Radon exposure and lung cancer: 11 things to know

After smoking, radon exposure is considered the second most common cause of lung cancer in the United States. It is usually suspected when someone who has never smoked or lived around anyone who smokes is diagnosed with lung cancer. 

But what is radon? How might you encounter it in everyday life? And, is there anything you can do to minimize your risk of exposure?

We spoke with Ernest Hawk, M.D., vice president and head of Cancer Prevention and Population Sciences. Here’s what he shared.

What is radon, and how are people normally exposed to it? 

Radon is a naturally occurring, odorless, colorless, tasteless, invisible and radioactive gas that escapes from certain uranium-containing soils and rock formations. It becomes problematic when enclosed living spaces are built over these areas, typically by seeping into foundational cracks and becoming concentrated in their airspaces. 

This seepage occurs most often at the ground floor level. But depending on the state of ventilation in a particular house — or how “tightly sealed” its windows and doors are — it could affect the upper living areas as well.

What is radon’s connection to lung cancer? 

The association between radon and lung cancer was originally reported in studies of underground miners, but it’s been confirmed in more recent studies of household exposure, too.

When breathed into the body, radon injures the lungs slightly. Typically, it requires years of exposure before it causes any health concerns. But over time, it can cause lung cancer by damaging the cells’ DNA.

How high is the risk of developing lung cancer from radon exposure? 

The Environmental Protection Agency estimates that radon exposure causes approximately 21,000 lung cancer deaths per year in the United States. About 2,900 of those deaths occur among people who have never smoked. 

Your risk of developing lung cancer is considerably higher if you smoke and live in a house affected by radon than if you don’t, but it also depends on the dose and duration of your radon exposure.

Are there any warning signs or symptoms of radon poisoning/radon-caused lung cancer? 

No. Unfortunately, the first signs of significant radon exposure are often the same as the symptoms that precede a lung cancer diagnosis:

• coughing
• shortness of breath, and
• hemoptysis (coughing up blood). 

There are no symptoms specific to radon exposure that I’m aware of.  

Are there any unique features of lung cancer that’s been caused by radon exposure? 

Not to my knowledge. This is an area of lung cancer investigation that has previously been understudied. But no molecular signatures of radon have been identified to date.  

Is lung cancer caused by radon exposure diagnosed or treated any differently than other types? 

Again, not that I’m aware of, though the field of lung cancer treatment has exploded over the last decade, with many interventions directed toward specific molecular derangements.

Still, none specifically have been identified as more commonly occurring in radon- versus tobacco-induced cancers. And there is currently no clinical way of identifying patients who have this subtype of lung cancer.

What’s considered an acceptable range of radon inside a home? 

The Centers for Disease Control and Prevention (CDC) and the surgeon general suggest the remediation of homes when measured levels exceed 4 pCuries/L. The World Health Organization suggests home remediation at a level of 3pCuries/L or higher.

When and how often should you get your home tested for radon pollution? 

The CDC recommends it:

• at the time of purchase, if it’s never been done before
• before and following any renovations, and 
• before deciding to live in the lower levels of a home, such as a basement bedroom. 

This last one is because radon levels tend to be higher in the lower levels of a home than in its upper levels.

Who should consider getting radon detectors or having radon mitigation systems installed? 

Anyone can have their home tested, as test kits are inexpensive and widely available. 

If radon levels are above the level recommended for action, speak with a professional mitigation specialist about sealing foundational cracks and installing a venting system.

Are there any geographical features that can increase your risk of radon exposure?

Yes. Some areas of the country are more commonly affected than others. My family home in Maryland is in such a region. When tested, we found that the ground floor had high levels; but it’s now at sub-threshold levels following successful remediation. However, high radon levels have been reported in every state, so home testing is appropriate for everyone.

And, if you're at high risk — as a heavy smoker, for instance, who has also had significant radon exposure — then it’s worth being screened for lung cancer. Low-dose CT screening can often detect early-stage lung cancer before it spreads.

What’s the one thing you want people to know about radon exposure and lung cancer?

Understanding your risks is an essential first step in preventing cancer. So, it’s worth having your home tested, if you never have before.

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