Radiation detriment and effective dose due to exposure to radon.

The study compares exposures to the lung caused by inhalation of radon and radon progeny with lung doses from external low-linear-energy-transfer (low-LET) radiation. For this purpose, lung cancer risks, lifetime effects and radiation detriments from chronic exposure to radon in homes and workplaces are calculated. The calculations apply accepted risk models derived from studies on miners and residential radon to the representative populations of International Commission on Radiological Protection (ICRP). In addition, comparable calculations are performed to determine risk quantities for the lung associated with low-LET radiation. In a working age population, a constant exposure to radon progeny of 1 working level month (WLM)/year results in a radiation detriment of 6.4∙10^-4per year (1.8∙10^-4yr^-1at a constant exposure of 1 mJ·h·m^-3yr^-1). For a whole population that is constantly exposed to a radon concentration of 100 Bq∙m^-3, the radiation detriment is 1.1∙10^-4per year. These values are based on epidemiological comparison using miner and residential studies separately. The relative biological effectiveness for alpha particles from the inhalation of radon and radon progeny is estimated to be around 10, which, despite of uncertainties, is significantly below the value of 20 recommended by ICRP for the radiation weighting factor of alpha particles. Comparison of results from epidemiological studies on radon in mines and in homes does not provide sufficient evidence that the fraction of unattached radon progeny has a significantly increased influence on the radiation risk und thus on the effective dose. An average annual effective dose of 6 mSv is determined for constant occupational exposure of a working age population to radon progeny with a rate of 1 WLM per year (1.7 mSv yr^-1per mJ∙h∙m^-3yr^-1). In the case of residential exposure, the average annual effective dose is 1.1 mSv, assuming that a whole population is constantly exposed to a radon activity concentration of 100 Bq∙m^-3. The dose coefficients determined in this study are lower than the corresponding values derived from biokinetic and dosimetric models and currently recommended by ICRP.