Radon in Westchester County, New York
Westchester County, New York, is in EPA radon Zone 3: predicted average indoor radon screening level less than 2 pCi/L (low potential). Radon laboratories reported 2,339 building tests here for 2008 to 2017: median 1.5 pCi/L, with 16.3% at or above EPA's 4 pCi/L action level (New York 24.2%, US 36.5%). New York state health records show 17.5% of 2,875 basement kit tests at or above 4 pCi/L.
Radon test results in Westchester County
| Test results | Period | Tests | Typical result | 4 pCi/L or more |
|---|---|---|---|---|
| Radon testing laboratories | 2008-2017 | 2,339 | median 1.5 pCi/L | 16.3% |
| New York radon program | 2023 | 19 | median 1.8 pCi/L | 5.6% |
| State health records, basement kit tests | 1987 on | 2,875 | average 2.8 pCi/L | 17.5% |
| State health records, first-floor kit tests | 1987 on | 799 | average 1.4 pCi/L | 5.3% |
| New York, all counties (labs) | 2008-2017 | 65,893 | n/a | 24.2% |
| United States (labs) | 2008-2017 | 1,408,802 | n/a | 36.5% |
Test results describe buildings whose owners chose to test and whose results reached the lab or agency, not a random sample; small counts swing widely. State and US shares are computed from county counts and percents. The laboratory data comes from national radon testing laboratories and supplements EPA's zone map.
Radon by town in Westchester County
New York state basement kit results by town since 1987, towns with the most tests first.
| Town, village or city | Basement tests | Average | 4 pCi/L or more |
|---|---|---|---|
| Greenburgh | 258 | 2.2 pCi/L | 9.7% |
| Cortlandt | 240 | 4.4 pCi/L | 20.8% |
| Mt. Pleasant | 205 | 2.2 pCi/L | 12.7% |
| Yorktown | 203 | 2.7 pCi/L | 21.2% |
| Yonkers | 172 | 2.2 pCi/L | 14% |
| Scarsdale | 169 | 2.3 pCi/L | 13% |
| White Plains | 169 | 2.7 pCi/L | 10.1% |
| New Castle | 149 | 2.3 pCi/L | 12.1% |
| New Rochelle | 148 | 1.9 pCi/L | 8.8% |
| Mamaroneck | 132 | 3.9 pCi/L | 31.1% |
| Bedford | 124 | 2.5 pCi/L | 14.5% |
| Rye | 115 | 2.3 pCi/L | 16.5% |
| Eastchester | 95 | 2.8 pCi/L | 17.9% |
| Lewisboro | 86 | 3.8 pCi/L | 33.7% |
| Ossining | 83 | 2.1 pCi/L | 12% |
| No. Castle | 79 | 4.5 pCi/L | 30.4% |
| Somers | 79 | 3.7 pCi/L | 31.6% |
| Harrison | 77 | 3.3 pCi/L | 22.1% |
| No. Salem | 63 | 3.7 pCi/L | 31.7% |
| Mt. Vernon | 62 | 2.9 pCi/L | 17.7% |
| Mt. Kisco | 49 | 2.3 pCi/L | 14.3% |
| Peekskill | 49 | 3.6 pCi/L | 20.4% |
| Pound Ridge | 38 | 3.6 pCi/L | 26.3% |
| Pelham | 31 | 2.7 pCi/L | 19.4% |
Radon in nearby counties
| County | EPA zone | Lab tests | 4 pCi/L or more |
|---|---|---|---|
| Rockland County, NY | Zone 3 | 641 | 14.6% |
| Western Connecticut Planning Region, CT | Mixed (Zones 1 and 2) | n/a | n/a |
| Putnam County, NY | Zone 1 | 637 | 24.7% |
| Bergen County, NJ | Zone 2 | n/a | n/a |
| Bronx County, NY | Zone 3 | 132 | 3.2% |
| Greater Bridgeport Planning Region, CT | Zone 1 | n/a | n/a |
The six counties with the nearest centers.
What to do about radon in Westchester County
Test the building. EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, and says there is no known safe level of exposure. The state health department runs the state's radon program.
Buying here? The Environmental Records Report lists this county's radon zone and test results with the flood zone, mapped faults, power lines and federal contamination records near the address.
Radon in Westchester County: questions
What is the radon level in Westchester County?
The median of the 2,339 laboratory tests reported for Westchester County (2008 to 2017) was 1.5 pCi/L, and 16.3% of them were at or above 4 pCi/L. New York state basement kits average 2.8 pCi/L. These are results of tested buildings; a single home can be far above or below them.
Is Westchester County in radon Zone 1?
No. EPA's 1993 map puts Westchester County in Zone 3 (predicted average indoor radon screening level less than 2 pCi/L (low potential)). EPA says homes in every zone can have high radon and should be tested.
How does radon in Westchester County compare with New York?
16.3% of laboratory tests in Westchester County were at or above 4 pCi/L for 2008 to 2017, against 24.2% across New York (65,893 tests) and 36.5% nationally. 34 of New York's 62 counties are in Zone 1.
Should I test for radon in Westchester County?
Yes. EPA recommends testing every home whatever its zone: "This map should not be used to determine if individual homes need to be tested." Fix the home at 4 pCi/L or more and consider a fix between 2 and 4 pCi/L; EPA says there is no known safe level of radon exposure.
More for Westchester County
- New York LLC lookupDepartment of State record for an LLC and the Westchester properties recorded to it.
- New York title insurance calculatorTIRSA owner's and loan policy premiums for Zone 2 (NYC and downstate) and Zone 1 counties.
- New York closing cost calculatorState and City transfer taxes, the 1% mansion tax, title premiums and the seller's net.
- Westchester loan limitsThis year's FHFA conforming, FHA and VA county loan limits for 1 to 4 unit homes, from FHFA's and HUD's official files.
- Westchester fair market rentHUD Fair Market Rents for studios to 4 bedrooms, the voucher payment standard range and the change from last year.
- Westchester property tax rateEffective property tax rate from Census survey data: median taxes paid against median home value, ranked in the state.
- Environmental records reportSuperfund, hazardous waste, leaking tank and brownfield sites near any Westchester address, with distances and a site map. A records search, not a Phase I.
- Superfund sites in New YorkEvery EPA Superfund site in New York with its status, county and a map, refreshed nightly from federal records.
- USDA eligibility map: New YorkHow much of each New York county is in a USDA-eligible rural area, the towns mapped ineligible, and a free address check.
- Opportunity zones in New YorkEvery designated Opportunity Zone tract in New York by county, from the IRS list, and the tracts eligible for the 2027 round.
- Census tract lookupThe census tract of any Westchester address with its FFIEC income level and HUD Qualified Census Tract and DDA status.
Other free hazard lookups
- Fault lines near an addressUSGS-mapped earthquake faults within 5 miles, their age and slip rate, and the USGS seismic hazard value.
- Power lines near an addressHigh-voltage transmission lines within 1 mile from federal maps, with voltage and distance.
- Flood zone lookupThe FEMA flood zone mapped at any US address. Not an official flood zone determination.
- Superfund sites near an addressThe nearest EPA Superfund (NPL) sites and their status.
All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).
Radon in every New York county · Radon map of every state
Data compiled 2026-10-20. County FIPS 36119. County-level screening information, not a radon measurement of any building.