Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Westchester County, New York
EPA puts Westchester County in Zone 3, its lowest radon zone, and only 18 radon tests from it are 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
16.3%
8.2 pts below NY
- Westchester
- 16.3%
- New York
- 24.5%
3,463 tests, 2008 to 2017
Median result
1.5pCi/L
Below action level
- Westchester
- 1.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
3,463
7th of 61 by tests
- Westchester
- 3,463
- 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
42 of 61
Middle half
- Westchester
- 16.3%
- Chemung
- 52.3%
By share, of 61 with 30+ tests
Read a result for Westchester County
Starts at Westchester County's median, 1.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.5 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. Westchester County's median reported result, 2008 to 2017.
The data
Westchester County, At a glance
Westchester County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Moderate across 85% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Westchester County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 8.3% |
| 2015 | 13.6% |
| 2016 | 15.2% |
| 2017 | 21.1% |
| 2018 | 10.3% |
| 2019 | 13.0% |
| 2020 | 11.1% |
| 2021 | 0.0% |
| 2022 | 0.0% |
| 2023 | 5.6% |
2023: 5.6%. Across these years the share ran from 0.0% to 21.1%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 18 tests were reported to CDC for Westchester 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).
Westchester County, Compared
Westchester County radon figures, compared
Calculated by Radon411Westchester County's 3,463 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.5 pCi/L and a maximum of 99.0 pCi/L, and 16.3% reached 4 pCi/L. New York as a whole (62 New York counties, pooled) comes to 24.5%: 8.2 points higher than here.
The newest figure, in 2023, counts only 18 tests (5.6% at or above 4 pCi/L), too few to compare, so this reading uses the 3,463-test figure.
Among its state's counties it ranks 42nd of 61 New York counties with 30 or more tests for the same period. Statewide for the same period, Chemung County reported the highest share (52.3%) and Bronx County the lowest (3.2%).
Below the action level, 2,104 tests (60.8%) came in under 2 pCi/L, against 51.7% statewide, and 796 tests (23.0%) fell between 2 and 4, against 23.7% statewide. The busiest year on file was 2018, with 126 tests reported; the quietest, 2022, had 3.
EPA's 1993 zone map puts Westchester County in Zone 3, a predicted county average under 2 pCi/L. USGS geology rates 85% of the county's land moderate radon potential.
Next door, the shares run from 3.2% in Bronx County to 27.4% in Fairfield County, CT, with Rockland County and Bronx County below Westchester County. Over 5 years of annual figures the share rose 4.7 points, from 8.3% in 2014 to 13.0% in 2019; its peak was 21.1% in 2017.
CDC also counts 206 tests taken after mitigation in Westchester County for the same period: tests in homes where a fix was already in.
Westchester CountyNew York, pooled
13.0% % of tests28.0% % of tests
| Year | Tests | Westchester County, at or above 4 pCi/L | New York, pooled |
|---|---|---|---|
| 2014 | 36 | 8.3% | 16.6% |
| 2016 | 79 | 15.2% | 20.4% |
| 2017 | 57 | 21.1% | 31.6% |
| 2018 | 126 | 10.3% | 26.9% |
| 2019 | 46 | 13.0% | 28.0% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Westchester County, State data
New York's own radon test data
MeasuredWhat New York's own agencies publish about radon tests in Westchester 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 Westchester 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
13.2%
Average result
2.2 pCi/L
Tests behind these figures
69.6 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.
Westchester County, Geology
The ground under Westchester County
PredictedMost of the ground under Westchester County is one class on USGS's geologic map: 84.5% of its land is moderate radon potential, with 15.2% high. The map puts 84.4% of Westchester County in the area it calls Manhattan Prong and 14.8% in Hudson Highlands. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Manhattan Prong | Gneiss, amphibolite, quartzite, marble, schist, diorite. | Moderate | 9 | 84.4% |
| Hudson Highlands | Amphibolitic gneiss, quartz-poor gneisses, and marbles. | High | 13 | 14.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Westchester County beside the ground around it
New York as a whole has more high-potential ground than Westchester County: 48.9% of its land, against 15.2% here. Of the 5 counties that border it, 3 have more high-potential ground, Putnam County the most at 96.6%.
The map rates the ground, not the air in any home.
Local help
Westchester County, Local resources
Radon testing and mitigation in Westchester County
Listed radon businesses with an address in Westchester 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: Elmsford
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
Westchester County, Questions
Questions about radon in Westchester County
Are radon levels high in Westchester County?
In 2023, 5.6% of the radon tests reported to CDC for Westchester County, New York were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. Of 61 New York counties with 30 or more tests for the same period, 41 reported a higher share; pooled, the state comes to 24.5%.
Which counties border Westchester County?
Westchester County borders 5 counties: Rockland County, NY, Bergen County, NJ, Bronx County, NY, Putnam County, NY and Fairfield County, CT.
Products
Westchester County, Products
Testing a home in Westchester County
In Westchester County, 16.3% of 3,463 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 Westchester 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
MonitorAranet
Radon One battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Westchester County, Bordering counties
Counties bordering Westchester County
Calculated by Radon411- Radon levels in Fairfield County, CTEPA zone 1
27.4%at or above 4 pCi/L
Median 2.1 pCi/L · 7,638 tests · 11.1 points above Westchester County
- Radon levels in Putnam County, NYEPA zone 1
24.7%at or above 4 pCi/L
Median 1.9 pCi/L · 1,020 tests · 8.4 points above Westchester County
- Radon levels in Rockland County, NYEPA zone 3
14.6%at or above 4 pCi/L
Median 1.5 pCi/L · 824 tests · 1.7 points below Westchester County
- Radon levels in Bronx County, NYEPA zone 3
3.2%at or above 4 pCi/L
Median 0.5 pCi/L · 185 tests · 13.1 points below Westchester County
- Radon levels in Bergen County, NJEPA zone 2
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Westchester County, Cities and towns
Cities and towns in Westchester County
The Census Bureau estimates 1,015,743 residents in Westchester County for July 1, 2025, 14,292 more than in 2020 (+1.4%). Packed into its land, that is 2,358 people per square mile. Its largest town, Yonkers, has 212,603 residents, 20.9% of the total. Together its 29 incorporated places hold 73.5% of those residents; the other 26.5% live outside any of them. CDC's 3,463 reported tests for 2008 to 2017 work out to 3.4 per 1,000 residents (2025 estimate), close to New York's 4.9.
From Yonkers to Buchanan, CDC publishes no figure by town: each reads Westchester County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Yonkers | 212,603 | +0.8% | 20.9% |
| New Rochelle | 85,864 | +7.1% | 8.5% |
| Mount Vernon | 72,304 | −1.7% | 7.1% |
| White Plains | 62,871 | +5.5% | 6.2% |
| Port Chester | 32,303 | +2.3% | 3.2% |
| Harrison | 32,273 | +14.7% | 3.2% |
| Ossining | 27,579 | +0.9% | 2.7% |
| Peekskill | 25,891 | +2.2% | 2.5% |
| Mamaroneck | 19,896 | −0.9% | 2.0% |
| Scarsdale | 18,194 | Level | 1.8% |
| Rye | 16,614 | +0.4% | 1.6% |
| Tarrytown | 11,890 | +0.8% | 1.2% |
- Dobbs Ferry
- Sleepy Hollow
- Mount Kisco
- Rye Brook
- Hastings-on-Hudson
- Croton-on-Hudson
- Pelham
- Briarcliff Manor
- Pleasantville
- Tuckahoe
- Larchmont
- Irvington
- Bronxville
- Pelham Manor
- Elmsford
- Ardsley
- Buchanan
29 incorporated places, 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).
Westchester County, Homes
Homes in Westchester County
Westchester County has 391,861 homes, and many share a building: 35% are in buildings of five or more, 44% are detached houses, against 41% across New York. Half of its homes were built before 1958, close to New York's 1958: 53% date from before 1960 and 10% from 2000 or later. 62% of occupied homes are lived in by their owner (New York: 54%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Westchester County | New York |
|---|---|---|
| Housing units | 391,861 | 8,539,536 |
| Detached houses | 44% | 41% |
| In buildings of 5 or more | 35% | 34% |
| Mobile homes | under 1% | 2% |
| Built before 1960 | 53% | 53% |
| Built since 2000 | 10% | 12% |
| Middle year built | 1958 | 1958 |
| Owner-occupied | 62% | 54% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.