Levels of Radon in Soils of Dodoma City, Central Tanzania

Abstract

Purpose: Humans receive radiation doses exceeding fifty percent (50%) of the total dose from natural sources as a result of inhaling radon and thoron gases and their daughters. Radon occurs naturally in soils and can diffuse into indoor environments leading to adverse health effects for inhabitants. In this study, measurement of levels of radon gas in soils was performed with the purpose of categorizing areas and highlighting the likelihood of high levels of radon in indoor environments.
 Design/Methodology/ Approach: The study targeted the environs of Dodoma where the rapid expansion of human settlements is ongoing or anticipated. For easy access and convenience, the study was conducted in areas located along main roads leading to the nearby towns/cities. Sampling was done by inserting the drilling rod to a depth of approximately one meter (1 m) below ground level with the aid of a heavy hammer. The alpha pump was used to suck the soil gas from the ground through a metallic tube (the capillary probe) and pressed it into the ionization chamber of the measuring instrument (AlphaGUARD). Radon concentration was read directly from the instrument’s display.
 Findings: It was found that radon concentrations in soil vary from 18.8 to 233.5 kBq.m-3. Based on the radon risk criterion, surveyed areas range from normal to high radon risk categories.
 Research Limitation/Implication: The study only covered a limited area in Dodoma City, and therefore the results may not be representative of the entire city or even the surrounding regions.
 Practical Implications: This study is useful in categorizing building areas based on radon risk criterion with the purpose of reducing possibilities of radon-related health risks; mainly lung cancer to the population.
 Social Implications: Radon is a proven cause of lung cancer in humans. Therefore, knowledge of radon levels in the study area will help in setting the mitigation measures necessary for public health protection.
 Originality / Value/ Novelty: The study demonstrates an approach for estimating radon levels in soils which is beneficial to current and future researchers, environmentalists and regulators, among others.