MSK medical physicist Dr. Michael Bellamy says many people are still unaware of the risks posed by radon exposure.
Most people have heard about radon being a health hazard. It is important to fully understand the danger it poses. Radon is a radioactive gas given off by soil, rock, and water. It results from the breakdown of naturally occurring radioactive isotopes in uranium buried deep underground. The Environmental Protection Agency (EPA) classifies radon as a carcinogen because it can get into the air and increase the risk of lung cancer.
You can’t see, smell, or taste radon gas, so it is easy to ignore the risk it carries. Here, Michael Bellamy, PhD, a medical physicist at Memorial Sloan Kettering Cancer Center (MSK) with expertise in radiation safety, dispels some of the most common myths about radon and describes what can be done to reduce its effects on lung cancer risk.
Myth 1: The link between radon and lung cancer risk is not clear.
The link between radon and lung cancer has been firmly established over the past four decades from studies in people and in the lab. The elevated lung cancer risk was first noticed in uranium miners, who worked in confined spaces underground for long periods. This led scientists to consider that radon exposure could be a wider problem.
“They performed studies measuring radon levels in homes, especially in areas where houses are buttoned up for heating and cooling for much of the year,” Dr. Bellamy explains. “Some homes had radon levels close to some of the lower levels in the mines.”
Into the 1980s and 1990s, there was still skepticism about whether the findings in miners could be applied to the risk in homes. But rigorous studies since 2000 effectively laid the question to rest, Dr. Bellamy says.
Exactly how radon causes lung cancer is also well understood — and explains why it does not seem to contribute to other cancers. Some forms of radioactive material can be absorbed into the body and may even concentrate in the bone, but radon gas goes only to the lungs.
“As radon gas breaks down, the particles lodge themselves in the alveoli, the tiny air sacs in the lungs,” Dr. Bellamy says. “Or the radon gas molecules themselves attach to small dust particles, which go into the deep part of the lungs. Either way, once present, the energy they give off can damage lung cells and eventually lead to cancer.”
Myth 2: The increased risk of lung cancer is not significant.
Major scientific organizations believe that radon contributes to approximately 12% of lung cancers annually in the United States. It is the second leading cause of lung cancer after smoking. Among smokers, the increase in risk is dramatic due to the synergistic effects of radon and smoking. The EPA estimates that radon exposure increases lung cancer risk eight to nine times in smokers compared with nonsmokers.
“It’s almost as if smoking sets you up and radon pushes you over the edge,” Dr. Bellamy says. “You have the chemical damage from smoking, and now you’re bringing in radiation exposure on top of that. Clearly, we encourage everyone to stop smoking — that’s most important. But if you are not going to quit, make sure you are aware of the radon level in your house.”
Myth 3: Only older homes have a high risk for radon exposure.
There is a misconception that radon exposure is a problem exclusive to older homes and buildings. Many people think newer constructions are designed to be radon-proof. However, risk of radon exposure is not determined by the age of a building but by the presence of uranium in the soil beneath it, which varies widely from one location to another.
While modern building codes could potentially include radon-resistant construction techniques, these are not universally applied. And even when used, they do not guarantee a radon-free environment. Testing for radon is the only way to assess the actual risk in any home regardless of its construction date.
Myth 4: Testing your house for radon is costly and time-consuming.
The typical test is simple and inexpensive. Test kits can be purchased at home improvement stores, hardware stores, or online for about $20 to $30. “It usually is about the size of a hockey puck and has perforated holes and charcoal inside,” Dr. Bellamy says. “You open it, like you would an air freshener, leave it sitting for a few days in your house in one of the lower-level rooms, and then send it off to a lab for testing.”
Radon is measured in picocuries per liter of air (pCi/L), an indicator of radioactivity. The average indoor radon level in the United States is about 1.3 pCi/L. The average outdoor level is about 0.4 pCi/L. Both the U.S. Surgeon General and EPA recommend fixing homes with radon levels at or above 4.0 pCi/L.
Many people are unaware of the high levels they may be facing. According to a 2022 report from the American Lung Association, radon tests showed that 22% of homes in Massachusetts were above the 4.0 pCi/L EPA action level.
Myth 5: Reducing the radon level inside your home is very expensive.
The process, called radon mitigation, is easier than most people think. Rather than trying to seal the house so that radon doesn’t seep in at all, the most common method diverts the radon gas from under the basement floor through a pipe to the outside — either through the roof like a chimney or through a wall to a vent. Once outdoors, the radon gas dissipates and is not a hazard.
Radon mitigation systems usually cost between $800 and $1,500. “A lot of companies are doing this now because of the EPA’s push to inform people about the potential risks of radon,” Dr. Bellamy says.
Myth 6: Radon is a problem only in certain parts of the country.
There are regions of the country with more and less radon. But it’s almost impossible to determine the risk at a specific location. Radon levels are very local. They depend on uranium deposits, soil composition, atmospheric conditions, home construction, and other factors.
Many homes must be tested for radon before being sold. But for those who are unclear about their own home, Dr. Bellamy recommends that everyone take the risk seriously and check reputable online resources, such as the EPA and the National Cancer Institute websites, if they want to learn more. “I think the EPA has a great message, which is very clear: ‘Test. Fix. Save a life.’ ”
Learn more about radon from the EPA and National Cancer Institute.
