New Jersey: 21 counties covered
Of 21 rated New Jersey counties, 7 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Bergen County
- Middlesex County
- Essex County
- Hudson County
- Ocean County
- Monmouth County
- Union County
- Camden County
- Passaic County
- Morris County
- Burlington County
- Mercer County
- Somerset County
- Gloucester County
- Atlantic County
- Cumberland County
- Sussex County
- Hunterdon County
- Warren County
- Cape May County
- Salem County