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Burlington County radon hot spots are not evenly distributed. The county runs from the Delaware River on the west to the Pinelands on the east, and the bedrock under those two halves is fundamentally different. NJ DEP publishes radon-potential maps at the township and zip-code level, and reading them carefully tells you something useful before you ever order a test kit: where in the county the elevated readings cluster, why, and which homes in your specific town are most likely to come back above the EPA action level of 4.0 pCi/L.
The Two Halves Of Burlington County
The simplest way to read NJ DEP’s data: draw a line down the county roughly along the Route 206 corridor. Everything west of that line sits on weathered sedimentary bedrock with measurable radium content. Everything east sits on the Cohansey aquifer and the sandy soils of the Pinelands National Reserve. Soil-radon-source potential is dramatically different on the two sides.
NJ DEP categorizes radon potential as Tier 1 (highest), Tier 2 (moderate), and Tier 3 (lowest). The published map for Burlington County shows:
- Tier 2 / Tier 3 mix across most of the western municipalities (Burlington City, Mount Holly, Bordentown, Riverside, Edgewater Park, Delanco)
- Tier 2 across the suburban ring (Mount Laurel, Marlton, Medford, Cinnaminson, Maple Shade, Moorestown, Delran, Willingboro)
- Tier 3 across most of the Pinelands east (Pemberton, Tabernacle, Shamong, Woodland, Southampton, Lumberton)
Tier 3 sounds like “low risk and you can ignore it.” That is not how the data actually plays out. Tier 3 is a regional bedrock-source rating; individual homes test on a different distribution. A Tier 3 township still produces a meaningful percentage of homes above 4.0 pCi/L because foundation type, sealing, and stack effect dominate over bedrock source for any specific structure.
Western Burlington County: Where The Readings Cluster High
The river-corridor towns sit on slate, shale, and weathered sedimentary rock with measurable uranium and radium content. Burlington City, Mount Holly, Bordentown, and Beverly each have stretches of pre-1900 housing stock with fieldstone basements that were never built tight against soil-gas infiltration. The combination produces the highest numerical readings we see in the county. Delaware River corridor radon details covers what mitigation looks like on this stock.
Mount Holly in particular has a tight cluster of high-result homes in the historic Mill Street and High Street stretches. Burlington City’s older brick rowhouses on Wood Street and the Riverbank district produce similar readings. These are not isolated outliers; they are predictable from the geology and the construction era.
Suburban Ring: Moderate But Persistent
Mount Laurel, Marlton, and Medford sit on the central upland of the county, mostly post-1955 construction on slabs or with mid-century basements. The bedrock-source rating is Tier 2, which translates to readings most commonly in the 2.0 to 6.0 pCi/L band. This is the zone where homes “feel safe” but actually fail buyer-inspection tests at meaningful rates. Mid-century slab-on-grade construction with finished basements is mitigation-eligible often enough that the suburban ring is the largest source of pre-closing radon mitigation work in the county. Suburban Mount Laurel radon details.
Cinnaminson and Maple Shade have a slightly different story: closer to the river but sitting on a transitional geology between river-corridor sediments and suburban upland. Test results vary widely by individual home. Worth a test even if the neighbor across the street reads low.
Pinelands East: Low Numbers On Average, Tall Outliers
The eastern Pinelands towns (Pemberton, Tabernacle, Shamong, Woodland, Southampton, Lumberton) sit on Tier 3 bedrock-source rating. Most homes test in the 1.0 to 3.0 pCi/L band. So why do we see steady call volume from these towns?
Two reasons. First, sandy soil moves radon faster than clay does. A modest soil-radon source produces a bigger living-space concentration when the soil-gas transport rate is high. Second, the older Pinelands farmhouses with dirt-floor crawlspaces have essentially no barrier between soil gas and the home’s air. A Tier 3 township with a Tier 3 source-strength reading still produces a 6.0 pCi/L test result if the home is a 1920s farmhouse on a dirt-floor crawl with no vapor barrier. Pinelands crawlspace radon details.
Pemberton Township specifically has a stock of older agricultural and tenant housing that produces the highest Pinelands readings. Tabernacle and Woodland follow a similar pattern in their older stock. Newer Tabernacle and Southampton subdivisions on slab-on-grade construction read low on average.
What The Map Cannot Tell You
NJ DEP zone maps measure source potential. They do not measure your specific home. The strongest predictor of your individual home’s radon level is the home itself, not the township average:
- Foundation type (basement, slab, crawlspace, dirt-floor, mixed)
- Year built and sealing tightness
- HVAC pattern (forced air vs. radiant, balanced vs. negative-pressure)
- Stack effect (chimney, attic ventilation, multi-story)
- Local soil permeability under your specific lot
A Tier 2 home with a tight slab can read 1.8 pCi/L. A Tier 3 home with a leaky crawlspace can read 8.5 pCi/L. The map is a starting point, not an answer.
How To Read Your Own Result In Context
If you have a recent test number, place it in the right context for your zone:
- Western river-corridor home, reads above 4.0 pCi/L: in line with the regional pattern. Mitigation is the standard response. Sub-slab depressurization details.
- Suburban ring home, reads 4.0 to 6.0 pCi/L: common pattern for the zone, often surfaced by buyer inspections. Mitigation is straightforward.
- Pinelands home, reads above 4.0 pCi/L: almost always indicates a crawlspace or dirt-floor issue rather than bedrock source. Mitigation is sub-membrane.
- Any zone, reads below 2.0 pCi/L: no immediate action. Re-test in 2 years or before any major foundation work.
- Any zone, reads 2.0 to 4.0 pCi/L: EPA suggests considering mitigation, especially if a child or long-term resident sleeps in the lowest level. Buyer inspections sometimes flag this band.
If Your Number Triggers Mitigation
The geology that produced the test result also drives the system design. Contact a NJ-DEP-certified mitigation contractor in our network with the property address, the test number, and the foundation type. Pinelands crawlspaces, river-corridor fieldstone basements, and suburban slabs each get a different system. The Burlington County radon hot spots map is a useful planning input, but the install design comes from the walk-through, not the map.
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Related read: why a winter radon reading in Medford or Evesham is the one that counts.