What Everyone Needs to Know About Radon Exposure and Lung Cancer
Posted on January 21, 2025
Source:
HealthCentral
Every two minutes in the U.S., someone is diagnosed with lung cancer, according to the American Lung Association. As you’d probably guess, the predominant cause of lung cancer is (and has been for many decades) smoking cigarettes, driving nearly 90% of cases annually.
However, in recent years, medical oncologists, surgeons, and researchers are beginning to notice that people who’ve never before touched a tobacco product now comprise an increasing segment of total lung cancer cases.
“Lung cancer is the leading cause of cancer death in this country, and we must do more to reduce this significant burden,” says Kevin Stewart, the director of environmental health at the American Lung Association, who is based in Essington, PA. While smoking cessation efforts are still important, “there needs to be more public education about other, lesser-known risks,” too, he adds. And with recent research suggesting that lung cancer diagnoses are starting to skew younger than in years past, increased awareness on this issue may be more pressing than ever.
Which begs the question: As tobacco use has steadily plummeted over the past few decades, what other dangers might account for the growing ratio of younger adults versus older adults being diagnosed with lung cancer?
Hidden Dangers Behind Lung Cancer
Top of a growing list of concerns: Radon. This naturally occurring radioactive gas is a serious lung cancer threat that everyone, smokers and non-smokers alike, need to be aware of, he warns. Radon is the product of the breakdown, or radioactive decay, of uranium, found in nearly all types of soil, which can then rise into your home through cracks and other openings in its foundation.
In fact, data show that radon exposure is now the second-leading cause of lung cancer, driving about 21,000 deaths in the U.S. per year. Research ties it to both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). And with so many Americans continuing to work from home due to the COVID-19 pandemic—with some people potentially facing radon exposure 24/7—those numbers may only rise.
If you’ve never heard of radon, you’re not alone. Several recent surveys reveal that a majority of Americans aren’t aware of this sneaky killer lurking in U.S. homes. That’s because it’s not something you can detect with any of your five senses. “It's invisible, colorless, odorless, and tasteless,” notes Stewart.
"Radon is often an unappreciated risk factor [for lung cancer] that has become more recognized over the last two decades,” says Michael Menefee, M.D., a medical oncologist who specializes in thoracic malignancies at the Cleveland Clinic in Ohio. “But we as a society—in terms of the medical society and local governments—could do a better job of making citizens aware of the potential risks and doing things to mitigate that risk.”
At the molecular level, radon is an atom. It seeps through both noticeable and unnoticeable openings on the ground floor of your home, such as cellars and basements, and can also enter buildings that are constructed with crawlspaces or are built slab-on-grade. “A microscopic crack is like the Grand Canyon to an atom of radon,” Stewart says, meaning it’s very easy for the gas to penetrate through the floor or walls and enter your home. The Environmental Protection Agency (EPA) also notes that radon can be dissolved in well water, especially in areas where drinking water is primarily sourced from groundwater.
Radon doesn’t just affect the ground floor of your home—the odorless gas can flow upward into the middle and upper levels of any building. “I've seen drawings that show buildings as vacuum cleaners, where, at the lower levels, there are openings that are negatively pressurized, relative to the soil,” he says.
Keep in mind, buildings are not airtight structures. As warm air rises throughout the mid- and upper levels of your home, the pressure at those levels increases, Stewart explains. Some of this air escapes around window frames, attics, and the building envelope. But “as the building loses air at the upper levels, air pressure is decreased at the lower levels,” he adds. Lower air pressure inside the building than in the outside atmosphere is the result—and “the building seeks to ‘make up’ that lost air,” he says.
Cue: radon entry. Air is drawn in around windows and doors at the lower levels of your home or building. “The building also draws in ‘soil gas,’ or the gas between grains of soil and rock under and around the building foundation,” Stewart adds, which contains radon. This air movement phenomenon is called the “stack effect,” he notes.
And this is how your home can work like a vacuum’s suction, with radon measuring at high levels at the lowest level of a building, says Stewart. “As that air moves—gradually if by natural air movement, more quickly if by forced air movement—throughout the house, it will also be mixed with incoming air from the outdoors. This, along with the natural slow decay of radon, results in lower levels of radon being typical for upper floors of a home than those found in its lower floors.”
Why Is Radon So Toxic?
Radon, on its own, does not cause most of its associated lung cancer risk—nor can it generally be inhaled at hazardous levels outdoors, where it is diluted by fresh air. Because the gas has a relatively long half-life of 3.8 days, people will breathe it in, and then breathe out most of it, before it ever has time to decay in the lungs, says Stewart.
However, once radon does undergo radioactive decay, the particles that it emits are toxic to human health, particularly the lungs. “Radon will decay and form radioactive elements that aren't gases anymore, but are now solids—atoms that, unlike radon, more easily stick to things,” he notes.
As radon decays, it forms atoms of polonium, Stewart explains, which then attach to other microscopic airborne particles in your home. As you breathe in these radioactive elements, they can become embedded into your lung tissue. Over a brief period of time, long before the lungs can clear them out, these atoms will further decay, emitting particles that damage your DNA and that can cause tumors in your lung tissue.
Exposure to radon decay products can go on for decades before symptoms arise. “There are no immediate symptoms of exposure,” Stewart says. “For example, you don’t immediately start coughing when you're exposed to radon.”
Where and How You Live Increases Radon Exposure
Geology can affect radon levels in your home. “There are parts of the country that have the types of rocks that are more likely to have higher levels of uranium and are more likely to be structured in such a way that radon, once it's formed, can get out of the rock more easily,” Stewart says.
In the case of Ohio, shale in the soil contains high concentrations of uranium. In South Dakota, where 59.8% of radon test results are at or above the action level recommended by the EPA, radon is believed to come from metamorphic rocks from the Rocky Mountains. You can see which states are at increased risk of high radon levels by looking at the Lung Association’s 2024 State of Lung Cancer Report, or by checking out the EPA Map of Radon Zones.
Still, it’s not wise to obsess over where you’re located in the country, Stewart points out, because that information alone doesn’t paint the whole picture. “You can't just look at the geology and say, ‘This place will definitely have high radon,’” he says. “It really does depend on what's going on right at the foundation of your individual building. We also recognize the factor of differences in climate among different areas of the country.”
For instance, some parts of the country have longer heating seasons and/or winters. “Generally speaking, it is the heating season of the year that tends to draw more radon into the house than other seasons, where you're not actively creating this suction effect in the house,” Stewart says. If your home has a radiant floor heating system installed on the ground floor, that warm air can push radon from the ground floor up into other levels of the home. In the winter, you may not be as likely to open up the windows and get cross-ventilation in the house.
Hawaii residents rarely deal with radon issues because of the state’s geology and climate. Plus, residents don’t usually have to heat their homes. “Those things work in concert to make Hawaii an almost radon-free state, but it's not 100% radon-free,” Stewart says. “Even in Hawaii, high radon levels have been found in homes.”
What lies beneath the foundation of your home or an apartment can also affect how much radon enters into it. Let’s say you’re living in Alaska. You may have the choice between a house with a foundation built over permafrost versus one that sits on a rocky foundation. Permafrost may inhibit radon from seeping into your home because as long as it remains frozen, it will continue to trap gas, keeping radon from seeping into your home’s foundation. Of course, with global warming at play, the thawing of permafrost is a real concern, since rising temps can release trapped radon gas into homes.
If you live in an apartment building, particularly on the upper levels, you will typically have far less exposure to radon than those living on the ground floor. Interestingly, NYC has a relatively low risk for radon exposure compared to the rest of New York state. Nevertheless, there are cases, such as in Florida, where building materials emitting radon can result in high levels of the gas in upper floors of high-rises.
Is Radon Behind a Rise in Younger Adults Getting Lung Cancer?
Younger adults being diagnosed with lung cancer with greater frequency is alarming—and causing experts to look for an explanation. According to recent data from UCLA Health, about 10% of people with lung cancer in the country are 55 or younger. Younger women may be more at risk than men. And shifting U.S. population numbers—with more younger “never-smokers” than in previous decades, as older long-time smokers dwindle in number—may not be the only factor to consider.
“When I started my career 20-plus years ago, almost all my patients were in their 60s, 70s, or 80s,” Dr. Menefee says. “I think the youngest patient I had was maybe 50 years old, and that was kind of shocking at that time. Now, we're clearly seeing people in their 30s and 40s developing lung cancer."
A logical question: Is radon exposure to blame? As work-from-home became a mainstream option after the global pandemic, particularly among Millennials and other younger adults in flexible work situations, it’s logical to conclude that exposure to radon may have increased over the past five years.
The Indoor Environments Association quantifies radon exposure based on how many hours per day a person spends at home. For instance, if a person usually spent 12 hours a day at home but now spends 24 hours a day at home, working remotely during the day and sleeping there at night, that means their annual radon exposure increased by 50%. Which could ultimately increase the risk of lifetime lung cancer threefold (albeit still a small number, raising it from 1% to 3%), according to the organization.
But there isn’t yet enough data, Dr. Menefee notes, to confirm that radon is the only culprit behind the changing ratio of lung cancer risks among younger adults, primarily because there is no exact way to pinpoint the exact cause of a particular individual’s lung cancer. Other environmental factors that we aren’t yet aware of could also be causing an earlier onset of lung cancer.