In the assessment of health effects due to inhalation of radon and thoron progeny aerosols, particle size is one of the most influential parameters. Therefore, the present work aimed at deposition of inhaled particles in different body organs (bone surfaces, spleen, breast, stomach, kidneys, lungs, liver, and ET airways) from radon and thoron progeny concentration were calculated taking into account eight age and sex groups for the inhibitors of Reasi district, Jammu & Kashmir, India. The estimated age dependent mean doses for different body organs due to inhalation of radon progeny through air for all age groups varied between 1.05E-08 and 0.08 n Svy− 1 and due to inhalation of thoron progeny varied between 7.72E-08 and 6.52E-04 Svy− 1 which were found to be well within the recommended limit of 1000 µSvy− 1(ICRP 2010). The percentage contribution of thoron progeny dose is negligible for spleen, brain, stomach ULI, and LLI, respectively and contributes only 1–4% to bone surfaces, kidneys, and liver for all age groups. However, The percentage contribution of radon progeny dose is negligible for all body organs except lungs and ET airways, respectively. A good positive correlation has been observed between all radon and thoron progeny concentrations.