How Common Is Radon in Homes?

On this page (7 sections)

1. How common is radon in homes across the United States?
2. Why can radon levels differ between nearby homes?
3. Can you tell if a home has radon without testing?
4. What does a radon test tell you?
5. How do you test for radon at home?
6. What should you do if a test finds raised radon?
7. How common is radon, and what should you do next?

Radon can be found in homes across the United States, but levels vary from house to house. A home's location or foundation type can't tell you its radon level, so testing is the way to find out.

The U.S. Environmental Protection Agency estimates that about 1 in 15 homes has raised radon.

That estimate describes a broad national pattern, not the odds for a particular house or neighborhood.

Radon is a naturally occurring radioactive gas that can move from soil into buildings. It has no color or smell, and a home can have raised levels without any obvious sign.

How common is radon in homes across the United States?

The EPA estimates that about 1 in 15 U.S. homes has raised radon. The estimate is useful for understanding why testing matters, but it doesn't predict an individual home's result.

Radon levels vary with local geology and the way a building connects to the ground. Homes on the same street can test differently, and a low regional average doesn't rule out a high reading in one house.

The EPA recommends testing all homes for radon. If you're deciding who needs a radon detector, the short answer is that any household can benefit from knowing its level.

Why can radon levels differ between nearby homes?

Two nearby homes can have different radon levels because each has different soil contact, openings, and airflow. A neighbor's test result can prompt you to test, but it can't stand in for a measurement in your home.

Radon may enter through cracks, construction joints, gaps around pipes, sump openings, or crawl spaces. Air pressure inside a home can draw soil gas through these paths, while weather and ventilation can affect how much builds up indoors.

Homes also differ in how rooms connect to the ground. A basement, slab, or crawl space can all have radon entry points, so homes without basements can still have radon.

A basement does not guarantee a particular result; see whether houses with basements have radon.

Is radon gas common even in newer homes?

Yes, newer homes can have radon because the gas comes from the ground, not from the age of the building. A newer foundation may still have pathways where soil gas can enter.

Older properties need testing too; see radon checks in older homes.

New construction, sealed windows, or energy-saving features don't prove a home is radon-free. Test after moving in, and follow local guidance about when to retest after renovations or changes to heating and ventilation.

Can you tell if a home has radon without testing?

No. You can't see or smell radon, and everyday signs in a home don't show its concentration.

A test is needed to measure the level.

Radon is not the same as natural gas used for cooking or heating. Learn whether radon is natural gas and what makes it different from fuel gas.

Color isn't a clue, either. Radon is colorless, so a visual check can't show whether it's present; see what color radon is.

What does a radon test tell you?

A radon test measures the level in the place and time tested. It gives you a basis for deciding whether to test again or ask a qualified radon professional about next steps.

Follow the test kit's directions for placement, timing, and mailing or returning the sample. Keep the test in the area you use as directed, and avoid conditions that could invalidate the result, such as opening windows when the instructions say to keep them closed.

A short-term test can provide an initial screening. If a result is raised or close to an action level, follow EPA or local health department guidance on confirmation and mitigation.

Do home radon detectors work?

Home radon detectors and test kits can help measure radon when used as directed. The right choice depends on whether you want an initial test or ongoing readings.

A mail-in kit includes a sample and lab processing, while an electronic monitor may display readings at home. Check how each option measures radon and follow its instructions; our guide explains whether home radon detectors work.

For a straightforward initial screen, the First Alert Radon Gas Test Kit includes test materials and lab fees, except New Jersey state fees, with results emailed within 72 hours after the lab receives the test. It is recommended for use only in the United States.

How do you test for radon at home?

Use a radon test kit or monitor according to its instructions, placing it in the recommended lived-in area. The test's timing and room conditions matter, so follow the exact steps supplied with the method you choose.

The EPA recommends testing the lowest lived-in level of a home, such as a basement or first floor. Don't test an unfinished area you don't use unless local guidance or the test instructions say to.

Our step-by-step guide covers how to test for radon at home, including where to place a test and how to handle the sample. If you use a natural gas detector for a separate concern, read our PT520A natural gas detector review; that type of detector doesn't measure radon.

What should you do if a test finds raised radon?

If your result reaches or exceeds the EPA action level of 4 pCi/L, contact a qualified radon professional about reducing the level. The EPA also advises considering mitigation for readings between 2 and 4 pCi/L.

Radon exposure over time increases lung cancer risk, and smoking adds to that risk. A test result is not a diagnosis, but it gives you information to guide a practical next step.

Don't rely on opening windows as a lasting fix. Ask a qualified professional about mitigation options and follow-up testing after work is complete.

A basement water alarm can serve a separate purpose in homes with a sump or water entry concern. The Basement Watchdog alarm has a detachable sensor on a 6 ft wire and a 110 dB alarm, but it does not detect radon.

Carbon monoxide alarms address another household gas hazard, not radon. The First Alert plug-in CO alarm has a digital display and battery backup for carbon monoxide monitoring.

How common is radon, and what should you do next?

Radon is common enough that every household should consider testing, while each home's actual level remains unknown until measured. National estimates explain the need, but your own test guides your decision.

Test the lowest lived-in level, follow the kit or monitor instructions, and use EPA guidance to interpret the result. If the result is raised, seek advice from a qualified radon professional and arrange follow-up testing after mitigation.

Frequently asked questions

How common is radon in homes?

Radon can occur in homes throughout the United States, though the amount varies by building and location. The EPA estimates that about 1 in 15 U.S. homes has raised radon, but a national estimate can't predict an individual home's level.

Testing is the only way to know.

Can a new home have radon?

Yes. A newer home can have radon because the gas comes from the ground and can enter through openings in a foundation or slab.

New construction and energy-efficient features don't guarantee a low level, so test after moving in and retest if you make major changes or follow local guidance.

Are homes without basements at risk for radon?

Yes. Radon can enter through a slab, crawl space, or other ground-contact area, so a basement isn't required.

Test the lowest lived-in level of the home, following the test kit's directions, even if the house is built on a slab.

Does a high radon level mean the whole neighborhood has it?

Not necessarily. Nearby homes can have different radon levels because soil, foundation details, air pressure, and ventilation vary.

A neighbor's result can be a reason to test, but it can't replace a measurement in your own home.