Fairfax city, VA: EPA's radon zone, explained

Fairfax city is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Fairfax city ranks higher in radon potential than 84% of rated counties (the 84th percentile).

Fairfax city by the numbers

Fairfax city, Virginia is home to about 26,340 people across 6.241 square miles. Averaged across its land area, Fairfax city runs about 4,220 people per square mile. By population, Fairfax city is the 503rd largest of every county sharing its EPA zone — the 53rd percentile by population within that zone.

What this actually means for a house in Fairfax city

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Fairfax city's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Fairfax city will test well under the action level, and EPA's guidance is to test regardless of zone.

If Fairfax city tests above the action level

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

Where Fairfax city'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.