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Radon Levels in Lehigh County, Pennsylvania

EPA puts Lehigh County in Zone 1, its highest radon zone, and 39.8% of its 3,103 reported radon tests (2020) were at or above 4 pCi/L. 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

    39.8%

    9.5 pts above PA

    Lehigh
    39.8%
    PA
    30.3%

    3,103 tests, 2020

  • Median result

    2.7pCi/L

    Below action level

    Lehigh
    2.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2020

  • Tests reported

    3,103

    10th of 63 by tests

    Lehigh
    3,103
    Montgomery
    10,508

    Reported to CDC before any fix, 2020

  • 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 PA

    31 of 63

    Middle half

    Lehigh
    39.8%
    Perry
    57.7%

    By share, of 63 with 30+ tests

Read a result for Lehigh County

Starts at Lehigh County's median, 2.7 pCi/L

2.7pCi/L

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

EPA’s reading of 2.7 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Lehigh County's median reported result, 2020.

Interpret this readingWhat a fix costs

The data

Lehigh County, At a glance

Lehigh County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Lehigh 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 Lehigh County, 2020

Share of reported tests at or above 4 pCi/L, by year, Lehigh County
Share of reported tests at or above 4 pCi/L, by year, Lehigh County
YearShare of reported tests at or above 4 pCi/L
201446.5%
201543.2%
201643.6%
201741.8%
201842.2%
201942.4%
202039.8%

2020: 39.8%. Across these years the share ran from 39.8% to 46.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 3,103 tests reported to CDC for Lehigh County over 2020, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Lehigh County, Compared

Lehigh County radon figures, compared

Calculated by Radon411

In Lehigh County, about 4 in 10 reported tests in 2020 (1,236 of 3,103) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 14.3 points higher. Across 67 Pennsylvania counties pooled together, 30.3% of tests reached that level, so Lehigh County runs 9.5 points above its state.

Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 21.8% (Montgomery County) to 53.5% (Schuylkill County). By share, Lehigh County is 31st of 63 Pennsylvania counties with 30 or more tests for the same period.

Year by year, 2014 opened at 46.5% and 2020 closed at 39.8% (down 6.7 points), with 2014 the high at 46.5%. Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 6362.8 pCi/L. Below the action level, 1,217 tests (39.2%) came in under 2 pCi/L, against 44.3% statewide, and 650 tests (20.9%) fell between 2 and 4, against 25.4% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 39.8% share point the same way here. USGS geology rates 100% of the county's land high radon potential.

The busiest year on file was 2015, with 5,017 tests reported; the quietest, 2018, had 3,056.

Share of reported tests at or above 4 pCi/L by year, Lehigh County against Pennsylvania2014 to 2020, years with 30 or more tests: Lehigh County 46.5% to 39.8%, the state's pooled share 30.3% in 2020.
Lehigh CountyPennsylvania, pooled
Share of reported tests at or above 4 pCi/L by year, Lehigh County against Pennsylvania: data table
YearTestsLehigh County, at or above 4 pCi/LPennsylvania, pooled
20143,85046.5%36.1%
20155,01743.2%37.8%
20164,27643.6%34.4%
20174,54741.8%35.1%
20183,05642.2%30.5%
20193,58542.4%31.4%
20203,10339.8%30.3%
Lehigh County against Pennsylvania, the United States and nearby counties, 2020
AreaTestsAt or above 4 pCi/LMedianDifference from Lehigh County
Lehigh County3,10339.8%2.7 pCi/LThis county
Pennsylvania, pooled67 counties, pooled93,66930.3%Not pooled−9.5 points
United States, pooled915 counties, pooled405,35525.5%Not pooled−14.3 points
Perry Countyhighest in the state18957.7%4.9 pCi/L+17.9 points
Philadelphia Countylowest in the state8,44210.6%1.7 pCi/L−29.2 points
Schuylkill County, PAborders it79753.5%4.5 pCi/L+13.7 points
Northampton County, PAborders it3,43441.3%2.9 pCi/L+1.5 points
Carbon County, PAborders it43840.6%3.0 pCi/L+0.8 points
Berks County, PAborders it2,63239.6%2.9 pCi/L−0.2 points
Bucks County, PAborders it7,06623.2%2.0 pCi/L−16.6 points
Montgomery County, PAborders it10,50821.8%2.0 pCi/L−18.0 points
Where Lehigh County's reported results fell, 2020, beside Pennsylvania and the United States
ResultLehigh County testsLehigh County sharePennsylvania shareU.S. shareAgainst Pennsylvania
Under 2 pCi/L1,21739.2%44.3%51.6%−5.1 points
2 to 4 pCi/L65020.9%25.4%22.9%−4.5 points
4 pCi/L and above1,23639.8%30.3%25.5%+9.5 points
Lehigh County ranked among the 63 Pennsylvania counties with 30 or more tests, by share at or above 4 pCi/L, 2020
CountyRankTestsAt or above 4 pCi/LMedian
Blair County26 of 6342442.0%3.2 pCi/L
Montour County27 of 6312341.5%3.1 pCi/L
Mifflin County28 of 6311141.4%2.7 pCi/L
Northampton County29 of 633,43441.3%2.9 pCi/L
Carbon County30 of 6343840.6%3.0 pCi/L
Lehigh County31 of 633,10339.8%2.7 pCi/L
Adams County32 of 6385239.7%2.8 pCi/L
Berks County33 of 632,63239.6%2.9 pCi/L
Centre County34 of 6367039.3%2.3 pCi/L
Warren County35 of 6311938.7%2.8 pCi/L
Jefferson County36 of 6325438.6%2.6 pCi/L
Lehigh County radon tests by year, against Pennsylvania's pooled share
YearTestsAt or above 4 pCi/LMedianHighestPennsylvania, pooledChange from the row before
20203,10339.8%2.7 pCi/L6362.8 pCi/L30.3%−2.6 points
20193,58542.4%3.1 pCi/L441.2 pCi/L31.4%+0.2 points
20183,05642.2%3.1 pCi/L394.3 pCi/L30.5%+0.4 points
20174,54741.8%3.0 pCi/L487.3 pCi/L35.1%−1.8 points
20164,27643.6%3.1 pCi/L294.0 pCi/L34.4%+0.4 points
20155,01743.2%3.0 pCi/L334.0 pCi/L37.8%−3.3 points
20143,85046.5%3.5 pCi/L1413.8 pCi/L36.1%First on file

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

Lehigh County, State data

Pennsylvania's own radon test data

Measured

What Pennsylvania's own agencies publish about radon tests in Lehigh County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What Pennsylvania DEP reports for the ZIP codes in Lehigh County

Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 36 ZIP codes that lie wholly or partly in Lehigh County, each with the state's own figures for it. Period: Period not stated by DEP.

ZIP codes in Lehigh County
ZIP codeWhat the state reports
18011Basement: average 5.4 pCi/L, 870 tests; First floor: average 3.9 pCi/L, 68 tests
18015Basement: average 6.9 pCi/L, 4,055 tests; First floor: average 4.2 pCi/L, 686 tests
18017Basement: average 6.6 pCi/L, 9,647 tests; First floor: average 3.8 pCi/L, 1,380 tests
18018Basement: average 5.8 pCi/L, 4,815 tests; First floor: average 3.0 pCi/L, 561 tests
18031Basement: average 12.6 pCi/L, 2,419 tests; First floor: average 6.8 pCi/L, 195 tests
18032Basement: average 7.1 pCi/L, 928 tests; First floor: average 3.5 pCi/L, 85 tests
18034Basement: average 7.4 pCi/L, 2,455 tests; First floor: average 6.1 pCi/L, 254 tests
18036Basement: average 20.1 pCi/L, 4,175 tests; First floor: average 17.6 pCi/L, 519 tests
18037Basement: average 10.9 pCi/L, 1,344 tests; First floor: average 6.5 pCi/L, 107 tests
18041Basement: average 4.8 pCi/L, 647 tests; First floor: average 2.7 pCi/L, 126 tests
18046Basement: figures not shown; First floor: figures not shown
18049Basement: average 8.3 pCi/L, 4,361 tests; First floor: average 4.5 pCi/L, 577 tests
18051Basement: average 20.4 pCi/L, 1,508 tests; First floor: average 9.3 pCi/L, 247 tests
18052Basement: average 8.0 pCi/L, 3,481 tests; First floor: average 4.0 pCi/L, 352 tests
18053Basement: average 27.5 pCi/L, 405 tests; First floor: average 12.1 pCi/L, 37 tests
18059Basement: average 15.1 pCi/L, 294 tests; First floor: average 5.8 pCi/L, 36 tests
18062Basement: average 6.6 pCi/L, 6,051 tests; First floor: average 4.2 pCi/L, 599 tests
18065Basement: average 15.3 pCi/L, 44 tests; First floor: figures not shown
18066Basement: average 21.0 pCi/L, 1,323 tests; First floor: average 6.6 pCi/L, 195 tests
18069Basement: average 17.0 pCi/L, 2,589 tests; First floor: average 9.5 pCi/L, 196 tests
18078Basement: average 18.1 pCi/L, 2,029 tests; First floor: average 13.2 pCi/L, 178 tests
18079Basement: figures not shown; First floor: figures not shown
18080Basement: average 19.6 pCi/L, 1,691 tests; First floor: average 7.9 pCi/L, 223 tests
18087Basement: average 4.5 pCi/L, 68 tests; First floor: figures not shown
18092Basement: average 14.1 pCi/L, 786 tests; First floor: average 10.0 pCi/L, 102 tests
18101Basement: average 4.9 pCi/L, 226 tests; First floor: average 1.1 pCi/L, 60 tests
18102Basement: average 5.2 pCi/L, 1,689 tests; First floor: average 2.5 pCi/L, 194 tests
18103Basement: average 7.1 pCi/L, 6,882 tests; First floor: average 4.8 pCi/L, 827 tests
18104Basement: average 6.8 pCi/L, 11,051 tests; First floor: average 4.2 pCi/L, 1,229 tests
18106Basement: average 8.4 pCi/L, 1,908 tests; First floor: average 4.3 pCi/L, 190 tests
18109Basement: average 5.1 pCi/L, 872 tests; First floor: average 2.7 pCi/L, 74 tests
18195Basement: figures not shown
18951Basement: average 4.6 pCi/L, 5,103 tests; First floor: average 2.1 pCi/L, 1,063 tests
19529Basement: average 23.0 pCi/L, 445 tests; First floor: average 8.0 pCi/L, 63 tests
19530Basement: average 18.7 pCi/L, 1,541 tests; First floor: average 9.2 pCi/L, 348 tests
19539Basement: average 10.7 pCi/L, 567 tests; First floor: average 7.1 pCi/L, 61 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.

Lehigh County, Geology

The ground under Lehigh County

Predicted

USGS's geologic map puts all of Lehigh County's mapped land in one class: high radon potential. The map puts 74.3% of Lehigh County in the area it calls Great Valley Section and 15.3% in New England Province/Reading Prong, with 2 smaller areas beside them. USGS gives both a radon index of 15, in the high band (12 to 17).

USGS's geologic areas under Lehigh County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Great Valley SectionSandstone, shale and siltstone.High1574.3%
New England Province/Reading ProngGranitic gneiss.High1515.3%
Newark BasinGray shale and fluvial sandstone.High127.3%
Appalachian Mountain SectionPaleozoic sandstone, shale, and limestone.High123.1%

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

Lehigh County beside the ground around it

Lehigh County has more high-potential ground than Pennsylvania as a whole: 100% of its land against 70.4%. Of the 6 counties that border it, none has as large a share of high-potential ground; Berks County comes nearest at 100%.

Share of land by USGS radon potential: Lehigh County, the 6 counties bordering it and Pennsylvania
AreaEPA zoneLow potentialModerate potentialHigh potential
Lehigh CountyZone 1NoneNone100%
Northampton CountyZone 1NoneNone99.8%
Berks CountyZone 1NoneNone100%
Carbon CountyZone 1None14.2%85.8%
Montgomery CountyZone 1NoneNone100%
Bucks CountyZone 1None11.0%89.0%
Schuylkill CountyZone 1NoneNone100%
Pennsylvania67 counties, pooled by land areaVaries0.7%28.9%70.4%

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

Local help

Lehigh County, Local resources

Radon testing and mitigation in Lehigh County

Listed radon businesses with an address in Lehigh County:

Listed radon professionals by town: Allentown, Emmaus, Macungie

What Pennsylvania's program says
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 of radon contamination in buildings.

What it means

Lehigh County, Questions

Questions about radon in Lehigh County

Are radon levels high in Lehigh County?

In 2020, 39.8% of the radon tests reported to CDC for Lehigh County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.7 pCi/L. Of 63 Pennsylvania counties with 30 or more tests for the same period, 30 reported a higher share; pooled, the state comes to 30.3%.

Which counties border Lehigh County?

Lehigh County borders 6 counties: Northampton County, Berks County, Carbon County, Montgomery County, Bucks County and Schuylkill County.

Products

Lehigh County, Products

Testing a home in Lehigh County

In Lehigh County, 39.8% of 3,103 tests reported to CDC in 2020 reached 4 pCi/L, against 30.3% pooled across Pennsylvania. In Zone 1 the year-round level in Lehigh 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

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

Explore

Lehigh County, Bordering counties

Counties bordering Lehigh County

Calculated by Radon411

Lehigh County, Cities and towns

Cities and towns in Lehigh County

The Census Bureau estimates 384,383 residents in Lehigh County for July 1, 2025, 9,934 more than in 2020 (+2.7%). Packed into its land, that is 1,113 people per square mile. Its largest town, Allentown, has 126,044 residents, 32.8% of the total. CDC's 3,103 reported tests for 2020 work out to 8.1 per 1,000 residents (2025 estimate), close to Pennsylvania's 7.2.

From Allentown to Coopersburg, CDC publishes no figure by town: each reads Lehigh County's.

The cities and towns in Lehigh County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Allentown126,044+0.3%32.8%
Bethlehemextends beyond Lehigh County79,644+5.2%Counted whole
Emmaus12,514+7.6%3.3%
Catasauqua6,590+1.2%1.7%
Fountain Hill4,835+0.1%1.3%
Slatington4,296+0.4%1.1%
Coplay3,532+5.7%0.9%
Macungie3,395+4.4%0.9%
Alburtis2,609+0.9%0.7%
Coopersburg2,535+3.5%0.7%

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 Lehigh County is counted whole, so it has no share.

Lehigh County, Homes

Homes in Lehigh County

Fewer than six in ten of Lehigh County's 150,547 homes are detached houses (50%, against 57% across Pennsylvania); the rest are attached, in shared buildings or mobile. Half of its homes were built before 1968, close to Pennsylvania's 1965: 42% date from before 1960 and 16% from 2000 or later. 65% of occupied homes are lived in by their owner (Pennsylvania: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Lehigh County, Pennsylvania, 2019 to 2023
HomesLehigh CountyPennsylvania
Housing units150,5475,779,663
Detached houses50%57%
In buildings of 5 or more16%13%
Mobile homes2%4%
Built before 196042%45%
Built since 200016%14%
Middle year built19681965
Owner-occupied65%69%

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