Radon dynamics and effective dose estimation in a touristic 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). 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 minimize 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 analyzed 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: Seasonal Auto-Regressive Integrated Moving Average (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, during the observation period (1 year), by the touristic guides and visitors was ca. 2 mSv/yr and 4 μSv/hr, 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.