Is Lancaster County, PA a radon risk area?

EPA's own radon map rates Lancaster County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Lancaster County lands in the 99th percentile for radon potential.

Where Lancaster County sits nationally

About 563,293 people live in Lancaster County, Pennsylvania, spread over 943.924 square miles. Averaged across its land area, Lancaster County runs about 597 people per square mile. Rank 34 by population within its EPA zone puts Lancaster County at the 97th percentile among zone peers. Geologically, Lancaster County is grouped into EPA Region 3 alongside 244 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Lancaster County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Being in Zone 1 raises the odds Lancaster County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Lancaster County

Nothing about Lancaster County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Pennsylvania's state radon program

Lancaster County's test kit answers today; a Airthings radon monitor keeps answering for Lancaster County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Lancaster County carries, the zone explainer covers what it does and doesn't tell you about any one house.