Radon Exhalation Rates of Soil Samples from Khon Kaen Province, Thailand
Radon, which can be also detected in water, forms naturally from the decay of uranium and radium found in different amounts in soil and rock. Radon from soil gases is the main cause of health hazards. Radon exhalation escapes from the ground into the air, where radon and radon progeny decays and produces radioactive particles. When inhaled, they can damage the deoxyribonucleic acid and potentially cause lung cancer. Hence, this study measured the radon exhalation rates in soil samples from 26 districts of Khon Kaen Province, Thailand by the active detector method. The closed-loop measurement system in the active detector was made up of the electronic radon detector and a bulk chamber in a 2.8-L volume. The measurement time for each sample was 24 h. Results showed that the radon concentration in soil samples varied from 5.60 to 67.10 Bq m-3 (average: 21.94±4.55 Bq m-3). The radon mass exhalation rates ranged from 7.34 to 17.51 mBq kg-1 h-1 (average: 11.39±3.38 mBq kg-1 h-1) while the radon surface exhalation rates were in the range of 0.29 to 1.31 mBq m-2 h-1 (average: 0.81±0.90 mBq m-2 h-1). The radon surface exhalation rate of the soil samples was below the average worldwide value of 57,600 mBq m-2 h-1 as set by the United Nations Scientific Committee on the Effects of Atomic Radiation. It was concluded that the soil from the province does not pose any radiological health hazard to the general public.