Radon levels in Pennsylvania: Moderate
The model predicts a population-weighted basement average of 2.3 pCi/L (model estimate) across Pennsylvania's 67 counties - about 1.3× the US average of 1.8 pCi/L. Above-ground floors average 1.5 pCi/L.
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.
49 / 67
EPA Zone 1 counties (73%)
17 / 1
Zone 2 / Zone 3 counties
2
counties predicted ≥ 4 pCi/L
33.2%
of measured tests ≥ 4 pCi/L (1988-2026)
Test Pennsylvania - the EPA says "consider fixing" in this range
The predicted basement average here is 2.3 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.
Monitor link goes to the Airthings store - use code RADONGRADE-10OFF at checkout for 10% off any Airthings monitor.
Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.
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What the data says about radon in Pennsylvania
On the EPA's 1993 radon zone map, 49 of Pennsylvania's 67 counties are EPA Zone 1 (73%), 17 are Zone 2 and 1 is Zone 3. Zone 1 - the highest-potential class, predicted screening average above 4 pCi/L - is the most common designation in Pennsylvania. That classification has not been revised since 1993; it describes counties, not homes, and elevated readings turn up in Zone 3 counties every year.
Pennsylvania models out at 2.3 pCi/L predicted basement average (moderate; 1.3× the US population-weighted average of 1.8). Of the 67 counties with predictions, 2 are predicted at or above 4 pCi/L, 57 in the 2-4 band and 8 below 2. The highest predicted county is Lebanon County at 4.8 pCi/L; the lowest is Philadelphia County at 0.9 - a 3.9 pCi/L spread that means a statewide average tells you little about any one county.
At ZIP-code resolution, 2.9% of Pennsylvania ZIPs are predicted at 4 pCi/L or higher in the basement and 79% at 2 or higher - below the national 4.2% at the action level but above the national 48.7% at 2 pCi/L. With more than half of ZIPs above 2, a test is worth doing before any purchase or renovation here.
Measured data exists for Pennsylvania: Pennsylvania Department of Environmental Protection publishes 1988-2026 results for 67 counties (1,872,999 tests). Weighted by test count, the measured mean is 5.7 pCi/L and 33.2% of results are at or above 4 pCi/L. The county with the largest share of elevated results is Fulton County (67.4%); the smallest is Philadelphia County (11.3%). In 67 of the 67 counties with both figures, the measured mean is higher than the model's long-term basement estimate - expected, because state tests are voluntary and skew toward basements and homeowners who suspected a problem. Each county page shows both side by side.
Pennsylvania counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 67 counties. The “Measured ≥ 4” column is the share of Pennsylvania Department of Environmental Protection test results at or above 4 pCi/L, 1988-2026.
| County | Predicted basement | Upstairs | Grade | EPA zone | Measured ≥ 4 | ZIPs |
|---|---|---|---|---|---|---|
| Lebanon County | 4.8 pCi/L | 2.5 | High | EPA Zone 1 | 64.4% | 9 |
| Centre County | 4.2 pCi/L | 2.3 | High | EPA Zone 1 | 55.3% | 22 |
| Franklin County | 4.0 pCi/L | 2.2 | Moderate | EPA Zone 1 | 56.9% | 18 |
| Cumberland County | 3.9 pCi/L | 2.3 | Moderate | EPA Zone 1 | 54.4% | 14 |
| Snyder County | 3.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 45.7% | 10 |
| Huntingdon County | 3.7 pCi/L | 1.9 | Moderate | EPA Zone 1 | 49.2% | 23 |
| Perry County | 3.7 pCi/L | 1.9 | Moderate | EPA Zone 1 | 60.7% | 13 |
| Mifflin County | 3.6 pCi/L | 2.2 | Moderate | EPA Zone 1 | 60.8% | 9 |
| Bedford County | 3.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 53.8% | 20 |
| Juniata County | 3.5 pCi/L | 1.9 | Moderate | EPA Zone 1 | 62.2% | 8 |
| Columbia County | 3.4 pCi/L | 1.8 | Moderate | EPA Zone 1 | 45.9% | 10 |
| Lycoming County | 3.4 pCi/L | 1.7 | Moderate | EPA Zone 1 | 42.1% | 16 |
| Fulton County | 3.4 pCi/L | 1.7 | Moderate | EPA Zone 1 | 67.4% | 10 |
| Clinton County | 3.4 pCi/L | 1.6 | Moderate | EPA Zone 1 | 40.9% | 8 |
| Dauphin County | 3.4 pCi/L | 2.1 | Moderate | EPA Zone 1 | 52.2% | 24 |
| Carbon County | 3.3 pCi/L | 1.7 | Moderate | EPA Zone 1 | 43.9% | 10 |
| Union County | 3.3 pCi/L | 2.0 | Moderate | EPA Zone 1 | 40.6% | 7 |
| Northumberland County | 3.2 pCi/L | 1.6 | Moderate | EPA Zone 1 | 39.9% | 16 |
| Montour County | 3.2 pCi/L | 1.9 | Moderate | EPA Zone 1 | 36.5% | 2 |
| Armstrong County | 3.1 pCi/L | 1.8 | Moderate | EPA Zone 1 | 51.7% | 16 |
| Lancaster County | 3.1 pCi/L | 2.2 | Moderate | EPA Zone 1 | 59.7% | 45 |
| York County | 3.1 pCi/L | 2.0 | Moderate | EPA Zone 1 | 57.2% | 35 |
| Venango County | 3.1 pCi/L | 1.8 | Moderate | EPA Zone 1 | 39.8% | 12 |
| Jefferson County | 3.1 pCi/L | 1.6 | Moderate | EPA Zone 2 | 53.8% | 18 |
| Clearfield County | 3.1 pCi/L | 1.7 | Moderate | EPA Zone 1 | 50.4% | 33 |
| Indiana County | 3.0 pCi/L | 1.6 | Moderate | EPA Zone 1 | 47.8% | 25 |
| Butler County | 3.0 pCi/L | 1.9 | Moderate | EPA Zone 1 | 45.4% | 26 |
| Schuylkill County | 3.0 pCi/L | 1.7 | Moderate | EPA Zone 1 | 54.1% | 36 |
| Cameron County | 3.0 pCi/L | 1.5 | Moderate | EPA Zone 1 | 50.6% | 3 |
| Clarion County | 2.9 pCi/L | 1.8 | Moderate | EPA Zone 1 | 43.7% | 18 |
| Berks County | 2.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 49% | 39 |
| Blair County | 2.8 pCi/L | 1.5 | Moderate | EPA Zone 1 | 41.3% | 11 |
| Beaver County | 2.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 47.7% | 18 |
| Bradford County | 2.8 pCi/L | 1.6 | Moderate | EPA Zone 1 | 44.8% | 21 |
| Adams County | 2.7 pCi/L | 1.7 | Moderate | EPA Zone 1 | 42.2% | 11 |
| Monroe County | 2.6 pCi/L | 1.5 | Moderate | EPA Zone 1 | 35.9% | 25 |
| Tioga County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 34.6% | 20 |
| Wyoming County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 38.8% | 5 |
| Elk County | 2.6 pCi/L | 1.2 | Moderate | EPA Zone 2 | 48.9% | 10 |
| Northampton County | 2.6 pCi/L | 1.9 | Moderate | EPA Zone 1 | 46.7% | 17 |
| Sullivan County | 2.6 pCi/L | 1.5 | Moderate | EPA Zone 1 | 34.1% | 7 |
| Crawford County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 2 | 28.5% | 17 |
| Potter County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 2 | 45.9% | 12 |
| Lehigh County | 2.5 pCi/L | 1.7 | Moderate | EPA Zone 1 | 45.7% | 24 |
| Fayette County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 33% | 35 |
| Forest County | 2.5 pCi/L | 1.3 | Moderate | EPA Zone 2 | 47.6% | 5 |
| Greene County | 2.5 pCi/L | 1.5 | Moderate | EPA Zone 2 | 29.8% | 18 |
| Susquehanna County | 2.4 pCi/L | 1.5 | Moderate | EPA Zone 1 | 35.7% | 22 |
| Lawrence County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 39.6% | 11 |
| Somerset County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 40.5% | 25 |
| Warren County | 2.4 pCi/L | 1.2 | Moderate | EPA Zone 2 | 42.6% | 13 |
| Westmoreland County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 1 | 39.1% | 52 |
| Washington County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 2 | 32.9% | 38 |
| Cambria County | 2.3 pCi/L | 1.2 | Moderate | EPA Zone 2 | 42.1% | 34 |
| Allegheny County | 2.2 pCi/L | 1.6 | Moderate | EPA Zone 1 | 32.3% | 89 |
| Mercer County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 33.3% | 17 |
| McKean County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 22.4% | 16 |
| Luzerne County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 1 | 28% | 32 |
| Pike County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 29.4% | 13 |
| Lackawanna County | 1.9 pCi/L | 1.3 | Low | EPA Zone 1 | 25.2% | 22 |
| Wayne County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 23.5% | 19 |
| Erie County | 1.8 pCi/L | 1.2 | Low | EPA Zone 2 | 26.4% | 26 |
| Chester County | 1.7 pCi/L | 1.4 | Low | EPA Zone 1 | 29.4% | 30 |
| Bucks County | 1.5 pCi/L | 1.1 | Low | EPA Zone 1 | 25.7% | 37 |
| Montgomery County | 1.5 pCi/L | 1.1 | Low | EPA Zone 1 | 24.5% | 52 |
| Delaware County | 1.2 pCi/L | 0.9 | Low | EPA Zone 1 | 17.5% | 36 |
| Philadelphia County | 0.9 pCi/L | 0.7 | Low | EPA Zone 3 | 11.3% | 46 |
Radon levels in Pennsylvania cities
The 12 most-populous Pennsylvania places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Philadelphia | 1,550,542 | 1.0 pCi/L | 0.8 | Low | 0% |
| Pittsburgh | 303,255 | 2.0 pCi/L | 1.5 | Moderate | 0% |
| Allentown | 124,880 | 2.3 pCi/L | 1.5 | Moderate | 0% |
| Reading | 94,903 | 2.3 pCi/L | 1.4 | Moderate | 0% |
| Erie | 92,957 | 1.5 pCi/L | 1.0 | Low | 0% |
| Bethlehem | 78,300 | 2.4 pCi/L | 1.8 | Moderate | 0% |
| Scranton | 75,805 | 1.7 pCi/L | 1.2 | Low | 0% |
| Lancaster | 57,153 | 2.8 pCi/L | 2.1 | Moderate | 0% |
| Levittown | 52,983 | 1.1 pCi/L | 0.8 | Low | 0% |
| Harrisburg | 50,012 | 2.6 pCi/L | 1.6 | Moderate | 17% |
| York | 44,867 | 3.0 pCi/L | 1.8 | Moderate | 0% |
| Wilkes-Barre | 44,254 | 1.6 pCi/L | 1.2 | Low | 0% |
Highest-radon ZIP codes in Pennsylvania
The 10 Pennsylvania ZIP codes with the highest predicted basement average (model estimate), out of 1,441 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 17046 | Lebanon County | 5.9 pCi/L | 2.6 | High |
| 17003 | Lebanon County | 5.9 pCi/L | 2.5 | High |
| 17032 | Dauphin County | 5.4 pCi/L | 1.9 | High |
| 17015 | Cumberland County | 5.2 pCi/L | 2.7 | High |
| 17042 | Lebanon County | 5.1 pCi/L | 2.6 | High |
| 16801 | Centre County | 4.9 pCi/L | 2.6 | High |
| 16823 | Centre County | 4.9 pCi/L | 2.5 | High |
| 18080 | Lehigh County | 4.8 pCi/L | 2.0 | High |
| 17026 | Lebanon County | 4.7 pCi/L | 2.3 | High |
| 17842 | Snyder County | 4.7 pCi/L | 1.8 | High |
Pennsylvania radon questions
- Is radon high in Pennsylvania?
- Pennsylvania's population-weighted predicted basement average is 2.3 pCi/L, about 1.3× the US average of 1.8. 2 of its 67 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 57 are in the 2-4 "consider fixing" range and 8 are below 2. 2.9% of Pennsylvania ZIP codes are predicted at 4 or higher.
- Which Pennsylvania county has the highest radon?
- Lebanon County has the highest predicted basement average in Pennsylvania at 4.8 pCi/L (EPA Zone 1). The lowest is Philadelphia County at 0.9 pCi/L. In measured state test data (1988-2026), Fulton County has the largest share of results at or above 4 pCi/L (67.4%). These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Pennsylvania?
- 49 of Pennsylvania's 67 counties (73%) are EPA Zone 1 (highest potential), 17 are Zone 2 and 1 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Pennsylvania?
- Yes - with some urgency. Pennsylvania's predicted average is in the moderate range, and 79% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.
- What do actual radon tests show in Pennsylvania?
- Pennsylvania Department of Environmental Protection publishes 1988-2026 test results for 67 Pennsylvania counties (1,872,999 tests). Weighted by test count, the measured mean is 5.7 pCi/L and 33.2% of results are at or above 4 pCi/L. The measured mean is higher than the model's long-term basement estimate in 67 of 67 comparable counties; state tests are voluntary and skew toward basements and homes where radon was suspected, while the model estimates the average across all homes.
Pennsylvania radon program
Pennsylvania's radon program page is at www.pa.gov; it lists testing and certified-mitigator guidance for the state. The EPA also keeps a directory of every state radon contact: EPA state radon contacts page. Then read how to test and what mitigation costs.