Radon in Delaware County, Pennsylvania
About 1 in 7 homes tested here were at or above the EPA action level.
- Below 2 pCi/L: 57%
- 2 to 4 pCi/L: 29%
- 4 pCi/L or more: 15%
- Typical level
- 1.8 pCi/L
- EPA radon zone
- Zone 1
- In Pennsylvania
- 66th of 67
EPA Zone 1, the highest radon potential (predicted average above 4 pCi/L). The EPA zone map dates from 1993 and is meant for planning; high levels are found in every zone.
What fixing radon costs in Delaware County
From 837 standard systems installed in the county since 2021, as reported to the state. Half of homeowners paid between the low and high figures.
What to do next
Test your home
Radon levels vary between neighboring houses, so area data can't tell you your own home's level. A short-term test takes 2 to 7 days in the lowest lived-in floor. A long-term test (90 days or more) gives a more reliable average.
If your result is 4 pCi/L or more, fix it
A certified professional installs a sub-slab system: a pipe and a quiet fan that pull radon from under the foundation and vent it above the roof. It usually takes a day; the costs are above.
It works: across Pennsylvania, the typical level dropped from 7.7 to 1.0 pCi/L after mitigation, and 95% of homes ended up below the action level.
Use a certified professional
Pennsylvania requires radon testers and mitigators to be certified. The state publishes the list of certified mitigation firms by county.
How Delaware County compares
Share of homes tested at or above 4 pCi/L, with neighboring counties. Lab data 2008–2017, the only source that covers every state.
| Pennsylvania | 41% | |
|---|---|---|
| United States | 36% | |
| Chester County | 29% | |
| Montgomery County | 27% | |
| Delaware County | 21% | |
| New Castle County, DE | 17% | |
| Philadelphia County | 12% |
Radon by zip code in Delaware County
Home tests reported to the Pennsylvania DEP since October 2016, most-tested zip codes first.
| Zip code | Homes tested | Tests | 4 or more | Median |
|---|---|---|---|---|
| 19063 | 4,728 | 23% | 2.3 pCi/L | |
| 19083 | 4,258 | 19% | 2.3 pCi/L | |
| 19026 | 3,925 | 16% | 1.8 pCi/L | |
| 19073 | 3,074 | 18% | 1.8 pCi/L | |
| 19064 | 3,013 | 20% | 2.3 pCi/L | |
| 19010 | 2,866 | 16% | 1.8 pCi/L | |
| 19018 | 2,496 | 12% | 1.8 pCi/L | |
| 19014 | 2,050 | 12% | 1.3 pCi/L | |
| 19342 | 2,039 | 17% | 1.8 pCi/L | |
| 19050 | 2,013 | 15% | 2.3 pCi/L | |
| 19008 | 1,932 | 19% | 1.8 pCi/L | |
| 19086 | 1,603 | 19% | 2.3 pCi/L | |
| 19082 | 1,517 | 10% | 1.8 pCi/L | |
| 19317 | 1,453 | 13% | 1.8 pCi/L | |
| 19036 | 1,404 | 5% | 1.3 pCi/L | |
| 19060 | 1,391 | 20% | 1.8 pCi/L | |
| 19061 | 1,378 | 5% | 1.3 pCi/L | |
| 19015 | 1,366 | 5% | 1.3 pCi/L | |
| 19023 | 1,172 | 3% | 1.3 pCi/L | |
| 19078 | 1,149 | 11% | 1.8 pCi/L | |
| 19081 | 1,148 | 17% | 1.8 pCi/L | |
| 19013 | 969 | 6% | 1.3 pCi/L | |
| 19032 | 798 | 3% | 1.3 pCi/L | |
| 19033 | 736 | 8% | 1.3 pCi/L | |
| 19070 | 729 | 18% | 2.3 pCi/L | |
| 19076 | 686 | 5% | 1.3 pCi/L | |
| 19079 | 615 | 2% | 1.3 pCi/L | |
| 19074 | 490 | 6% | 1.3 pCi/L | |
| 19094 | 359 | 8% | 1.8 pCi/L | |
| 19373 | 258 | 22% | 2.3 pCi/L | |
| 19029 | 243 | 2% | 1.3 pCi/L | |
| 19043 | 229 | 2% | 1.3 pCi/L | |
| 19022 | 214 | 8% | 1.8 pCi/L | |
| 19319 | 32 | 19% | 1.8 pCi/L | |
| 19017 | 20 | 10% | 1.3 pCi/L | |
| 19052 | Too few tests | 11 | – | – |
| 19080 | Too few tests | 4 | – | – |
| 19028 | Too few tests | 2 | – | – |
| 19051 | Too few tests | 1 | – | – |
| 19242 | Too few tests | 1 | – | – |
"–" means fewer than 20 tests, too few for a reliable figure.
Sources
- EPA Map of Radon Zones (public domain).
- CDC Environmental Public Health Tracking Network, radon tests from labs, 2008–2017. Pre-mitigation tests only.
- Pennsylvania Department of Environmental Protection, radon test results and mitigation register via data.pa.gov (public domain). Test records don't say whether a test was taken before or after mitigation.
Last updated October 2026. How we calculate these numbers.