Measurement Method Studies on Radon and Radon-Thoron Progeny

Radon and thoron exposure represents the largest component of public radiation dose from natural sources. While radon and thoron gases themselves contribute to this exposure, their short-lived decay products account for the majority of the effective dose. Accurate dose assessment therefore relies on precise measurements of radon and thoron progeny, including their activity concentrations, unattached fractions, and aerosol size distributions. Additionally, due to their radioactive properties and suitable half-lives, radon and its decay products serve as valuable tracers in atmospheric and environmental research, especially in applications requiring long-term continuous monitoring. This paper reviews recent progress and achievements from the Environmental Radioactivity Laboratory of Peking University in the development of measurement methods for radon and radon-thoron progeny. It highlights innovative aspects, fundamental performance characteristics, and key technical specifications of the methods and instruments designed for various measurement purposes and employed in practical applications.