Radon Pros in Maryland

About Radon in Maryland

Last updated: March 2026

Maryland's radon risk follows the state's elevation gradient from west to east. Western Maryland — Frederick, Washington, Allegany, and Garrett counties — is EPA Zone 1 with significant radon risk driven by Appalachian geology. The Baltimore metropolitan area is classified as Zone 2 with moderate risk, though many homes in the western suburbs test above the EPA action level. The Eastern Shore is Zone 3 with generally lower levels. Maryland does not require state-specific radon licensing, relying on the Maryland Department of the Environment's voluntary radon program and national NRPP/NRSB certification. In real estate transactions, radon testing is not mandated but is increasingly common in the Baltimore metro and Frederick County markets. Maryland's radon profile is shaped by its compact geography — within a two-hour drive, risk ranges from extreme (western mountains) to moderate (Baltimore metro) to low (Eastern Shore). Frederick County, the state's fastest-growing area, consistently reports some of the highest radon levels in Maryland. Washington County also has elevated readings. The Maryland Department of the Environment recommends testing all homes, noting that even Zone 2 and Zone 3 homes can have individual readings above action levels. Homeowners in the Baltimore western suburbs (Ellicott City, Columbia, Catonsville) should be particularly attentive to radon testing.