Environment
Radon. The #2 cause of lung cancer you’ve never tested for
Applies to: Lung
Radon is an odorless radioactive gas and the leading cause of lung cancer in never-smokers. Testing costs about $15, and fixing a high level is far cheaper than you'd think.
Full guide
The bottom line
Radon is a colorless, odorless radioactive gas that seeps up from the ground into homes. It is the second leading cause of lung cancer after smoking, and the leading cause among people who never smoked. It causes an estimated 21,000 lung cancer deaths a year in the US. And testing for it costs about $15. Almost no one does it.
How it gets into your home
Radon comes from the natural breakdown of uranium in soil and rock. It enters through cracks in foundations, gaps around pipes, and crawl spaces, then accumulates, especially in basements and lower floors. Any home can have high radon: new or old, drafty or sealed, with or without a basement. You cannot predict it by looking. You have to test.
How to test (it’s genuinely this easy)
Buy a short-term radon test kit for $15-$30 at any hardware store or online. You place it in the lowest lived-in level of your home for a few days, then mail it to a lab. Or buy a continuous digital radon monitor (like Airthings, ~$150-$250) that tracks levels over time and syncs to your phone. For a one-time check, the cheap kit is plenty.
What the numbers mean
Radon is measured in picocuries per liter (pCi/L). The EPA action level is 4.0 pCi/L or higher — at or above this, you should fix it. The EPA also suggests considering action between 2 and 4. The average indoor level is about 1.3; outdoor air is about 0.4. There is no truly "safe" level, but lower is better.
If your level is high
Radon is fixable. A radon mitigation system — essentially a vent pipe and fan that pulls radon from beneath your foundation and releases it above the roof — typically costs $800-$2,500 and reduces levels dramatically. Use a certified radon mitigation professional (find one through your state radon program or the national certification bodies below).
Resources
- EPA Radon: epa.gov/radon. The national guide, plus a map of radon zones.
- National Radon Hotline: 1-800-SOS-RADON (1-800-767-7236).
- Your state radon program — many offer free or discounted test kits.
- AARST-NRPP (nrpp.info) and NRSB (nrsb.org) — find certified radon testers and mitigators.
- Airthings, Ecosense — continuous home radon monitors, if you want ongoing tracking.
