Indoor Radon Levels in Thermal Spas and the Compliance with the European BSS Directive: A Portuguese Case Study

Abstract

Radon is a radioactive gas produced from the decay of uranium. It can be found in many types of soils and rocks, such as granite. Radon is the most important cause of lung cancer after smoking. The aim of this study was to evaluate continuously the radon concentration in two Portuguese thermal spas (A and B) between December 2018 and August 2019 (average of 107 days). The indoor air radon concentration was measured using CR-39 passive detectors in the following spaces: thermal pool, spa pool, ORL (inhalation therapy rooms), vichy shower, vichy nozzle, berthelot, whirlpool cabin and reception. The results showed that the radon concentration values at thermal spa A are much higher than the indoor air radon concentration values obtained at thermal spa B. In fact, 90% (17 values) of the indoor air radon concentration values at thermal spa A do not comply with the reference level established in the EURATOM Directive 2013/59 (300 Bq/m3) and within the Portuguese legislation the Decree-Law 108/2018, of December 3. Therefore, generic and immediate actions should be adopted to reduce the exposure namely: strengthening the ventilation system, providing workers with personal protective equipment, and, informing the workers about the “existing exposure situation”. Long-term actions should also be adopted as foreseen in the Decree-Law 108/2018, of December 3, including developing a radiological control plan for the facilities and workers.