Tag: Property Damage

North Dakota has the second-highest average indoor radon level of any U.S. state, estimated at approximately 8.2 pCi/L statewide. The North Dakota Department of Environmental Quality estimates that approximately 65% of North Dakota homes have radon levels above 4.0 pCi/L. North Dakota’s geology — including glacial lake sediments, shale, and uranium-bearing lignite formations — creates extremely high radon potential across the entire state.

EPA Radon Zone Designation

North Dakota is predominantly EPA Radon Zone 1. All North Dakota counties are Zone 1 — the highest radon potential designation. The uniform Zone 1 designation reflects the consistent geology of glacial deposits and shale formations across the entire state. No county in North Dakota has a Zone 2 or Zone 3 designation.

Radon Contractor Licensing in North Dakota

North Dakota requires radon contractors to hold current NRPP or NRSB national certification to perform radon services in the state. The North Dakota Department of Environmental Quality administers radon program resources and maintains information on certified professionals. North Dakota does not have a separate state radon contractor licensing statute independent of national certification. Verify contractor credentials at nrpp.info or nrsb.org before hiring any radon professional.

Radon Disclosure Requirements in North Dakota

North Dakota’s real estate disclosure law requires sellers to disclose known material defects. While North Dakota does not have a radon-specific disclosure statute, the general material defect disclosure duty covers known elevated radon conditions. Given that approximately 65% of North Dakota homes exceed the EPA action level, radon testing is standard practice in North Dakota real estate transactions. Buyers should include radon contingencies in all purchase offers.

Radon-Resistant New Construction (RRNC) in North Dakota

North Dakota does not have a statewide mandate requiring RRNC for all new construction. However, given the state’s extreme radon prevalence with all counties in Zone 1 and an average exceeding twice the EPA action level, EPA and NDDEQ strongly recommend RRNC for all new North Dakota residential construction. All new homes in North Dakota should include passive RRNC features per AARST-ANSI RRNC-2022 at minimum.

Highest-Radon Counties and Areas in North Dakota

All 53 North Dakota counties are Zone 1 with high radon potential. The highest average readings have historically been documented in western North Dakota counties overlying oil-bearing shale formations (Divide, Burke, Mountrail, McLean, Mercer, Oliver, Morton, Grant, Emmons counties) and in central North Dakota where glacial lake bed sediments from prehistoric Lake Agassiz are present (Cass, Ransom, Richland, Sargent counties in the east).

Testing Resources for North Dakota Residents

The North Dakota Department of Environmental Quality administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

How high is radon in North Dakota?

North Dakota has the second-highest average indoor radon level in the U.S. — approximately 8.2 pCi/L statewide. About 65% of North Dakota homes exceed the EPA action level of 4.0 pCi/L. All 53 counties are designated EPA Zone 1.

Does North Dakota require radon contractor certification?

NRPP or NRSB national certification is required. There is no separate North Dakota-specific licensing statute. Verify credentials at nrpp.info or nrsb.org before hiring.

Should every North Dakota home be tested for radon?

Yes — emphatically. With 65% of homes above the EPA action level and all counties in Zone 1, every North Dakota home should be tested. The question in North Dakota is not whether radon is likely to be present, but how high the level is.

Montana has among the highest radon levels in the western United States, with an estimated statewide average around 5.7 pCi/L and approximately 45% of Montana homes testing above the EPA action level. Montana’s geology — including granitic batholiths, uranium-bearing rock formations, and glacial deposits — creates high radon potential across much of the state. Every Montana county is designated Zone 1 or Zone 2 by EPA.

EPA Radon Zone Designation

Montana is predominantly EPA Radon Zone 1. Most Montana counties are Zone 1. The highest-radon areas are concentrated in western Montana where granitic rock formations (including the Boulder, Idaho, and Bitterroot batholiths) produce significant uranium and radon. Central Montana counties overlying shale formations also show elevated levels.

Radon Contractor Licensing in Montana

Montana requires radon contractors to hold current NRPP or NRSB national certification. Montana’s radon program is administered through the Montana Department of Environmental Quality. Montana does not have a separate state radon contractor licensing statute beyond the national certification requirement. The DEQ provides resources on radon testing and maintains information on certified professionals. Verify contractor credentials directly at nrpp.info or nrsb.org.

Radon Disclosure Requirements in Montana

Montana’s real estate disclosure requirements include the Montana Residential Property Disclosure Act, which requires sellers to disclose known material defects. Elevated radon is a known material condition that sellers should disclose under this general duty. Montana does not have a radon-specific disclosure statute, but the standard Montana real estate disclosure form includes questions about environmental conditions. Buyers should include radon contingencies in purchase offers and conduct independent testing.

Radon-Resistant New Construction (RRNC) in Montana

Montana does not have a statewide RRNC mandate for new construction. However, given Montana’s high radon prevalence and Zone 1 designation across most of the state, EPA and MDEQ strongly recommend RRNC for all new Montana residential construction. Some Montana municipalities may have adopted local RRNC requirements. Buyers of new Montana construction should request RRNC features — the incremental cost during construction is minimal compared to post-construction remediation.

Highest-Radon Counties and Areas in Montana

Western Montana counties overlying granitic batholiths have the highest radon levels in the state: Missoula, Ravalli, Mineral, Sanders, and Powell counties in the western region. Cascade County (Great Falls) and Lewis and Clark County (Helena) in central Montana also show elevated levels. The MDEQ publishes county-level radon data from testing surveys.

Testing Resources for Montana Residents

The Montana Department of Environmental Quality administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

Is Montana a high-radon state?

Yes. Montana has among the highest radon levels in the western U.S., with an estimated average of 5.7 pCi/L and approximately 45% of homes above the EPA action level. All Montana residents should test their homes.

Does Montana require radon contractor licensing?

Montana requires NRPP or NRSB national certification. There is no separate Montana-specific licensing. Verify contractor credentials at nrpp.info or nrsb.org before hiring.

What parts of Montana have the highest radon?

Western Montana counties overlying granitic batholiths — including Missoula, Ravalli, Mineral, Sanders, and Powell counties — have the highest concentrations. Central Montana counties also show elevated levels.

Indiana has significant radon risk across much of the state, with an estimated 35–40% of Indiana homes testing above the EPA action level of 4.0 pCi/L. Indiana’s geology — including glacial till deposits from the last ice age across much of the northern and central state, and Devonian black shale in parts of the state — creates elevated radon potential. The Indiana State Department of Health estimates that radon may be responsible for a significant portion of lung cancer deaths in Indiana annually.

EPA Radon Zone Designation

Indiana is predominantly EPA Radon Zone 1. Indiana counties range from Zone 1 in the northern glaciated portion of the state to Zone 2 in central Indiana and Zone 2-3 in southern Indiana. The highest-radon areas are generally in the northern counties where glacial till deposits are thickest and the geology most radon-productive.

Radon Contractor Licensing in Indiana

Indiana requires radon contractors to hold current NRPP or NRSB national certification. Indiana does not have a separate state-specific radon contractor licensing statute — national certification through NRPP or NRSB serves as the operative credential for professional radon work in Indiana. The Indiana State Department of Health maintains information on certified radon professionals and the state radon program. Verify contractor certification through nrpp.info or nrsb.org before engaging any radon professional.

Radon Disclosure Requirements in Indiana

Indiana’s real estate disclosure form requires sellers to disclose known conditions that materially affect the property, including environmental hazards. While Indiana does not have a radon-specific disclosure statute, the general material defect disclosure requirement covers known elevated radon conditions. Indiana real estate contracts routinely include radon contingencies. The Indiana Association of Realtors provides guidance to agents on radon disclosure best practices. Sellers with known elevated radon levels should disclose and document this information.

Radon-Resistant New Construction (RRNC) in Indiana

Indiana does not have a statewide RRNC mandate for new residential construction. The Indiana Residential Code does not require RRNC features as a standard provision statewide. EPA and ISDH recommend RRNC for new construction in Zone 1 northern Indiana counties. The IRC Appendix F provisions may be adopted locally. Buyers of new construction in Indiana should ask their builder about RRNC inclusion, particularly in northern Zone 1 counties.

Highest-Radon Counties and Areas in Indiana

Indiana’s highest-radon areas are concentrated in the northern glaciated counties. Lake, LaPorte, Porter, St. Joseph, Elkhart, and Kosciusko counties in northwestern and north-central Indiana have shown elevated average radon levels in state surveys. The Indianapolis metropolitan area (Marion, Hamilton, Hendricks, Johnson, Hancock counties) shows moderate to high radon levels. Southern Indiana counties generally have lower but still meaningful radon potential.

Testing Resources for Indiana Residents

The Indiana State Department of Health administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

What percentage of Indiana homes have elevated radon?

Approximately 35–40% of Indiana homes are estimated to have radon levels above 4.0 pCi/L. Northern Indiana counties with glacial geology tend to show the highest readings.

Does Indiana require radon contractor certification?

Indiana requires NRPP or NRSB national certification for radon professionals. There is no separate Indiana-specific licensing statute — national certification is the operative credential. Verify at nrpp.info or nrsb.org before hiring.

Does Indiana require RRNC for new construction?

No statewide mandate. EPA recommends RRNC for new construction in Zone 1 northern Indiana counties. Ask your builder directly about RRNC inclusion before signing a new construction contract.

Colorado has some of the highest radon levels in the western United States, with an estimated average indoor radon level around 6.2 pCi/L — well above the EPA action level of 4.0 pCi/L. The Colorado Department of Public Health and Environment estimates that approximately 50% of Colorado homes have elevated radon. Colorado’s geology — including uranium-rich geological formations in the Front Range, granitic bedrock, and shale — creates high radon potential across much of the state, including the heavily populated Denver metro corridor.

EPA Radon Zone Designation

Colorado is predominantly EPA Radon Zone 1. Most Front Range and mountain Colorado counties are Zone 1. The highest-risk areas include counties along the Front Range corridor (El Paso, Jefferson, Arapahoe, Adams, Boulder, Larimer counties) and the western slope counties overlying uranium-bearing geology. Eastern plains counties are generally Zone 2 to Zone 3.

Radon Contractor Licensing in Colorado

Colorado requires radon contractors to hold current NRPP or NRSB certification to perform radon measurement and mitigation work. The Colorado Department of Public Health and Environment’s radon program maintains a list of certified radon professionals. Colorado does not have a separate state radon contractor licensing statute independent of national certification — NRPP or NRSB certification is the operative requirement. Verify contractor certification at nrpp.info or nrsb.org before hiring.

Radon Disclosure Requirements in Colorado

Colorado does not have a radon-specific disclosure statute for residential real estate transactions. However, Colorado’s general real estate disclosure law requires sellers to disclose known material adverse facts — and known elevated radon test results almost certainly qualify as a material fact under this standard. Real estate contracts in Colorado routinely include radon contingencies, and radon testing during the inspection period is standard practice in the Front Range metro area. The Colorado Real Estate Commission’s disclosure form does not include a specific radon question, but agents and sellers have a common law duty to disclose known adverse conditions.

Radon-Resistant New Construction (RRNC) in Colorado

Colorado has enacted RRNC requirements for new residential construction in high-radon areas. Some Colorado municipalities — particularly in El Paso County (Colorado Springs) and the Denver metro — require RRNC features for new construction. The IRC Appendix F provisions have been adopted in various Colorado jurisdictions. The CDPHE strongly recommends RRNC for all new construction in Colorado’s Zone 1 areas. Buyers of new Colorado construction should confirm with the builder and local building department whether RRNC is required and what specific provisions apply.

Highest-Radon Counties and Areas in Colorado

Colorado’s highest-radon areas include Front Range counties: El Paso (Colorado Springs area), Jefferson (Denver west suburbs), Arapahoe, Adams, Boulder, and Larimer counties. Mountain counties including Eagle, Summit, Park, and Teller also show elevated radon. Western slope counties overlying uranium-bearing geology in the Grand Junction area (Mesa County) have historically high readings. The CDPHE maintains county-level radon data on their website.

Testing Resources for Colorado Residents

The Colorado Department of Public Health and Environment administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

Is Colorado a high-radon state?

Yes. Colorado has one of the highest average indoor radon levels in the western U.S., estimated at 6.2 pCi/L statewide. Approximately 50% of Colorado homes test above the EPA action level. Radon is a significant public health concern across Colorado’s Front Range and mountain communities.

Does Colorado require radon disclosure in real estate?

Colorado has no radon-specific disclosure statute, but sellers have a common law duty to disclose known material adverse facts — including known elevated radon levels. Radon contingencies and testing are standard in Colorado real estate transactions.

What counties in Colorado have the highest radon?

El Paso, Jefferson, Arapahoe, Adams, Boulder, and Larimer counties along the Front Range have high average radon levels. Mountain counties including Eagle, Summit, Park, and Teller also show elevated readings. Western slope counties near Grand Junction have historically high concentrations.

Minnesota has consistently high radon levels, with the Minnesota Department of Health estimating that approximately 2 in 5 Minnesota homes (40%) have radon levels above 4.0 pCi/L. Minnesota’s geology — including granitic bedrock, glacial outwash, and uranium-bearing formations — produces elevated radon potential across much of the state. The Minnesota Radon Awareness Act, enacted in 2014, established specific disclosure and awareness requirements.

EPA Radon Zone Designation

Minnesota is predominantly EPA Radon Zone 1. Most Minnesota counties are Zone 1. The highest-radon areas are concentrated in the Iron Range of northeastern Minnesota (where uranium-bearing rock is prevalent), the granite regions of central Minnesota, and the glaciated plains of western Minnesota. The Twin Cities metropolitan area has significant radon risk, particularly in older housing stock.

Radon Contractor Licensing in Minnesota

Minnesota requires radon contractors to hold current NRPP or NRSB certification AND a Minnesota-specific radon contractor license issued by the Minnesota Department of Health. Minnesota’s radon contractor licensing program is among the more comprehensive in the Midwest. Licensed contractors must pass examinations, carry insurance, and complete continuing education. The MDH maintains a searchable database of licensed radon contractors. Since 2014, hiring an unlicensed radon contractor in Minnesota is a violation of the Minnesota Radon Awareness Act.

Radon Disclosure Requirements in Minnesota

The Minnesota Radon Awareness Act (Minnesota Statutes Chapter 144.4961) enacted in 2014 established specific radon disclosure requirements for real estate transactions. Key provisions: sellers must disclose to buyers whether the home has been tested for radon and provide any test results; sellers must provide the Minnesota Department of Health radon disclosure form; any mitigation system must be disclosed. Minnesota also requires that the EPA radon pamphlet or equivalent MDH materials be provided to buyers. These requirements apply to single-family homes and condominiums.

Radon-Resistant New Construction (RRNC) in Minnesota

Minnesota does not have a statewide mandate requiring RRNC for all new construction, but the MDH strongly recommends RRNC. Some Minnesota municipalities — particularly in the Twin Cities metro area — have incorporated RRNC requirements locally. Minnesota’s building code includes provisions that enable RRNC adoption. Given Minnesota’s high radon prevalence, the MDH recommends all new residential construction in Zone 1 areas include RRNC features per AARST-ANSI RRNC-2022.

Highest-Radon Counties and Areas in Minnesota

Minnesota’s highest-radon areas include the Iron Range counties of northeastern Minnesota (St. Louis, Lake, Cook counties), granite bedrock areas in central Minnesota (Morrison, Todd, Otter Tail counties), and western Minnesota counties in the glaciated plains. The Minneapolis-Saint Paul metropolitan area spans multiple high-radon counties including Hennepin, Ramsey, Anoka, Dakota, Washington, and Scott. The MDH publishes county-level radon data based on testing results reported to the state.

Testing Resources for Minnesota Residents

The Minnesota Department of Health administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

Does Minnesota have a radon disclosure law?

Yes. The Minnesota Radon Awareness Act (2014) requires sellers to disclose known radon test results and provide MDH radon disclosure materials to buyers in real estate transactions. Mitigation systems must also be disclosed.

Does Minnesota require radon contractor licensing?

Yes. Minnesota requires both NRPP or NRSB national certification AND a Minnesota-specific radon contractor license. Verify license status through the Minnesota Department of Health before hiring any contractor.

What is the radon level in Minnesota homes?

The Minnesota Department of Health estimates approximately 40% of Minnesota homes — roughly 2 in 5 — have radon levels above 4.0 pCi/L. Minnesota’s average is among the highest in the nation, making testing essential for all Minnesota homes.

Ohio has significant radon risk across much of the state, with an estimated 46% of Ohio homes testing above 4.0 pCi/L according to the Ohio Department of Health. Ohio’s geology — including glacial till, black shale, and limestone formations — produces elevated radon potential across the northern and central portions of the state. The Ohio Department of Health estimates that over 2 million Ohio homes have elevated radon levels.

EPA Radon Zone Designation

Ohio is predominantly EPA Radon Zone 1. Most Ohio counties are Zone 1 or Zone 2. The highest-radon areas are concentrated in the glaciated portions of northwestern and north-central Ohio and the black shale formations in central Ohio. Southern Ohio counties in the Appalachian region tend toward Zone 2, though individual homes can exceed 4.0 pCi/L throughout the state.

Radon Contractor Licensing in Ohio

Ohio requires radon contractors to hold current NRPP or NRSB certification to legally perform radon measurement and mitigation services. Ohio’s radon certification program is administered by the Ohio Department of Health. The ODH maintains a list of certified radon professionals searchable by location. Contractors performing radon services in Ohio without current certification may be operating in violation of state requirements. Always verify certification status directly with the ODH before hiring.

Radon Disclosure Requirements in Ohio

Ohio’s real estate disclosure law requires sellers to disclose known material defects, and the Ohio residential property disclosure form includes a specific question about radon — asking whether the seller has received a radon test report and if so, what the results were, and whether a radon mitigation system is installed. Sellers who have received radon test results must disclose them. Ohio buyers routinely include radon contingencies in purchase offers.

Radon-Resistant New Construction (RRNC) in Ohio

Ohio does not have a statewide RRNC mandate for new construction. The Ohio Building Code does not require RRNC features as a standard provision in all jurisdictions. However, EPA strongly recommends RRNC for new Ohio construction, particularly in Zone 1 northern and central counties. Buyers of new construction should ask builders directly about RRNC inclusion. The IRC Appendix F provisions are available for local adoption, and some Ohio municipalities have incorporated RRNC requirements.

Highest-Radon Counties and Areas in Ohio

Ohio’s highest-radon areas include the glaciated till counties of northwestern and north-central Ohio (Defiance, Fulton, Henry, Williams, Wood counties in the northwest; Wyandot, Hancock, Crawford, Marion, Morrow, Knox in the north-central region) and the black shale formation counties of central Ohio including Delaware, Franklin, Licking, and Fairfield counties. The Ohio Geological Survey and Ohio Department of Health have published county-level radon data.

Testing Resources for Ohio Residents

The Ohio Department of Health administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

What percentage of Ohio homes have elevated radon?

The Ohio Department of Health estimates approximately 46% of Ohio homes test above the EPA action level of 4.0 pCi/L — representing over 2 million Ohio homes with elevated radon. Testing is strongly recommended for all Ohio homes.

Does Ohio require radon contractor certification?

Yes. Ohio requires radon contractors to hold current NRPP or NRSB certification. Verify credentials through the Ohio Department of Health radon program before hiring any contractor for testing or mitigation.

Does Ohio require RRNC for new construction?

No statewide mandate exists. EPA strongly recommends RRNC for new Ohio construction, particularly in Zone 1 areas. Buyers of new construction should ask builders whether RRNC features are included.

Pennsylvania consistently ranks among the highest-radon states in the U.S., with an estimated average indoor radon level around 6.0 pCi/L statewide. The Pennsylvania Department of Environmental Protection estimates that approximately 40% of Pennsylvania homes have radon levels above the EPA action level. Pennsylvania’s geology — including Reading Prong granite, black shale, and carbonate rock formations — creates particularly high radon potential in the southeastern and south-central regions of the state.

EPA Radon Zone Designation

Pennsylvania is predominantly EPA Radon Zone 1. The majority of Pennsylvania counties are Zone 1, with particularly high radon potential in counties overlying the Reading Prong geological formation in the southeast (Bucks, Chester, Montgomery, Berks, Lehigh, Northampton counties) and limestone/carbonate geology in the south-central region (Adams, Cumberland, Franklin, York, Lancaster counties). Some northern and western counties are Zone 2.

Radon Contractor Licensing in Pennsylvania

Pennsylvania has a comprehensive radon contractor licensing program administered by the Pennsylvania Department of Environmental Protection. Radon measurement and mitigation contractors must hold a Pennsylvania state license to legally perform radon services in the state. Pennsylvania licensing requires passing state examinations (or demonstrating NRPP/NRSB certification), carrying liability insurance, and completing continuing education. The DEP maintains an online searchable database of licensed radon professionals at dep.pa.gov. Performing radon work without a Pennsylvania license is illegal and a violation of the Radon Certification Act.

Radon Disclosure Requirements in Pennsylvania

Pennsylvania has specific radon disclosure requirements under its real estate disclosure law. Sellers must complete the Seller’s Property Disclosure Statement, which includes questions about radon — specifically whether the property has been tested and what the results were, and whether a radon mitigation system is present. Pennsylvania does not require sellers to test before selling, but known results must be disclosed. Given Pennsylvania’s high radon prevalence, radon contingencies are standard in Pennsylvania real estate transactions, and buyers routinely request independent testing.

Radon-Resistant New Construction (RRNC) in Pennsylvania

Pennsylvania does not have a statewide mandate requiring RRNC for all new construction, but the Pennsylvania DEP strongly recommends RRNC for new homes — particularly in Zone 1 counties. Some municipalities within Pennsylvania have adopted local RRNC requirements. The IRC Appendix F RRNC provisions are available for local adoption. Buyers of new construction in Pennsylvania should ask their builder directly whether RRNC features are included, particularly in the high-radon southeastern and south-central counties.

Highest-Radon Counties and Areas in Pennsylvania

Pennsylvania’s highest-radon areas include counties overlying the Reading Prong geological formation: Bucks, Chester, Montgomery, Berks, Lehigh, and Northampton in the southeast. South-central counties including Adams, York, Lancaster, Cumberland, and Franklin — which overlie limestone and carbonate geology — also show high average radon levels. The PA DEP’s county-level radon data is available on their website and shows average indoor radon measurements for each county based on test results submitted to the program.

Testing Resources for Pennsylvania Residents

The Pennsylvania Department of Environmental Protection administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

Does Pennsylvania require radon contractor licensing?

Yes. Pennsylvania has a comprehensive Radon Certification Act requiring contractors to hold a state license for radon measurement and mitigation work. Verify license status through the Pennsylvania DEP radon program before hiring any contractor.

What parts of Pennsylvania have the highest radon levels?

The Reading Prong geological formation in southeastern Pennsylvania (Bucks, Chester, Montgomery, Berks, Lehigh, Northampton counties) has some of the nation’s highest radon concentrations. South-central counties including Adams, York, Lancaster, Cumberland, and Franklin also show elevated average radon levels.

Is radon testing required when buying a house in Pennsylvania?

Not legally required, but strongly recommended and standard practice. Pennsylvania sellers must disclose known radon test results, but they are not required to test before selling. Buyers should always conduct independent testing during the inspection contingency period.

Related Radon Resources

• EPA Radon Zone Map: What Zone 1, 2, and 3 Mean
• NRPP and NRSB Radon Contractor Certification Explained
• Radon Disclosure Laws: What Sellers Must Tell Buyers
• How to Find and Hire a Good Radon Contractor

Iowa has the highest average indoor radon levels of any U.S. state. The Iowa Department of Public Health estimates that approximately 71% of Iowa homes test above the EPA action level of 4.0 pCi/L, and Iowa’s statewide average indoor radon level of roughly 8.5 pCi/L is the highest in the nation. Every county in Iowa is designated EPA Radon Zone 1.

EPA Radon Zone Designation

Iowa is predominantly EPA Radon Zone 1. All 99 Iowa counties are Zone 1 — the highest radon potential designation — reflecting the state’s geology of uranium-rich glacial deposits, black shale, and granite-derived soils across the entire state.

Radon Contractor Licensing in Iowa

Iowa requires radon contractors to hold certification from NRPP or NRSB to legally conduct radon measurement and mitigation work. Iowa’s radon program enforces contractor certification requirements and maintains a list of certified professionals. Performing radon mitigation without certification in Iowa may violate state public health regulations. Verify any contractor’s current certification status through the Iowa Department of Public Health radon program website before hiring.

Radon Disclosure Requirements in Iowa

Iowa requires sellers of real property to disclose known radon test results. The Iowa disclosure requirement applies to residential real estate transactions and directs sellers to disclose whether the property has been tested for radon and the results of any such test. Iowa also requires that buyers be provided information about radon and its health risks. Given that 71% of Iowa homes exceed the EPA action level, radon contingencies and testing are standard practice in Iowa real estate transactions.

Radon-Resistant New Construction (RRNC) in Iowa

Iowa mandates radon-resistant new construction features for new residential construction. As a Zone 1 state with the nation’s highest average radon levels, Iowa’s building code requirements include RRNC provisions for new homes. Builders constructing new homes in Iowa should confirm current RRNC requirements with their local building department, as specific requirements have evolved and local adoption varies. EPA strongly recommends full RRNC per AARST-ANSI RRNC-2022 for all new Iowa construction.

Highest-Radon Counties and Areas in Iowa

All 99 Iowa counties are Zone 1. The counties with historically highest average radon measurements include Linn, Polk, Johnson, Scott, and Black Hawk — the state’s most populous counties — as well as the geological formation areas in north-central and northeastern Iowa where glacial deposits are thickest. Iowa State University Extension and IDPH have documented elevated radon across the entire state, with rural counties in northern Iowa showing some of the highest averages.

Testing Resources for Iowa Residents

The Iowa Department of Public Health administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.

Frequently Asked Questions

Is Iowa a high-radon state?

Iowa is the highest-radon state in the U.S. by average indoor concentration. Approximately 71% of Iowa homes test above the EPA action level of 4.0 pCi/L, and Iowa’s statewide average of roughly 8.5 pCi/L exceeds all other states. Testing is essential for every Iowa home.

Are radon contractors required to be licensed in Iowa?

Yes. Iowa requires radon measurement and mitigation contractors to hold current NRPP or NRSB certification. Verify contractor credentials through the Iowa Department of Public Health radon program before hiring.

Does Iowa require radon disclosure when selling a home?

Yes. Iowa sellers must disclose known radon test results to buyers. Given that the majority of Iowa homes exceed the EPA action level, radon testing and disclosure are standard components of Iowa real estate transactions.

Related Radon Resources

• EPA Radon Zone Map: What Zone 1, 2, and 3 Mean
• NRPP and NRSB Radon Contractor Certification Explained
• Radon Disclosure Laws: What Sellers Must Tell Buyers
• Radon-Resistant New Construction: Building Codes Explained

Radon disclosure in real estate is not governed by a single federal law. Instead, a patchwork of state statutes, administrative rules, and general real estate disclosure obligations creates a varied landscape in which seller requirements differ dramatically by state. In some states, sellers must proactively disclose any known radon test result above a threshold. In others, radon disclosure falls under the general duty to disclose material defects — and sellers who know about elevated radon and say nothing may face post-closing liability even without a specific radon statute.

No Federal Radon Disclosure Law for Residential Sales

Federal law does not mandate radon disclosure for the sale of private residential property. The Indoor Radon Abatement Act of 1988 directed EPA to develop guidance but created no seller disclosure obligation. The Real Estate Settlement Procedures Act (RESPA) and Truth in Lending Act (TILA) govern financial disclosures in real estate transactions but do not address radon. The only federal radon disclosure requirement applies to HUD-assisted housing, where tenants and buyers must be notified of known radon hazards.

Three Types of State Radon Disclosure Frameworks

Type 1: Specific Radon Disclosure Statute

Some states have enacted radon-specific disclosure statutes that explicitly require sellers to disclose radon-related information. Requirements vary by state but may include:

• Disclosure of any known radon test result (regardless of level)
• Disclosure of any known radon test result at or above the EPA action level
• Disclosure of the presence of a radon mitigation system
• Provision of the EPA “Home Buyer’s and Seller’s Guide to Radon” pamphlet
• Disclosure of whether any test has ever been conducted in the home

States with explicit radon disclosure statutes or regulations include (as of 2026): Florida, Illinois, Maine, Virginia, and others. Statute specifics change — verify current requirements with your state real estate commission or a licensed real estate attorney.

Type 2: General Material Defect Disclosure

Nearly all states require sellers to disclose known material defects in the property — conditions that would affect the property’s value or a buyer’s decision to purchase. In states without a radon-specific disclosure law, elevated radon can still constitute a known material defect that must be disclosed under the general duty.

The key word is “known.” A seller who has never tested does not have a disclosure obligation they are not aware of. A seller who tested five years ago, found 12 pCi/L, and never mitigated or disclosed — that is a different legal situation in most states, regardless of whether a radon-specific law exists. Courts in multiple states have found liability under general misrepresentation or fraud theories when sellers concealed known radon test results even without state radon disclosure statutes.

Type 3: No Specific Requirement (Buyer Beware)

A smaller number of states have neither a specific radon disclosure statute nor a general material defect disclosure requirement robust enough to clearly cover radon. In these states, the buyer’s primary protection is their own due diligence — testing during the inspection contingency period. Buyers in these states should always include a radon contingency in their purchase offer and conduct independent testing.

What Sellers Should Disclose (Best Practice, All States)

Regardless of state-specific requirements, the following disclosure approach protects sellers from post-closing liability and reflects ethical practice:

• Disclose all known radon test results — not just recent ones and not just elevated ones
• Disclose the presence of any radon mitigation system, including the type, installation date, and contractor
• Disclose whether the home has ever been tested and what the results were
• Provide copies of all test reports and post-mitigation testing documentation
• Do not selectively disclose only favorable results while omitting unfavorable historical tests

Sellers who test before listing — and mitigate if needed — have the most straightforward disclosure position: known test results, documented mitigation, confirmed post-mitigation levels. The paper trail protects against post-closing claims.

What Buyers Should Know

• Include a radon contingency in your offer: Specifies the test protocol, the threshold (typically 4.0 pCi/L), and the remedies available to you if the threshold is exceeded
• Conduct independent testing: Do not rely on seller-provided test results as your only verification — even in states where sellers are required to disclose, the seller’s test may be old, improperly conducted, or selectively presented
• Request all historical test results: Ask specifically for all test results ever conducted — not just the most recent one
• Verify any existing mitigation system: Request contractor documentation, post-mitigation test results, and check that the U-tube manometer shows the system is operating

Frequently Asked Questions

Am I required to disclose radon when selling my house?

It depends on your state. States with radon-specific disclosure statutes require disclosure of known results; most other states require disclosure of known material defects that would affect a buyer’s decision — which elevated radon likely qualifies as. Consult a real estate attorney in your state for specific obligations. As a practical matter, failing to disclose known elevated radon exposes sellers to post-closing litigation risk in most jurisdictions even where no specific statute exists.

Do I have to disclose old radon test results?

Yes, if you are aware of them. “Known material defect” disclosure obligations apply to all known information — not just recent or convenient information. A radon test result from 10 years ago showing 15 pCi/L, followed by no mitigation or retesting, is a known condition that almost certainly triggers disclosure obligations under either specific radon statutes or general defect disclosure requirements.

What if the seller did not disclose a known radon problem?

If a seller knew about elevated radon and failed to disclose it in a state with a disclosure obligation (either radon-specific or general material defect), the buyer may have grounds for post-closing claims including fraud, misrepresentation, or breach of contract. Remedies vary by state but may include cost of mitigation, diminution in property value, or in egregious cases, rescission of the transaction. Consult a real estate attorney in your state with the specific facts of the situation.