Radon in New Jersey: County Zones and How to Test
New Jersey has counties in more than one EPA radon zone, which is exactly when a county-level answer earns its keep. Enter your ZIP for your county's zone, the map's 1993 vintage stated, and how to run a real test.
New Jersey's 21 counties split 7 Zone 1, 11 Zone 2 and 3 Zone 3 on the 1993 EPA Map of Radon ZonesYour county's radon report
Every county your ZIP touches, zone, vintage and caveat attachedNew Jersey's seven Zone 1 counties follow the Reading Prong and the Highlands across the state's northwest, the same uranium-bearing formation that produced the famous Pennsylvania discoveries of the 1980s, and reach down through Hunterdon, Somerset, Mercer and Monmouth. The Pine Barrens and the Shore south of that line drop to Zones 2 and 3. The DEP maintains municipal-level radon potential assignments newer and finer than the 1993 county map.
Every New Jersey county on the 1993 EPA Map of Radon Zones
The zones below are EPA's assignments from the 1993 Map of Radon Zones, which has never been revised, so their vintage is part of the fact. EPA built them from indoor measurements, geology, aerial radioactivity, soil parameters and foundation types, per county, and they predict county averages rather than describing any home.
EPA, Radon Zones Map (accessible text version)“Zone 1 (red zones) Highest potential; average indoor radon levels may be greater than 4 pCi/L (picocuries per liter). Zone 2 (orange zones) Moderate potential; average indoor radon levels may be between 2 and 4 pCi/L. Zone 3 (yellow zones) Low potential; average indoor radon levels may be less than 2 pCi/L.”
7 counties
- Hunterdon County
- Mercer County
- Monmouth County
- Morris County
- Somerset County
- Sussex County
- Warren County
11 counties
- Bergen County
- Burlington County
- Camden County
- Cumberland County
- Essex County
- Gloucester County
- Hudson County
- Middlesex County
- Passaic County
- Salem County
- Union County
3 counties
- Atlantic County
- Cape May County
- Ocean County
EPA prints one sentence in bold on every one of its state zone map PDFs, New Jersey's included, and it is the right way to leave this table:
EPA, state Maps of Radon Zones (printed on every state map PDF)“All homes should be tested, regardless of zone designation.”
EPA, Radon Zones Map (accessible text version)“The map should not be used to determine if a home in a given zone should be tested for radon. Homes with elevated levels of radon have been found in all three zones. All homes should be tested for radon.”
What New Jersey has published since the map
For New Jersey, the 1993 EPA zones above are the newest county-level assignment published as data: the state program had no county-level radon test summary published as data as of 2026-09-01. The state program is the place to ask for newer local numbers, and a test of your own home outranks every map ever drawn.
EPA, EPA Map of Radon Zones and Supplemental Information“EPA's Map of Radon Zones can be supplemented with available state-developed or other data to further understand the radon potential for a specific area.”
Testing a New Jersey home, in EPA's words and one link to the state
The state program is the practical door: New Jersey Department of Environmental Protection, Radon Program, 609-984-5425 (contact as listed by EPA, 2026-09-01). Many state programs mail free or discounted test kits, and January, National Radon Action Month on EPA's calendar, is when most of those campaigns run. Winter is also when a short-term test is easiest to run properly, because the test wants the house closed up and winter does that for you.
EPA, A Citizen's Guide to Radon“Follow the instructions that come with your test kit. If you are doing a short-term test, close your windows and outside doors and keep them closed as much as possible during the test.”
EPA, What is EPA's Action Level for Radon and What Does it Mean?“The EPA recommends homes be fixed if the radon level is 4 pCi/L (picocuries per liter) (150 becquerels per meter cubed (Bq/m3)) or more. Because there is no known safe level of exposure to radon, the EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L (75 - 150 Bq/m3).”
EPA's two testing pages cover the rest: A Citizen's Guide to Radon (EPA 402/K-12/002) and EPA, Find a Radon Test Kit or Measurement and Mitigation Professional. If a test comes back at or above 4.0 pCi/L, the fix is a mitigation system, and the state program keeps the list of certified installers. This site sells nothing and certifies nobody.
The health case, in EPA's words
Health guidance on radon is EPA's. Here it is, verbatim, with the door to the rest of it.
EPA, Health Risk of Radon“Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked.”
EPA, National Radon Action Month Information“You can’t see, smell or taste radon, but it could be present at a dangerous level in your home. Radon is the leading cause of lung cancer deaths among nonsmokers in America and claims the lives of about 21,000 Americans each year.”
The full picture, including EPA's risk tables by smoking status and the 2005 Surgeon General advisory, is at EPA, Health Risk of Radon. Questions about your own risk belong with your doctor, especially if you smoke or ever did.