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 Calvert County, Maryland
EPA puts Calvert County in Zone 1, its highest radon zone, and 30.2% of its 1,205 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
30.2%
6.3 pts above MD
- Calvert
- 30.2%
- Maryland
- 23.9%
1,205 tests, 2008 to 2017
Median result
2.0pCi/L
Below action level
- Calvert
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
1,205
10th of 19 by tests
- Calvert
- 1,205
- Montgomery
- 10,969
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Maryland
7 of 19
Middle half
- Calvert
- 30.2%
- Washington
- 56.0%
By share, of 19 with 30+ tests
Read a result for Calvert County
Starts at Calvert County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 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. Calvert County's median reported result, 2008 to 2017.
The data
Calvert County, At a glance
Calvert County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Calvert County in
USGS geologic potential: High across 88% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Calvert County, 2008 to 2017, laboratory
Under 2 pCi/L: 49%2 to 4 pCi/L: 21%4 pCi/L and above: 30%
Of 1,205 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 589 | 48.9% |
| 2 to 4 pCi/L | 252 | 20.9% |
| 4 pCi/L and above | 364 | 30.2% |
What these figures count
These are the 1,205 tests reported to CDC for Calvert 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).
Calvert County, Compared
Calvert County radon figures, compared
Calculated by Radon411In Calvert County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (364 of 1,205) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 5.5 points lower. Across 24 Maryland counties pooled together, 23.9% of tests reached that level, so Calvert County runs 6.3 points above its state.
Of 4 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 17.4% (Anne Arundel County) to 24.1% (Charles County). By share, Calvert County is 7th of 19 Maryland counties with 30 or more tests for the same period.
Half the tests came in under 2.0 pCi/L and half over it; the single highest reached 83.7 pCi/L. Below the action level, 589 tests (48.9%) came in under 2 pCi/L, against 56.6% statewide, and 252 tests (20.9%) fell between 2 and 4, against 19.5% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 30.2% share point the same way here. USGS geology rates 88% of the county's land high radon potential. CDC also counts 111 tests taken after mitigation in Calvert County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Calvert County went from 963 tests (2005 to 2014) to 1,205 (2008 to 2017), the share going from 28.7% to 30.2%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Calvert County, Geology
The ground under Calvert County
PredictedUSGS's geologic map puts all of Calvert County's mapped land in one class: high radon potential. 88.3% of it lies in the area the map calls Western Shore, 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 |
|---|---|---|---|---|
| Western Shore | Tertiary gravel, sand, silt, clay. | High | 12 | 88.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Calvert County beside the ground around it
Calvert County has more high-potential ground than Maryland as a whole: 88.3% of its land against 36.7%. Of the 4 counties that border it, none has as large a share of high-potential ground; Prince George's County comes nearest at 38.8%.
The map rates the ground, not the air in any home.
Local help
Calvert County, Local resources
Radon testing and mitigation in Calvert County
- Maryland's radon programMaryland Department of HealthMaryland's radon program offers free or discounted test kits, and answers questions about testing and mitigation in Maryland.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Maryland residents may be eligible for a free radon test kit.
- Compare kits
- Professionals in Maryland5 professionals are listed in Maryland.
What Maryland's program says
- Phone
- 1-866-703-3266
What it means
Calvert County, Questions
Questions about radon in Calvert County
Are radon levels high in Calvert County?
Over the 2008 to 2017 laboratory totals, 30.2% of the radon tests reported to CDC for Calvert County, Maryland were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 19 Maryland counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 23.9%.
Which counties border Calvert County?
Calvert County borders 4 counties: St. Mary's County, Prince George's County, Charles County and Anne Arundel County.
Products
Calvert County, Products
Testing a home in Calvert County
In Calvert County, 30.2% of 1,205 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 23.9% pooled across Maryland. In Zone 1 the year-round level in Calvert 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
Monitor
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Calvert County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Calvert County
Explore
Calvert County, Bordering counties
Counties bordering Calvert County
Calculated by Radon411- Radon levels in Charles CountyEPA zone 2
24.1%at or above 4 pCi/L
Median 1.8 pCi/L · 477 tests · 6.1 points below Calvert County
- Radon levels in St. Mary's CountyEPA zone 2
20.9%at or above 4 pCi/L
Median 1.8 pCi/L · 636 tests · 9.3 points below Calvert County
- Radon levels in Prince George's CountyEPA zone 2
19.0%at or above 4 pCi/L
Median 1.4 pCi/L · 1,603 tests · 11.2 points below Calvert County
- Radon levels in Anne Arundel CountyEPA zone 2
17.4%at or above 4 pCi/L
Median 1.4 pCi/L · 4,088 tests · 12.8 points below Calvert County
Calvert County, Cities and towns
Cities and towns in Calvert County
The Census Bureau estimates 94,484 residents in Calvert County for July 1, 2025, 1,562 more than in 2020 (+1.7%). That works out to 443 people per square mile of land. No town dominates: Chesapeake Beach, the largest, has 6,466 residents, 6.8% of the total. Together its 2 incorporated places hold 9.1% of those residents; the other 90.9% live outside any of them. Testing is reported here more often than across the state: CDC's 1,205 reported tests for 2008 to 2017 come to 12.8 for every 1,000 residents (2025 estimate), against 7.7 for Maryland.
From Chesapeake Beach to North Beach, CDC publishes no figure by town: each reads Calvert County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Chesapeake Beach | 6,466 | +1.7% | 6.8% |
| North Beach | 2,179 | +1.5% | 2.3% |
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).
Calvert County, Homes
Homes in Calvert County
Calvert County is a place of houses on their own lots: 87% of its 35,960 homes are detached single-family houses, against 51% across Maryland. Much of Calvert County is recent building: 26% of its homes have gone up since 2000 and the middle year built is 1990, against 1979 for Maryland. Owners live in 87% of the occupied homes (Maryland: 67%), so for most households a test and a fix are their own to order.
| Homes | Calvert County | Maryland |
|---|---|---|
| Housing units | 35,960 | 2,545,532 |
| Detached houses | 87% | 51% |
| In buildings of 5 or more | 5% | 23% |
| Mobile homes | 1% | 1% |
| Built before 1960 | 11% | 27% |
| Built since 2000 | 26% | 20% |
| Middle year built | 1990 | 1979 |
| Owner-occupied | 87% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.