Radon Levels in Delaware
Delaware is classified as an EPA Zone 2 state with a moderate risk for radon. Average indoor radon levels range from 1.5 to 4.5 pCi/L, and approximately 20% of Delaware homes test above the EPA action level of 4.0 pCi/L.
Delaware Radon Summary
Key Facts About Radon in Delaware
- Northern Delaware (New Castle County) has the highest radon levels
- Southern Delaware's sandy coastal plain has lower levels
- The state recommends testing all homes
Delaware Testing Requirements & Recommendations
Delaware Division of Public Health recommends testing all homes and includes radon in home inspection recommendations.
Radon-resistant new construction techniques are required in Zone 1 areas of Delaware.
Major Cities in Delaware
Radon levels can vary significantly within Delaware depending on local geology. All residents — regardless of city — should test their specific home, as neighborhood-level radon varies independently of broader state and county averages.
What Should Delaware Residents Do?
Test Your Home
Use a short-term charcoal test kit ($15–$25) for an initial reading, or a continuous radon detector for ongoing monitoring. Test in your basement or lowest livable area.
Understand Your Result
If your result is below 2.0 pCi/L: monitor periodically. Between 2.0–4.0 pCi/L: consider mitigation. Above 4.0 pCi/L: the EPA recommends mitigation. Above 8.0 pCi/L: take action promptly.
Hire a Certified Contractor if Needed
Look for NRPP or NRSB-certified radon mitigation contractors in Delaware. Mitigation systems typically cost $800–$2,500 and can reduce radon levels by 50–99%.
Verify with a Follow-Up Test
After mitigation, test again to confirm the system is working. Retest every 2 years, or after significant home renovations.
Some links are affiliate links. Learn more.
