“Radon”: a Lung Cancer Threat Next Door – Chula’s Engineering Professor Suggests Ways to Protect Ourselves

Radon is a radioactive element naturally found in rocks, soil, sand, and water, which humans generally use in construction. This dangerous gas is second only to smoking in contributing to lung cancer. A Chula engineering professor suggests ways to defend ourselves from this threat.

A social media post by one doctor about his lung cancer has caused panic and anxiety for many, not just over the cancer itself, but over the possible cause of the disease.

We are well aware that the number one cause of “lung cancer” is “smoking.” Those looking to avoid this disease will then stay away from smokers or cigarette smoke. During the last decade, a new cause of lung cancer made itself known as “PM2.5.” Many people have turned to check the air quality before doing outdoor activities and wearing masks that can filter dust particles. Most recently, we have been introduced to “radon,” another lung cancer contributing factor, which has been around for a long time and is closer to us than we think but has only caught the eyes of the public in recent months.  

Assoc. Prof. Nares Chankow, an expert in environmental radiation measurement from the Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, said that “radon” is a radioactive element that is the second leading cause of lung cancer after smoking. The International Agency for Research on Cancer (IARC), WHO, has concluded that radon is a carcinogen and is a cause of lung cancer in humans, but shockingly this gas can be found right in our homes!

“Radon and lung cancer” is a topic that has been studied for over 10 years, especially in the United States. Before purchasing a house, many Americans will ask to see the amount of radon in the area first.”

Assoc. Prof. Nares added that in November 2022, the Environmental Protection Agency (EPA), an American organization that provides knowledge on radon in a manual for the public, warned people to take special caution regarding radon as they were entering winter when the air tends to be overcast.

Where does radon come from?

Assoc. Prof. Nares explained that environmental radiation can be found anywhere on Earth. Radiation that occurs naturally, e.g., radiation in rocks, soil, sand, or even in the human body, accounts for roughly 80% of the radiation that humans are exposed to. The other 20% comes from man-made radiation, most of which is the radiation used in the diagnosis and treatment of diseases, such as X-rays or radiotherapy for cancer.

Most natural radioactive elements have short half-lives, causing them to decay until none remains. However, some have long half-lives and can still be found scattered in rocks, soil, sand, minerals, and other natural resources found in the Earth’s crust, including water from surface and underground water sources. 

“Radioactive substances that occur naturally and can still be found nowadays are Uranium-238, Thorium-232, and Potassium-40. Radon is an element that occurs in the decay chains of uranium and thorium. As a gas, radon can be naturally found in the air. When humans utilize resources from the Earth’s crust, such as rocks, soil, and sand, in construction, those materials release radon. Without proper ventilation, residents run a risk of inhaling radon in large amounts, which can accumulate in the body and cause harm.”

How is radon dangerous?

Dr. Rawiwan Kritsananuwat, Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, added on the danger of uranium that, “radon is a colorless, odorless, and tasteless noble gas, which is undetected to humans. So, we can never know whether we’re breathing in this gas or not.”

“Once we breathe in radon, it starts to decay into alpha rays, creating new radioactive elements. This new radioactive element is solid and decays into other radon daughters ending in lead, which is stable and accumulates in the lungs. This can cause the lung cells to receive alpha rays and lead poisoning, leading to a risk of lung cancer.”

How Much Radon Is in Our Home?

Dr. Rawiwan explained that radon comes from uranium in soil, rocks, sand, underground water, natural gases, and construction materials. Therefore, the level of radon depends on the amount of uranium and radium (part of the uranium decay) in the soil.

“Soil in different areas contains different levels of uranium. In Bangkok, the soil has less uranium than in other provinces. Mostly, soil that has high levels of uranium comes from areas with granite in the R-horizon or with decomposed granite as the parent material. It was also found that mud sludge from hot springs contains high levels of radium as well.” 

The Natural Radiation Survey and Analysis Research Unit, Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, under the lead of Prof. Dr. Supitcha Chanyotha, researches and analyzes the amounts of natural radioactive elements in samples taken from representative provinces from every region in Thailand to create a basic radiation database. The Department of Mineral Resources has also created a map of uranium and thorium in Thailand for the public.

Even within the same area, the level of radon on the surface and underground or at different levels of the building may also differ.

“The lower levels of the house, like in the basement or the ground floor, are at the highest risk of being exposed to radon. So, if there are cracks like those between drainage or water pipes or areas with holes drilled in, then radon can seep through.”

Referring to the measurements taken at the Faculty of Engineering, Dr. Rawiwan stated that the amount of radon on the first floor dropped to one-third of the original measurement after the doors and windows were opened and the ventilating fan was turned on, and the amount rose 3-4 times when measured in the basement.

The concentration of radon gas which is considered dangerous is 148 Bq/m3 (US EPA) and above. On average, the indoor concentration is at 40 Bq/m3, while the outdoor level is 10 Bq/m3. Nowadays, there are 2 methods of testing radon levels in residences, which are using the CR39 film and the RAD7 machine.

“CR39 detectors determine the concentration of radon by measuring the alpha particles released from radon on films. The CR39 is placed in a device through which radon can pass and then left in a spot for roughly 1-3 months. The CR39 is then observed to measure the alpha tracks to calculate the concentration of radon. The analysis of the tracks on CR39 takes a long time and must be done by experts, but the cost of this method is low.”

The Department of Nuclear Engineering, the Faculty of Engineering, Chulalongkorn University, is the first organization in Thailand to operate a radon radiation concentration calibration system and offers a service for measuring radon in industries in Thailand and neighboring countries.

“Another method that can measure radon in real-time is using the RAD7 radon detector, which requires pumping air into the machine, which can then read the concentration of radon immediately. The RAD7 can measure the level of radon in both air and water samples. Underground water, like groundwater or hot springs, is usually found to have high levels of radon.

Preventing radon from entering the body

Despite its dangers, there are ways to protect ourselves from radon. Assoc. Prof. Nares has suggested a few ways.

If you live in a place with good ventilation, radon will disperse into the air and naturally disappear. Those working outdoors do not have to worry, while those working and living indoors should open the windows to let the air flow regularly.

 Before entering a room that has been shut for a long time, the ventilation system should be turned on first. Small spaces should have good airflow or a ventilation system installed. In European countries, every house is required by law to have a ventilation system, especially in the basement as it receives radon from the ground on all sides.

Since radon can seep through the cracks in the house, all cracks should be filled. The ground should be packed or sealed, and concrete can be used to fill the cracks. There is less chance of radon leaking through the walls as many painting products have the quality of resisting heat and water.

Air purifiers with charcoal filters can detect vapor and radon gas. When choosing an air purifier, you should go for one that has charcoal and High-Efficiency Particulate Air Filter (HEPA). Assoc. Prof. Nares added, “I don’t want people to panic over radon too much. Radon is simply one contributing factor to lung cancer, but the cancer also depends on other factors like exposure to other hazardous chemicals, smoking, and the resistance or adaptability of the cells in the body. Everybody has cancer cells in their body, so it depends on how well we take care of ourselves.”

“If any house has a lung cancer patient who lives on the ground floor or in the basement, in a confined space without proper ventilation, and has the air-conditioner on all day, you may request to have the house tested for radon concentration. The Department of Nuclear Engineering, the Faculty of Engineering, Chulalongkorn University, has the equipment and the techniques to measure radon levels and can offer advice and measuring services for the safety of everyone.”

You can contact the Department of Nuclear Engineering, the Faculty of Engineering, Chulalongkorn University, at 0-2218-6781 or by Email: nutech.chula@gmail.com.

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