What EPA's radon map says about Bronx County

EPA's own radon map rates Bronx 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 Bronx County lands in the 32nd percentile for radon potential.

Bronx County by the numbers

About 1,384,724 people live in Bronx County, New York, spread over 42.201 square miles. Population density there runs about 32,813 people per square mile. Among counties sharing Bronx County's EPA zone, it outranks 98% of them by population. Geologically, Bronx County is grouped into EPA Region 2 alongside 82 other counties that share its rock and soil setting.

What this actually means for a house in Bronx County

Bronx County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. A Zone 3 label describes Bronx County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Next steps for a home in Bronx County

Mitigation cost doesn't depend on Bronx County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find New York's state radon program

Bronx County's test kit answers today; a Airthings radon monitor keeps answering for Bronx 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

The methodology guide shows exactly which EPA and Census sources feed Bronx County's numbers. Whatever zone Bronx County carries, the zone explainer covers what it does and doesn't tell you about any one house.