Is Northumberland County, VA a radon risk area?

EPA places Northumberland County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally, Northumberland County ranks higher in radon potential than 9% of rated counties (the 9th percentile).

Northumberland County by the numbers

About 12,397 people live in Northumberland County, Virginia, spread over 191.433 square miles. Averaged across its land area, Northumberland County runs about 65 people per square mile. Rank 765 by population within its EPA zone puts Northumberland County at the 26th percentile among zone peers. Geologically, Northumberland 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

At Zone 3, Northumberland County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. A Zone 3 label describes Northumberland County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Northumberland County

Nothing about Northumberland 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 Virginia's state radon program

Northumberland County's test kit answers today; a Airthings radon monitor keeps answering for Northumberland 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.