Radon concentration in air, hot spring water, and bottled mineral water in one hot spring area in Thailand

摘要

Hot springs are famous as spa resorts throughout the world. However, these areas usually have high natural radioactivity from radon gas. In this study radon concentrations in air, hot spring water, and bottled mineral water produced in a spa area of Suan Phueng district, Ratchaburi province, Thailand were measured. Radon concentrations in air were in the range of 10-17 and 11-147 Bq/m~3 for outdoor and indoor, respectively. Committed effective dose from inhale of radon were assessed and found to be in the range of 0.004-0.025, 0.25-0.6, and 1.134 mSv/y for visitor, local people and resort workers, respectively. These doses were in the range of 1.2 mSv/y regulated by UNSCEAR for the general public. Radon in hot spring water ranged from 2-154 Bq/L. Radon in bottled mineral water produced from the hot spring water were in the range of 17-22 and 0.2-0.3 Bq/L for those that stored for 7 and 90 days, respectively, after production. Radon concentration levels were in the range of the US Environmental Protection Agency reference level for radon in air which is 148 Bq/m~3 and alternative maximum concentration limit (AMCL) for raw water which is 150 Bq/L. However, when considering the USEPA (Maximum concentration limit), 11 Bq/L, for radon in drinking water, the mineral water should be stored for at least 8-9 days after bottling before selling to the market.