Radon levels in Philadelphia, Pennsylvania
LowEPA Zone 3Predicted long-term basement average of 1.0 pCi/L (model estimate) across the 46 modeled ZIP codes in Philadelphia - about 45% below the US average of 1.8, about 56% below the Pennsylvania average of 2.3. Ranked #12 of 12 Pennsylvania cities on this site. Most of the city lies in Philadelphia County.
Test Philadelphia, PA once anyway - radon varies house to house
The predicted basement average here is 1.0 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. Measured state test results are shown separately below, labeled with their source and years. How the numbers work.
1.0 ± 0.10
pCi/L predicted basement mean (model SD)
0.8 ± 0.09
pCi/L predicted upstairs (above-ground) mean
0.6-1.4
range of ZIP-level basement predictions in the city
0%
of Philadelphia ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)
Measured radon tests in Philadelphia County (Pennsylvania Department of Environmental Protection, 1988-2025)
Actual results from home radon tests reported to the state, separate from the model estimate above. Coverage: 1988-2026.
- Measured mean
- 2.3 pCi/L
- Measured median
- 1.6 pCi/L
- Results ≥ 4 pCi/L
- 11.3%
- Results ≥ 2 pCi/L
- 38.8%
- Basement tests, mean
- 2.5 pCi/L
- Sample
- 116,698 tests
| Figure | Model (predicted) | State tests (measured) |
|---|---|---|
| Mean, pCi/L | 0.9 basement | 2.3 (2.5 basement) |
| Share ≥ 4 pCi/L | not a model output | 11.3% |
The measured mean runs 1.4 pCi/L above the model because state test data is voluntary and skews toward basements, winter, and homeowners who already suspected a problem, while the model estimates the long-term average across all homes.
Source: Radon Test Results September 1986 - Current Annual County Environmental Protection, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection. Public Domain (as stated on data.pa.gov). Method and download.
What this means for Philadelphia
The typical Philadelphia home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 0.6 to 1.4 pCi/L.
The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). The 1993 EPA zone (3) for Philadelphia and the 2001-2021 model agree here.
Comparable Pennsylvania cities: Levittown (1.1), Erie (1.5), Wilkes-Barre (1.6), Scranton (1.7).
ZIP codes in Philadelphia
ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.
| ZIP | Share of city | Basement | Upstairs | Grade |
|---|---|---|---|---|
| 19153 | 5% | 1.1 ± 0.07 | 0.8 | Low |
| 19128 | 5% | 1.2 ± 0.10 | 1.0 | Low |
| 19154 | 5% | 1.1 ± 0.06 | 0.9 | Low |
| 19114 | 4% | 1.2 ± 0.06 | 0.8 | Low |
| 19116 | 4% | 1.0 ± 0.13 | 0.9 | Low |
| 19131 | 4% | 1.2 ± 0.10 | 0.8 | Low |
| 19115 | 4% | 1.4 ± 0.10 | 1.1 | Low |
| 19124 | 4% | 0.8 ± 0.11 | 0.7 | Low |
| 19111 | 4% | 1.1 ± 0.20 | 0.6 | Low |
| 19136 | 4% | 0.9 ± 0.07 | 0.7 | Low |
| 19145 | 4% | 0.6 ± 0.14 | 0.7 | Low |
| 19148 | 3% | 0.9 ± 0.08 | 0.6 | Low |
| 19144 | 3% | 1.1 ± 0.16 | 0.7 | Low |
| 19134 | 3% | 0.7 ± 0.10 | 0.6 | Low |
| 19119 | 3% | 1.1 ± 0.09 | 0.8 | Low |
| 19120 | 2% | 0.9 ± 0.14 | 0.6 | Low |
| 19104 | 2% | 0.9 ± 0.09 | 0.7 | Low |
| 19118 | 2% | 1.4 ± 0.08 | 1.0 | Low |
| 19140 | 2% | 0.8 ± 0.09 | 0.6 | Low |
| 19143 | 2% | 0.7 ± 0.10 | 0.7 | Low |
| 19152 | 2% | 0.9 ± 0.08 | 0.7 | Low |
| 19121 | 2% | 0.8 ± 0.13 | 0.7 | Low |
| 19137 | 2% | 0.9 ± 0.08 | 0.7 | Low |
| 19149 | 2% | 0.8 ± 0.09 | 0.6 | Low |
| 19151 | 2% | 1.1 ± 0.10 | 0.8 | Low |
| 19135 | 2% | 0.8 ± 0.08 | 0.7 | Low |
| 19132 | 2% | 1.1 ± 0.12 | 0.6 | Low |
| 19129 | 2% | 1.3 ± 0.08 | 0.9 | Low |
| 19112 | 1% | — | — | no model |
| 19138 | 1% | 1.1 ± 0.10 | 0.7 | Low |
| 19139 | 1% | 0.6 ± 0.20 | 0.6 | Low |
| 19141 | 1% | 1.1 ± 0.13 | 0.7 | Low |
| 19142 | 1% | 0.7 ± 0.10 | 0.6 | Low |
| 19146 | 1% | 1.0 ± 0.09 | 0.7 | Low |
| 19150 | 1% | 1.1 ± 0.11 | 0.8 | Low |
| 19122 | 1% | 1.0 ± 0.07 | 0.7 | Low |
| 19125 | 1% | 1.0 ± 0.07 | 0.7 | Low |
| 19133 | 1% | 0.8 ± 0.10 | 0.7 | Low |
| 19147 | 1% | 0.8 ± 0.15 | 0.7 | Low |
| 19123 | 1% | 0.9 ± 0.08 | 0.7 | Low |
| 19126 | 1% | 1.2 ± 0.09 | 0.7 | Low |
| 19130 | 1% | 0.9 ± 0.15 | 0.7 | Low |
| 19106 | 1% | 0.8 ± 0.07 | 0.6 | Low |
| 19103 | 1% | 0.8 ± 0.10 | 0.6 | Low |
| 19107 | <1% | 0.7 ± 0.13 | 0.5 | Low |
| 19127 | <1% | 1.2 ± 0.07 | 0.9 | Low |
| 19102 | <1% | 0.8 ± 0.09 | 0.6 | Low |
| 19108 | <1% | — | — | no model |
| 19109 | <1% | — | — | no model |
Testing help in Pennsylvania
Pennsylvania's radon program page is at www.pa.gov; it lists testing and certified-mitigator guidance. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.
Philadelphia radon questions
- Is radon high in Philadelphia, Pennsylvania?
- Low. Averaging the model's ZIP-code predictions across Philadelphia (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.0 pCi/L - about 45% below the US average of 1.8 and about 56% below the Pennsylvania average of 2.3. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Philadelphia ranks 12 of 12 Pennsylvania cities on this site.
- What do actual radon tests show around Philadelphia?
- Pennsylvania Department of Environmental Protection publishes results for Philadelphia County (not the city alone) covering 1988-2025 (116,698 tests): an average of 2.3 pCi/L, a median of 1.6, 11.3% of results at or above the 4 pCi/L action level. These are voluntary home tests, so they skew toward basements and toward homes where radon was suspected; the model's predicted basement average for Philadelphia is 1.0 pCi/L.
- Which Philadelphia ZIP codes have the highest radon?
- Predictions for the 46 modeled ZIP codes in Philadelphia range from 0.6 to 1.4 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
- Should I test for radon in Philadelphia?
- Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Philadelphia's low predicted average describes the typical home, not yours.
- What does EPA Radon Zone 3 mean for Philadelphia?
- Philadelphia sits mainly in Philadelphia County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.
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