Relationship between indoor ambient dose equivalent rates and the architectural style of stand-alone houses in locations with high soil naturally-occurring-radionuclide concentrations.

There have been numerous studies relating house construction materials with the indoor gamma dose rate mainly coming from natural radionuclide activities. The relationship between the outdoor gamma dose rate and the soil's naturally occurring radionuclide content is well documented. Few studies, however, have investigated the historical evolution of indoor gamma dose levels due to the principal materials used in house construction in geographical areas where outdoor natural radiation levels are significant. The present work was carried out in an area of Spain with high outdoor gamma dose levels (on average, 0.267 microSv/h) due to the natural radioactive characteristics of its soils, considering a great variety of stand-alone houses built from the beginning of the 18th century until today, with different styles, architectural techniques, and materials in their construction. The measured ambient dose equivalent rates in those houses decreased as the date of their construction was more recent. In conclusion, today's architectural style, which uses materials of practically universal origin, not only attenuates part of the irradiation due to the composition of the location's soil but also contributes less to the indoor gamma dose rate due to the relatively low naturally occurring radionuclide concentration of their building materials.