Is radon dangerous?
Yes. Radon can cause lung cancer, EPA and PA DEP say. The risk comes from breathing it at home for years, and you can lower it by testing and fixing your home.
Part of our radon guides for York County homeowners.
How Does Radon Harm You?
It damages your lungs over time. PA DEP's Citizen's Guide to Radon (revised 2014) explains how:
You breathe it in
Radon gas breaks down into radioactive particles in the air you breathe.
Particles get trapped
The particles can get trapped in your lungs.
Lung tissue is damaged
As they break down, they release small bursts of energy that can lead to lung cancer over your lifetime.
Not everyone exposed to high radon gets lung cancer, DEP says, and it may be many years before it shows up. Your chances depend mostly on how much radon is in your home, how much time you spend there, and whether you smoke or have ever smoked.
How Big Is the Risk From Radon?
It grows with the level and is far higher for smokers. EPA's tables give the lifetime risk of dying of lung cancer for people who live at one radon level their whole life.
Lifetime risk of dying of lung cancer from radon · US EPA. The average outdoor level is about 0.4 pCi/L.
At 4 pCi/L, the risk for people who never smoked is about the same as the risk of dying in a car crash. Former smokers may fall between the two: EPA says their risk may be higher than a never smoker's and lower than a smoker's.
In PA DEP's results, over half of York County ZIP codes have a basement average of 10 pCi/L or more. Those come from short-term, closed-house basement tests, which DEP says tend to read higher than a year-round level. Only a test of your own home tells you your level.
Why Is Smoking Worse With Radon?
The two together raise your risk sharply. DEP calls smoking combined with radon an especially serious health risk, and says that if you stop smoking and lower your home's radon level, you can reduce your risk.
How Sure Are Scientists That Radon Causes Lung Cancer?
Sure that it does, less sure how many deaths it causes. DEP says scientists know more about radon risks than about most other cancer-causing substances, because the estimates come from studies of underground miners.
EPA says two studies reported in 2005, which pooled earlier studies of radon in homes, confirmed the risks the miner studies predicted. DEP says some scientists dispute the exact number of deaths, but all major health groups, including the CDC, the American Lung Association and the American Medical Association, agree that radon causes thousands of preventable lung cancer deaths every year.
What Should You Do About Radon in Your Home?
Test your home. DEP says testing is the only way to know if your family is at risk. EPA says to fix your home if your level is 4 pCi/L or higher, and to consider fixing between 2 and 4 pCi/L.
Radon Health FAQs
Can radon cause lung cancer if I don't smoke?
Yes. EPA estimates radon is the number one cause of lung cancer among non-smokers. Of the roughly 21,000 radon lung cancer deaths a year in EPA's 2003 estimate, EPA says about 2,900 are among people who have never smoked.
Is any level of radon safe?
EPA says no. PA DEP's Citizen's Guide says EPA believes any radon exposure carries some risk and no level of radon is safe. Levels below 4 pCi/L still pose some risk, and lowering your level lowers your risk.
Are children at greater risk from radon?
It isn't known. PA DEP's Citizen's Guide says children have been reported to have greater risk than adults of certain cancers from radiation, but there are currently no conclusive data on whether children are at greater risk than adults from radon.
Is radon in well water dangerous?
It adds some risk, but in most cases a small one next to radon from the soil. PA DEP's consumer's guide says most of the risk from radon in water comes from radon released into the air when you shower or use water in other ways. Swallowing it is a small risk.
Keep Reading About Radon in York County
Sources
- US EPA: Health Risk of Radon
- PA DEP: Pennsylvania Citizen's Guide to Radon (2900-BK-DEP0375)
- PA DEP: Pennsylvania Consumer's Guide to Radon Reduction
- PA DEP radon test results by ZIP code
Guide last updated Oct 2026. Published by Radon Mitigation York. How we write our guides.