Radiological Impact of Radon and Thoron Levels in Dwellings Measured using Solid State Nuclear Track Detectors

Radon, thoron and their short-lived decay products in indoor places are recognized as the main sources of public exposure from the natural radioactivity. Radon (Rn-222) and thoron (Rn-220) are produced from soil and rocks due to presence of primordial radionuclide of U-238 and Th-232 in them. Radon migrates and appears predominantly by diffusion process in indoor environment. The decay products of radon can attach to surface of aerosols, dust and smoke particles which may be inhaled & become deeply trapped in the lungs. Thus, due to potential health hazards attributed to inhalation of radioactive contaminated air, it is necessary to assess the level of these radioactive pollutants. In the present study, measurements of indoor radon, thoron and their equilibrium equivalent concentration (EEC) were carried out in different dwellings of villages situated in Palwal district, Haryana, India by using single entry face pinhole based Rn-222/Rn-220 discriminated twin cup dosimeter and deposition-based progeny sensors (DTPS/DRPS). The 150 dwellings were selected mainly targeting different type building materials used in construction of houses. Solid State Nuclear Track Detectors (LR-115 type-II) used for this time integrated measurements of gases due to their cost effectiveness, portability and easy to use feature. The measured concentrations of indoor Rn-222, Rn-220, EERC and EETC obtained in present investigation were compared with recommended limits by International Commission on Radiological Protection and World Health Organization.