Mercer County · NJDEP Radon Potential: Tier 1 — high
NJDEP assigns every New Jersey municipality a radon-potential tier; Tier 1 is the highest, meaning at least 25% of tested homes met or exceeded 4.0 pCi/L. It doesn't mean every house is high — radon varies house to house even on the same street — but it makes testing genuinely important here, and it triggers the state's radon-resistant new-construction requirement (N.J.A.C. 5:23-10).
1 NJDEP-certified radon business is based in Mercer County:
Trenton · mitigation
All Mercer County companies · full New Jersey list
NJDEP designates Princeton Boro and Princeton Township a Tier 1 municipality — its highest radon-potential classification. In the published NJDEP dataset, 12615 homes in Princeton Boro and Princeton Township were tested and 34% measured at or above the EPA action level of 4.0 pCi/L. Any individual home can be high or low — testing is the only way to know yours.
Yes. New Jersey's radon hazard subcode (N.J.A.C. 5:23-10) requires radon-resistant construction techniques for new residential construction in Tier 1 municipalities like Princeton Boro and Princeton Township, including a gas-permeable layer, vapor barrier, and a vent pipe.
New Jersey law requires radon testing and mitigation businesses to be certified by the NJDEP Radon Program. 1 certified mitigation business is based in Mercer County, and statewide firms serve the area too. Homeowners may legally test their own home with a kit, but hire a certified tester for a real-estate transaction.
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