What EPA's radon map says about Lehigh County

EPA places Lehigh County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Lehigh County in the 98th percentile nationally for radon potential — higher than 98% of the counties EPA has rated.

Where Lehigh County sits nationally

About 385,655 people live in Lehigh County, Pennsylvania, spread over 345.336 square miles. Averaged across its land area, Lehigh County runs about 1,117 people per square mile. Among counties sharing Lehigh County's EPA zone, it outranks 95% of them by population. EPA's geology-based Region 3 groups Lehigh County with 244 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Lehigh County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. That doesn't mean every Lehigh County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Lehigh County tests above the action level

Mitigation cost doesn't depend on Lehigh 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

Lehigh County's test kit answers today; a Airthings radon monitor keeps answering for Lehigh 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

The methodology guide shows exactly which EPA and Census sources feed Lehigh County's numbers. Whatever zone Lehigh County carries, the zone explainer covers what it does and doesn't tell you about any one house.