Updated November 2026 · Data: EPA Map of Radon Zones and PA DEP · Sources
Pennsylvania has some of the highest indoor radon levels in the United States. 49 of its 67 counties are in EPA Zone 1, the group with the highest predicted levels, and the Pennsylvania Department of Environmental Protection (DEP) estimates that about 40% of homes in the state are above the EPA action level of 4 pCi/L. Find your county below, then learn how to test your home and what to do if the result is high.
Your county’s zone is not your home’s radon level. Homes with high radon are found in every zone. The EPA recommends testing every home, whatever its zone.
Map of radon test results by county
Radon test results by county (PA DEP data)
Pennsylvania DEP keeps a public database of 3,299,152 radon tests in homes since 1986. Statewide, 33.9% were at or above 4 pCi/L. The table is sorted by the share of high results; click a county for results by ZIP code, by community and mitigation costs.
| County | Tests | Median (pCi/L) | At or above 4 pCi/L |
|---|---|---|---|
| Fulton | 873 | 6.8 | 66.2% |
| Juniata | 2,060 | 5.3 | 59.4% |
| Perry | 7,093 | 5.3 | 57.7% |
| Mifflin | 4,865 | 5.1 | 57.1% |
| Lebanon | 33,192 | 5.2 | 55.8% |
| Centre | 48,551 | 4.5 | 53.5% |
| York | 98,592 | 4.3 | 52.7% |
| Franklin | 28,025 | 4.3 | 52.5% |
| Bedford | 4,855 | 4.3 | 52.3% |
| Lancaster | 134,381 | 4.2 | 51.3% |
| Cumberland | 100,225 | 4.1 | 50.8% |
| Clearfield | 12,074 | 4.0 | 50.4% |
| Jefferson | 5,605 | 4.0 | 50.2% |
| Schuylkill | 23,398 | 4.0 | 50.1% |
| Armstrong | 5,553 | 4.0 | 50.0% |
| Huntingdon | 4,710 | 3.9 | 49.4% |
| Berks | 90,907 | 3.8 | 48.6% |
| Cameron | 533 | 3.6 | 46.5% |
| Dauphin | 87,670 | 3.5 | 46.5% |
| Beaver | 34,132 | 3.6 | 46.5% |
| Elk | 4,001 | 3.6 | 45.7% |
| Columbia | 12,855 | 3.5 | 45.6% |
| Snyder | 5,754 | 3.4 | 45.4% |
| Butler | 53,015 | 3.5 | 44.9% |
| Lehigh | 105,192 | 3.3 | 44.6% |
| Northampton | 97,505 | 3.3 | 44.2% |
| Clarion | 4,243 | 3.5 | 44.0% |
| Indiana | 10,439 | 3.4 | 43.9% |
| Carbon | 13,831 | 3.1 | 43.5% |
| Potter | 2,207 | 3.0 | 43.4% |
| Warren | 4,919 | 3.2 | 43.1% |
| Bradford | 6,371 | 3.1 | 43.0% |
| Venango | 6,316 | 3.2 | 42.3% |
| Lycoming | 18,705 | 3.1 | 42.2% |
| Cambria | 18,647 | 3.3 | 41.8% |
| Union | 9,790 | 3.1 | 41.6% |
| Northumberland | 12,214 | 3.0 | 41.4% |
| Somerset | 7,022 | 3.1 | 41.3% |
| Clinton | 5,763 | 3.0 | 41.2% |
| Forest | 360 | 3.0 | 41.1% |
| Blair | 19,543 | 3.0 | 40.8% |
| Wyoming | 4,734 | 3.1 | 39.4% |
| Adams | 22,095 | 2.8 | 38.7% |
| Montour | 5,226 | 2.9 | 38.7% |
| Westmoreland | 74,636 | 3.1 | 38.2% |
| Lawrence | 10,394 | 3.0 | 36.8% |
| Tioga | 4,240 | 2.6 | 36.3% |
| Monroe | 62,061 | 2.6 | 35.8% |
| Susquehanna | 4,743 | 2.7 | 35.2% |
| Sullivan | 817 | 2.5 | 34.0% |
| Washington | 43,317 | 2.8 | 33.3% |
| Allegheny | 355,558 | 2.6 | 32.5% |
| Mercer | 11,947 | 2.6 | 31.5% |
| Fayette | 8,916 | 2.7 | 31.1% |
| Crawford | 6,882 | 2.4 | 30.7% |
| Greene | 1,866 | 2.6 | 30.6% |
| Pike | 33,264 | 2.2 | 29.9% |
| Chester | 260,876 | 2.2 | 29.3% |
| Luzerne | 65,527 | 2.1 | 27.6% |
| Erie | 49,438 | 2.0 | 26.4% |
| Bucks | 285,640 | 2.1 | 25.6% |
| Lackawanna | 42,996 | 2.1 | 25.5% |
| Wayne | 19,322 | 2.1 | 24.9% |
| Montgomery | 389,643 | 2.1 | 24.6% |
| McKean | 2,162 | 1.7 | 21.6% |
| Delaware | 193,083 | 1.8 | 17.8% |
| Philadelphia | 193,783 | 1.5 | 10.8% |
PA DEP mitigation records also show what homeowners pay: the median reported cost of a radon mitigation system in Pennsylvania was $1,400 in 2025 and $1,445 in 2026 (systems reported through October 2026). See our radon mitigation cost guide.
Radon by city in Pennsylvania
Cities and towns (by mailing address) with at least 5,000 tests in the PA DEP database. Click a city for results by ZIP code and local mitigation costs.
| City | County | Tests | At or above 4 pCi/L |
|---|---|---|---|
| Abington | Montgomery | 7,061 | 19.8% |
| Aliquippa | Beaver | 7,060 | 45.0% |
| Allentown | Lehigh | 36,915 | 43.7% |
| Allison Park | Allegheny | 10,387 | 45.3% |
| Altoona | Blair | 8,457 | 37.6% |
| Ambler | Montgomery | 15,721 | 24.2% |
| Ardmore | Montgomery | 6,771 | 14.5% |
| Aston | Delaware | 5,731 | 13.7% |
| Bala Cynwyd | Montgomery | 6,246 | 29.1% |
| Beaver Falls | Beaver | 5,102 | 47.3% |
| Bellefonte | Centre | 6,407 | 58.5% |
| Bensalem | Bucks | 11,383 | 13.5% |
| Berwyn | Chester | 10,869 | 32.0% |
| Bethel Park | Allegheny | 9,954 | 28.4% |
| Bethlehem | Northampton | 40,967 | 40.5% |
| Bloomsburg | Columbia | 6,730 | 43.4% |
| Blue Bell | Montgomery | 12,248 | 23.5% |
| Bridgeville | Allegheny | 5,139 | 26.5% |
| Broomall | Delaware | 8,024 | 20.6% |
| Bryn Mawr | Delaware | 10,334 | 19.0% |
| Bushkill | Pike | 5,497 | 29.9% |
| Butler | Butler | 12,805 | 52.2% |
| Camp Hill | Cumberland | 16,508 | 55.2% |
| Canonsburg | Washington | 10,801 | 28.2% |
| Carlisle | Cumberland | 21,375 | 48.8% |
| Chadds Ford | Delaware | 5,458 | 12.8% |
| Chalfont | Bucks | 11,752 | 31.9% |
| Chambersburg | Franklin | 12,344 | 53.2% |
| Chester Springs | Chester | 11,658 | 29.2% |
| Clarks Summit | Lackawanna | 7,399 | 33.9% |
| Coatesville | Chester | 19,254 | 43.3% |
| Collegeville | Montgomery | 20,101 | 26.5% |
| Conshohocken | Montgomery | 8,707 | 24.0% |
| Coopersburg | Lehigh | 6,727 | 43.7% |
| Coraopolis | Allegheny | 10,033 | 36.3% |
| Cranberry Township | Butler | 12,083 | 36.5% |
| Dallas | Luzerne | 5,479 | 33.1% |
| Danville | Montour | 5,562 | 38.3% |
| Devon | Chester | 5,439 | 28.8% |
| Dillsburg | York | 5,912 | 47.5% |
| Douglassville | Berks | 5,242 | 40.7% |
| Downingtown | Chester | 32,651 | 33.6% |
| Doylestown | Bucks | 34,954 | 31.1% |
| Drexel Hill | Delaware | 11,636 | 16.8% |
| DuBois | Clearfield | 6,509 | 54.2% |
| East Stroudsburg | Monroe | 13,234 | 36.9% |
| Easton | Northampton | 26,872 | 44.2% |
| Elizabethtown | Lancaster | 7,473 | 47.5% |
| Elkins Park | Montgomery | 7,117 | 29.4% |
| Emmaus | Lehigh | 7,322 | 46.9% |
| Enola | Cumberland | 5,635 | 46.5% |
| Ephrata | Lancaster | 6,891 | 53.8% |
| Erie | Erie | 33,347 | 22.2% |
| Exton | Chester | 9,341 | 18.8% |
| Feasterville-Trevose | Bucks | 5,568 | 23.3% |
| Gettysburg | Adams | 8,442 | 31.2% |
| Gibsonia | Allegheny | 14,126 | 43.2% |
| Gilbertsville | Montgomery | 5,589 | 33.5% |
| Glen Mills | Delaware | 6,807 | 16.1% |
| Glenmoore | Chester | 5,010 | 33.5% |
| Glenshaw | Allegheny | 5,317 | 44.1% |
| Glenside | Montgomery | 11,538 | 22.9% |
| Greensburg | Westmoreland | 17,271 | 37.3% |
| Hanover | York | 13,651 | 46.8% |
| Harleysville | Montgomery | 10,928 | 24.8% |
| Harrisburg | Dauphin | 51,601 | 47.0% |
| Hatboro | Montgomery | 7,235 | 21.1% |
| Hatfield | Montgomery | 6,247 | 20.5% |
| Havertown | Delaware | 16,209 | 20.3% |
| Hawley | Pike | 6,293 | 29.0% |
| Hershey | Dauphin | 11,128 | 36.9% |
| Holland | Bucks | 9,586 | 23.0% |
| Horsham | Montgomery | 6,965 | 19.7% |
| Hummelstown | Dauphin | 12,387 | 51.5% |
| Huntingdon Valley | Montgomery | 10,238 | 28.1% |
| Indiana | Indiana | 6,536 | 43.7% |
| Irwin | Westmoreland | 7,001 | 33.3% |
| Jamison | Bucks | 5,528 | 22.1% |
| Jenkintown | Montgomery | 5,978 | 35.0% |
| Johnstown | Cambria | 11,841 | 41.9% |
| Kennett Square | Chester | 11,183 | 23.6% |
| King of Prussia | Montgomery | 9,340 | 19.2% |
| Lafayette Hill | Montgomery | 6,239 | 21.8% |
| Lake Ariel | Wayne | 7,719 | 20.0% |
| Lancaster | Lancaster | 48,270 | 46.8% |
| Landenberg | Chester | 5,175 | 19.6% |
| Langhorne | Bucks | 15,429 | 21.0% |
| Lansdale | Montgomery | 25,952 | 20.7% |
| Lansdowne | Delaware | 6,040 | 17.8% |
| Latrobe | Westmoreland | 5,451 | 38.3% |
| Lebanon | Lebanon | 13,874 | 54.9% |
| Levittown | Bucks | 6,628 | 6.5% |
| Lewisburg | Union | 6,365 | 38.7% |
| Lititz | Lancaster | 18,292 | 54.9% |
| Macungie | Lehigh | 10,251 | 37.2% |
| Malvern | Chester | 19,227 | 33.2% |
| Manheim | Lancaster | 6,473 | 60.5% |
| Mars | Butler | 7,529 | 42.1% |
| Mechanicsburg | Cumberland | 39,355 | 51.4% |
| Media | Delaware | 17,386 | 25.9% |
| Milford | Pike | 8,525 | 32.6% |
| Monroeville | Allegheny | 8,840 | 36.5% |
| Morrisville | Bucks | 8,062 | 18.2% |
| Mount Joy | Lancaster | 6,188 | 52.1% |
| Mountain Top | Luzerne | 6,680 | 29.1% |
| Murrysville | Westmoreland | 6,418 | 44.7% |
| Nazareth | Northampton | 9,896 | 49.6% |
| New Castle | Lawrence | 6,488 | 33.2% |
| New Cumberland | Cumberland | 6,367 | 49.3% |
| New Hope | Bucks | 12,271 | 31.7% |
| Newtown | Bucks | 26,444 | 22.3% |
| Newtown Square | Delaware | 10,325 | 18.0% |
| Norristown | Montgomery | 20,978 | 19.0% |
| North Wales | Montgomery | 13,624 | 23.2% |
| Palmyra | Lebanon | 8,186 | 54.6% |
| Paoli | Chester | 6,651 | 40.4% |
| Perkasie | Bucks | 9,903 | 29.0% |
| Philadelphia | Philadelphia | 192,748 | 10.8% |
| Phoenixville | Chester | 22,801 | 25.8% |
| Pittsburgh | Allegheny | 180,311 | 29.3% |
| Plymouth Meeting | Montgomery | 5,702 | 20.2% |
| Pottstown | Montgomery | 20,714 | 28.2% |
| Quakertown | Bucks | 9,954 | 29.5% |
| Reading | Berks | 24,551 | 46.8% |
| Red Lion | York | 5,351 | 60.8% |
| Richboro | Bucks | 7,272 | 34.6% |
| Royersford | Montgomery | 9,453 | 25.6% |
| Schwenksville | Montgomery | 6,606 | 25.0% |
| Scranton | Lackawanna | 11,178 | 17.1% |
| Sewickley | Allegheny | 13,354 | 41.1% |
| Shippensburg | Cumberland | 5,448 | 49.0% |
| Sinking Spring | Berks | 5,568 | 47.9% |
| Southampton | Bucks | 7,903 | 22.8% |
| Springfield | Delaware | 10,690 | 24.0% |
| State College | Centre | 29,555 | 51.9% |
| Stroudsburg | Monroe | 9,572 | 42.9% |
| Tobyhanna | Monroe | 5,283 | 17.9% |
| Upper Darby | Delaware | 6,912 | 11.8% |
| Wallingford | Delaware | 5,856 | 19.0% |
| Warminster | Bucks | 11,223 | 21.7% |
| Warrington | Bucks | 9,290 | 26.2% |
| Washington | Washington | 8,258 | 34.3% |
| Washington Crossing | Bucks | 5,430 | 36.9% |
| Wayne | Delaware | 21,248 | 27.0% |
| Waynesboro | Franklin | 5,086 | 49.8% |
| West Chester | Chester | 56,700 | 21.9% |
| Wexford | Allegheny | 17,786 | 46.1% |
| Whitehall | Lehigh | 6,735 | 44.6% |
| Wilkes-Barre | Luzerne | 8,092 | 14.4% |
| Williamsport | Lycoming | 8,131 | 35.6% |
| Willow Grove | Montgomery | 6,597 | 10.2% |
| Wynnewood | Montgomery | 9,422 | 22.5% |
| Yardley | Bucks | 28,116 | 22.0% |
| York | York | 35,470 | 52.5% |
EPA radon zones by county in Pennsylvania
The table lists the EPA radon zone for each of the 67 counties in Pennsylvania. The zone shows the predicted average indoor radon screening level for homes in that county.
| County | EPA zone | Predicted average indoor level |
|---|---|---|
| Adams | Zone 1 | Above 4 pCi/L |
| Allegheny | Zone 1 | Above 4 pCi/L |
| Armstrong | Zone 1 | Above 4 pCi/L |
| Beaver | Zone 1 | Above 4 pCi/L |
| Bedford | Zone 1 | Above 4 pCi/L |
| Berks | Zone 1 | Above 4 pCi/L |
| Blair | Zone 1 | Above 4 pCi/L |
| Bradford | Zone 1 | Above 4 pCi/L |
| Bucks | Zone 1 | Above 4 pCi/L |
| Butler | Zone 1 | Above 4 pCi/L |
| Cambria | Zone 2 | 2 to 4 pCi/L |
| Cameron | Zone 1 | Above 4 pCi/L |
| Carbon | Zone 1 | Above 4 pCi/L |
| Centre | Zone 1 | Above 4 pCi/L |
| Chester | Zone 1 | Above 4 pCi/L |
| Clarion | Zone 1 | Above 4 pCi/L |
| Clearfield | Zone 1 | Above 4 pCi/L |
| Clinton | Zone 1 | Above 4 pCi/L |
| Columbia | Zone 1 | Above 4 pCi/L |
| Crawford | Zone 2 | 2 to 4 pCi/L |
| Cumberland | Zone 1 | Above 4 pCi/L |
| Dauphin | Zone 1 | Above 4 pCi/L |
| Delaware | Zone 1 | Above 4 pCi/L |
| Elk | Zone 2 | 2 to 4 pCi/L |
| Erie | Zone 2 | 2 to 4 pCi/L |
| Fayette | Zone 2 | 2 to 4 pCi/L |
| Forest | Zone 2 | 2 to 4 pCi/L |
| Franklin | Zone 1 | Above 4 pCi/L |
| Fulton | Zone 1 | Above 4 pCi/L |
| Greene | Zone 2 | 2 to 4 pCi/L |
| Huntingdon | Zone 1 | Above 4 pCi/L |
| Indiana | Zone 1 | Above 4 pCi/L |
| Jefferson | Zone 2 | 2 to 4 pCi/L |
| Juniata | Zone 1 | Above 4 pCi/L |
| Lackawanna | Zone 1 | Above 4 pCi/L |
| Lancaster | Zone 1 | Above 4 pCi/L |
| Lawrence | Zone 2 | 2 to 4 pCi/L |
| Lebanon | Zone 1 | Above 4 pCi/L |
| Lehigh | Zone 1 | Above 4 pCi/L |
| Luzerne | Zone 1 | Above 4 pCi/L |
| Lycoming | Zone 1 | Above 4 pCi/L |
| McKean | Zone 2 | 2 to 4 pCi/L |
| Mercer | Zone 2 | 2 to 4 pCi/L |
| Mifflin | Zone 1 | Above 4 pCi/L |
| Monroe | Zone 1 | Above 4 pCi/L |
| Montgomery | Zone 1 | Above 4 pCi/L |
| Montour | Zone 1 | Above 4 pCi/L |
| Northampton | Zone 1 | Above 4 pCi/L |
| Northumberland | Zone 1 | Above 4 pCi/L |
| Perry | Zone 1 | Above 4 pCi/L |
| Philadelphia | Zone 3 | Below 2 pCi/L |
| Pike | Zone 2 | 2 to 4 pCi/L |
| Potter | Zone 2 | 2 to 4 pCi/L |
| Schuylkill | Zone 1 | Above 4 pCi/L |
| Snyder | Zone 1 | Above 4 pCi/L |
| Somerset | Zone 2 | 2 to 4 pCi/L |
| Sullivan | Zone 1 | Above 4 pCi/L |
| Susquehanna | Zone 1 | Above 4 pCi/L |
| Tioga | Zone 1 | Above 4 pCi/L |
| Union | Zone 1 | Above 4 pCi/L |
| Venango | Zone 1 | Above 4 pCi/L |
| Warren | Zone 2 | 2 to 4 pCi/L |
| Washington | Zone 2 | 2 to 4 pCi/L |
| Wayne | Zone 2 | 2 to 4 pCi/L |
| Westmoreland | Zone 1 | Above 4 pCi/L |
| Wyoming | Zone 1 | Above 4 pCi/L |
| York | Zone 1 | Above 4 pCi/L |
What the EPA radon zones mean
- Zone 1 (highest potential): predicted average indoor screening level greater than 4 pCi/L. In Pennsylvania: 49 counties (73%).
- Zone 2 (moderate potential): predicted average between 2 and 4 pCi/L. In Pennsylvania: 17 counties (25%).
- Zone 3 (low potential): predicted average below 2 pCi/L. In Pennsylvania: 1 county (1%).
The EPA built the map from indoor radon measurements, geology, soil permeability and type of house foundation. It was made to help governments and builders target resources, not to decide whether a single home needs testing.
Pennsylvania counties with the highest radon potential
49 counties in Pennsylvania are in Zone 1: Adams, Allegheny, Armstrong, Beaver, Bedford, Berks, Blair, Bradford, Bucks, Butler, Cameron, Carbon, Centre, Chester, Clarion, Clearfield, Clinton, Columbia, Cumberland, Dauphin, Delaware, Franklin, Fulton, Huntingdon, Indiana, Juniata, Lackawanna, Lancaster, Lebanon, Lehigh, Luzerne, Lycoming, Mifflin, Monroe, Montgomery, Montour, Northampton, Northumberland, Perry, Schuylkill, Snyder, Sullivan, Susquehanna, Tioga, Union, Venango, Westmoreland, Wyoming, York.
How to test for radon in Pennsylvania
Testing is the only way to know your home’s radon level. Short-term test kits sold at hardware stores and by Pennsylvania-certified labs typically cost about $20 to $30, according to PA DEP. Test in the lowest lived-in level of the home, with windows and doors closed, and follow the kit instructions.
- Do-it-yourself kits: fine for homeowners testing their own home.
- Certified testers: in Pennsylvania, anyone who tests, mitigates or analyzes radon for others must be certified by DEP. Use the DEP radon services directory or call 1-800-23-RADON.
- Buying or selling a home: radon tests are a common part of home inspections; ask for a test by a DEP-certified tester.
If your radon level is high
The EPA recommends fixing your home if the radon level is 4 pCi/L or higher, and considering a fix between 2 and 4 pCi/L. The usual fix is a radon mitigation system (sub-slab depressurization), which pulls radon from under the foundation and vents it above the roof.
- PA DEP says a permanent mitigation system typically costs $800 to $1,200. Compare other estimates in our radon mitigation cost guide.
- Hire a DEP-certified mitigation contractor; Pennsylvania requires certification.
- After a system is installed, DEP recommends testing again every two years.
Learn more: safe radon levels · how to test · test kits compared · radon and home sales · radon in well water
Pennsylvania radon program
The PA DEP Radon Division certifies radon testers, mitigators and labs and answers questions from residents.
- Radon Hotline: 1-800-23-RADON (800-237-2366)
- Radon Division: 717-783-3594
- List of certified testers, mitigators and labs: DEP radon services directory
Frequently asked questions
Is radon a problem in Pennsylvania?
Yes. 49 of Pennsylvania’s 67 counties are in EPA Zone 1, the highest-potential group, and PA DEP estimates that about 40% of Pennsylvania homes are above the EPA action level of 4 pCi/L.
Which Pennsylvania counties have the most radon?
The 49 counties in EPA Zone 1, listed above, have the highest predicted average indoor levels. High readings are also found in Zone 2 and Zone 3 counties, so every home should be tested.
How much does a radon test cost in Pennsylvania?
PA DEP says short-term kits typically cost about $20 to $30 at hardware and home improvement stores or from Pennsylvania-certified labs. A test by a certified professional costs more.
How much does radon mitigation cost in Pennsylvania?
According to PA DEP, a permanent radon mitigation system typically costs $800 to $1,200. The final price depends on the home’s foundation and layout.
Sources
- PA DEP: Radon Test Results, 1986 to current (data.pa.gov) (retrieved November 2026)
- PA DEP: Radon Mitigation System, 1987 to current (data.pa.gov) (retrieved November 2026)
- U.S. EPA: EPA Map of Radon Zones (county data file, June 2024)
- PA DEP: DEP encourages Pennsylvanians to test their homes for radon during Radon Action Month (January 12, 2026)
- PA DEP: Radon Division (checked November 2026)
- PA DEP: Radon services directory (checked November 2026)
- U.S. EPA: A Citizen’s Guide to Radon (PDF, 2016)