Aerosol sampling for radiological protection: Which particle size aerosol sampler to select?

Sampling of radioactive aerosols for the purpose of assessing or predicting occupational radiation doses has become an important issue in European countries. In particular, the 96/29/Euratom Council Directive specifies that aerosol sampling results can be used for assessing the individual dose when individual in vivo and/or bioassay methods are not possible or give insufficient results. This is precisely the case for exposures by inhalation to naturally occurring radioactive materials (NORM), for which bioassay methods may be associated with high detection limits while, in comparison, traditional aerosol sampling methods may lead to lower detection limits in terms of dose. A generic method has been developed to facilitate the identification of the particle size aerosol sampler to select (following the inhalable, thoracic or respirable convention) for minimizing the respective biases between the true and estimated exposure and the true and estimated effective dose associated with exposure by inhalation to any radioactive compound. Calculation based on this method has been applied to various radioactive compounds (of different absorption rates and particle size dispersion characteristics) of the 23'8U and 232Th natural chains. This paper presents the key elements of the method and the main results of its application to exposures by inhalation to NORM. (author)