Radon Testing: Common Questions Answered
Radon Testing: straight answers to the questions people actually ask, with the figures behind them.
Testing indoor air for radon, a radioactive gas from soil and rock that you cannot see, smell or taste.
Key takeaways
- EPA action level: 4 pCi/L or higher: fix the home
- Between 2 and 4 pCi/L: EPA recommends considering a fix
- Most useful single change: Test every home, whatever its age or location; neighbors' results do not predict yours.
- Commonest mistake: Assuming new homes or homes without basements are radon-free.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What is Radon Testing?
Testing indoor air for radon, a radioactive gas from soil and rock that you cannot see, smell or taste.
Why does it matter?
Radon is the second leading cause of lung cancer in the US and the leading cause among people who have never smoked, and testing is the only way to know your level.
EPA action level for Radon Testing?
4 pCi/L or higher: fix the home.
Between 2 and 4 pCi/L for Radon Testing?
EPA recommends considering a fix.
Homes with elevated radon for Radon Testing?
About 1 in 15 US homes, per EPA.
Lung cancer deaths linked to radon for Radon Testing?
About 21,000 a year, per EPA.
What is the single most useful thing to do?
Test every home, whatever its age or location; neighbors' results do not predict yours.
What is the most common mistake?
Assuming new homes or homes without basements are radon-free.
When should I see a doctor?
See your doctor about lung cancer screening and any symptoms if you have lived with high radon, especially if you smoke or used to. See your doctor for a cough that will not go away, coughing up blood, chest pain or unexplained weight loss, and call 911 for severe trouble breathing or coughing up large amounts of blood.
More questions, answered
Do apartments need radon testing?
Radon is usually highest on the lowest floors, so ground-floor and basement units are most worth testing. Higher floors usually have lower levels, but elevated readings can still happen. If you live on a lower floor, a simple test is a reasonable step, and your state radon program can advise.
Can an air purifier remove radon?
Standard air purifiers are not a substitute for mitigation. Radon is a gas, and HEPA filters are designed to catch particles. The proven approach is to stop the gas entering the home, usually with a soil depressurization system, and then retest to confirm the level has dropped.
Is a digital radon monitor as good as a test kit?
Continuous digital monitors can be useful for watching trends over time and spotting changes, such as a mitigation fan failing. For decisions about repairs or a home sale, use a test device or professional measurement that meets the standards your state recognizes, and follow the placement instructions carefully.
Does opening windows lower radon?
Opening windows can temporarily lower levels by diluting indoor air, but levels usually return when windows close. It is not a reliable long-term fix, and it can skew a test result. For testing, keep windows and outside doors closed as directed, apart from normal coming and going.
Is radon a problem only in certain states?
Some regions tend to have higher levels, and EPA publishes radon zone maps, but high readings have been found in every state. Maps describe average risk across an area, not the level in your home. Testing is the only way to know your own home's level.
Should a home sale fall through over radon?
Not usually. High radon is a fixable problem. Buyers and sellers often agree on mitigation before closing or a price adjustment. Make sure testing follows your state's rules for real estate transactions, and ask for a post-mitigation test result as proof the system works.
Related topics
- Air Quality: What the Evidence Actually Says (Respiratory Health)
- Carbon Monoxide During Power Outages: What the Evidence Actually Says (Heat, Cold and Weather Safety)
- Sun Protection: What the Evidence Actually Says (Skin Health)
- Reducing Cancer Risk: Sorting the Evidence From the Noise (Cancer Awareness)
Where to go next
- New to Radon Testing? Start Here
- Radon Testing: Just the Figures
- Radon Testing — the reference entry
- Environmental Health: The Complete Guide
- What the Guidance Really Says About Mold at Home
- What the Guidance Really Says About Drinking Water and Private Wells
When to speak to a doctor
See your doctor about lung cancer screening and any symptoms if you have lived with high radon, especially if you smoke or used to. See your doctor for a cough that will not go away, coughing up blood, chest pain or unexplained weight loss, and call 911 for severe trouble breathing or coughing up large amounts of blood.
Where this comes from
- EPA — A Citizen's Guide to Radon
- National Cancer Institute — Radon and Cancer
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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