Harris County, TX radon potential

Harris County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Harris County sits at the 33rd percentile nationally for radon potential — above 33 of every 100 rated counties.

Where Harris County sits nationally

Harris County, Texas is home to about 5,009,302 people across 1,707.103 square miles. Population density there runs about 2,934 people per square mile. Within its own EPA zone, Harris County is bigger by population than 100% of the counties that share it. Harris County falls in EPA Radon Region 6, one of 503 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Harris County's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for Harris County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Harris County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Texas's state radon program

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

Where Harris County's figures come from

Harris County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.