Abstract

The health impact of the exposure of populations to radon-222 and 220 is no longer to be demonstrated when they are exposed to high concentrations of volumetric activities. The measurement of radon requires specific techniques. The aim of this study was to identify the measurement methods allowing the identification and measurement of radon-222 and thoron-220 inside and outside homes and in establishments receiving the public. A systematic review of the literature was conducted. We identified scientific articles that addressed the issue of radon-222 and 220 exposure. The searches included all worldwide literature from 2000 to 2021. A total of three hundred and seventy (370) articles were collected from the search engines www.semanticscholar.org. The criteria were defined and applied to select relevant articles for the review. Then, a specific selection was made to eliminate articles with similarities in terms of methodology and the objective of the measurement in the different countries of publication. Finally, a global analysis of all the articles retained after the first selection was performed. The data analysis was performed with Excel. For this review, three hundred and eleven (311) publications were identified and included in our selection criteria, i.e., 84%. 0.3% of these publications were written in French. 43 specific and exclusively distinct articles were identified in the 311 pre-selected articles. The measurement of radon had become an issue in the scientific world since the 2010s. The present review showed that four sources of natural exposure are possible for humans. These are: water, soil, indoor air in rooms and public buildings and outdoor air. From this review, three techniques for measuring the exposure of radon-222 and thoron-220 were identified. These are: Solid Nuclear Trace Detectors (SNTD), gamma & alpha spectrometry and Liquid Scintillation Technique (LSC). 8 detectors based on these techniques have been identified in this review and have a representativeness greater than or equal to 4%. The Columbia Resin-39 (CR-39) solid-state nuclear trace detector is the most representative (32%) including the African context of radon-222 measurement in premises. The observation-based evaluation of the three measurement techniques showed that NSTDs are the most recommended for passive measurement of indoor radon. Liquid scintillators are the most recommended for the active measurement of radon in drinking water. However, the spectrometry technique (HpGe, Alphaguard) has also been shown to be effective in the active measurement of radon in liquid compartments. For the quantitative and qualitative analysis of radionuclides present in a soil sample, including radon and its solid progeny, gamma or alpha spectrometry remains the technique of choice. The measurement of radon-222 and thoron-220 requires a precise technique adapted to the measurement environment (indoor, outdoor, water, soil and food). The present review has allowed to note an absence of scientific research on the subject of exposure due to radon-222 in Benin. It allowed to identify the three representative techniques in formation of the measurement compartment.