The textbook "A Passive Dosimeter for Estimating Radon and Thoron in Dwellings" offers a comprehensive analysis of the measurement methods for the radioactive gases radon and thoron that occur in residential spaces. These gases are significant factors in the natural radiation exposure of the population. The book describes the development of a time-integrated measurement method based on passive dosimeters with nuclear track detectors. This method allows for long-term measurements of radon and thoron concentrations, taking into account both daily and seasonal variations. The cost-effective technique is particularly suitable for large-scale surveys in areas with high background radiation and serves to estimate population doses for epidemiological studies. The detailed presentation of the methodology and results makes this book a valuable resource for professionals and researchers in the field of radiation measurement and assessment.