CFD modeling of radon progeny transport and deposition in the human respiratory tract

Regarded as the predominant source of natural radiation exposure worldwide, the inhalation of radon and its radioactive progeny represents a silent yet significant danger. The solid particles emitted during the decay of radon are notably radioactive and have the ability to deeply penetrate the lungs, where they can cause considerable damage to the respiratory pathways. In order to refine our understanding of the health repercussions induced by the inhalation of these radon progeny, our study has implemented a sophisticated modeling of the deposition of radioactive particles within the human respiratory system, relying on the computational fluid dynamics method. This cutting-edge technique has allowed us to accurately estimate the effective dose resulting from exposure to radon decay products. Our simulations, reflecting varied respiratory intensities corresponding to activities ranging from light (15 L/min) to intense (60 L/min), have revealed that larger diameter particles are preferentially deposited in the bronchi, especially during more sustained inhalations, due to their increased inertia. These data are essential for understanding the distribution of particles and their potential for harm. The air velocity field and deposition patterns were meticulously obtained and analyzed, thus providing detailed information on the mechanisms of particulate deposition. Furthermore, the dose conversion factor (DCF) for radon progeny was calculated for different airflows, incorporating the measured deposition rates. The obtained DCF values, ranging between (6.62–11.35 mSv WLM⁻¹), are in harmony with the ranges established by the International Commission on Radiological Protection, which are (5.4–10.6 mSv WLM⁻¹). The importance of this study lies in its contribution to global health safety, offering more reliable dose estimates that will serve as a basis for the development of more effective radiological protection guidelines. Ultimately, this work illuminates the path toward better knowledge of risks associated with radon, a step further toward safeguarding public health.