Radon levels in New Jersey: Low
The model predicts a population-weighted basement average of 1.3 pCi/L (model estimate) across New Jersey's 21 counties - about 27% below the US average of 1.8 pCi/L. Above-ground floors average 0.8 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
7 / 21
EPA Zone 1 counties (33%)
11 / 3
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0%
of ZIP codes predicted ≥ 4 pCi/L
Test New Jersey once anyway - radon varies house to house
The predicted basement average here is 1.3 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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What the data says about radon in New Jersey
According to the EPA zone map, 7 of New Jersey's 21 counties are EPA Zone 1 (33%), 11 are Zone 2 and 3 are Zone 3. Zone 2 (predicted screening average of 2-4 pCi/L) is the most common designation, with the 7 Zone 1 counties marking where the EPA expected the highest potential. Treat the map as a coarse prior: it predates two decades of test data and never replaces a test in your own home.
The 2001-2021 national model predicts a population-weighted basement average of 1.3 pCi/L for New Jersey (low range, 27% below the US average of 1.8). Of the 21 counties with predictions, 0 are predicted at or above 4 pCi/L, 3 in the 2-4 band and 18 below 2. The highest predicted county is Warren County at 2.3 pCi/L; the lowest is Hudson County at 1.0 - a 1.3 pCi/L spread that means a statewide average tells you little about any one county.
10.4% of the state's modeled ZIP codes are predicted at or above 2 pCi/L, and 0% at or above the 4 pCi/L action level - below the national shares of 4.2% and 48.7%. No ZIP in the state is predicted above 4 on average - but averages hide individual homes, which is why the EPA still asks everyone to test.
New Jersey counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 21 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Warren County | 2.3 pCi/L | 1.6 | Moderate | EPA Zone 1 | 10 |
| Sussex County | 2.3 pCi/L | 1.6 | Moderate | EPA Zone 1 | 18 |
| Hunterdon County | 2.1 pCi/L | 1.6 | Moderate | EPA Zone 1 | 17 |
| Morris County | 1.8 pCi/L | 1.1 | Low | EPA Zone 1 | 44 |
| Somerset County | 1.7 pCi/L | 1.2 | Low | EPA Zone 1 | 23 |
| Salem County | 1.4 pCi/L | 0.8 | Low | EPA Zone 2 | 7 |
| Cape May County | 1.4 pCi/L | 0.7 | Low | EPA Zone 3 | 13 |
| Mercer County | 1.3 pCi/L | 0.9 | Low | EPA Zone 1 | 20 |
| Middlesex County | 1.3 pCi/L | 0.9 | Low | EPA Zone 2 | 36 |
| Gloucester County | 1.3 pCi/L | 0.8 | Low | EPA Zone 2 | 23 |
| Burlington County | 1.3 pCi/L | 0.8 | Low | EPA Zone 2 | 28 |
| Monmouth County | 1.3 pCi/L | 0.8 | Low | EPA Zone 1 | 48 |
| Cumberland County | 1.3 pCi/L | 0.7 | Low | EPA Zone 2 | 13 |
| Union County | 1.3 pCi/L | 0.7 | Low | EPA Zone 2 | 26 |
| Atlantic County | 1.2 pCi/L | 0.7 | Low | EPA Zone 3 | 23 |
| Ocean County | 1.2 pCi/L | 0.7 | Low | EPA Zone 3 | 28 |
| Passaic County | 1.2 pCi/L | 0.7 | Low | EPA Zone 2 | 27 |
| Bergen County | 1.2 pCi/L | 0.7 | Low | EPA Zone 2 | 66 |
| Essex County | 1.2 pCi/L | 0.6 | Low | EPA Zone 2 | 31 |
| Camden County | 1.1 pCi/L | 0.7 | Low | EPA Zone 2 | 33 |
| Hudson County | 1.0 pCi/L | 0.5 | Low | EPA Zone 2 | 15 |
Radon levels in New Jersey cities
The 22 most-populous New Jersey places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Newark | 304,960 | 1.1 pCi/L | 0.6 | Low | 0% |
| Jersey City | 291,657 | 0.9 pCi/L | 0.5 | Low | 0% |
| Paterson | 156,452 | 1.0 pCi/L | 0.6 | Low | 0% |
| Elizabeth | 135,829 | 1.0 pCi/L | 0.5 | Low | 0% |
| Trenton | 89,620 | 1.2 pCi/L | 0.8 | Low | 0% |
| Toms River | 88,791 | 1.2 pCi/L | 0.7 | Low | 0% |
| Clifton | 88,461 | 1.1 pCi/L | 0.6 | Low | 0% |
| Camden | 71,100 | 0.8 pCi/L | 0.6 | Low | 0% |
| Bayonne | 70,300 | 1.0 pCi/L | 0.6 | Low | 0% |
| East Orange | 69,556 | 1.1 pCi/L | 0.6 | Low | 0% |
| Passaic | 68,903 | 1.0 pCi/L | 0.6 | Low | 0% |
| Union City | 64,462 | 1.1 pCi/L | 0.5 | Low | 0% |
| Vineland | 60,797 | 1.3 pCi/L | 0.7 | Low | 0% |
| Hoboken | 57,010 | 1.0 pCi/L | 0.6 | Low | 0% |
| New Brunswick | 55,846 | 1.4 pCi/L | 1.0 | Low | 0% |
| Perth Amboy | 55,249 | 1.1 pCi/L | 0.7 | Low | 0% |
| Plainfield | 54,670 | 1.5 pCi/L | 1.0 | Low | 0% |
| Lakewood | 53,805 | 1.1 pCi/L | 0.7 | Low | 0% |
| West New York | 50,754 | 1.0 pCi/L | 0.6 | Low | 0% |
| Hackensack | 45,736 | 1.1 pCi/L | 0.7 | Low | 0% |
| Sayreville | 45,496 | 1.2 pCi/L | 0.8 | Low | 0% |
| Linden | 43,950 | 1.1 pCi/L | 0.6 | Low | 0% |
Highest-radon ZIP codes in New Jersey
The 10 New Jersey ZIP codes with the highest predicted basement average (model estimate), out of 549 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 08802 | Hunterdon County | 2.9 pCi/L | 1.9 | Moderate |
| 07838 | Warren County | 2.8 pCi/L | 1.8 | Moderate |
| 07832 | Warren County | 2.8 pCi/L | 1.8 | Moderate |
| 07865 | Warren County | 2.6 pCi/L | 1.9 | Moderate |
| 07863 | Warren County | 2.6 pCi/L | 1.8 | Moderate |
| 08826 | Hunterdon County | 2.6 pCi/L | 1.9 | Moderate |
| 07460 | Sussex County | 2.6 pCi/L | 1.8 | Moderate |
| 08827 | Hunterdon County | 2.6 pCi/L | 1.8 | Moderate |
| 07848 | Sussex County | 2.5 pCi/L | 1.7 | Moderate |
| 08804 | Hunterdon County | 2.5 pCi/L | 1.8 | Moderate |
New Jersey radon questions
- Is radon high in New Jersey?
- New Jersey's population-weighted predicted basement average is 1.3 pCi/L, about 27% below the US average of 1.8. 0 of its 21 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 3 are in the 2-4 "consider fixing" range and 18 are below 2. 0% of New Jersey ZIP codes are predicted at 4 or higher.
- Which New Jersey county has the highest radon?
- Warren County has the highest predicted basement average in New Jersey at 2.3 pCi/L (EPA Zone 1). The lowest is Hudson County at 1.0 pCi/L. These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in New Jersey?
- 7 of New Jersey's 21 counties (33%) are EPA Zone 1 (highest potential), 11 are Zone 2 and 3 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in New Jersey?
- Yes. Even though New Jersey's predicted average is below 2 pCi/L, the EPA recommends every home be tested - radon varies house to house, and 10.4% of New Jersey ZIP codes are still predicted at 2 pCi/L or higher.
New Jersey radon program
New Jersey's radon program page is at www.nj.gov; it lists testing and certified-mitigator guidance for the state. The EPA also keeps a directory of every state radon contact: EPA state radon contacts page. Then read how to test and what mitigation costs.