Kinetics and Radioactive Equilibrium of Radon and Radon Progenies in Indoor Air

Human exposure to radon and radon progenies can lead to the development of respiratory diseases, including lung cancer. Accurate predictive models are needed to better understand the effects of inhaled radionuclides on human health. This study aimed at developing a theoretical/analytical approach to simultaneously predict time-dependent changes in the distributions of radon and radon progenies in the air, in aerosols, and on surfaces. Various indoor, aerosol, and radiological processes were combined to develop the approach. The developed approach conserves the total number of nuclides, but it neither requires iteration nor assumes a steady state or radioactive equilibrium. We verified the theoretical/analytical approach by comparing its accuracy to the analytical and steady-state solutions of kinetic equations for the behavior of radon and radon progenies, as well as the numerical analysis of the equations and measurements for the indoor concentrations of the radionuclides. The results of this study can provide useful insights that can enhance our understanding of the behavior of radon and radon progenies in indoor environments with limited ventilation (e.g., underground facilities) and facilitate radiation-induced health risk assessment in areas where precautions are warranted because of the potential for long-term exposure to radon.