Survey of the Rn dose conversion factor for offices

The Rn dose conversion factor (DCF), which relates the effective dose to the exposure to the potential α energy concentration (PAEC) of inhaled Rn progeny, was surveyed for 23 occupied and air-conditioned offices in Hong Kong using the bronchial dosimeter for Rn progeny proposed by Yu and Guan in 1998. The mean values of PAEC deposited in the tracheobronchial region (PAECT–B), total PAEC in air (PAECT) and the concentration of Rn (RC) for the offices were 0.13±0.12 mWL, 3.4±3.3 mWL and 30±12 Bq m−3, respectively. An average bronchial deposition fraction of Rn progeny was obtained as 0.037 (range: 0.033–0.051), which gave a DCF of 9.5 (range: 8.4–13) mSv WLM−1. The annual effective dose (E) was estimated to be 0.38±0.35 mSv yr−1 for the offices.