41%tests ≥ 4 pCi/L
9,968tests on record
3.0median pCi/L
Zone 1EPA zone (1993 prediction)

Test results in Union County

ResultShareEPA guidance
Below 2 pCi/L36%Below EPA's levels
2 to 4 pCi/L23%Consider fixing
4 pCi/L or more41%EPA recommends fixing

What the data shows

Where Union County sits among Pennsylvania's 67 counties with dataEach dot is a county's share of tests at or above 4 pCi/L · Pennsylvania county radon test results, 1987–2026
0%20%40%60%

How Union County compares

Union County ranks 5 of 7 among its neighboursShare of tests at or above 4 pCi/L · Pennsylvania county radon test results, 1987–2026 · whisker: 95% range
Mifflin County57%Centre County53%Snyder County45%Lycoming County42%Union County41%Clinton County40%Northumberland County40%Pennsylvania 34%
Data table
AreaTests ≥ 4 pCi/LTests
Mifflin County57%4,918
Centre County53%48,973
Snyder County45%5,873
Lycoming County42%19,016
Union County41%9,968
Clinton County40%5,898
Northumberland County40%12,774
Pennsylvania (67 counties)34%3,356,893

Same source as Union County.

What it means for your home

About 1 in 2 results in Union County were at or above 4 pCi/L, where the EPA recommends a fix. Only a test shows your own home's level.

Levels in pCi/L from the EPA. The WHO reference level is 100 Bq/m³, about 2.7 pCi/L.

Test your home

Start with a short-term test (2–90 days) and confirm a result of 4 pCi/L or more with a second test. EPA guide

Sponsored: we earn a commission on purchases through these links. We haven't tested Airthings monitors yet.

Prefer a digital monitor? See Airthings radon monitors, or enter code radonbycounty-10OFF at their discount store for 10% off.

Fixing high radon

No local job records yet. National range: $800–$2,500, average $1,200 (EPA, 2003). Cost guide →

Pennsylvania licenses radon mitigators. Source

Buying or selling here

Pennsylvania's required Seller's Property Disclosure Statement asks whether the seller knows of hazardous substances on the property, including radon (49 Pa. Code § 35.335a). Source

Checked against the official text on 2026-11-03. Not legal advice.

About this data

Source: Pennsylvania county radon test results (Pennsylvania Department of Environmental Protection). Period: 1987–2026. Tests: 9,968. Read the methodology →

These are voluntary and real-estate tests, not a random sample of homes, so they describe tested homes rather than every home.

About this page

Published by Ray Roman, editor of Radon by County. Figures are loaded from the cited source and spot-checked against it. Editorial policy · About us