Radon dynamics and effective dose estimation in a volcanic cave: La
Cueva del Viento, Tenerife (Canary Islands, Spain)
Abstract
La Cueva del Viento is a volcanic lava tube located in Tenerife Island
(Canary Islands, Spain). With 18.2 km in length, it is the
6th longest volcanic tube on Earth. Its touristic
section, 180 m long, receives more than 28,200 visitants each year.
According to the European and Spanish legislation, a radon monitoring
program is required to minimise the radon exposition of workers,
tourists, and cavers. In this work, we studied the radon concentration
dynamics in the touristic section of the cave for ca. 1 year, using both
passive and active radon detectors. Pluviometry and external air
temperature played an important role in the seasonal and daily
variations of indoor radon concentrations. Daily fluctuations during the
dry season were analysed using time series (Box-Jenkins methodology) and
frequency analysis (Fourier and Wavelet transforms) methods. The
experimental radon time-series was well-fitted using a seasonal
autoregressive integrated moving average model: SARIMA
(2,0,1)(2,1,0)24, and its value, in a short-time window
(ca. 1 week) was conveniently forecasted. Finally, this work revealed
that the annual effective doses received by the touristic guides and
visitors was ca. 2 mSv/year and 4 µSv/h, respectively. We concluded that
the touristic exploitation of La Cueva del Viento is safe for both
tourists and guides. However, based on our results, La Cueva del Viento
had to be classified as a “Monitoring zone” and a regular monitoring
program should be implemented.