Most homes tell you something before a concern becomes obvious—a stain, a draft, an unfamiliar sound, or a change in the air.
Radon is different.
This naturally occurring radioactive gas has no color, odor, or taste. It can enter a home through foundation cracks, construction joints, gaps around pipes, sump openings, and other pathways from the soil below. Because it leaves no warning signs a homeowner can recognize, testing is the only way to know a home’s radon level.
Why Every Home Deserves a Test
The U.S. Environmental Protection Agency recommends that all homes be tested for radon. A home’s age, foundation type, or location cannot determine its radon level.
Conditions can vary from one property to the next—even between neighboring homes—because the soil, geology, foundation openings, and air pressure within each house are different.
Radon is the second-leading cause of lung cancer in the United States after smoking—and the leading cause among people who have never smoked. That makes testing important information, but not a reason for panic. Elevated radon levels can usually be reduced using established mitigation methods.
What the Result Actually Means
Radon is measured in picocuries per liter of air, written as pCi/L.
- Below 2 pCi/L: This is below the range in which the EPA advises homeowners to consider mitigation, although no radon level is considered entirely risk-free.
- Between 2 and 4 pCi/L: The EPA recommends considering steps to reduce the level. This should not be dismissed as merely something to monitor.
- At or above 4 pCi/L: The EPA recommends fixing the home after the result has been confirmed according to appropriate testing guidance.
A radon result does not identify exactly where the gas is entering, and it does not prescribe a particular repair. It gives the homeowner something more useful: a reliable basis for deciding whether additional testing or a conversation with a qualified radon professional should come next.
Short-Term and Long-Term Testing
A short-term test remains in the home for between two and 90 days, depending on the device. It provides a faster reading and is often used as the first step.
A long-term test remains in place for more than 90 days. Because radon levels can change from day to day and season to season, a long-term test is more likely to reflect the home’s year-round average.
If an initial short-term result is 4 pCi/L or higher, EPA guidance calls for a follow-up test. That may be a long-term test for a better understanding of the annual average or a second short-term test when an answer is needed sooner. The higher the first result, the more important prompt follow-up becomes.
Real-estate transactions may use different, time-sensitive testing procedures, so buyers and sellers should follow applicable state requirements and qualified testing protocols.
If You Already Have a Mitigation System
A mitigation system is not something to install and forget.
Locate its warning device or pressure indicator and learn what its normal operating position looks like. That indicator can help show whether the system is moving air correctly, but it does not measure the home’s current radon level.
The EPA recommends testing after mitigation work is completed and retesting at least every two years to confirm that radon levels remain low. Fans and other system components can eventually fail, even when the system still appears intact.
Three Invisible Checks—Three Different Questions
Radon testing is often discussed alongside carbon monoxide and smoke alarms, but each serves a different purpose.
A radon test measures the concentration of radon in the home. Carbon monoxide alarms should be installed on every level and outside sleeping areas. Smoke alarms should be installed on every level, inside bedrooms, and outside sleeping areas. Interconnected smoke alarms provide greater protection because when one sounds, they all sound.
Alarm placement, testing, and replacement should follow the manufacturer’s instructions and applicable local requirements.
What to Actually Do With This
Find out whether your home has been tested, when the test was performed, where the device was placed, and what the result was.
If the information is old, incomplete, or unavailable, testing creates a useful baseline. If a mitigation system is present, record its installation information, check its operating indicator, and confirm when the home was last retested.
This is not about assuming the worst. It is about knowing the one number your home cannot reveal on its own.
Ready to Organize What Your Home Is Telling You?
The GenTree Property Intelligence Report™ helps you document observations and available information from eight areas of the home—including radon testing history, mitigation systems, and other invisible-hazard considerations—and turn them into clearer priorities for appropriate follow-up.
The report does not test for radon, certify alarms, evaluate indoor air quality, or replace qualified professionals. It helps you record what is known, identify what remains unanswered, and prepare for better conversations with the right experts.
Available for $149.
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