Thoron exhalation rates in areas of Japan
Thoron exhalation rates were measured with a newly made portable instrument at 33 areas in 7 prefectures of Japan. Thoron exhalation rates ranged from 49 to 4890 mBq m–2 s–1. Radon exhalation rates were also measured in many of the areas at the same time and ranged from 2.1 to 11 mBq m–2 s–1. Thoron exhalation rates showed a rough correlation with radon exhalation rates. Both exhalation rates also showed a rough correlation with geological features.