Clarke County, VA Radon Zone Data

Clarke County, VA: EPA's radon zone, explained

EPA places Clarke 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. Rank it against the rest of the country and Clarke County lands in the 79th percentile for radon potential.

Clarke County by the numbers

Clarke County, Virginia is home to about 15,598 people across 175.958 square miles. Averaged across its land area, Clarke County runs about 89 people per square mile. By population, Clarke County is the 648th largest of every county sharing its EPA zone — the 39th percentile by population within that zone. Geologically, Clarke 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

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Clarke County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Some Clarke 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 Clarke County tests above the action level

For a Clarke County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Virginia's state radon program

For Clarke County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Clarke County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Clarke County's figures come from

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.