Measurement of radon exhalation rate from building materials: The case of Highland Region of Ecuador

Abstract

Exposure to 222-Radon (Rn) usually occurs in closed environments as effect of the Rn exhaled from building materials, soil or water. While building materials provide a protection barrier to outdoor natural radiation (terrestrial and cosmic), their radionuclide composition could increase the indoor Rn exposure. In fact, the Rn exhalation of building materials is of great importance from the viewpoint of mitigation and public health in very specific conditions. This work presents the Rn exhalation rates of 40 building materials (concrete blocks, clay brick, granite and concrete samples) produced and used in Ecuador, as well as the effective dose for a reference dwelling. Rn concentration measurements were performed using the closed chamber method and a RAD7 equipment. The resulting Rn exhalation rates were found to be in the range from 0 to 7.83 Bq·m-2·h-1. The highest surface exhalation rate was detected in granite samples, while clay bricks show Rn exhalation below the minimum detection level (0.05Bq·m-2·h-1). In the reference dwelling, the effective dose rates caused by Rn exhalation from building material range from 0.019 up to 0.112 mSv/y. However, the effective dose rate depends on the exposure time and quantity of granite used. Our results could be of immediate help to choose suitable building materials to ensure a safe indoor environment for the dwellers.