Radon in ZIP code 20777
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ZIP 20777 crosses 2 county lines. Most of its land (98.3%) is in Howard County, Maryland. EPA’s radon zone for this area: Zone 1, highest potential.
Predicted average indoor screening level above 4 pCi/L.
Predicted average indoor screening level above 4 pCi/L.
What this means for homes in 20777
EPA built its zone map county by county in 1993, so every address in each part of 20777 shares its county’s prediction. The zone is a starting point, not a measurement of your house. Zone 1 areas like this one have a high share of homes above 4 pCi/L, so testing is a priority.
Because 20777 crosses county lines, your county depends on your street. Your property tax bill or county assessor site shows which county you are in. Next: read how to test your home, then check the number with the level calculator.
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Nearby ZIP codes in Howard County
Maryland radon help
The Maryland radon program (410-537-3193) can help with test kits, local data and credentialed professionals: health.maryland.gov/phpa/OEHFP/EH/pages/radon.aspx.
Frequently asked questions
What is the radon zone for ZIP code 20777?
ZIP 20777 spans 2 counties. The highest-potential zone among them is Zone 1 (highest potential). Howard County: Zone 1 (98.3% of the ZIP's land); Montgomery County: Zone 1 (1.7% of the ZIP's land).
Should I test for radon in 20777?
Yes. EPA recommends testing every home regardless of zone, because radon varies from house to house. Fix the home if a confirmed result is 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L.
Free checklist · PDF
Radon Test Checklist
A one-page, step-by-step checklist for running a home radon test right the first time, and what to do with the number.
- Short-term vs. long-term test: which to use
- Closed-house conditions and where to place the kit
- What 2, 4 and 8 pCi/L mean and when to fix
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