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