The purpose of this project is to present a simple and specific method to assess the radon progeny hazards in the home and to apply this method. Equations presently are available to calculate lung dose for adults using a typical particle size distribution. Using these equations for children results in an underestimation of lung dose. In order to determine the lung dose for any age individual and particle size distribution, this research developed equations using a lung model by D. Crawford-Brown. These equations may be used to estimate annual lung dose from information concerning the radon progeny concentration, unattached fraction, and aerosol size distribution. Measurements of radon and radon progeny were performed in two upstate New York homes which were identified as having potentially elevated radon concentrations. Sampling procedures for unattached fractions developed by A. George and a computer program to determine working levels from gross alpha counts on air filters were applied to obtain the necessary parameters for the lung dose calculations. Estimates of lung dose equivalent to the subsegmental bronchioles for the two families were calculated from these specific measurements, with the assumption of a typical particle size distribution. Therefore, a method both for sampling radon progeny and for calculating lung dose to various groups under differing particle size distributions and unattached fractions is presented.