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Radon Levels in Howard County, Maryland

Zone 1Highest predicted potential250 square miles · 6 bordering counties

What this means for you

  • Your area: EPA rates Howard 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 4,549 radon tests reported to CDC for Howard County (2008 to 2017), 30.8% 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.

Over the 2008 to 2017 laboratory totals, 30.8% of the radon tests reported to CDC for Howard County, Maryland came back at or above the EPA action level of 4 pCi/L, and the median result was 2.0 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 91% of the county's land area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Howard County, 2008 to 2017, laboratory

Tests reported
4,549
At or above 4 pCi/L
30.8%
Median result
2.0 pCi/L
Reported results by concentration band, Howard County, 2008 to 2017, laboratory
Under 2 pCi/L: 50%2 to 4 pCi/L: 20%4 pCi/L and above: 31%

Of 4,549 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.

Reported results by concentration band, Howard County, 2008 to 2017, laboratory: data table
Result bandTests Calculated by Radon411Share Measured
Under 2 pCi/L2,26149.7%
2 to 4 pCi/L88719.5%
4 pCi/L and above1,40130.8%

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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

Howard County, In figures

Howard County in figures

What the published data says about Howard County, in words. A zone and a share of tests describe an area, never the level in any one home.

  • Predicted

    Predicted

    EPA places Howard County in Zone 1, highest predicted potential, as it does 7 other counties of Maryland's 24.

    Of the 6 bordering counties, EPA places Baltimore County, Carroll County, Frederick County and Montgomery County in Zone 1 and Anne Arundel County and Prince George's County in Zone 2.

  • Reported tests and local record

    CDC publishes no annual figure for Howard County; its figure is a laboratory total for 2008 to 2017: 30.8% of 4,549 reported tests were at or above 4 pCi/L.

    Maryland's radon program and its page are under Local resources.

Howard County, Comparison

How Howard County compares

Measured

Howard 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

Measured

2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.

  1. Carroll CountyMD3,334 tests41.9%
  2. Howard CountyThis page4,549 tests30.8%
  3. Frederick CountyMD3,933 tests28.1%
  4. Baltimore CountyMD7,706 tests19.1%
  5. Prince George's CountyMD1,603 tests19.0%
  6. Montgomery CountyMD10,969 tests18.0%
  7. Anne Arundel CountyMD4,088 tests17.4%

Median reported result

Measured

2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.

  1. Carroll CountyMD3,334 tests2.8 pCi/L
  2. Howard CountyThis page4,549 tests2.0 pCi/L
  3. Frederick CountyMD3,933 tests1.5 pCi/L
  4. Anne Arundel CountyMD4,088 tests1.4 pCi/L
  5. Baltimore CountyMD7,706 tests1.4 pCi/L
  6. Prince George's CountyMD1,603 tests1.4 pCi/L
  7. Montgomery CountyMD10,969 tests1.3 pCi/L

Each figure is that county’s own published CDC figure for 2008 to 2017, laboratory, counting radon tests reported to CDC, not homes. Howard 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. Every Maryland county’s own figure is in the Maryland county table.

CDC publishes this figure only for counties here, so there is no state or national number to compare Howard County, Maryland with.

Howard County, Bordering counties

Counties bordering Howard County

Calculated by Radon411

Howard County, Local resources

Local resources in Maryland

Who to ask in Maryland: the state's radon program, test kits and professionals.

Maryland's radon program

Maryland Department of Health

Maryland’s radon program answers questions about testing, mitigation and the rules where you live.

Phone
1-866-703-3266
Visit the program's page(opens in a new tab)

Test kits

The program says: Maryland residents may be eligible for a free radon test kit.

Radon professionals

5 professionals are listed in Maryland.

Professionals in Maryland

Howard County, Questions

Questions about radon in Howard County

Common questions8 questions, answered from the figures above

How do I get a radon test in Howard 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 Howard County as a service area yet. The Maryland 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 stateMaryland radon program

Are radon levels high in Howard County?

In 2017, 30.8% of the radon tests reported to CDC for Howard County, Maryland were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. That is a share of reported tests, not of homes. EPA places Howard 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.

What a radon level meansRadon in Maryland

Who does radon mitigation in Howard County?

No listed mitigator names Howard County as a service area yet; the Maryland directory lists 5 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 Maryland requires one.

How radon mitigation worksWhat mitigation costsMitigators in Maryland

What EPA radon zone is Howard County in?

EPA places Howard County, Maryland 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 Howard 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 Howard County?

Howard County borders 6 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 Howard County, Maryland in 2017. They describe tests other people carried out in other buildings, and none of them measures yours.

  • 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.

    How to test a home
  • If you are buying

    Ask for past results and any system's post-mitigation test, and test during the sale.

    Buying a house: radon guide
  • If you are selling

    Testing before you list puts the timing in your hands; disclosure rules differ by state.

    Selling a house: radon guide
  • 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.

    Radon in rental homes

How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.

Howard County, Products

Testing and mitigation products

Whatever the figures for Howard County show, only a test tells you about one home.

Howard County / Next steps

What to do next

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.