Measurement of radon concentration in laboratories of the civil engineering course of Federal Technological University of Parana and the contribution of construction materials to dose limits

Radon is a radioactive, carcinogenic gas present in nearly the entire Earth's crust, which tends to accumulate indoors. The dose of radon received depends on both its indoor concentration and the duration of exposure. Building materials, which contain elements from the Earth's crust, also contain naturally occurring radioactive materials, typically in small amounts. However, materials of magmatic origin, such as granite, tend to be significant potential sources of radon. To assess the safety of environments where construction materials are handled, it is important to evaluate the physical risks associated with ionizing radiation (such as radon), both in the materials and in the environment. In this study, radon concentrations were measured in indoor environments and construction materials used in civil engineering laboratories (coded as 1, 2, 11, 12, and 16) at the Federal Technological University of Paraná, Ecoville Campus in Curitiba. For this, 50 passive diffusion chambers equipped with CR-39 detectors were placed in 5 laboratories, with 10 detectors per laboratory. Additionally, construction materials frequently used in these laboratories were analyzed using an active detector, AlphaGuard, which measures alpha activity concentrations through an ionization chamber. The results indicated that the construction materials handled in the laboratories have little impact on the indoor radon concentration. The majority of the radon activity concentrations were mainly influenced by the soil beneath the laboratory. Of the diffusion chambers, 14 % showed concentrations between 200 and 400 Bq/m³, a level of concern, and 2 % of the chambers showed concentrations above 400 Bq/m³, indicating the need for monitoring and mitigation actions. However, given that the limits established are conservative and considering the exposure time of users, it was concluded that the indoor environments analyzed do not pose a physical risk from ionizing radiation.