Short answer: the median radon test in Delaware County was 1.9 pCi/L (CDC, lab tests 2008 to 2017). That is lower than most of Pennsylvania, but a low median still leaves plenty of homes above 4 pCi/L.
How Delaware County compares
Delaware County’s median of 1.9 pCi/L ranks #65 of 67 Pennsylvania counties with CDC data. The middle Pennsylvania county median is 3.8 pCi/L, so Delaware County is below the state’s typical county. EPA puts the county in Zone 1, the highest-potential zone on EPA’s map (predicted average indoor level above 4 pCi/L).
These numbers come from tests homeowners and buyers chose to run, not a random survey. They show local risk; they cannot predict the level in your house.
Certified radon mitigation pros based in Delaware County
Each listing below appears on Pennsylvania DEP’s certified mitigation list dated September 1, 2026. We show the city on file and the DEP certification number so you can confirm it.
Gary Olinchak
Certified individual based in Crum Lynne, PA
PA DEP certified mitigationCertification #3003
Certified firms in neighboring counties
- Safe Shelter Environmental (West Chester, Chester County)
- Accurate Radon Control Inc (Green Lane, Montgomery County)
- Airotox (Lansdale, Montgomery County)
- Radon Technology & Enviromental Inc (Royersford, Montgomery County)
- Radon-Rid LLC (Phoenixville, Montgomery County)
- RVS Radon Mitigation, LLC. (Philadelphia, Philadelphia County)
Radon in counties next to Delaware
| County | Median pCi/L | EPA zone |
|---|---|---|
| New Castle, DE | 1.8 | Zone 2 (moderate) |
| Chester, PA | 2.2 | Zone 1 (high) |
| Montgomery, PA | 2.2 | Zone 1 (high) |
| Philadelphia, PA | 1.5 | Zone 3 (low) |
What to do in Delaware County
- Test your home. EPA recommends testing every home below the third floor, whatever the county average.
- Fix it at 4 pCi/L or higher. EPA also suggests considering a fix between 2 and 4 pCi/L.
- Use a certified pro. In Pennsylvania, radon mitigation for pay requires DEP certification. Check the number against the state list before you sign.
- Retest after the system is installed.
Sources
- County median radon levels and test counts: CDC Environmental Public Health Tracking Network, radon tests from labs, 10-year period 2008 to 2017 (ephtracking.cdc.gov).
- Radon zones: U.S. EPA Map of Radon Zones (epa.gov/radon).
- Certified mitigation firms and individuals: Pennsylvania DEP list of certified radon mitigation firms dated September 1, 2026 (PDF), checked October 24, 2026.
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