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The incidence of lung cancer in the Gejiu area of Yunnan Province ranks the first inthe world. The radon level (indoor, soil) was measured in the Gejiu area by the SSNTDmethod from 1990 to 1996. The result indicates an extensive high-level of indoor radon in thatarea though U and Th are lower in local limestones. The indoor radon level of houses located inthe geologic fault zone is 6 times high that 2 km far from the fau1t zone. The reason probably isthat the radon level of soil in the fault is 6-8 times high that 1 km far from the faults. Ourdata indicate that a lower range of rad0n levels, 0 - 100 Bq’ m- 3, exists in healthy families.However, a higher radon level, over 800 Bq’ m- 3, is often f0und corresponding to that of can-cer patients’ homes (the house-owners are suffering from either lung cancer or leukaemia or liv-er cancer). Obviously, an increase in lung cancer incidence follows an increase in indoor radonlevel. The risk of cancer induced by indoor radon is no longer an inference, but a fact.
The incidence of lung cancer in the Gejiu area of Yunnan Province ranks the first inthe world. The radon level (indoor, soil) was measured in the Gejiu area by the SSNTDmethod from 1990 to 1996. The result indicates an extensive high-level of indoor radon in thatarea though U and Th are lower in local limestones. The indoor radon level of houses located inthe geologic fault zone is 6 times high that 2 km far from the fau1t zone. The reason probably isthat the radon level of soil in the fault is 6-8 times high that 1 km far from the faults. Ourdata that a lower range of radon levels, 0-100 Bq ’m- 3, exists in healthy families. Even, a higher radon level, over 800 Bq’ m- 3, is often f0und corresponding to that of can-cer patients’ homes (the house-owners are suffering from either lung cancer or leukemia or liv-er cancer). Obviously, an increase in lung cancer incidence follows an increase in indoor radonlevel. The risk of cancer induced by indoor radon is no longer an infer ence, but a fact.