Study of correlation between radon (²²²Rn) gas in soil and indoor radon with dose assessment in the bauxite bearing area of Fongo-Tongo, Western Cameroon

ABSTRACT

The aim of the current work is to study the correlation between ²²²Rn gas in soil and indoor ²²²Rn concentrations. Markus 10 and RADTRAK detectors were used to measure ²²²Rn concentrations at 1 m depth in soil 30 points and 50 dwellings respectively. These concentrations varied from 35 kBq m⁻³ to 255 kBq m⁻³ with a geometric mean of 67 (18) kBq m⁻³, and from 85 Bq m⁻³ to 410 Bq m⁻³, with a geometric mean of 152 (26) Bq m⁻³ respectively in the soil gas and dwellings. In additional, 99% of the measurement points had concentrations higher than the limit value of 40 kBq m⁻³ according to the Swedish criterion for risk levels; 94% of the houses had radon concentrations higher than 100 Bq m⁻³, the reference value of the World Health Organization (WHO). When there was not a good air flow between the outside and the inside of the dwelling, the correlation coefficients were R² = 0.82 and R² = 0.73 respectively for the earthen and concrete dwellings. Under the best natural ventilation conditions, these correlation coefficients decrease significantly. Their values were R² = 0.54 and R² = 0.34 respectively for the earthen and concrete dwellings. Furthermore, a RadonEye +2 detector revealed a daily ²²²Rn accumulation reaching values of 800 Bq m⁻³ in some dwellings when all doors and windows were closed. Architecturally, dwellings built with sealed materials such as cement and concrete, whose do not facilitate ²²²Rn diffusion and transport, have lower ²²²Rn concentrations and effective dose than others These results show that ²²²Rn gas in soil and in confined air in dwellings are strongly correlated.

KEYWORDS:

• Markus 10
• RADTRAK2®
• RadonEye+2
• radon
• correlation
• inhalation dose

Acknowledgement

We also extend our acknowledgments to Dr Zora S. Žunić from the Institut of Nuclear Sciences Vinca of Belgrade, Serbia for reading the manuscript.

Author contributions

All authors contributed to the study. Conceptualization [Léonard Boris Djeufack], [Saïdou], [Mikhail Zhukvosky] Material preparation, data collection and analysis were performed by [Léonard Boris Djeufack], [Laurelle Tsafack Kendjou] and [Yerima Hamadou Abba]. The first draft of the manuscript was written by [Léonard Boris Djeufack]; [Guillaume Samuel Bineng] and [Oumar Bobbo Modibo] all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.

Additional information

Funding

This work was supported by the International Atomic Energy Agency (IAEA) within the framework of the Technical Cooperation (TC) Project CMR9009 titled “Establishing a national ²²²Rn plan for controlling public exposure due to ²²²Rn indoors”. The Government of Cameroon supported field works through the Public Investment Budget 2020 and 2021 of the Ministry of Scientific Research and Innovation.