A recent survey of Wat Tharnnamron hot spring in Tashang District, Surat Thani Province, revealed a maximum external gamma radiation of 1,200 microroentgens per hour and a maximum radon concentration of 2,823.7 Becquerels per liter. These values substantially confirm the presence of a significant amount of the long-lived radionuclide 226Ra, which is a bone-seeking radioisotope. The investigators propose as necessary a measure that should be undertaken by the local authority, that is, to erect a warning sign providing brief information about the risk of exposure to the radioactive gas in order to prevent any adverse effect resulting from exposure, especially from consuming the water.

Key words: hot spring, radon gas, 226Ra, gamma radiation, measure for safety