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Delaware Radon Map and Levels by County

Delaware's counties span EPA Zones 2 and 3. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    16.7%

    19.0 pts below U.S.

    Delaware
    16.7%
    U.S.
    35.7%

    12,214 tests across 3 counties, 2008 to 2017

  • Rank among states

    42 of 47

    Ten lowest states

    Delaware
    16.7%
    North Dakota
    59.3%

    By share, every state pooled the same way, 2008 to 2017

  • Counties in EPA Zone 1

    0 of 3

    None at highest potential

    Zone 1
    0
    Zone 2
    1

    Most counties sit in Zone 3; Zone 1 is the highest potential

  • Highest county

    17.0%

    New Castle County

    New Castle
    17.0%
    Sussex
    10.4%

    Counties with 30+ tests, 2008 to 2017

Read a result for Delaware

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 pCi/L

At or above 4 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. 16.7% of Delaware's reported tests reached 4 pCi/L, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Delaware, At a glance

Delaware at a glance

Predicted: EPA radon zone

3 of 3 counties classified

EPA classifies counties, not states. Of the 3 counties in Delaware with a zone, 1 is in Zone 2 and 2 in Zone 3.

  • Zone 2: Moderate predicted potential2 to 4 pCi/L1 of 3 counties · 33.3%
  • Zone 3: Lower predicted potentialless than 2 pCi/L2 of 3 counties · 66.7%

An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Delaware's radon test figures by county: 3 of its 3 counties have one. Each one's share is in the county list.

How to read these figures

Delaware, Compared

Delaware radon figures, compared

Calculated by Radon411
Delaware, 2008 to 2017, laboratory
16.7%
of 12,214 tests at or above 4 pCi/L, pooled
Against the U.S.
−19.0points
35.7% pooled
Rank among the states
42 of 47
1 is the highest share
Counties with 30 or more tests
3
Highest
17.0%
New Castle County
Lowest
10.4%
Sussex County

Fewer reported tests reach 4 pCi/L in Delaware than in most states: 16.7% of 12,214 over the 2008 to 2017 laboratory totals, from 3 counties. Nationally the pooled share is 35.7%: 19.0 points higher than here. Among 47 states pooled the same way it ranks 42nd, with Arizona (16.8%) above it and Oklahoma (12.7%) below.

New Castle County reports the highest share (17.0% of 10,247 tests) and Sussex County the lowest (10.4%); the most tests came from New Castle County, 10,247 of them at 17.0%. EPA's 1993 map puts 0 of its 3 classified counties in Zone 1; the tests reported since bear that out at 16.7%.

By band, 2 counties at 15% to 30%, 1 county at 5% to 15%. Across its 4 overlapping ten-year totals, the share went from 17.9% (2005 to 2014) to 16.7% (2008 to 2017), within 2 points, with 2005 to 2014 the highest at 17.9%.

Delaware ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2008 to 2017, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
Alabama37 of 476512,56921.9%
Vermont38 of 471410,60021.7%
South Carolina39 of 474626,48119.4%
Alaska40 of 47983018.2%
Arizona41 of 47133,58916.8%
Delaware42 of 47312,21416.7%
Oklahoma43 of 475281412.7%
California44 of 47569,41510.3%
Texas45 of 471384,61510.2%
District of Columbia46 of 4712,1268.7%
Louisiana47 of 47364992.2%
Delaware's highest counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/L
New Castle County1 of 310,24717.0%
Kent County2 of 31,51616.9%
Sussex County3 of 345110.4%
Delaware's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2008 to 2017, laboratory
ShareCountiesTheir testsFor example
50% or more00None
30% to 50%00None
15% to 30%211,763New Castle County, Kent County
5% to 15%1451Sussex County
Under 5%00None
Delaware ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 2017312,21416.7%35.7%−0.6 points
2007 to 2016311,01617.3%35.8%−0.4 points
2006 to 201539,83617.6%36.3%−0.3 points
2005 to 201438,69117.9%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

Delaware, Counties

Delaware counties by EPA zone

Predicted

The map of Delaware, then its 3 counties zone by zone, each with its reported share at or above 4 pCi/L and a report of its own.

Delaware radon map by county: EPA radon zones. Map of Delaware's 3 counties shaded by EPA radon zone: Zone 2 in amber, Zone 3 in pale sand. 0 in Zone 1, 1 in Zone 2, 2 in Zone 3.
Delaware radon map by countyEPA radon zones for Delaware's counties: 0 counties in Zone 1, 1 county in Zone 2, 2 counties in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 3 highest in Delaware, 2008 to 2017

Local help

Delaware, Local resources

Local resources in Delaware

Who to ask in Delaware: its radon program, test kits and professionals.

What Delaware's program says
Phone
1-800-464-HELP

What it means

Delaware, Questions

Questions about radon in Delaware

Is radon a problem in Delaware?

Delaware has 3 counties on EPA's Map of Radon Zones: Zone 1, the highest predicted potential, for 0; Zone 2 for 1; Zone 3 for 2. Pooled from 3 counties, 16.7% of the 12,214 radon tests reported to CDC over the 2008 to 2017 laboratory totals were at or above 4 pCi/L, 42nd of 47 states.

Who does radon mitigation in Delaware?

Radon411's Delaware directory lists 2 radon businesses for testing, mitigation or both, each with the licensing list it was read from.

Which Delaware counties have the highest radon?

By the share of reported tests at or above 4 pCi/L, 2008 to 2017, laboratory: New Castle County 17.0% (10,247 tests), Kent County 16.9% (1,516 tests), Sussex County 10.4% (451 tests).

Which EPA region is Delaware in?

Delaware is in EPA Region 3: Mid-Atlantic.

Products

Delaware, Products

Testing a home in Delaware

16.7% of the 12,214 tests reported to CDC for Delaware over the 2008 to 2017 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Delaware; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Delaware homes, compared

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