An Investigation of Soil Radiation Levels in the Territory of Ulaanbaatar City

This study focuses on the gamma spectrometry analysis of soil samples collected from 180 locations across every kilometer in the densely populated areas of Ulaanbaatar city to determine the activity concentrations of natural radioactive isotopes, including radium-226, thorium-232, potassium-40, and the man-made radioactive isotope cesium-137. Following the analysis, the radium equivalent activity was calculated, and the equivalent dose rate of the soil was measured with a dosimeter at the locations, thereby revealing the background radiation level of the city's soil. The objective of the study was to establish the external and internal hazard indices, outdoor external dose rate, indoor external dose rate, annual outdoor effective dose rate, annual indoor effective dose rate, and excess lifetime cancer risk at selected locations across every kilometer within the densely populated areas of Ulaanbaatar city. It is important to note that the gamma spectrometry analysis of the samples was conducted by the accredited laboratory of the Nuclear Physics Research Center (NPRC) at the National University of Mongolia (NUM). The findings were processed, plotted on a map of Ulaanbaatar city, and published for each soil in Ulaanbaatar, indicating that the activity and content of the isotopes are generally within the permissible limits. In the future, this study will be expanded to create an ecological atlas of soil radiation in the capital city of Ulaanbaatar. This investigation will be an important baseline for future monitoring of soil radiation levels