Radon Pros in Massachusetts

About Radon in Massachusetts

Last updated: March 2026

Massachusetts radon risk is concentrated in the western and central portions of the state, where ancient granite bedrock produces elevated soil-gas radon levels. The Berkshire region and Connecticut River Valley have the highest readings, classified as EPA Zone 1. Greater Boston and the eastern part of the state are mostly Zone 2 — moderate risk — but plenty of homes in the metro area test above the EPA action level of 4.0 pCi/L. Massachusetts does not require state-specific radon licensing, relying on national NRPP and NRSB certification as the professional standard. In real estate transactions, radon testing is not mandated but is increasingly common, particularly in the western suburbs and central Massachusetts communities where awareness has grown. Massachusetts is notable for the contrast between its Zone 2 classification in the Boston metro and the actual test results — many eastern Massachusetts homes, particularly those with older granite foundations, test above action levels despite the moderate zone classification. The Massachusetts Department of Public Health recommends testing all homes with ground contact. The state's older housing stock, with stone and block foundations that may have more soil-gas entry points, can be particularly susceptible. Homeowners should not rely on zone maps alone and should test individually.