What EPA's radon map says about Morris County

EPA places Morris 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 Morris County lands in the 99th percentile for radon potential.

Morris County by the numbers

About 523,053 people live in Morris County, New Jersey, spread over 461.027 square miles. Averaged across its land area, Morris County runs about 1,135 people per square mile. Among counties sharing Morris County's EPA zone, it outranks 96% of them by population. EPA's geology-based Region 2 groups Morris County with 82 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Morris County

Morris County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. 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 Morris County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Morris County tests above the action level

Mitigation cost doesn't depend on Morris 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 Jersey's state radon program

Morris County's test kit answers today; a Airthings radon monitor keeps answering for Morris County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.