Airborne contamination in the indoor environment and its implications for dose

Previous work has indicated that radiation doses from deposition on human skin, hair and clothing may contribute significantly to the dose received after a major nuclear accident, such as that, which happened at Chernobyl in 1986. The available data was, however, sparse and associated with considerable variation, clearly showing a need for further investigations to verify preliminary conclusions, examine processes in greater detail and identify important factors causing the observed parameter variation. For instance, the impacts of thermophoresis, electrophoresis, skin moisture and wind speed on the deposition of contaminant aerosol were examined, and since the previous measurements had indicated that elemental iodine could be a particularly problematic contaminant, experimental work was additionally undertaken to examine the process of deposition of this species to skin. Since both clearance and percutaneous penetration of deposited contaminants could play important roles in determining doses, experimental programmes were dedicated to the identification of parameters of interest in these contexts. Also doses from contamination on different surfaces in the indoor environment have in the past traditionally been neglected, and a theoretical approach, based on measurements, was developed for accurate prediction of these doses under different conditions. Also resuspension of deposited matter and its role in dose formation, by subsequent deposition or inhalation, was investigated through experiments. Contact transfer of contaminants from an indoor surface to human skin may give yet another contribution to dose and also the relevant parameters in this direction were examined experimentally. The ultimate goal of the investigations was to enable the determination of the various contributions to dose in a contaminated indoor environment. A model methodology was developed and an example of its use was given. It was found that after a major nuclear accident, doses from indoor deposition to humans, deposition on indoor surfaces and inhalation in the indoor environment would all be important to consider.