Introduction: Due to the widespread belief that 220Rn's levels are minimal due to its shorter half life and that its contribution to the overall inhalation dose is neglected in the presence of other important natural radiation sources, data for 220Rn in indoor and industrial environments are few.
 Objectives: To find the distribution of radon, thoron and their progeny levels with wall and floor distances.
 Methods: The experimental methodology is as per the standard protocol provided by the Environmental Assessment Division, Department of Atomic Energy, Bhabha Atomic Research Centre, Government of India, Mumbai for radon groups working in the country. Measurements of radiation levels and the concentrations of radionuclides in the environment are accomplished employing appropriate nuclear instruments. The radon, thoron and their progeny levels were determined using Solid State Nuclear Track Detectors and the tracks formed in these films were counted by Spark Counter detailed methods are discussed elsewhere.
 Results At the room's walls, ceiling, and floors, 220Rn concentrations were highest and rapidly decreased as one moved away from them. Indoors, the concentration of 220Rn progeny is independent of the distance between walls. Research on 220Rn diffusion from each wall of the construction materials used and factors affecting the levels of 220Rn progeny in homes are two examples of the extensive and continuous study needed to estimate the dosage due to 220Rn and its offspring.
 Conclusions: The assessment of public exposure to natural radiation, particularly the exposure from 220Rn and its offspring, has to be conducted more thoroughly across the country.