Radon health hazard in mud-built homes

Closeup view of the porous exterior wall of a 'mud house' constructed with compacted soil
Closeup view of the porous exterior wall of a ‘mud house’ constructed with compacted soil.

Assessment and remediation of radon and thoron radiation health hazard in mud-built homes in developing countries

Submitted to IGCP

Radioactive radon gas is being generated from uranium and thorium trace metals in soil. Dry, porous mud walls and floors of mud-built homes in developing countries emit radon into room air. Radiation damage in lung tissue results from two radon isotopes and their radioactive decay products. The longer-lived radon-222 with a half-life of ca. 3.8 days can be effectively diluted by venting with outside air. In contrast, radon-220 (called thoron) with a half-life of only ca. 55 seconds can only be mitigated by sealing of porous surfaces.

Typical tight sleeping quarters are often close to walls and floors where thoron originates. A high radiation dose may cause lung cancer. The thoron health hazard is unique to mud houses because porous mud surfaces are typically not sealed by gas-impermeable wall coverings or tiles.

VNU graduate student Nguyễn-Ánh Nguyệt treats a section of a mud wall with a chemical solution to reduce porosity and the emanation of radon and thoron into room air
VNU graduate student Nguyễn-Ánh Nguyệt treats a section of a mud wall with a chemical solution to reduce porosity and the emanation of radon and thoron into room air.

Our project mainly focuses on: (1) developing recommendations for affordable and reasonable detection methods for radon and thoron in mud-built homes; (2) assessing the concentrations and distributions of thoron and radon in mud house air in Vietnam (as an example of developing countries); (3) affordable, non-toxic and socially acceptable sealing of porous mud surfaces in homes to prevent escape of thoron and radon, and to improve public health.

In this ancient coffee house in Đồng Văn, we discovered high thoron concentrations in the air space between a mud wall and its dilapidated plastic wall covering.
In this ancient coffee house in Đồng Văn, we discovered high thoron concentrations in the air space between a mud wall and its dilapidated plastic wall covering.
Collection of soil gas in a buried, perforated beer can that is connected via tubing to a radon detector
Collection of soil gas in a buried, perforated beer can that is connected via tubing to a radon detector.

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Compaction of wet soil with structural reinforcements to generate artificial soil bricks for radon/thoron measurements
Compaction of wet soil with structural reinforcements to generate artificial soil bricks for radon/thoron measurements.
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After drying and receiving various types of surface treatments, soil bricks are ready for measurements of their radon/thoron emission.
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After drying and receiving various types of surface treatments, soil bricks are ready for measurements of their radon/thoron emission.
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Recording of radon and thoron emissions from mud bricks that are placed in a plastic box. The air in the box is stirred by a fan and measured by a SARAD RTM 2200 instrument in closed-circuit mode.

 

Geosciences are improving the lives of people in Vietnam