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Radon Levels in Delaware County, New York

EPA puts Delaware County in Zone 1, its highest radon zone, and only 13 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

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  • Share at 4+ pCi/L

    27.6%

    3.1 pts above NY

    Delaware
    27.6%
    New York
    24.5%

    1,001 tests, 2008 to 2017

  • Median result

    1.8pCi/L

    Below action level

    Delaware
    1.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,001

    25th of 61 by tests

    Delaware
    1,001
    Erie
    13,822

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in New York

    28 of 61

    Middle half

    Delaware
    27.6%
    Chemung
    52.3%

    By share, of 61 with 30+ tests

Read a result for Delaware County

Starts at Delaware County's median, 1.8 pCi/L

1.8pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 1.8 pCi/L

Below 2 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Delaware County's median reported result, 2008 to 2017.

Interpret this reading

The data

Delaware County, At a glance

Delaware County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Delaware County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Delaware County, 2023

Share of reported tests at or above 4 pCi/L, by year, Delaware County
Share of reported tests at or above 4 pCi/L, by year, Delaware County
YearShare of reported tests at or above 4 pCi/L
201428.6%
201571.4%
201650.0%
201764.7%
201827.8%
201940.0%
202040.0%
202166.7%
20220.0%
202323.1%

2023: 23.1%. Across these years the share ran from 0.0% to 71.4%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 13 tests were reported to CDC for Delaware 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).

How to read these figures

Delaware County, Compared

Delaware County radon figures, compared

Calculated by Radon411

Delaware County's 1,001 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.8 pCi/L and a maximum of 830.0 pCi/L, and 27.6% reached 4 pCi/L. New York as a whole (62 New York counties, pooled) comes to 24.5%: 3.1 points lower than here.

The newest figure, in 2023, counts only 13 tests (23.1% at or above 4 pCi/L), too few to compare, so this reading uses the 1,001-test figure.

Among its state's counties it ranks 28th 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, 514 tests (51.3%) came in under 2 pCi/L, against 51.7% statewide, and 211 tests (21.1%) fell between 2 and 4, against 23.7% statewide. The busiest year on file was 2015, with 21 tests reported; the quietest, 2022, had 3.

EPA's 1993 zone map puts Delaware County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.

Next door, the shares run from 19.8% in Sullivan County to 37.6% in Otsego County, with Broome County, Schoharie County and Sullivan County below Delaware County.

CDC also counts 16 tests taken after mitigation in Delaware County for the same period: tests in homes where a fix was already in.

Delaware County against New York, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Delaware County
Delaware County1,00127.6%1.8 pCi/LThis county
New York, pooled62 counties, pooled97,14524.5%Not pooled−3.1 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+8.1 points
Chemung Countyhighest in the state1,53752.3%4.3 pCi/L+24.7 points
Bronx Countylowest in the state1853.2%0.5 pCi/L−24.4 points
Otsego County, NYborders it1,45237.6%2.8 pCi/L+10.0 points
Chenango County, NYborders it96133.4%2.6 pCi/L+5.8 points
Wayne County, PAborders it25232.5%2.8 pCi/L+4.9 points
Ulster County, NYborders it3,59429.8%2.2 pCi/L+2.2 points
Greene County, NYborders it52527.6%2.0 pCi/LLevel
Broome County, NYborders it5,89924.9%1.8 pCi/L−2.7 points
Schoharie County, NYborders it50421.8%1.7 pCi/L−5.8 points
Sullivan County, NYborders it25719.8%1.3 pCi/L−7.8 points
Where Delaware County's reported results fell, 2008 to 2017, laboratory, beside New York and the United States
ResultDelaware County testsDelaware County shareNew York shareU.S. shareAgainst New York
Under 2 pCi/L51451.3%51.7%39.6%−0.4 points
2 to 4 pCi/L21121.1%23.7%24.7%−2.6 points
4 pCi/L and above27627.6%24.5%35.7%+3.1 points
Delaware County ranked among the 61 New York counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Rensselaer County23 of 611,57729.5%2.1 pCi/L
Onondaga County24 of 619,11428.4%2.0 pCi/L
Tompkins County25 of 613,37228.0%2.3 pCi/L
Cayuga County26 of 6172627.8%2.1 pCi/L
Greene County27 of 6152527.6%2.0 pCi/L
Delaware County28 of 611,00127.6%1.8 pCi/L
Wayne County29 of 6179326.9%2.0 pCi/L
Washington County30 of 611,59325.6%2.0 pCi/L
Broome County31 of 615,89924.9%1.8 pCi/L
Putnam County32 of 611,02024.7%1.9 pCi/L
Orleans County33 of 6114324.5%2.0 pCi/L
Delaware County radon tests by year, against New York's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNew York, pooledChange from the row before
20231323.1%1.7 pCi/L13.9 pCi/L32.0%+23.1 points
202230.0%0.1 pCi/L0.1 pCi/L22.4%−66.7 points
2021366.7%5.0 pCi/L6.5 pCi/L18.9%+26.7 points
2020540.0%2.0 pCi/L14.1 pCi/L22.7%Level
20191040.0%2.6 pCi/L10.0 pCi/L28.0%+12.2 points
20181827.8%1.9 pCi/L26.7 pCi/L26.9%−36.9 points
20171764.7%5.2 pCi/L14.1 pCi/L31.6%+14.7 points
20161050.0%3.5 pCi/L15.2 pCi/L20.4%−21.4 points
20152171.4%7.3 pCi/L66.6 pCi/L21.4%+42.8 points
20141428.6%1.8 pCi/L31.2 pCi/L16.6%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Delaware County, State data

New York's own radon test data

Measured

What New York's own agencies publish about radon tests in Delaware 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 Delaware 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

46.3%

Average result

7.4 pCi/L

Tests behind these figures

16 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.

Delaware County, Geology

The ground under Delaware County

Predicted

Most of the ground under Delaware County is one class on USGS's geologic map: 99.9% of its land is high radon potential, with 0.1% moderate. All of it lies in the area the map calls Allegheny Plateau, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Delaware County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Allegheny PlateauShale, limestone, and sandstone.High1299.9%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Delaware County beside the ground around it

Delaware County has more high-potential ground than New York as a whole: 99.9% of its land against 48.9%. Of the 8 counties that border it, 4 have more high-potential ground, Broome County the most at 100%.

Share of land by USGS radon potential: Delaware County, the 8 counties bordering it and New York
AreaEPA zoneLow potentialModerate potentialHigh potential
Delaware CountyZone 1None0.1%99.9%
Otsego CountyZone 1None1.6%98.4%
Sullivan CountyZone 1None0.2%99.8%
Schoharie CountyZone 1None12.5%87.5%
Chenango CountyZone 1NoneNone100%
Greene CountyZone 1NoneNone100%
Wayne County, PAZone 2None96.4%3.6%
Ulster CountyZone 1NoneNone100%
Broome CountyZone 1NoneNone100%
New York62 counties, pooled by land areaVaries22.0%28.2%48.9%

The map rates the ground, not the air in any home.

Local help

Delaware County, Local resources

Radon testing and mitigation in Delaware County

What New York's program says
Phone
518-402-7556
Email
radon@health.ny.gov
Licensing of radon professionals
NYS does not certify or license radon testers.

What it means

Delaware County, Questions

Questions about radon in Delaware County

Are radon levels high in Delaware County?

In 2023, 23.1% of the radon tests reported to CDC for Delaware County, New York were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.7 pCi/L. Of 61 New York counties with 30 or more tests for the same period, 27 reported a higher share; pooled, the state comes to 24.5%.

Which counties border Delaware County?

Delaware County borders 8 counties: Otsego County, NY, Sullivan County, NY, Schoharie County, NY, Chenango County, NY, Greene County, NY, Wayne County, PA, Ulster County, NY and Broome County, NY.

Products

Delaware County, Products

Testing a home in Delaware County

In Delaware County, 27.6% of 1,001 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 24.5% pooled across New York. In Zone 1 the year-round level in Delaware County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Delaware County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Delaware County

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Delaware County, Bordering counties

Counties bordering Delaware County

Calculated by Radon411

Delaware County, Cities and towns

Cities and towns in Delaware County

Delaware County's population has barely moved since 2020: 44,305 residents on July 1, 2025 against 44,215 then, by the Census Bureau's estimates. That works out to 31 people per square mile of land. No town dominates: Sidney, the largest, has 3,588 residents, 8.1% of the total. Testing is reported here more often than across the state: CDC's 1,001 reported tests for 2008 to 2017 come to 22.6 for every 1,000 residents (2025 estimate), against 4.9 for New York.

From Sidney to Fleischmanns, CDC publishes no figure by town: each reads Delaware County's.

The cities and towns in Delaware County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sidney3,588−3.2%8.1%
Delhi3,526+26.7%8.0%
Walton2,824−3.1%6.4%
Depositextends beyond Delaware County1,404−3.4%Counted whole
Stamford1,034−2.7%2.3%
Hancock885−3.1%2.0%
Margaretville485−7.4%1.1%
Hobart384−3.0%0.9%
Franklin269−3.2%0.6%
Fleischmanns223−3.5%0.5%

10 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). A place that extends beyond Delaware County is counted whole, so it has no share.

Delaware County, Homes

Homes in Delaware County

Delaware County is a place of houses on their own lots: 76% of its 30,038 homes are detached single-family houses, against 41% across New York. Much of Delaware County is recent building: 13% of its homes have gone up since 2000 and the middle year built is 1971, against 1958 for New York. Owners live in 77% of the occupied homes (New York: 54%), so for most households a test and a fix are their own to order.

Homes in Delaware County, New York, 2019 to 2023
HomesDelaware CountyNew York
Housing units30,0388,539,536
Detached houses76%41%
In buildings of 5 or more4%34%
Mobile homes12%2%
Built before 196041%53%
Built since 200013%12%
Middle year built19711958
Owner-occupied77%54%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.