How urgently should you test your home for radon?
The EPA and the Surgeon General recommend testing every home. Enter your ZIP code or town to see your county's EPA radon zone and what real home tests there have found.
Example result for ZIP 08540. Enter your ZIP code or town above to see yours.
County map
Click a county to look it up.
Counties in this state as a table
What an EPA radon zone tells you, and what it doesn't
In 1993 the EPA assigned every U.S. county to one of three zones, using indoor radon measurements, geology, aerial radioactivity, soil and foundation types. The map was built to help governments target programs and building codes. The EPA says it should not be used to decide whether a particular home needs testing: homes with high radon have been found in all three zones.
Zone 1: highest potential
Predicted average indoor radon screening level greater than 4 pCi/L.
Zone 2: moderate potential
Predicted average indoor radon screening level between 2 and 4 pCi/L.
Zone 3: low potential
Predicted average indoor radon screening level less than 2 pCi/L.
pCi/L is picocuries per liter of air, the U.S. unit for radon. Zones are 1993 predictions. The county test averages shown with each result are real home measurements reported from 2008 to 2017, so the two can differ.
Reading your test result
| Your result | EPA guidance |
|---|---|
| 4 pCi/L or higher | Fix your home. If the first result came from a short-term test, confirm it with a second short-term test or a long-term test. |
| 2 to 4 pCi/L | Consider fixing your home. The EPA notes that levels under 4 pCi/L still pose a risk and in many cases can be reduced. |
| Under 2 pCi/L | Lowest range. Test again if you start living on a lower floor or make major changes to the home. |
Radon in plain terms
Where it comes from
Radon forms as uranium in soil and rock breaks down. It enters homes through cracks and gaps in floors and foundations.
Why it matters
Radon is the second leading cause of lung cancer in the U.S. after smoking. The EPA estimates it causes about 21,000 lung cancer deaths a year.
You can't sense it
It has no color, smell, or taste. A test is the only way to know your level.
Testing is simple
Short-term kits stay in place for 2 to 90 days. Long-term kits run more than 90 days and better reflect your year-round average.