EPA radon zones
Maryland radon map: every county's zone
8 of Maryland's 24 counties are EPA radon zone 1 (predicted average above 4 pCi/L), 9 are zone 2 and 7 are zone 3. High readings occur in every zone, so EPA recommends testing every home.
Allegany CountyZone 2
Anne Arundel CountyZone 2
Baltimore cityZone 2
Baltimore CountyZone 1
Calvert CountyZone 1
Caroline CountyZone 3
Carroll CountyZone 1
Cecil CountyZone 2
Charles CountyZone 2
Dorchester CountyZone 3
Frederick CountyZone 1
Garrett CountyZone 2
Harford CountyZone 1
Howard CountyZone 1
Kent CountyZone 3
Montgomery CountyZone 1
Prince George's CountyZone 2
Queen Anne's CountyZone 3
Somerset CountyZone 2
St. Mary's CountyZone 2
Talbot CountyZone 3
Washington CountyZone 1
Wicomico CountyZone 3
Worcester CountyZone 3
How much does radon mitigation cost?
Most single-family systems cost $800 to $2,500 installed, depending on foundation type and how many suction points are needed. A follow-up test confirms the system works.
What do the zones mean?
EPA radon zones describe counties, not houses. Zone 1 counties have a predicted average indoor level above 4 picocuries per liter (pCi/L), Zone 2 between 2 and 4, Zone 3 below 2. Homes with high levels are found in every zone, which is why EPA recommends that every home be tested, and fixed at 4 pCi/L or above.
Maryland cities: water and radon
Source: EPA Map of Radon Zones.