Test results in Chester County
| Result | Share | EPA guidance |
|---|---|---|
| Below 2 pCi/L | 45% | Below EPA's levels |
| 2 to 4 pCi/L | 25% | Consider fixing |
| 4 pCi/L or more | 29% | EPA recommends fixing |
What the data shows
- Higher share of high results than 10 of 67 Pennsylvania counties.
- Below the Pennsylvania rate of 34%.
- Higher than 2 of 4 neighbouring counties.
- 55% of results at or above 2 pCi/L.
- 1236.7 tests per 1,000 homes (Pennsylvania: 578.1).
- Median result 2.2 pCi/L: between the 2 and 4 pCi/L EPA levels.
How Chester County compares
Data table
| Area | Tests ≥ 4 pCi/L | Tests |
|---|---|---|
| Lancaster County | 51% | 135,473 |
| Berks County | 48% | 92,641 |
| Chester County | 29% | 262,789 |
| Montgomery County | 24% | 393,614 |
| Delaware County | 18% | 194,425 |
| Pennsylvania (67 counties) | 34% | 3,356,893 |
Same source as Chester County. Other bordering counties: Cecil County, Maryland, New Castle County, Delaware.
What it means for your home
About 1 in 3 results in Chester 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.
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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: 1986–2026. Tests: 262,789. 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