Locations and reports
Radon Levels in Delaware County, Pennsylvania
What this means for you
- Your area: EPA rates Delaware County Zone 1, the highest of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 6,041 radon tests reported to CDC for Delaware County (2020), 14.7% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
In 2020, 14.7% of the radon tests reported to CDC for Delaware County, Pennsylvania came back at or above the EPA action level of 4 pCi/L, and the median result was 1.8 pCi/L. EPA's Map of Radon Zones places the county in Zone 1, highest predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: Low across 76% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Delaware County, 2020
- Tests reported
- 6,041
- At or above 4 pCi/L
- 14.7%
- Median result
- 1.8 pCi/L
Of 6,041 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 3,223 | 53.3% |
| 2 to 4 pCi/L | 1,929 | 31.9% |
| 4 pCi/L and above | 889 | 14.7% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).
Delaware County, In figures
Delaware County in figures
What the published data says about Delaware County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Delaware County in Zone 1, highest predicted potential, as it does 48 other counties of Pennsylvania's 67.
Of the 5 bordering counties, EPA places Chester County and Montgomery County in Zone 1, Gloucester County and New Castle County in Zone 2 and Philadelphia County in Zone 3.
Reported tests
MeasuredCDC has annual figures for Delaware County for 7 years, 2014 to 2020. In 2020, 14.7% of 6,041 reported tests were at or above 4 pCi/L.
Across those years the share ranged from 14.7% (2020) to 20.7% (2015). Few tests in a year can move it a long way.
Local record
Pennsylvania's radon program is the Radon Division, run by Department of Environmental Protection; its contacts are under Local resources.
The county's largest incorporated places are Chester, Yeadon and Lansdowne; the figures here cover them as part of the county.
Delaware County, Reported testing
Reported testing over time
Measured| Year | Median reported result | Highest reported result | Share of tests at or above 4 pCi/L |
|---|---|---|---|
| 2014 | 1.9 pCi/L | 98.3 pCi/L | 19.4% |
| 2015 | 2.0 pCi/L | 125.6 pCi/L | 20.7% |
| 2016 | 1.9 pCi/L | 62.9 pCi/L | 17.0% |
| 2017 | 1.8 pCi/L | 85.9 pCi/L | 17.0% |
| 2018 | 1.8 pCi/L | 105.1 pCi/L | 16.2% |
| 2019 | 1.8 pCi/L | 125.0 pCi/L | 15.3% |
| 2020 | 1.8 pCi/L | 65.1 pCi/L | 14.7% |
What these figures count
Every percentage here is a share of radon tests reported to CDC for Delaware County in 2020. It is not a share of homes in Delaware County, and it is not a random sample: it counts only the tests people chose to run and that were reported.
The shares and the median are calculated from pre-mitigation tests (6,041 for 2020). CDC also reports the number of buildings tested (3,894), a different count, so the two totals are not interchangeable.
Delaware County, State data
Pennsylvania's own radon test data
MeasuredWhat Pennsylvania'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.
What Pennsylvania DEP reports for the ZIP codes in Delaware County
Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 45 ZIP codes that lie wholly or partly in Delaware County, each with the state's own figures for it. Period: Period not stated by DEP.
| ZIP code | What the state reports |
|---|---|
| 19003 | Basement: average 2.5 pCi/L, 3,078 tests; First floor: average 1.3 pCi/L, 723 tests |
| 19008 | Basement: average 3.4 pCi/L, 3,658 tests; First floor: average 2.0 pCi/L, 714 tests |
| 19010 | Basement: average 3.2 pCi/L, 4,858 tests; First floor: average 1.7 pCi/L, 1,151 tests |
| 19013 | Basement: average 1.8 pCi/L, 814 tests; First floor: average 0.9 pCi/L, 165 tests |
| 19014 | Basement: average 2.3 pCi/L, 2,998 tests; First floor: average 1.2 pCi/L, 383 tests |
| 19015 | Basement: average 1.6 pCi/L, 1,460 tests; First floor: average 1.0 pCi/L, 233 tests |
| 19017 | Basement: average 2.4 pCi/L, 57 tests; First floor: figures not shown |
| 19018 | Basement: average 2.3 pCi/L, 2,340 tests; First floor: average 1.3 pCi/L, 418 tests |
| 19022 | Basement: average 1.3 pCi/L, 160 tests; First floor: figures not shown |
| 19023 | Basement: average 1.5 pCi/L, 967 tests; First floor: average 1.0 pCi/L, 197 tests |
| 19026 | Basement: average 2.7 pCi/L, 5,518 tests; First floor: average 1.7 pCi/L, 1,002 tests |
| 19029 | Basement: average 1.4 pCi/L, 171 tests; First floor: average 0.9 pCi/L, 34 tests |
| 19032 | Basement: average 1.2 pCi/L, 646 tests; First floor: average 1.0 pCi/L, 49 tests |
| 19033 | Basement: average 2.1 pCi/L, 799 tests; First floor: average 1.1 pCi/L, 113 tests |
| 19036 | Basement: average 1.6 pCi/L, 1,200 tests; First floor: average 1.2 pCi/L, 168 tests |
| 19041 | Basement: average 3.9 pCi/L, 1,595 tests; First floor: average 1.9 pCi/L, 348 tests |
| 19043 | Basement: average 1.4 pCi/L, 212 tests; First floor: average 1.0 pCi/L, 48 tests |
| 19050 | Basement: average 2.8 pCi/L, 3,542 tests; First floor: average 1.5 pCi/L, 835 tests |
| 19052 | Basement: figures not shown; First floor: figures not shown |
| 19060 | Basement: average 2.6 pCi/L, 871 tests; First floor: figures not shown |
| 19061 | Basement: average 2.5 pCi/L, 2,384 tests; First floor: average 1.4 pCi/L, 375 tests |
| 19063 | Basement: average 4.1 pCi/L, 8,556 tests; First floor: average 2.5 pCi/L, 1,260 tests |
| 19064 | Basement: average 3.7 pCi/L, 5,237 tests; First floor: average 2.1 pCi/L, 821 tests |
| 19070 | Basement: average 2.9 pCi/L, 839 tests; First floor: average 2.2 pCi/L, 115 tests |
| 19073 | Basement: average 3.0 pCi/L, 4,853 tests; First floor: average 1.8 pCi/L, 871 tests |
| 19074 | Basement: average 1.8 pCi/L, 438 tests; First floor: average 1.2 pCi/L, 83 tests |
| 19076 | Basement: average 2.0 pCi/L, 479 tests; First floor: average 0.9 pCi/L, 94 tests |
| 19078 | Basement: average 2.1 pCi/L, 1,205 tests; First floor: average 1.1 pCi/L, 184 tests |
| 19079 | Basement: average 1.9 pCi/L, 607 tests; First floor: average 0.9 pCi/L, 82 tests |
| 19081 | Basement: average 2.7 pCi/L, 1,739 tests; First floor: average 1.5 pCi/L, 306 tests |
| 19082 | Basement: average 2.3 pCi/L, 2,841 tests; First floor: average 1.1 pCi/L, 694 tests |
| 19083 | Basement: average 3.0 pCi/L, 8,162 tests; First floor: average 1.8 pCi/L, 1,294 tests |
| 19085 | Basement: average 2.4 pCi/L, 1,955 tests; First floor: average 1.4 pCi/L, 464 tests |
| 19086 | Basement: average 2.9 pCi/L, 2,853 tests; First floor: average 1.7 pCi/L, 514 tests |
| 19087 | Basement: average 5.7 pCi/L, 12,385 tests; First floor: average 3.6 pCi/L, 2,801 tests |
| 19094 | Basement: average 2.1 pCi/L, 416 tests; First floor: average 1.1 pCi/L, 52 tests |
| 19096 | Basement: average 3.1 pCi/L, 4,474 tests; First floor: average 1.9 pCi/L, 960 tests |
| 19113 | Basement: figures not shown |
| 19153 | Basement: average 0.9 pCi/L, 259 tests; First floor: average 0.6 pCi/L, 62 tests |
| 19312 | Basement: average 6.2 pCi/L, 5,455 tests; First floor: average 4.0 pCi/L, 1,193 tests |
| 19317 | Basement: average 2.5 pCi/L, 2,878 tests; First floor: average 1.5 pCi/L, 421 tests |
| 19319 | Basement: average 3.8 pCi/L, 50 tests; First floor: figures not shown |
| 19342 | Basement: average 2.7 pCi/L, 3,277 tests; First floor: average 1.6 pCi/L, 509 tests |
| 19373 | Basement: average 3.4 pCi/L, 632 tests; First floor: average 1.8 pCi/L, 109 tests |
| 19382 | Basement: average 3.0 pCi/L, 13,001 tests; First floor: average 1.8 pCi/L, 2,090 tests |
- DEP's report gives the number of tests, the highest result and the average result for each floor tested; it states no period.
- DEP says the smartest thing to do is to test your home for radon, no matter where you live.
- A ZIP code that crosses the county line is listed whole; its figures cover all of it.
Measured: Pennsylvania DEP data, Period not stated by DEP.
Delaware County, Comparison
How Delaware County compares
MeasuredDelaware County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2020, highest first. Each county’s own published CDC figure.
- Chester CountyPA6,770 tests24.0%
- Montgomery CountyPA10,508 tests21.8%
- Delaware CountyThis page6,041 tests14.7%
- Gloucester CountyNJ4,453 tests13.5%
- Philadelphia CountyPA8,442 tests10.6%
Median reported result
Measured2020, highest first. Each county’s own published CDC figure.
- Chester CountyPA6,770 tests2.0 pCi/L
- Montgomery CountyPA10,508 tests2.0 pCi/L
- Delaware CountyThis page6,041 tests1.8 pCi/L
- Philadelphia CountyPA8,442 tests1.7 pCi/L
- Gloucester CountyNJ4,453 tests1.2 pCi/L
Each figure is that county’s own published CDC figure for 2020, counting radon tests reported to CDC, not homes. Delaware County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. No published CDC figure for 2020: New Castle County, DE. Every Pennsylvania county’s own figure is in the Pennsylvania county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Delaware County, Pennsylvania with.
Delaware County, Bordering counties
Counties bordering Delaware County
Calculated by Radon4115 counties share a boundary with Delaware County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
Delaware County, Local resources
Local resources in Pennsylvania
Who to ask in Pennsylvania: the state's radon program, test kits and professionals.
Radon Division
Department of Environmental Protection
Pennsylvania’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 800-237-2366
- Licensing of radon professionals
The Radon Certification Act requires DEP to establish by regulation, a certification program for persons conducting radon gas and radon progeny testing, laboratory analysis and mitigation...
Test kits
The program says: Through an EPA-funded program, hospitals give parents of newborn children a packet of information which includes a coupon for a free radon test kit from the DEP.
Radon professionals
755 professionals are listed in Pennsylvania.
Professionals in PennsylvaniaDelaware County, Cities and towns
Cities and towns in Delaware County
The radon figures on this page are for Delaware County as a whole. They do not differ by city or town.
- Chester
- Yeadon
- Lansdowne
- Darby
- Collingdale
- Brookhaven
- Ridley Park
- Glenolden
- Clifton Heights
- Folcroft
- Swarthmore
- Prospect Park
- Sharon Hill
- Norwood
- Media
- Aldan
- Chester Heights
- Upland
- Morton
- East Lansdowne
- Colwyn
- Eddystone
- Marcus Hook
- Parkside
The other 4 places in Delaware County
- Trainer
- Millbourne
- Rose Valley
- Rutledge
28 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files.
Delaware County, Questions
Questions about radon in Delaware County
Common questions8 questions, answered from the figures above
How do I get a radon test in Delaware County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Delaware County as a service area yet. The Pennsylvania radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by statePennsylvania radon program
Are radon levels high in Delaware County?
In 2020, 14.7% of the radon tests reported to CDC for Delaware County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. That is a share of reported tests, not of homes. EPA places Delaware County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
Who does radon mitigation in Delaware County?
No listed mitigator names Delaware County as a service area yet; the Pennsylvania directory lists 755 companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Pennsylvania requires one.
How radon mitigation worksWhat mitigation costsMitigators in Pennsylvania
What EPA radon zone is Delaware County in?
EPA places Delaware County, Pennsylvania in Zone 1, which EPA describes as highest predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Delaware County?
Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Delaware County?
Delaware County borders 5 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Delaware County, Pennsylvania in 2020. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Delaware County, Products
Testing and mitigation products
Whatever the figures for Delaware County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Delaware County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.