What EPA's radon map says about Dauphin County

EPA's own radon map rates Dauphin County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Dauphin County in the 98th percentile nationally for radon potential — higher than 98% of the counties EPA has rated.

How Dauphin County compares

About 293,029 people live in Dauphin County, Pennsylvania, spread over 524.87 square miles. That works out to roughly 558 people per square mile. Among counties sharing Dauphin County's EPA zone, it outranks 93% of them by population. Dauphin County falls in EPA Radon Region 3, one of 245 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Dauphin County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Dauphin County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some Dauphin County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

If Dauphin County tests above the action level

Mitigation cost doesn't depend on Dauphin County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Pennsylvania's state radon program

Dauphin County's test kit answers today; a Airthings radon monitor keeps answering for Dauphin County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.