10/15/2025
Non-smokers get lung cancer more often than most people realize.
In the U.S., about 10%–20% of lung cancers—roughly 20,000 to 40,000 cases each year—happen in people who never smoked (or smoked fewer than 100 ci******es in their lifetime). That’s not rare. It’s a major public-health issue.
So what’s driving those cases?
A big piece of the puzzle is radon, a natural radioactive gas that seeps into homes from soil and rock. You can’t see it or smell it, but breathing it for years damages lung tissue. The U.S. EPA estimates about 21,000 lung-cancer deaths each year are linked to radon, making it the #1 cause of lung cancer in people who don’t smoke and the #2 cause overall (after smoking).
What about secondhand smoke?
Yes—secondhand smoke causes lung cancer, too. Among adults who don’t smoke, secondhand smoke is linked to ~7,300 lung-cancer deaths per year in the U.S., and it raises a non-smoker’s lung-cancer risk by 20–30%. Radon is also a contributor to non-smoker lung cancer, with CDC estimating ~2,900 of these non-smoker cases tied to radon each year. The bottom line: both matter, and both are preventable exposures.
“Isn’t there a safe level?”
Government guidance is practical, not a promise of safety. The EPA “action level” is 4.0 pCi/L—that’s the point where they recommend fixing your home. But they’re clear: there’s no known safe level of radon, and they even suggest considering fixes between 2 and 4 pCi/L. Think of the number like a speedometer for radon: lower is always better.
Easy way to picture risk without the jargon:
Global health agencies find that for each step up in radon, lung-cancer risk goes up in a straight line—about 16% higher risk for every typical “step” (100 Bq/m³ ≈ 2.7 pCi/L) of long-term exposure. That means reducing your home’s radon number meaningfully lowers risk over time.
How common is radon in homes?
Nearly 1 in 15 U.S. homes has radon at or above the EPA’s action level. That’s millions of homes nationwide, across every kind of neighborhood and construction type. You won’t know your number until you test.
California specifics:
Radon has been found in every California county. The state and geological survey publish radon potential maps to show areas where high readings are more likely—but maps can’t predict a single house. Testing is the only way to know.
Want a concrete California datapoint? The American Lung Association reports that about 8.2% of California test results are at or above the EPA action level—putting California in the higher tier nationally. Again: that doesn’t mean your home has high radon; it means enough homes do that testing is smart.
Radon and smoking together: a dangerous multiplier.
If someone smokes in a home with elevated radon, risks stack, not swap. Smoking remains the #1 cause overall, and radon remains the #1 cause in never-smokers; together they multiply risk—another reason every home should test and fix radon, and everyone should avoid smoke exposure.
What homeowners can do (and what builders should plan for):
• Test every home—especially basements and first floors. Short-term tests are simple, and professional testing gives fast, reliable results.
• Mitigate if your number is high. Radon systems are proven, quiet, and typically installed in a day. They lower the number—and your long-term risk.
• Build with radon in mind. California acknowledges radon potential statewide. Radon-resistant new construction and post-build testing are best practice for safer, healthier homes.
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Local call to action (A.S.E. Safety Consulting, LLC): bryanwbaldwin@yahoo.com 1-916-288-7777
Serving Placer, Nevada, Sacramento, El Dorado, and surrounding counties. We provide certified radon testing, clear reports in plain language, and mitigation guidance if needed. Protect your family. Test your home. Message this page to schedule. (If you’re building or buying, ask about pre-purchase and post-construction testing options.)
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Sources: CDC; U.S. EPA; WHO; California Dept. of Public Health; California Geological Survey; American Lung Association. (See citations throughout.)
