;Padilla et al, 2013).…”

“…This value (0.56) was selected as the average value obtained in ca. 900 measurements in caves and it is usually reported in many underground working places such as caves (Alvarez-Gallego et al, 2015;Cigna, 2005;Yamada et al, 2021).…”

Editorial for the Special Issue “Atmospheric Radon Measurements, Control, Mitigation and Management”

“…The published articles are intended to provide guidance and solutions for correctly measuring and evaluating radon in different environments and the efficient management of radon levels in affected buildings for radiation protection of the population. An attempt has been made to classify the contributions below [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]:  Three papers aim to define radon awareness and policy perspectives, to set-up radon specific norms to control of the health risk of radon exposure in the Republic of Moldova and to better define measurement procedures, approaches and standard guidelines for Romanian Schools.…”