Understanding Post-Earthquake Radon: Nuclear Engineering Professors at Chulalongkorn University Suggest Radon Measurement  

In the aftermath of the 8.2 magnitude earthquake on March 28, 2025, which affected many parts of Thailand, professors from the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, have warned of the increased risk of radon gas exposure—particularly in Bangkok, where seismic activity may cause underground fissures that allow radon to seep into homes and buildings. As radon is a naturally occurring radioactive gas linked to lung cancer, the department urges the public to monitor indoor radon levels and improve ventilation in ground-level areas. Chulalongkorn University is the first institution in Thailand equipped with a radon calibration system and offers professional radon measurement services for households, industries, and public institutions to promote safety and build public confidence. 

Earthquake Impact and Urban Geological Risks in Bangkok 

Following the 8.2 magnitude earthquake on March 28, 2025, the seismic waves affected Thailand, causing damage to various buildings. In Bangkok, particularly, as a city situated on soft soil layers, there is an increased possibility of underground fissures developing. The consequence may be greater diffusion and dispersal of underground radon in residential areas and buildings. A professor from the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, has provided interesting observations about the connection between seismic vibrations from earthquakes and health risks from radon. 

 Natural Origin and Health Impacts of Radon Gas 

According to Dr. Rawiwan Kritsananuwat, Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, radon is a radioactive gas found in the Earth’s crust, naturally occurring from the decay of uranium in soil and rock. It typically diffuses through cracks in the ground and fissures in buildings and house foundations into the ambient air. The gas is colorless, odorless, and tasteless, making it impossible for humans to notice it directly. 

Although it cannot be detected with human senses, this gas is considered the second leading cause of lung cancer after smoking. However, we should not panic or be excessively fearful of radon, as lung cancer develops from multiple combined factors, not from radon exposure alone. 

 “When we inhale radon, it decays, emitting alpha radiation and transforming into new radioactive elements, which are solid. These elements continue to decay into daughter elements until they ultimately become stable lead that accumulates in the alveoli. As a result, lung cells are damaged by both alpha radiation and lead toxicity, which leads to an increased risk of developing lung cancer,” explained Dr. Rawiwan. 

Radon Concentration Variability and Measurement Methods 

The concentration levels of radon entering buildings vary according to the underlying bedrock geology, the building construction and foundation type, and the height within the building. Lower floors in contact with the ground typically have higher concentration values than upper floors. The average global indoor radon concentration is 40 Bq/m³. A value of over 160 Bq/m³ is considered a risk level. The outdoor radon value is approximately 10 Bq/m³. 

“Even in the same area, the amount of radon at ground level, underground, or on different floors varies. The lower floors of houses, such as basements and first floors, tend to have the highest amounts of radon. Therefore, if there are cracks or joints in these areas, radon can more easily spread into buildings and homes,” observed Dr. Rawiwan. 

For radon measurement, Dr. Rawiwan says that there are several methods. One method uses a CR-39 track detector, which can detect traces of alpha particles emitted by radon. The CR-39 track detector is placed in a device that allows radon to pass through, then positioned in the area to be monitored for a period of 1-3 months. We then analyze the detector by counting the number of traces and calculating the radon concentration. Although this method takes time and requires expert analysis, its advantage is the low cost. 

Another popular method is using real-time radon measuring equipment, specifically the RAD7 device, which can draw in air for measurement and display radon concentration values immediately. Additionally, the RAD7 can also measure radon in water samples, especially in underground water sources such as groundwater or hot springs, which often contain high levels of radon. 

In cases where underground radon levels need to be measured for early earthquake warning systems, a special measuring device called the RAD in soil can be used. It works by placing equipment into soil layers to monitor changes in radon quantities, which in some cases can serve as preliminary indicators of potential earthquakes. 

  ”The Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, has modern measuring equipment and is the first institution in Thailand with a calibration system for radon radioactivity concentration. We provide radon measurement services for various industries both domestically and in neighboring countries, including indoor radon measurement services to build confidence and alleviate public concerns,” said Dr. Rawiwan. 

Immediate Prevention Measures in Residences 

Assoc. Prof. Nares Chankow from the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, advised that protection against radon dangers can begin even before abnormal events occur, especially in residences at risk of indoor gas accumulation. The basic approach that can be implemented immediately is opening windows or ventilation channels regularly, particularly in lower floors or areas adjacent to the ground, where radon is more likely to penetrate than in upper floors. 

“Regularly opening windows for ventilation helps reduce radon accumulation. If cracks are found in floors or walls, you should open windows for ventilation and repair these cracks immediately to prevent radon from the ground or crack surfaces from spreading into the house.” 

For houses with crawl spaces or elevated floors, which are considered high-risk areas for directly receiving radon from the ground, an easy and cost-effective preventive approach is using floor covering materials such as linoleum or flooring equipment available at general construction material stores. These can be laid over the ground beneath the house to help reduce gas infiltration into living spaces. 

Assoc. Prof. Nares offered a policy recommendation that at the national level, a network should be developed to study the relationship between earthquakes and continuous radon measurement, using the Internet of Things (IoT) to collect real-time data, as well as establish a nationwide surveillance network system. This would help sustainably enhance disaster preparedness and prevention capabilities for the future. 

Public Access to Radon Testing Services at Chula 

Those who wish to measure radon levels in their buildings, houses, or high-risk areas can contact the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University. The department is equipped with the necessary equipment, measurement techniques, and expert personnel. 

Contact the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University at 0-2218-6781 or E-mail: nutech.chula@gmail.com . 

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