Relationship between indoor and outdoor aerosol concentration following the Chernobyl accident

The integrated air concentration of aerosols inside and outside a house with closed windows and doors have been measured following the Chernobyl accident. The indoor concentration of caesium was about one-fourth of that outdoors. A model for coupling the reduction in indoor dose, the internal deposition velocity, the filtering factor of houses, and the air exchange rate are presented. Instead of using the concept of dry deposition velocity indoors when assessing the dose it is suggested that the total deposition in the house per unit time be defined by a deposition factor. Values of local deposition velocities and of the deposition factor are given. (author)