---
title: "Pennsylvania Radon Levels by County (PA DEP Test Data)"
description: "Median basement radon and share of tests at or above 4 pCi/L for every Pennsylvania county, from PA DEP's public test results."
canonical: https://radonroster.com/pa/radon-levels-by-county/
---

# Pennsylvania radon levels by county

Computed 2026-10-11 from PA DEP's [Radon Test Results, September 1986 - Current](https://data.pa.gov/Energy-and-the-Environment/Radon-Test-Results-September-1986-Current-Annual-C/vkjb-sx3k) (PA Open Data Portal, public domain). Statewide, 37% of 2,644,033 basement tests were at or above 4 pCi/L. These are tests reported to DEP, not a random survey: repeat and post-mitigation tests are included. Basement readings usually run higher than living-floor readings.

For EPA's county zone classifications, see the [EPA Map of Radon Zones](https://www.epa.gov/radon/epa-map-radon-zones). EPA recommends fixing a home at 4 pCi/L or more and considering it between 2 and 4 pCi/L ([EPA](https://www.epa.gov/radon/what-epas-action-level-radon-and-what-does-it-mean)).

| Rank | County | Basement tests | Median (pCi/L) | % basement ≥ 4 | % first floor ≥ 4 | Certified firms |
| --- | --- | --- | --- | --- | --- | --- |
| 1 | [Fulton](https://radonroster.com/pa/county/fulton/) | 707 | 7.6 | 70% | 52% | 0 |
| 2 | [Juniata](https://radonroster.com/pa/county/juniata/) | 1,802 | 5.6 | 62% | 45% | 0 |
| 3 | [Perry](https://radonroster.com/pa/county/perry/) | 5,953 | 6.0 | 61% | 39% | 1 |
| 4 | [Lebanon](https://radonroster.com/pa/county/lebanon/) | 26,763 | 6.3 | 60% | 37% | 4 |
| 5 | [Mifflin](https://radonroster.com/pa/county/mifflin/) | 3,773 | 5.5 | 59% | 53% | 1 |
| 6 | [Franklin](https://radonroster.com/pa/county/franklin/) | 20,850 | 5.2 | 59% | 37% | 5 |
| 7 | [York](https://radonroster.com/pa/county/york/) | 81,840 | 4.9 | 56% | 33% | 8 |
| 8 | [Centre](https://radonroster.com/pa/county/centre/) | 39,814 | 5.2 | 56% | 42% | 4 |
| 9 | [Jefferson](https://radonroster.com/pa/county/jefferson/) | 4,562 | 4.7 | 56% | 28% | 0 |
| 10 | [Schuylkill](https://radonroster.com/pa/county/schuylkill/) | 18,758 | 4.9 | 56% | 30% | 5 |
| 11 | [Bedford](https://radonroster.com/pa/county/bedford/) | 4,040 | 4.7 | 55% | 23% | 1 |
| 12 | [Cumberland](https://radonroster.com/pa/county/cumberland/) | 76,621 | 4.8 | 55% | 37% | 6 |
| 13 | [Lancaster](https://radonroster.com/pa/county/lancaster/) | 109,372 | 4.7 | 55% | 39% | 9 |
| 14 | [Armstrong](https://radonroster.com/pa/county/armstrong/) | 4,627 | 4.3 | 53% | 24% | 2 |
| 15 | [Huntingdon](https://radonroster.com/pa/county/huntingdon/) | 3,984 | 4.3 | 53% | 25% | 3 |
| 16 | [Clearfield](https://radonroster.com/pa/county/clearfield/) | 10,793 | 4.3 | 53% | 27% | 1 |
| 17 | [Carbon](https://radonroster.com/pa/county/carbon/) | 9,429 | 4.4 | 53% | 23% | 2 |
| 18 | [Potter](https://radonroster.com/pa/county/potter/) | 1,636 | 4.1 | 51% | 20% | 0 |
| 19 | [Dauphin](https://radonroster.com/pa/county/dauphin/) | 67,255 | 4.1 | 51% | 24% | 9 |
| 20 | [Columbia](https://radonroster.com/pa/county/columbia/) | 10,285 | 4.1 | 51% | 24% | 2 |
| 21 | [Berks](https://radonroster.com/pa/county/berks/) | 78,443 | 4.0 | 51% | 37% | 9 |
| 22 | [Snyder](https://radonroster.com/pa/county/snyder/) | 4,749 | 4.0 | 50% | 20% | 2 |
| 23 | [Bradford](https://radonroster.com/pa/county/bradford/) | 4,704 | 3.8 | 49% | 27% | 1 |
| 24 | [Cameron](https://radonroster.com/pa/county/cameron/) | 439 | 3.9 | 49% | 40% | 0 |
| 25 | [Forest](https://radonroster.com/pa/county/forest/) | 261 | 3.6 | 49% | 21% | 0 |
| 26 | [Beaver](https://radonroster.com/pa/county/beaver/) | 30,533 | 3.8 | 48% | 33% | 6 |
| 27 | [Northampton](https://radonroster.com/pa/county/northampton/) | 78,045 | 3.7 | 48% | 26% | 7 |
| 28 | [Elk](https://radonroster.com/pa/county/elk/) | 3,519 | 3.8 | 48% | 26% | 1 |
| 29 | [Clarion](https://radonroster.com/pa/county/clarion/) | 3,576 | 3.8 | 48% | 20% | 0 |
| 30 | [Warren](https://radonroster.com/pa/county/warren/) | 3,863 | 3.7 | 47% | 26% | 1 |
| 31 | [Lehigh](https://radonroster.com/pa/county/lehigh/) | 85,538 | 3.6 | 47% | 29% | 11 |
| 32 | [Butler](https://radonroster.com/pa/county/butler/) | 45,628 | 3.6 | 47% | 30% | 12 |
| 33 | [Northumberland](https://radonroster.com/pa/county/northumberland/) | 10,034 | 3.6 | 46% | 16% | 1 |
| 34 | [Monroe](https://radonroster.com/pa/county/monroe/) | 39,824 | 3.6 | 46% | 17% | 11 |
| 35 | [Venango](https://radonroster.com/pa/county/venango/) | 5,018 | 3.6 | 46% | 22% | 2 |
| 36 | [Lycoming](https://radonroster.com/pa/county/lycoming/) | 15,471 | 3.6 | 46% | 21% | 2 |
| 37 | [Indiana](https://radonroster.com/pa/county/indiana/) | 9,119 | 3.6 | 46% | 24% | 2 |
| 38 | [Clinton](https://radonroster.com/pa/county/clinton/) | 4,724 | 3.5 | 46% | 19% | 2 |
| 39 | [Union](https://radonroster.com/pa/county/union/) | 8,075 | 3.5 | 45% | 19% | 1 |
| 40 | [Adams](https://radonroster.com/pa/county/adams/) | 16,668 | 3.4 | 44% | 17% | 6 |
| 41 | [Somerset](https://radonroster.com/pa/county/somerset/) | 5,585 | 3.4 | 44% | 22% | 1 |
| 42 | [Cambria](https://radonroster.com/pa/county/cambria/) | 16,349 | 3.4 | 43% | 22% | 4 |
| 43 | [Wyoming](https://radonroster.com/pa/county/wyoming/) | 4,072 | 3.4 | 43% | 14% | 0 |
| 44 | [Blair](https://radonroster.com/pa/county/blair/) | 17,390 | 3.2 | 43% | 22% | 3 |
| 45 | [Tioga](https://radonroster.com/pa/county/tioga/) | 3,242 | 3.2 | 42% | 15% | 1 |
| 46 | [Montour](https://radonroster.com/pa/county/montour/) | 4,297 | 3.2 | 42% | 20% | 0 |
| 47 | [Susquehanna](https://radonroster.com/pa/county/susquehanna/) | 3,719 | 3.2 | 41% | 13% | 1 |
| 48 | [Westmoreland](https://radonroster.com/pa/county/westmoreland/) | 66,800 | 3.2 | 40% | 25% | 17 |
| 49 | [Sullivan](https://radonroster.com/pa/county/sullivan/) | 622 | 3.1 | 39% | 16% | 0 |
| 50 | [Pike](https://radonroster.com/pa/county/pike/) | 21,604 | 2.9 | 38% | 13% | 7 |
| 51 | [Lawrence](https://radonroster.com/pa/county/lawrence/) | 9,105 | 3.1 | 38% | 23% | 2 |
| 52 | [Mercer](https://radonroster.com/pa/county/mercer/) | 9,723 | 2.9 | 35% | 13% | 0 |
| 53 | [Crawford](https://radonroster.com/pa/county/crawford/) | 5,647 | 2.8 | 35% | 11% | 3 |
| 54 | [Washington](https://radonroster.com/pa/county/washington/) | 38,759 | 2.9 | 34% | 21% | 7 |
| 55 | [Allegheny](https://radonroster.com/pa/county/allegheny/) | 311,850 | 2.7 | 34% | 21% | 44 |
| 56 | [Greene](https://radonroster.com/pa/county/greene/) | 1,562 | 2.8 | 34% | 16% | 0 |
| 57 | [Fayette](https://radonroster.com/pa/county/fayette/) | 7,625 | 2.9 | 34% | 16% | 3 |
| 58 | [Chester](https://radonroster.com/pa/county/chester/) | 212,529 | 2.4 | 31% | 20% | 18 |
| 59 | [Bucks](https://radonroster.com/pa/county/bucks/) | 199,252 | 2.5 | 31% | 14% | 19 |
| 60 | [Luzerne](https://radonroster.com/pa/county/luzerne/) | 55,278 | 2.4 | 31% | 11% | 13 |
| 61 | [Wayne](https://radonroster.com/pa/county/wayne/) | 14,704 | 2.4 | 29% | 11% | 4 |
| 62 | [Erie](https://radonroster.com/pa/county/erie/) | 41,146 | 2.2 | 28% | 14% | 6 |
| 63 | [Montgomery](https://radonroster.com/pa/county/montgomery/) | 296,621 | 2.4 | 28% | 12% | 29 |
| 64 | [Lackawanna](https://radonroster.com/pa/county/lackawanna/) | 36,863 | 2.3 | 28% | 9% | 9 |
| 65 | [McKean](https://radonroster.com/pa/county/mckean/) | 1,583 | 2.1 | 27% | 8% | 0 |
| 66 | [Delaware](https://radonroster.com/pa/county/delaware/) | 151,566 | 2.0 | 20% | 8% | 12 |
| 67 | [Philadelphia](https://radonroster.com/pa/county/philadelphia/) | 155,445 | 1.7 | 12% | 5% | 10 |