Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
Locations and reports
Radon Levels in Bronx County, New York
EPA puts Bronx County in Zone 3, its lowest radon zone, and only 1 radon test from it is on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
3.2%
21.3 pts below NY
- Bronx
- 3.2%
- New York
- 24.5%
185 tests, 2008 to 2017
Median result
0.5pCi/L
Below action level
- Bronx
- 0.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
185
54th of 61 by tests
- Bronx
- 185
- Erie
- 13,822
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in New York
61 of 61
Lowest quarter
- Bronx
- 3.2%
- Chemung
- 52.3%
By share, of 61 with 30+ tests
Read a result for Bronx County
Starts at Bronx County's median, 0.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.5 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Bronx County's median reported result, 2008 to 2017.
The data
Bronx County, At a glance
Bronx County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Moderate across 81% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Bronx County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 100.0% |
| 2016 | 0.0% |
| 2017 | 100.0% |
| 2020 | 0.0% |
| 2023 | 0.0% |
2023: 0.0%. Across these years the share ran from 0.0% to 100.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 1 test was reported to CDC for Bronx County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Bronx County, Compared
Bronx County radon figures, compared
Calculated by Radon411Only 6 of 185 radon tests reported for Bronx County over the 2008 to 2017 laboratory totals reached 4 pCi/L (3.2%). The median result, 0.5 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 17.5 pCi/L.
The newest figure, in 2023, counts only 1 test (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 185-test figure.
Across 62 New York counties pooled together, 24.5% of tests reached that level, so Bronx County runs 21.3 points below its state. Against the national pool of 35.7%, the gap is 32.5 points lower. Its place in the state: 61st of 61 New York counties with 30 or more tests for the same period.
Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 3.2% share point the same way here. Of 3 neighbours with a figure, all 3 reported a larger share at or above 4 pCi/L; the spread is 5.3% (Queens County) to 16.3% (Westchester County).
Below the action level, 155 tests (83.8%) came in under 2 pCi/L, against 51.7% statewide, and 24 tests (13.0%) fell between 2 and 4, against 23.7% statewide. USGS geology rates 81% of the county's land moderate radon potential.
The busiest year on file was 2014, with 1 tests reported; the quietest, 2023, had 1.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Bronx County, State data
New York's own radon test data
MeasuredWhat New York's own agencies publish about radon tests in Bronx County, with their period. These are not CDC's figures and are never added to them.
MeasuredState figures, not CDC's
What the New York State Department of Health reports for Bronx County
Indoor air radon testing data (Environmental Public Health Tracker): short-term charcoal canister tests requested through the NYSDOH Radon Program, presented as five-year rolling averages. Period: 2015-2019. The publisher also lists 15 earlier periods.
Share at or above 4 pCi/L
20%
Average result
10.6 pCi/L
Tests behind these figures
1.3 tests a year on average
- Every figure is a five-year rolling average: the average result is the rolling average of each year's mean, and the test count is an average per year.
- The data only include tests requested through the NYSDOH Radon Program, and therefore may not capture all radon tests performed in a county.
- The data include both screening tests and post-mitigation tests, as it is not always possible to tell them apart.
- Radon testing by homeowners is optional in New York, so the values may not be representative of every home in the county.
- These figures describe tests reported to the New York State Department of Health in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.
Measured: New York State Department of Health data, 2015-2019.
Bronx County, Geology
The ground under Bronx County
PredictedMost of the ground under Bronx County is one class on USGS's geologic map: 80.6% of its land is moderate radon potential, with 1.1% low. The map puts 80.6% of Bronx County in the area it calls Manhattan Prong and 1.1% in Atlantic Coastal Plain. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 7, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Manhattan Prong | Gneiss, amphibolite, quartzite, marble, schist, diorite. | Moderate | 9 | 80.6% |
| Atlantic Coastal Plain | Glacial deposits and marine sediments. | Low | 7 | 1.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Bronx County beside the ground around it
Across New York 48.9% of the land is rated high; none of Bronx County's is. Of the 4 counties that border it, 2 have more high-potential ground, Westchester County the most at 15.2%.
The map rates the ground, not the air in any home.
Local help
Bronx County, Local resources
Radon testing and mitigation in Bronx County
- Radon ProgramRadon Program, run by New York State Department of Health, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in New York.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Providing patients with information about how low-cost test kits may be obtained from the Radon Program.
- Compare kits
- Professionals in New York88 professionals are listed in New York.
Listed radon professionals by town: New York
What New York's program says
- Phone
- 518-402-7556
- radon@health.ny.gov
- Licensing of radon professionals
NYS does not certify or license radon testers.
What it means
Bronx County, Questions
Questions about radon in Bronx County
Are radon levels high in Bronx County?
In 2023, 0.0% of the radon tests reported to CDC for Bronx County, New York were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 61 New York counties with 30 or more tests for the same period, 60 reported a higher share; pooled, the state comes to 24.5%.
Which counties border Bronx County?
Bronx County borders 4 counties: New York County, NY, Bergen County, NJ, Queens County, NY and Westchester County, NY.
Products
Bronx County, Products
Testing a home in Bronx County
In Bronx County, 3.2% of 185 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 24.5% pooled across New York. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Bronx County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-1011S rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 12 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Bronx County, Bordering counties
Counties bordering Bronx County
Calculated by Radon411- Radon levels in Westchester County, NYEPA zone 3
16.3%at or above 4 pCi/L
Median 1.5 pCi/L · 3,463 tests · 13.1 points above Bronx County
- Radon levels in New York County, NYEPA zone 3
7.1%at or above 4 pCi/L
Median 0.2 pCi/L · 759 tests · 3.9 points above Bronx County
- Radon levels in Queens County, NYEPA zone 3
5.3%at or above 4 pCi/L
Median 0.8 pCi/L · 419 tests · 2.1 points above Bronx County
- Radon levels in Bergen County, NJEPA zone 2
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Bronx County, Cities and towns
Cities and towns in Bronx County
About 1,406,332 people live in Bronx County by the Census Bureau's estimate for July 1, 2025, 54,901 fewer than in 2020 (−3.8%). Packed into its land, that is 33,348 people per square mile. New York, the largest place on its list (8,584,629 residents in all), extends beyond Bronx County, so no share of the total is worked out for it. Reported testing is thin here: 185 tests over 2008 to 2017, or 0.1 for every 1,000 residents (2025 estimate), where New York as a whole comes to 4.9.
New York is the one incorporated place here; CDC publishes no figure by town, so it reads Bronx County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| New Yorkextends beyond Bronx County | 8,584,629 | −1.9% | Counted whole |
One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Bronx County is counted whole, so it has no share.
Bronx County, Homes
Homes in Bronx County
Bronx County has 553,231 homes, and many share a building: 72% are in buildings of five or more, 6% are detached houses, against 41% across New York. Half of its homes were built before 1954, close to New York's 1958: 58% date from before 1960 and 11% from 2000 or later. Most occupied homes here are rented: owners live in 20% (New York: 54%). A tenant can run a test; a fix is the landlord's to make.
| Homes | Bronx County | New York |
|---|---|---|
| Housing units | 553,231 | 8,539,536 |
| Detached houses | 6% | 41% |
| In buildings of 5 or more | 72% | 34% |
| Mobile homes | under 1% | 2% |
| Built before 1960 | 58% | 53% |
| Built since 2000 | 11% | 12% |
| Middle year built | 1954 | 1958 |
| Owner-occupied | 20% | 54% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.