Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Union County, Pennsylvania
EPA puts Union County in Zone 1, its highest radon zone, and high results are common there: 44.5% of the 182 radon tests reported to CDC (2020) came back 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
Share at 4+ pCi/L
44.5%
14.2 pts above PA
- Union
- 44.5%
- PA
- 30.3%
182 tests, 2020
Median result
3.3pCi/L
Below action level
- Union
- 3.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2020
Tests reported
182
46th of 63 by tests
- Union
- 182
- Montgomery
- 10,508
Reported to CDC before any fix, 2020
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in PA
16 of 63
Top quarter
- Union
- 44.5%
- Perry
- 57.7%
By share, of 63 with 30+ tests
Read a result for Union County
Starts at Union County's median, 3.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.3 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Union County's median reported result, 2020.
The data
Union County, At a glance
Union County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Union County in
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 Union County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 52.1% |
| 2015 | 53.2% |
| 2016 | 39.3% |
| 2017 | 45.4% |
| 2018 | 47.1% |
| 2019 | 45.6% |
| 2020 | 44.5% |
2020: 44.5%. Across these years the share ran from 39.3% to 53.2%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 182 tests reported to CDC for Union 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).
Union County, Compared
Union County radon figures, compared
Calculated by Radon411In Union County, about 4 in 10 reported tests in 2020 (81 of 182) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 19.0 points higher. Across 67 Pennsylvania counties pooled together, 30.3% of tests reached that level, so Union County runs 14.2 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 39.3% (Centre County) to 54.1% (Clinton County). By share, Union County is 16th of 63 Pennsylvania counties with 30 or more tests for the same period.
Year by year, 2014 opened at 52.1% and 2020 closed at 44.5% (down 7.6 points), with 2015 the high at 53.2%. Half the tests came in under 3.3 pCi/L and half over it; the single highest reached 266.0 pCi/L. Below the action level, 59 tests (32.4%) came in under 2 pCi/L, against 44.3% statewide, and 42 tests (23.1%) fell between 2 and 4, against 25.4% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 44.5% share point the same way here. USGS geology rates 100% of the county's land high radon potential.
The busiest year on file was 2016, with 270 tests reported; the quietest, 2014, had 140.
Union CountyPennsylvania, pooled
44.5% % of tests30.3% % of tests
| Year | Tests | Union County, at or above 4 pCi/L | Pennsylvania, pooled |
|---|---|---|---|
| 2014 | 140 | 52.1% | 36.1% |
| 2015 | 235 | 53.2% | 37.8% |
| 2016 | 270 | 39.3% | 34.4% |
| 2017 | 205 | 45.4% | 35.1% |
| 2018 | 189 | 47.1% | 30.5% |
| 2019 | 215 | 45.6% | 31.4% |
| 2020 | 182 | 44.5% | 30.3% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Union County, State data
Pennsylvania's own radon test data
MeasuredWhat Pennsylvania's own agencies publish about radon tests in Union 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 Union County
Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 13 ZIP codes that lie wholly or partly in Union County, each with the state's own figures for it. Period: Period not stated by DEP.
| ZIP code | What the state reports |
|---|---|
| 17810 | Basement: average 6.2 pCi/L, 112 tests; First floor: figures not shown |
| 17829 | Basement: figures not shown; First floor: figures not shown |
| 17835 | Basement: figures not shown; First floor: figures not shown |
| 17837 | Basement: average 7.4 pCi/L, 4,696 tests; First floor: average 3.3 pCi/L, 646 tests |
| 17844 | Basement: average 11.9 pCi/L, 1,122 tests; First floor: average 2.5 pCi/L, 274 tests |
| 17845 | Basement: average 13.3 pCi/L, 68 tests; First floor: average 2.5 pCi/L, 30 tests |
| 17855 | Basement: average 8.3 pCi/L, 124 tests; First floor: average 2.9 pCi/L, 36 tests |
| 17856 | Basement: average 9.9 pCi/L, 364 tests; First floor: average 3.3 pCi/L, 38 tests |
| 17870 | Basement: average 9.7 pCi/L, 2,373 tests; First floor: average 4.7 pCi/L, 363 tests |
| 17885 | Basement: figures not shown; First floor: figures not shown |
| 17886 | Basement: average 9.4 pCi/L, 102 tests; First floor: figures not shown |
| 17887 | Basement: figures not shown; First floor: figures not shown |
| 17889 | Basement: average 19.8 pCi/L, 581 tests; First floor: average 16.2 pCi/L, 62 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.
Union County, Geology
The ground under Union County
PredictedUSGS's geologic map puts all of Union County's mapped land in one class: high radon potential. All of it lies in the area the map calls Appalachian Mountain Section, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Appalachian Mountain Section | Paleozoic sandstone, shale, and limestone. | High | 12 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Union County beside the ground around it
Union 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; Mifflin County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Union County, Local resources
Radon testing and mitigation in Union County
- Radon DivisionRadon Division, run by Department of Environmental Protection, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Pennsylvania.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe 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.
- Compare kits
- Professionals in Pennsylvania151 professionals are listed in Pennsylvania.
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
Union County, Questions
Questions about radon in Union County
Are radon levels high in Union County?
In 2020, 44.5% of the radon tests reported to CDC for Union County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.3 pCi/L. Of 63 Pennsylvania counties with 30 or more tests for the same period, 15 reported a higher share; pooled, the state comes to 30.3%.
Which counties border Union County?
Union County borders 6 counties: Snyder County, Northumberland County, Lycoming County, Clinton County, Centre County and Mifflin County.
Products
Union County, Products
Testing a home in Union County
In Union County, 44.5% of 182 tests reported to CDC in 2020 reached 4 pCi/L, against 30.3% pooled across Pennsylvania. In Zone 1 the year-round level in Union 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
MonitorAEGTEST
HOUND-1011S rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 12 hours
Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Union County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Union County
Explore
Union County, Bordering counties
Counties bordering Union County
Calculated by Radon411- Radon levels in Clinton CountyEPA zone 1
54.1%at or above 4 pCi/L
Median 4.5 pCi/L · 133 tests · 9.6 points above Union County
- Radon levels in Northumberland CountyEPA zone 1
49.8%at or above 4 pCi/L
Median 3.9 pCi/L · 275 tests · 5.3 points above Union County
- Radon levels in Lycoming CountyEPA zone 1
45.2%at or above 4 pCi/L
Median 3.5 pCi/L · 562 tests · 0.7 points above Union County
- Radon levels in Snyder CountyEPA zone 1
42.4%at or above 4 pCi/L
Median 2.8 pCi/L · 99 tests · 2.1 points below Union County
- Radon levels in Mifflin CountyEPA zone 1
41.4%at or above 4 pCi/L
Median 2.7 pCi/L · 111 tests · 3.1 points below Union County
- Radon levels in Centre CountyEPA zone 1
39.3%at or above 4 pCi/L
Median 2.3 pCi/L · 670 tests · 5.2 points below Union County
Union County, Cities and towns
Cities and towns in Union County
About 42,313 people live in Union County by the Census Bureau's estimate for July 1, 2025, 346 fewer than in 2020 (−0.8%). That works out to 134 people per square mile of land. No town dominates: Lewisburg, the largest, has 5,226 residents, 12.4% of the total. Together its 4 incorporated places hold 22.9% of those residents; the other 77.1% live outside any of them. Reported testing is thin here: 182 tests over 2020, or 4.3 for every 1,000 residents (2025 estimate), where Pennsylvania as a whole comes to 7.2.
From Lewisburg to Hartleton, CDC publishes no figure by town: each reads Union County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Lewisburg | 5,226 | +1.4% | 12.4% |
| Mifflinburg | 3,436 | −1.1% | 8.1% |
| New Berlin | 771 | −2.9% | 1.8% |
| Hartleton | 245 | −2.0% | 0.6% |
4 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).
Union County, Homes
Homes in Union County
Of Union County's 16,158 homes, 71% are detached houses, against 57% across Pennsylvania; 9% are in buildings of five or more homes. Much of Union County is recent building: 14% of its homes have gone up since 2000 and the middle year built is 1973, against 1965 for Pennsylvania. 71% 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 | Union County | Pennsylvania |
|---|---|---|
| Housing units | 16,158 | 5,779,663 |
| Detached houses | 71% | 57% |
| In buildings of 5 or more | 9% | 13% |
| Mobile homes | 8% | 4% |
| Built before 1960 | 38% | 45% |
| Built since 2000 | 14% | 14% |
| Middle year built | 1973 | 1965 |
| Owner-occupied | 71% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.