Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
Locations and reports
Radon Levels in Washington County, Maine
EPA puts Washington County in Zone 2, its middle radon zone, and 29.6% of its 54 reported radon tests (2008 to 2017, laboratory totals) 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
Share at 4+ pCi/L
29.6%
8.0 pts below ME
- Washington
- 29.6%
- Maine
- 37.6%
54 tests, 2008 to 2017
Median result
1.6pCi/L
Below action level
- Washington
- 1.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
54
15th of 16 by tests
- Washington
- 54
- Cumberland
- 4,076
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Maine
12 of 16
Middle half
- Washington
- 29.6%
- York
- 48.4%
By share, of 16 with 30+ tests
Read a result for Washington County
Starts at Washington County's median, 1.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.6 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Washington County's median reported result, 2008 to 2017.
The data
Washington County, At a glance
Washington County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Washington County is a
USGS geologic potential: Moderate across 46% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Washington County, 2008 to 2017, laboratory
Under 2 pCi/L: 56%2 to 4 pCi/L: 15%4 pCi/L and above: 29%
Of 54 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 30 | 55.6% |
| 2 to 4 pCi/L | 8 | 14.8% |
| 4 pCi/L and above | 16 | 29.6% |
What these figures count
These are the 54 tests reported to CDC for Washington County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Washington County, Compared
Washington County radon figures, compared
Calculated by Radon411Washington County's 54 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.6 pCi/L and a maximum of 74.8 pCi/L, and 29.6% reached 4 pCi/L. Maine as a whole (16 Maine counties, pooled) comes to 37.6%: 8.0 points higher than here.
Among its state's counties it ranks 12th of 16 Maine counties with 30 or more tests for the same period. Statewide for the same period, York County reported the highest share (48.4%) and Penobscot County the lowest (16.4%).
Below the action level, 30 tests (55.6%) came in under 2 pCi/L, against 41.4% statewide, and 8 tests (14.8%) fell between 2 and 4, against 21.0% statewide. CDC's ten-year totals for Washington County went from 50 tests (2005 to 2014) to 54 (2008 to 2017), the share going from 32.0% to 29.6%.
EPA's 1993 zone map puts Washington County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 46% of the county's land moderate radon potential.
Next door, the shares run from 16.4% in Penobscot County to 45.1% in Aroostook County, with Penobscot County below Washington County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Washington County, Geology
The ground under Washington County
PredictedNo class of ground holds half of Washington County on USGS's geologic map: 45.5% of its land is moderate radon potential, 19.3% high and 30.8% low. The map puts 45.5% of Washington County in the area it calls Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal Province and 30.8% in Coastal Province, with 2 smaller areas beside them. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal Province | Heterogeneous metamorphic and igneous rocks. | Moderate | 11 | 45.5% |
| Coastal Province | Glacial lake clay and marine clay. | Low | 8 | 30.8% |
| Coastal Province | Granodiorite to syenite. | High | 13 | 18.2% |
| Coastal Province | Granite, granodiorite, and mafic metamorphic rocks. | High | 13 | 1.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Washington County beside the ground around it
On high-potential ground Washington County is close to Maine as a whole: 19.3% of its land against 24.5%. Of the 3 counties that border it, 1 has more high-potential ground, Hancock County the most at 43.4%.
The map rates the ground, not the air in any home.
Local help
Washington County, Local resources
Radon testing and mitigation in Washington County
- Maine Radiation Control ProgramMaine Radiation Control Program, run by Maine Center for Disease Control & Prevention, licenses or certifies radon professionals, and answers questions about testing and mitigation in Maine.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- See the Maine directoryNo professionals are listed in Maine yet. The state program can point you to registered testers and mitigators.
What Maine's program says
- Phone
- 207-287-5676
- radon.dhhs@maine.gov
- Licensing of radon professionals
Under Maine law, only the owner or occupant of a residence or someone registered with the state to provide these services, may test for radon, install and/or advise on the installation of a radon reduction (mitigation) system.
What it means
Washington County, Questions
Questions about radon in Washington County
Are radon levels high in Washington County?
Over the 2008 to 2017 laboratory totals, 29.6% of the radon tests reported to CDC for Washington County, Maine were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.6 pCi/L. Of 16 Maine counties with 30 or more tests for the same period, 11 reported a higher share; pooled, the state comes to 37.6%.
Which counties border Washington County?
Washington County borders 3 counties: Hancock County, Penobscot County and Aroostook County.
Products
Washington County, Products
Testing a home in Washington County
In Washington County, 29.6% of 54 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 37.6% pooled across Maine. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Washington County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Washington County, Bordering counties
Counties bordering Washington County
Calculated by Radon411- Radon levels in Aroostook CountyEPA zone 1
45.1%at or above 4 pCi/L
Median 3.5 pCi/L · 608 tests · 15.5 points above Washington County
- Radon levels in Hancock CountyEPA zone 1
39.1%at or above 4 pCi/L
Median 2.6 pCi/L · 327 tests · 9.5 points above Washington County
- Radon levels in Penobscot CountyEPA zone 1
16.4%at or above 4 pCi/L
Median 0.8 pCi/L · 1,491 tests · 13.2 points below Washington County
Washington County, Cities and towns
Cities and towns in Washington County
The Census Bureau estimates 31,334 residents in Washington County for July 1, 2025, 243 more than in 2020 (+0.8%). That works out to 12 people per square mile of land. No town dominates: Calais, the largest, has 3,083 residents, 9.8% of the total. Together its 2 incorporated places hold 13.9% of those residents; the other 86.1% live outside any of them. Reported testing is thin here: 54 tests over 2008 to 2017, or 1.7 for every 1,000 residents (2025 estimate), where Maine as a whole comes to 8.4.
From Calais to Eastport, CDC publishes no figure by town: each reads Washington County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Calais | 3,083 | Level | 9.8% |
| Eastport | 1,285 | +0.2% | 4.1% |
2 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).
Washington County, Homes
Homes in Washington County
Washington County is a place of houses on their own lots: 81% of its 21,703 homes are detached single-family houses, against 70% across Maine. Half of its homes were built before 1975, close to Maine's 1976: 37% date from before 1960 and 18% from 2000 or later. Owners live in 78% of the occupied homes (Maine: 74%), so for most households a test and a fix are their own to order.
| Homes | Washington County | Maine |
|---|---|---|
| Housing units | 21,703 | 746,552 |
| Detached houses | 81% | 70% |
| In buildings of 5 or more | 3% | 9% |
| Mobile homes | 11% | 8% |
| Built before 1960 | 37% | 35% |
| Built since 2000 | 18% | 20% |
| Middle year built | 1975 | 1976 |
| Owner-occupied | 78% | 74% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.