Massachusetts has meaningful radon risk, with approximately 25-30% of Massachusetts homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including granitic bedrock in western Massachusetts (Berkshires), the Nashoba Zone metamorphic rocks in the MetroWest region, and glacial till overlying uranium-bearing geology across much of the state — creates radon potential across significant portions of the state. The Department of Public Health Radiation Control Program administers radon program resources for Massachusetts residents.
EPA Radon Zone Designation
Zone 1 in western Massachusetts and portions of the MetroWest region, Zone 2 in the greater Boston area and eastern Massachusetts.
Highest-Radon Areas in Massachusetts
Western Massachusetts counties (Hampden, Hampshire, Franklin, Berkshire) overlying Berkshire granitic and metamorphic geology are Zone 1. Worcester County and Middlesex County (MetroWest) are Zone 1 to Zone 2. The greater Boston area (Suffolk, Norfolk, eastern Middlesex) is generally Zone 2.
Radon Contractor Requirements in Massachusetts
NRPP or NRSB national certification. Massachusetts has no separate state radon licensing statute beyond national certification. The Department of Public Health Radiation Control Program maintains radon program resources. Verify contractor credentials at nrpp.info or nrsb.org before engaging any radon professional for measurement or mitigation work.
Radon Disclosure in Massachusetts
Massachusetts’s real estate disclosure law includes the Massachusetts Mandatory Disclosure Law and associated seller’s disclosure form. Known elevated radon conditions are material information that sellers should disclose. Radon testing is standard in Massachusetts real estate transactions.
Testing Resources for Massachusetts Residents
Contact the Department of Public Health Radiation Control Program for the most current list of certified radon professionals, any available test kit programs, and jurisdiction-specific requirements that may have been updated since this page was last reviewed. The national NRPP contractor directory (nrpp.info) is searchable by zip code and provides real-time certification verification.
Frequently Asked Questions
What parts of Massachusetts have the highest radon?
Western Massachusetts (Berkshires, Pioneer Valley) and the MetroWest region of central Massachusetts have the highest radon potential. Greater Boston generally has lower but still meaningful levels. All Massachusetts homes should be tested.
Does Massachusetts require radon contractor certification?
NRPP or NRSB national certification is the operative requirement. No separate Massachusetts licensing statute. Verify credentials at nrpp.info or nrsb.org.
Is radon a concern in Boston or Worcester?
Worcester County is Zone 1 to Zone 2 with significant radon risk. Boston (Suffolk County) is generally Zone 2 with lower but still meaningful potential. Radon testing is recommended throughout Massachusetts.
Boston Metro Radon Context
Greater Boston — Suffolk, Norfolk, and eastern Middlesex counties — is generally Zone 2. This does not mean radon-free: Zone 2 designation reflects lower average concentrations relative to Zone 1, but individual homes throughout the Boston metro can and do test above 4.0 pCi/L. Older Boston-area housing stock (triple-deckers, condo conversions of older homes with concrete block foundations) can have elevated radon even in Zone 2 areas. Cambridge (Middlesex County) and Somerville are Zone 2 with meaningful risk. Waltham and Newton are at the Zone 1/2 boundary.
Worcester and MetroWest Radon
Worcester County is the highest-radon county in Massachusetts — a Zone 1 area driven by Nashoba Zone metamorphic rocks and granitic formations that extend through central Massachusetts. The Worcester metro (Worcester, Shrewsbury, Westborough, Marlborough) shows elevated average radon. The MetroWest region — Framingham, Natick, Milford, Millis — also shows Zone 1 characteristics. Berkshire County (Pittsfield, Lenox) in western Massachusetts overlies Berkshire crystalline geology and is Zone 1 with some of the state’s highest average readings.
Massachusetts Testing Resources
The Massachusetts Department of Public Health (MDPH) Radiation Control Program administers the state radon program. MDPH provides certified contractor information, county-level radon survey data, and educational materials. Massachusetts participates in EPA’s SIRG program. Contact MDPH for the current certified contractor list. The Massachusetts Association of REALTORS provides radon guidance to its members, and radon testing is standard practice in Massachusetts real estate transactions across all county types.
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