Category: Regulations & Certification

Georgia has meaningful radon risk, with approximately 20% of Georgia homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including Blue Ridge granitic and metamorphic geology in northern Georgia, Piedmont crystalline rock zone in north-central Georgia, and uranium-bearing formations in the Georgia Piedmont — creates radon potential across significant portions of the state. The Department of Natural Resources Environmental Protection Division administers radon program resources for Georgia residents.

EPA Radon Zone Designation

Zone 1 in northern Georgia Blue Ridge and Piedmont counties, Zone 2-3 in central and southern Georgia.

Highest-Radon Areas in Georgia

Northern Georgia counties overlying Blue Ridge and Piedmont geology — Rabun, Towns, Union, Fannin, Gilmer, Pickens, Cherokee, Forsyth, Hall, and Habersham counties — are Zone 1. The Atlanta metropolitan area (Fulton, DeKalb, Gwinnett, Cobb counties) spans Zone 1 to Zone 2. Central and southern Georgia counties are generally Zone 2 to Zone 3.

Radon Contractor Requirements in Georgia

NRPP or NRSB national certification. Georgia has no separate state radon licensing statute. The Department of Natural Resources Environmental Protection Division 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 Georgia

Georgia’s real estate disclosure requirements include the Georgia Brokerage Relationships in Real Estate Transactions Act, which requires disclosure of known adverse material facts. Known elevated radon conditions are material information that should be disclosed. Radon testing is recommended in northern Georgia and metro Atlanta transactions.

Testing Resources for Georgia Residents

Contact the Department of Natural Resources Environmental Protection Division 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

Is the Atlanta area high in radon?

The Atlanta metropolitan area spans Zone 1 to Zone 2. Fulton, DeKalb, Gwinnett, and Cobb counties have moderate to elevated radon potential. Testing is recommended for all Atlanta metro homes.

Does Georgia require radon contractor licensing?

NRPP or NRSB national certification is required. No separate Georgia licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

What parts of Georgia have the highest radon?

Northern Georgia Blue Ridge counties — Rabun, Towns, Union, Fannin, Gilmer, Pickens — have the highest potential. The greater Atlanta metro area is Zone 1 to Zone 2. Central and southern Georgia have lower but still meaningful levels.

Atlanta Metro Radon Specifics

The Atlanta metropolitan area spans a broad range of radon conditions from Zone 1 in the northern counties to Zone 2 in the inner metro and Zone 2-3 in southern suburban counties. Cherokee County (Canton) and Forsyth County (Cumming) in northern metro Atlanta overlie Appalachian Piedmont granite and show Zone 1 radon potential. Fulton County (Atlanta) spans Zone 1 to Zone 2 — northern Fulton (Alpharetta, Johns Creek, Roswell) shows higher levels than southern Fulton (College Park, East Point). DeKalb County (Decatur, Stone Mountain) is Zone 2. Gwinnett County shows Zone 1 to Zone 2 levels across its rapidly developed communities.

North Georgia Mountain Communities

The North Georgia mountain counties — Rabun (Clayton), Towns (Hiawassee), Union (Blairsville), Fannin (Blue Ridge), Gilmer (Ellijay), Pickens (Jasper), and Cherokee (Canton) — overlie the Blue Ridge crystalline rock province with elevated uranium content. These counties are Zone 1 with Georgia’s highest average radon concentrations. The active retirement and vacation home market in the North Georgia mountains means significant real estate turnover among buyers who may not be aware of the area’s radon risk. Mountain homes with basement construction are particularly vulnerable.

Georgia Testing Resources

The Georgia Department of Natural Resources (GDNR) Environmental Protection Division administers radon program resources. GDNR provides certified contractor information and educational materials. Georgia participates in EPA’s SIRG program. Contact GDNR for the current certified contractor list. The Georgia Geological Survey has published radon potential information for Georgia counties. Search nrpp.info by zip code for certified Georgia radon contractors in your specific area.

North Carolina has meaningful radon risk, with approximately 20-25% of North Carolina homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including Appalachian metamorphic and granitic rock in western North Carolina, Piedmont crystalline rock zone, and uranium-bearing granite in the Carolina Terrane — creates radon potential across significant portions of the state. The Department of Health and Human Services Radiation Protection Section administers radon program resources for North Carolina residents.

EPA Radon Zone Designation

Zone 1 in western North Carolina Appalachian counties, Zone 2 across the Piedmont, Zone 3 in the coastal plain.

Highest-Radon Areas in North Carolina

Western North Carolina counties overlying the Appalachian geology — Buncombe (Asheville), Henderson, Polk, Rutherford, McDowell, Burke, Caldwell, Watauga, Avery, and Mitchell counties — are Zone 1 or Zone 2. The Piedmont triangle region (Mecklenburg/Charlotte, Wake/Raleigh, Guilford/Greensboro) is Zone 2. Coastal plain counties are generally Zone 3.

Radon Contractor Requirements in North Carolina

NRPP or NRSB national certification. North Carolina has no separate state radon licensing statute. The Department of Health and Human Services Radiation Protection Section 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 North Carolina

North Carolina’s Residential Property Disclosure Act requires sellers to disclose known material defects. Known elevated radon conditions are material information. Radon testing is particularly recommended in western North Carolina and the Piedmont region.

Testing Resources for North Carolina Residents

Contact the Department of Health and Human Services Radiation Protection Section 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

Is radon a concern in Asheville or Charlotte?

Buncombe County (Asheville) is Zone 1 or Zone 2 with significant radon potential. Mecklenburg County (Charlotte) is Zone 2 with moderate risk. Testing is recommended for all western NC and Piedmont homes.

Does North Carolina require radon contractor licensing?

NRPP or NRSB national certification is required. No separate NC licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

What parts of North Carolina have the highest radon?

Western NC Appalachian counties — Buncombe, Henderson, Watauga, Avery, Mitchell — have the highest potential. The Piedmont crystalline zone (Charlotte, Raleigh, Greensboro areas) has moderate to elevated risk. Coastal plain counties have the lowest potential.

Western North Carolina Appalachian Radon

Western North Carolina’s mountain communities — Asheville (Buncombe County), Hendersonville (Henderson County), Brevard (Transylvania County), Boone (Watauga County), Banner Elk (Avery County), and Burnsville (Yancey County) — sit in Zone 1 with significant radon potential. The Blue Ridge Mountains of western NC are composed of Proterozoic crystalline rocks including granites, gneisses, and schist with elevated uranium content. The popular retirement and resort market in western NC means active real estate turnover — radon should be a standard contingency in all western NC transactions. Older mountain homes with stone and block foundations can have very high radon concentrations.

Piedmont Triangle Radon

The Research Triangle area — Wake County (Raleigh), Durham County, and Orange County (Chapel Hill) — is Zone 2 with moderate radon potential. The Carolina Slate Belt and Triassic Basin geology beneath the Triangle creates meaningful radon conditions. Mecklenburg County (Charlotte) is Zone 2. Guilford County (Greensboro, High Point) and Forsyth County (Winston-Salem) are also Zone 2. The Piedmont’s rapid growth and extensive new construction means RRNC inclusion during homebuilding is a significant missed opportunity — most new Piedmont NC homes are built without passive RRNC features.

North Carolina Testing Resources

The North Carolina Department of Health and Human Services (NCDHHS) Radiation Protection Section administers the state radon program. NCDHHS provides certified contractor information, county-level radon data from the NC Radon Survey, and educational resources. North Carolina participates in EPA’s SIRG program. Contact NCDHHS for the current certified contractor list and test kit guidance. The NC Geological Survey has published geological radon potential assessments for regions of the state.

Washington has meaningful radon risk, with approximately 25-30% of Washington homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including granitic rock in the Cascade Range and Okanogan Highlands, uranium-bearing basalt formations in eastern Washington’s Columbia Basin, and glacial outwash deposits across the Puget Sound region — creates radon potential across significant portions of the state. The Department of Health administers radon program resources for Washington residents.

EPA Radon Zone Designation

Zone 1 in eastern Washington and portions of the Cascade Range, Zone 2 across western Washington.

Highest-Radon Areas in Washington

Eastern Washington counties overlying the Columbia Plateau basalt and Okanogan granite formations — Okanogan, Ferry, Stevens, Pend Oreille, and Spokane counties — are Zone 1. The greater Seattle area (King, Pierce, Snohomish counties) is Zone 2. The Spokane metropolitan area (Spokane County) is Zone 1 with elevated radon potential.

Radon Contractor Requirements in Washington

NRPP or NRSB national certification. Washington has no separate state radon licensing statute. The Department of Health 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 Washington

Washington’s seller disclosure law requires disclosure of known material defects through the Washington Seller Disclosure Statement. Known elevated radon conditions are material information. Radon testing is recommended statewide and is common in eastern Washington transactions.

Testing Resources for Washington Residents

Contact the Department of Health 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

Is the Seattle area high in radon?

The greater Seattle area (King, Pierce, Snohomish counties) is Zone 2 with moderate radon potential. Testing is still recommended for all Seattle metro homes, particularly those with basements. Eastern Washington (Spokane area) has higher radon concentrations.

Does Washington require radon contractor licensing?

NRPP or NRSB national certification is required. No separate Washington licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

What parts of Washington have the highest radon?

Eastern Washington counties — Okanogan, Ferry, Stevens, Pend Oreille, and Spokane — overlying Columbia Plateau basalt and Okanogan granite have the highest potential. The Spokane metropolitan area is Zone 1 with elevated risk.

Spokane and Eastern Washington Radon

Spokane County is Zone 1 — the highest-radon area in Washington State. The Spokane area’s geology includes granitic basement rock, Columbia River Basalt, and glacial outwash that create elevated radon conditions. The city of Spokane and its suburbs (Spokane Valley, Liberty Lake, Cheney, Medical Lake) all have elevated radon potential. Pend Oreille County and Stevens County in the northeastern corner of Washington overlie the Selkirk Mountains granitic geology with very high radon potential. Ferry County (Republic area) and Okanogan County in north-central Washington also show Zone 1 characteristics.

Puget Sound Region Radon

The greater Seattle area — King, Pierce (Tacoma), and Snohomish (Everett) counties — is Zone 2 with moderate but meaningful radon risk. Kitsap County (Bremerton, Bainbridge Island) and Thurston County (Olympia) are Zone 2. The Puget Sound lowlands’ glacially deposited soils have lower radon production than eastern Washington’s bedrock geology, but Zone 2 represents thousands of homes with elevated concentrations. South King County (Auburn, Kent, Renton) and Pierce County’s Puyallup Valley communities show moderate radon levels. Snohomish County communities closer to the Cascade foothills (Monroe, Snohomish, Granite Falls) show higher readings than lowland communities.

Washington Testing Resources

The Washington State Department of Health (DOH) Office of Radiation Protection administers the state radon program. DOH provides certified contractor information, county-level radon survey data, and educational resources. Washington participates in EPA’s SIRG program. Contact DOH for the current certified contractor list. The Washington State Geological Survey provides detailed geological radon potential information for homeowners seeking sub-county context. Search nrpp.info by zip code for certified Washington radon contractors.

Oregon has meaningful radon risk, with approximately 30% of Oregon homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including uranium-bearing volcanic rock in the Cascade Range, granitic basement rock in the Klamath Mountains of southwestern Oregon, and sedimentary formations in the Willamette Valley — creates radon potential across significant portions of the state. The Health Authority Radiation Protection Services administers radon program resources for Oregon residents.

EPA Radon Zone Designation

Zone 1 in portions of the Cascade Range and southern Oregon, Zone 2 across much of western Oregon, Zone 1-2 in central and eastern Oregon.

Highest-Radon Areas in Oregon

The Portland metropolitan area (Multnomah, Washington, Clackamas counties) is Zone 2 with meaningful radon risk. Southern Oregon counties overlying Klamath Mountain and Cascade geology — Josephine, Jackson, Klamath, and Lake counties — are Zone 1. Central Oregon counties including Deschutes (Bend area) and Jefferson show elevated levels.

Radon Contractor Requirements in Oregon

NRPP or NRSB national certification. Oregon has no separate state radon licensing statute. The Health Authority Radiation Protection Services 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 Oregon

Oregon’s property disclosure law requires sellers to disclose known material defects. Known elevated radon conditions are material information. Radon testing is common in Oregon real estate transactions, particularly in southern Oregon and the Portland metro area.

Testing Resources for Oregon Residents

Contact the Health Authority Radiation Protection Services 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

Is the Portland area high in radon?

The Portland metro area (Multnomah, Washington, Clackamas counties) is Zone 2 with meaningful radon risk. Testing is recommended for all Portland metro homes, particularly those with basements.

Does Oregon require radon contractor licensing?

NRPP or NRSB national certification is required. No separate Oregon licensing statute. Verify credentials at nrpp.info or nrsb.org.

What parts of Oregon have the highest radon?

Southern Oregon counties — Josephine, Jackson, Klamath, Lake — overlying Klamath Mountain and Cascade geology have the highest potential. Central Oregon (Deschutes/Bend area) also shows elevated levels. Portland metro is Zone 2 with meaningful risk.

Southern Oregon Radon: Klamath Mountains and Cascades

Southern Oregon has the state’s highest radon concentrations. Josephine County (Grants Pass) and Jackson County (Medford, Ashland) overlie the Klamath Mountains — ancient ocean crust and island arc geology with elevated heavy mineral content including uranium-bearing formations. Douglas County (Roseburg) is at the transition between the Klamath Mountains and the Cascades. Klamath County (Klamath Falls) and Lake County in south-central Oregon also show significant radon levels from volcanic and basement rock geology. Southern Oregon homebuyers should treat radon testing as mandatory.

Portland Metro and Willamette Valley Radon

The Portland metropolitan area — Multnomah, Washington, Clackamas, and Clark (Washington state) counties — is Zone 2 with moderate radon risk. The Willamette Valley’s primarily sedimentary geology creates lower radon conditions than southern Oregon or the Cascade foothills, but Zone 2 still represents meaningful risk. Washington County (Beaverton, Hillsboro) shows slightly higher levels than downtown Portland due to proximity to Tualatin Mountains geology. Clackamas County (Lake Oswego, Oregon City) at the valley edge shows Zone 1 to Zone 2 transition. Hood River County (Columbia Gorge area) and The Dalles (Wasco County) show elevated levels from Columbia River Basalt formations.

Oregon Testing Resources

The Oregon Health Authority (OHA) Radiation Protection Services administers the state radon program. OHA provides certified contractor information, county-level radon survey data, and educational materials. Oregon participates in EPA’s SIRG program. Contact OHA for the current certified contractor list and test kit guidance. The Oregon Geological Survey has published radon potential maps providing sub-county geological risk information for homeowners seeking more precise local context.

Vermont has meaningful radon risk, with approximately 40% of Vermont homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including granitic and metamorphic bedrock throughout the state — including the Green Mountains granitic core, the Connecticut River Valley schist and gneiss, and uranium-bearing rocks in the northeastern Kingdom — creates radon potential across significant portions of the state. The Department of Health administers radon program resources for Vermont residents.

EPA Radon Zone Designation

Zone 1 across most of the state due to granitic and metamorphic geology — Vermont’s bedrock geology creates significant radon potential statewide.

Highest-Radon Areas in Vermont

Chittenden County (Burlington), Washington County (Montpelier), and Addison County (Middlebury) show significant radon levels due to granitic geology. The Northeast Kingdom counties of Orleans, Essex, and Caledonia have high radon potential. Franklin and Grand Isle counties also show elevated levels.

Radon Contractor Requirements in Vermont

NRPP or NRSB national certification. Vermont has no separate state radon licensing statute. The Department of Health 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 Vermont

Vermont’s Property Transfer Disclosure Statement requires sellers to disclose known material defects. Vermont does not have a radon-specific disclosure statute, but known elevated radon is material information. Radon testing is standard practice in Vermont real estate transactions.

Testing Resources for Vermont Residents

Contact the Department of Health 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

Is Vermont a high-radon state?

Yes. Approximately 40% of Vermont homes exceed 4.0 pCi/L — one of the highest rates in New England. Vermont’s granitic and metamorphic bedrock creates significant radon potential statewide.

Does Vermont require radon contractor licensing?

NRPP or NRSB national certification is required. No separate Vermont licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

Is radon a concern in Burlington or Montpelier?

Yes. Chittenden County (Burlington) and Washington County (Montpelier) are Zone 1 areas with significant radon potential. Testing is recommended for all Vermont homes.

Burlington and Chittenden County Radon

Chittenden County (Burlington, South Burlington, Williston, Shelburne, Colchester) is Vermont’s most populous county and a Zone 1 radon area. Burlington sits at the transition between the Champlain Valley lowlands (lower radon) and the Green Mountains foothills (higher radon), with radon levels varying significantly by neighborhood. East-side Burlington communities closer to the Green Mountain foothills generally test higher than those on the Champlain lakefront. Chittenden County’s active real estate market makes radon testing standard practice in buyer due diligence.

Northeast Kingdom Radon

Vermont’s Northeast Kingdom — Orleans, Essex, and Caledonia counties — has some of the state’s highest radon potential due to the Northeastern Highlands geology of granites, gneisses, and schist. These rural communities have extensive older housing stock with stone foundations, unfinished basements, and minimal sealing — creating multiple radon entry pathways. Northeast Kingdom homeowners are among those most likely to benefit from testing and mitigation, and the region’s housing affordability relative to Chittenden County means many homes have not been tested or upgraded.

Vermont Testing Resources

The Vermont Department of Health (VDH) Occupational and Radiological Health Program administers the state radon program. VDH provides certified contractor information, county-level radon survey data, and educational resources. Vermont participates in EPA’s SIRG program. Contact VDH for the current certified contractor list and test kit guidance. Vermont has been active in radon public health education, and the VDH radon program has developed materials specific to Vermont’s older housing types and geological context.

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.

New Hampshire has meaningful radon risk, with approximately 40% of New Hampshire homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including extensive granitic bedrock — the White Mountains and Merrimack Valley granite formations create some of the highest radon potential in New England. New Hampshire’s bedrock is among the most uranium-rich in the eastern United States — creates radon potential across significant portions of the state. The Department of Health and Human Services Radiological Health Section administers radon program resources for New Hampshire residents.

EPA Radon Zone Designation

Zone 1 across most of the state due to extensive granitic geology — New Hampshire sits on the White Mountain Magma Series and Merrimack Valley granite formations.

Highest-Radon Areas in New Hampshire

Hillsborough County (Manchester, Nashua), Merrimack County (Concord), Rockingham County (Portsmouth), and Grafton County (Plymouth, Hanover) all show elevated radon levels. White Mountain counties including Carroll and Grafton have high granitic bedrock radon potential.

Radon Contractor Requirements in New Hampshire

NRPP or NRSB national certification. New Hampshire has no separate state licensing statute. The Department of Health and Human Services Radiological Health Section 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 New Hampshire

New Hampshire’s real estate disclosure form requires disclosure of known material defects. Known elevated radon conditions should be disclosed. Radon testing is standard practice in New Hampshire real estate.

Testing Resources for New Hampshire Residents

Contact the Department of Health and Human Services Radiological Health Section 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

Is New Hampshire a high-radon state?

Yes. Approximately 40% of NH homes exceed 4.0 pCi/L — one of the highest rates in New England. NH’s granite-rich bedrock is among the most uranium-rich in the eastern U.S. Testing is essential for all NH homes.

Does New Hampshire require radon contractor licensing?

No separate NH licensing statute. NRPP or NRSB national certification is the operative credential. Search nrpp.info for certified New Hampshire contractors.

Is radon a concern in Manchester or Concord?

Yes. Hillsborough County (Manchester) and Merrimack County (Concord) are Zone 1 areas with significant radon potential. Testing is strongly recommended for all southern New Hampshire homes.

Manchester and Nashua Area Radon

Hillsborough County — New Hampshire’s most populous county, containing Manchester and Nashua — is Zone 1 with elevated radon risk throughout the county. Manchester, Nashua, Bedford, and Merrimack sit on Merrimack Valley granite formations with high uranium content. The greater Manchester-Nashua metropolitan area has among the highest residential radon testing rates in the Northeast because real estate agents and buyers in the area have long recognized radon as a standard inspection item. Rockingham County (Portsmouth area, including Salem and Derry) also shows significant Zone 1 radon levels.

White Mountains and Lakes Region Radon

Carroll County (Conway, North Conway, Wolfeboro) in the White Mountains and Lakes Region overlies the Ossipee Ring Dike — a geological formation of particular interest for radon, as ring dikes are associated with alkaline igneous rock that can have elevated uranium content. Grafton County (Plymouth, Hanover — home of Dartmouth College) is Zone 1. The White Mountains granitic formations create consistently high radon potential across the recreational and resort communities of northern New Hampshire. Second homes and vacation properties in these areas should be tested, as seasonal occupancy without testing represents an unacknowledged exposure risk.

New Hampshire Testing Resources

The New Hampshire Department of Health and Human Services (NHDHHS) Radiological Health Section administers the state radon program. NHDHHS provides certified contractor information, county-level radon survey data, and educational resources. New Hampshire participates in EPA’s SIRG program. Contact NHDHHS for the current certified contractor list. New Hampshire has historically had robust radon testing participation rates, and NHDHHS’s survey data provides detailed county-level risk information.

Alaska has meaningful radon risk, with approximately 35% of Alaska homes estimated to have levels above the EPA action level of 4.0 pCi/L. The state’s geology — including granitic basement rock in southeastern Alaska and the Alaska Range, uranium-bearing formations in interior Alaska, and the unique radon dynamics created by permafrost-modified soil gas pathways — creates radon potential across significant portions of the state. The Alaska Division of Environmental Health administers radon program resources for Alaska residents.

EPA Radon Zone Designation

Zone 1 across much of the state due to granitic bedrock, permafrost dynamics, and uranium-bearing geological formations throughout interior and southeastern Alaska.

Highest-Radon Areas in Alaska

Fairbanks (Interior), Anchorage (Southcentral), and Juneau (Southeast) metropolitan areas all have meaningful radon risk. Interior Alaska counties show some of the state’s highest readings due to granitic and uranium-bearing geology.

Radon Contractor Requirements in Alaska

NRPP or NRSB national certification. Alaska has no separate state licensing statute. The Alaska Division of Environmental Health 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 Alaska

Alaska has no radon-specific disclosure statute. General material defect disclosure obligations apply to known elevated radon conditions.

Testing Resources for Alaska Residents

Contact the Alaska Division of Environmental Health 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

Does Alaska have a radon problem?

Yes. Approximately 35% of Alaska homes exceed 4.0 pCi/L. Interior Alaska (Fairbanks area) has the highest radon potential due to granitic and uranium-bearing geology. All Alaska homeowners should test.

Does Alaska require radon contractor licensing?

No separate Alaska licensing statute. NRPP or NRSB national certification is the operative credential. Search nrpp.info for certified Alaska contractors.

Is radon a concern in Fairbanks or Anchorage?

Yes. The Fairbanks North Star Borough (interior Alaska) has elevated radon potential. Anchorage has moderate to elevated risk. Testing is recommended throughout Alaska regardless of location.

Interior Alaska Radon Risk

Interior Alaska — particularly the Fairbanks North Star Borough — has the state’s highest average radon concentrations. Fairbanks sits on geological formations including granite, schist, and mineralized zones associated with historic gold mining. The Fairbanks area’s extreme temperature differential (interior Alaska winters can reach -50°F) creates an unusually powerful stack effect — homes are tightly sealed for energy efficiency, and the massive indoor-outdoor temperature gap drives strong radon draw from the sub-slab zone. The combination of uranium-bearing geology and extreme building pressure dynamics makes Fairbanks one of the higher-risk communities in the country on a per-home basis.

Anchorage and Southeast Alaska

Anchorage (Municipality of Anchorage) sits on glacial till and lake deposits that generally create lower radon conditions than interior Alaska’s bedrock geology, but meaningful radon risk still exists. Hillside communities in Anchorage that are closer to the Chugach Range bedrock show higher average levels than lower-elevation areas. Southeast Alaska communities — Juneau, Sitka, Ketchikan — overlie the Coast Mountains granite that extends from British Columbia, creating moderate to elevated radon potential in some areas. Eagle River and the Mat-Su Borough (Wasilla, Palmer) show elevated levels due to proximity to range geology.

Alaska Testing Resources

The Alaska Division of Environmental Health administers radon program resources. Alaska’s radon program provides educational materials and can direct homeowners to certified testing services. Due to Alaska’s geographic remoteness and small population in many areas, finding locally certified radon professionals can be more challenging than in the contiguous 48 states — the NRPP directory (nrpp.info) is the primary tool for identifying certified Alaska contractors. Mail-in laboratory radon test kits are the most practical testing option for many Alaskan communities.

Missouri has significant radon risk across much of the state, with an estimated 35–40% of Missouri homes testing above the EPA action level of 4.0 pCi/L. Missouri’s geology — including limestone and dolomite formations in the Ozark plateau, granite in the St. Francois Mountains, and glacial till in northern Missouri — creates varied but often elevated radon potential. The Missouri Department of Health and Senior Services administers the state radon program.

EPA Radon Zone Designation

Missouri counties range from Zone 1 in portions of northern and central Missouri to Zone 2 in the Ozark plateau and Zone 2-3 in the Mississippi lowlands of southeastern Missouri (“Bootheel”). The highest-radon areas include northern Missouri glaciated counties (Adair, Linn, Macon, Shelby, Knox, Lewis, Marion, Ralls, Pike, and Monroe counties), the St. Francois Mountains counties (St. Francois, Iron, Reynolds, Shannon), and the St. Louis metropolitan area (St. Louis County, St. Charles County).

Radon Contractor Requirements in Missouri

Missouri requires radon contractors to hold NRPP or NRSB national certification. Missouri’s radon program is administered through the Missouri Department of Health and Senior Services. Missouri does not have a separate state radon contractor licensing statute beyond national certification requirements. Verify contractor credentials at nrpp.info or nrsb.org before hiring.

Radon Disclosure in Missouri

Missouri’s Seller’s Disclosure Statement requires sellers to disclose known material defects. Missouri does not have a radon-specific disclosure statute, but known elevated radon conditions are material information that sellers should disclose under the general duty. Radon testing is recommended during the inspection period for all Missouri real estate transactions, particularly in northern and central Missouri and the St. Louis metro area.

Frequently Asked Questions

Is the St. Louis area high in radon?

St. Louis County and St. Charles County are in Zone 1 or Zone 2 with meaningful radon risk. Radon testing is recommended for all St. Louis metro homes. Older homes in the area with block foundations or basements should be prioritized.

Does Missouri require radon contractor certification?

NRPP or NRSB national certification is required. No separate Missouri licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

What parts of Missouri have the highest radon?

Northern Missouri glaciated counties and the St. Francois Mountain counties of southeastern Missouri have the highest potential. The Kansas City and St. Louis metropolitan areas have significant radon risk. The Bootheel counties of extreme southeastern Missouri have generally lower levels.

Kansas City Metro Radon Risk

The Kansas City metropolitan area — which spans both Missouri and Kansas — has significant radon risk on the Missouri side. Jackson County (Kansas City proper) and the surrounding Missouri suburbs including Clay, Platte, Cass, and Ray counties show Zone 1 to Zone 2 radon levels. The Missouri side of the metro has glaciated geology in the north (Clay, Platte, Ray) transitioning to limestone and shale geology southward. Kansas City’s extensive older housing stock — particularly the bungalow and ranch-style homes with basements built throughout the post-WWII era — represents a significant untested population.

St. Louis Metro Radon

St. Louis County and St. Charles County on the Missouri side of the St. Louis metropolitan area are Zone 1 to Zone 2. The St. Francis Mountains geology (St. Francois County) — ancient Precambrian granite exposed at the surface — creates particularly high radon potential in Missouri’s Lead Belt region southeast of St. Louis. Jefferson County (south St. Louis suburbs) shows elevated readings. The city of St. Louis (independent city, Zone 2) has lower average levels than suburban St. Louis County but still warrants testing in older housing.

Missouri Testing Resources

The Missouri Department of Health and Senior Services (MDHSS) Radon Program provides certified contractor lists, county-level radon data from the Missouri Residential Radon Survey, and educational resources. Missouri participates in EPA’s SIRG program. The Missouri Geological Survey has published radon potential maps that provide more granular geological risk assessment than EPA’s county-level zone designations. Contact MDHSS for the current certified contractor list and test kit availability.

Connecticut has significant radon risk, particularly in its northern and western counties where the Reading Prong geological formation extends from Pennsylvania and New York into Connecticut. The Connecticut Department of Energy and Environmental Protection (DEEP) estimates that approximately 30% of Connecticut homes have radon levels above 4.0 pCi/L. Connecticut has enacted radon contractor certification requirements and maintains an active state radon program.

EPA Radon Zone Designation

Connecticut’s northern and western counties — Litchfield, Tolland, Windham, and Hartford counties — are Zone 1, reflecting the Reading Prong and Berkshire granitic geology extending from New York. New Haven and Middlesex counties are generally Zone 2. Fairfield County (southwestern Connecticut, bordering New York) shows elevated levels in its northern portions. New London County is Zone 2 to Zone 3.

Radon Contractor Requirements in Connecticut

Connecticut requires radon contractors to hold current NRPP or NRSB national certification. Connecticut’s radon program is administered through CT DEEP. Connecticut does not have a separate state radon licensing statute — national certification is the operative credential. Verify contractor credentials at nrpp.info or nrsb.org before hiring. CT DEEP maintains radon program information and resources on its website.

Radon Disclosure in Connecticut

Connecticut’s real estate disclosure law requires sellers to disclose known material defects through the Connecticut Residential Property Disclosure Report. The CT disclosure form includes environmental conditions — sellers with knowledge of elevated radon test results should disclose them. Connecticut real estate transactions routinely include radon testing contingencies, particularly in northern and western counties.

Frequently Asked Questions

What parts of Connecticut have the highest radon?

Northern and western Connecticut counties overlying Reading Prong and Berkshire granitic geology — Litchfield, Tolland, Windham, and northern Hartford counties — have the highest radon potential. The Hartford metro area shows moderate to high levels. Fairfield County (Stamford, Greenwich) is generally lower but northern Fairfield towns show elevated readings.

Does Connecticut require radon contractor certification?

NRPP or NRSB national certification is the operative requirement in Connecticut. No separate state licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

Is radon testing important in Hartford or New Haven?

Yes. Hartford County is Zone 1 with significant radon risk. New Haven County is Zone 2. Radon testing is recommended throughout Connecticut and should be standard in real estate transactions in northern and western Connecticut especially.

Hartford Area Radon Specifics

Hartford County — Connecticut’s most populous county — is Zone 1 with significant radon risk across the greater Hartford area including West Hartford, Glastonbury, Simsbury, Avon, and Canton. The county’s Triassic basin sediments in the Connecticut River valley and the surrounding Proterozoic crystalline bedrock create a complex radon geology. Older Hartford-area homes with block or stone foundations are particularly vulnerable. The University of Connecticut campus in Storrs (Tolland County, Zone 1) is another Zone 1 community where student and faculty housing should be tested.

Reading Prong Extension into Connecticut

The Reading Prong geological formation extends into northwestern Connecticut through Litchfield County — the same uranium-rich granite that creates high radon in Montgomery County, Pennsylvania and Morris County, New Jersey reaches into Connecticut’s northwestern corner. Litchfield County communities including Torrington, Litchfield, and Winsted overlie this geology. Fairfield County’s northern towns — Ridgefield, New Canaan, Darien, and Greenwich (which borders New York’s Westchester County) — transition from lower Zone 2 coastline geology to higher-radon interior geology.

Connecticut Testing Resources

The Connecticut Department of Energy and Environmental Protection (CT DEEP) provides radon testing resources, certified contractor information, and county-level radon data. Connecticut participates in EPA’s SIRG program. CT DEEP’s radon program publishes indoor radon survey data from Connecticut residential testing. Contact CT DEEP for the current certified contractor list and test kit guidance. The NRPP directory (nrpp.info) provides real-time certification verification for Connecticut contractors.