What Radon Level Is Safe?

Homeowners often ask whether there is a “safe” radon number. The U.S. EPA says there is no known safe level of radon exposure. Risk generally increases as radon exposure increases.

What Does 4.0 pCi/L Mean?

The EPA recommends taking action to reduce radon when a home tests at 4.0 picocuries per liter (pCi/L) or higher. The EPA also says homeowners should consider reducing radon when results are between 2.0 and 4.0 pCi/L.

What If My Result Is Below 4.0?

A result below 4.0 pCi/L does not mean there is zero risk. EPA guidance notes that even homes below the action level may benefit from future retesting, especially if living patterns or the home change.

Should I Retest an Elevated Result?

The appropriate next step depends on the type of test, the result, and the situation. Real-estate testing may follow specific short-term testing protocols, while homeowners who are not under a deadline may have different confirmation options.

See our guide to when you should retest for radon.

Why Your Home's Number Matters More Than a County Average

Radon varies from property to property. A regional map, neighbor's result, or county average cannot determine the level inside your specific home.

EPA Source

U.S. EPA Radon Publications and Basic Radon Facts

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Radon Testing DMV provides professional 48-hour radon testing for homeowners and real estate transactions across Northern Virginia, Maryland, and Washington, DC.

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General educational information only. For current federal guidance, see the U.S. EPA radon resources linked on this page.