Radon measurements in underground dwellings from two prefectures in China.

Radon, an established lung carcinogen, remains the single most important environmental radiation exposure. Yet, an excess of lung cancer from breathing radon in homes has not been consistently demonstrated in studies conducted to date. To address several major problems that have hindered previous studies of lung cancer and radon in homes, we have embarked upon a lung cancer case-control study in Gansu Province, China, where a substantial proportion of the population live in underground dwellings. In this paper, we report on results of a pilot study in which radon measurements were made for 3 days in the summer in 40 homes under normal occupancy conditions using short-term E-PERM detectors and for 6 months from February through August in 49 homes using long-term alpha-track detectors. Useable E-PERM data were obtained from 38 homes and useable alpha-track data from 47 homes. For both types of detectors, measurements were approximately log-normally distributed. Arithmetic and geometric means were 233 and 185 Bq m-3 (range 74-1,590 Bq m-3) for E-PERM measurements and 165 and 158 Bq m-3 (range 74-592 Bq m-3) for alpha-track measurements, respectively; 68% of E-PERM measured homes and 55% of alpha-track measured homes exceeded 148 Bq m-3. Alpha-track measurements made at the entry, middle, and rear areas of the underground dwellings did not differ significantly (arithmetic means of 168, 162, and 165 Bq m-3 with standard deviations 63, 73, and 48, respectively), which suggests that air circulation may be minimal. The underground dwellings measured in the pilot study had high radon levels and the underground dwellers may provide an excellent population for studying indoor radon and risk of lung cancer.