Is Johnson County, AR a radon risk area?

EPA's own radon map rates Johnson County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Rank it against the rest of the country and Johnson County lands in the 16th percentile for radon potential.

How Johnson County compares

About 26,172 people live in Johnson County, Arkansas, spread over 660.99 square miles. Averaged across its land area, Johnson County runs about 40 people per square mile. Rank 525 by population within its EPA zone puts Johnson County at the 49th percentile among zone peers. Geologically, Johnson County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Johnson County's Zone 3 prediction is the low end of the scale. Even at Zone 3, Johnson County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Next steps for a home in Johnson County

Nothing about Johnson 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 Arkansas's state radon program

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

More on how this number was built

Johnson County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.