The United States does not have a single federal radon law. Instead, radon regulation in America is a patchwork of federal guidelines, state licensing and disclosure laws, building code requirements, and voluntary programs — each operating independently. Understanding this structure explains why radon requirements differ dramatically between states, why some transactions require certified professionals while others do not, and why “federal radon law” is largely a misnomer.
Federal Radon Framework: Guidelines, Not Mandates
At the federal level, the EPA is the primary radon authority. The EPA’s radon program operates almost entirely through guidance, technical assistance, and voluntary programs — not regulatory mandates. Two federal statutes form the legal foundation:
Indoor Radon Abatement Act (IRAA) of 1988
The Indoor Radon Abatement Act, enacted as Title III of the Toxic Substances Control Act (TSCA), established the federal policy framework for radon. Key provisions:
- Declared that the national long-term goal is reducing indoor radon to outdoor levels (~0.4 pCi/L)
- Directed EPA to publish technical guidance and establish a radon measurement proficiency program
- Authorized grants to states for radon programs, technical assistance, and public education
- Directed EPA to develop model construction standards for radon-resistant new construction
- Did not establish mandatory testing requirements, mandatory action levels, or federal licensing requirements for contractors
Residential Lead-Based Paint Hazard Reduction Act of 1992 (Title X)
Title X of the Housing and Community Development Act included radon provisions affecting federally assisted housing. It directed HUD to develop radon testing and mitigation requirements for HUD-assisted housing in high-radon areas and required disclosure of known radon hazards in federally assisted housing transactions.
EPA’s Role: Guidance Authority
EPA’s primary radon tools are guidance documents, technical standards, and voluntary programs:
- EPA Action Level (4.0 pCi/L): EPA’s recommended action level for mitigation. It is a guidance value, not a regulatory standard — there is no federal penalty for having a home above 4.0 pCi/L, and no federal requirement to test or mitigate.
- EPA Radon Measurement Proficiency (RMP) Program: Established the original framework for certifying radon measurement professionals. Now administered through NRPP (AARST) and NRSB as independent certification bodies.
- State Indoor Radon Grants (SIRG): EPA provides annual grants to state radon programs under IRAA. These grants fund state testing programs, contractor certification, public outreach, and radon-resistant new construction promotion.
- Radon Zone Map: EPA’s Map of Radon Zones designates all U.S. counties as Zone 1 (highest potential, predicted average above 4.0 pCi/L), Zone 2 (moderate, 2.0–4.0 pCi/L), or Zone 3 (lowest potential, below 2.0 pCi/L). The map informs but does not compel action.
State Authority: Where Regulation Actually Happens
States are the primary regulatory actors in radon. Through their police powers over public health, states have enacted a wide range of radon-specific laws:
Contractor Licensing
Approximately 20+ states require radon professionals to hold a state license or certification to legally conduct radon measurement or mitigation. Requirements vary significantly:
- Some states (e.g., New Jersey, Pennsylvania, Florida) have comprehensive licensing programs with examination, continuing education, and liability insurance requirements
- Some states accept NRPP or NRSB national certification as sufficient
- Some states require state-specific licensing in addition to national certification
- States without licensing requirements allow anyone to conduct radon work — no examination or certification needed
Real Estate Disclosure
Many states have enacted radon disclosure requirements for real estate transactions. Common structures:
- Known results disclosure: Sellers must disclose any known radon test results (Florida, Illinois, Maine, and others)
- Mitigation system disclosure: Sellers must disclose the presence of an existing radon mitigation system
- EPA pamphlet distribution: Some states require providing the EPA “Home Buyer’s and Seller’s Guide to Radon” to buyers
- No specific radon disclosure law: The general material defect disclosure duty under real estate law may cover known elevated radon in most states even without a specific radon statute
School and Public Building Requirements
Illinois, New Jersey, Pennsylvania, and several other states require radon testing in schools and/or childcare facilities. Requirements differ in frequency, action levels, and who conducts testing.
Rental Property Requirements
Some states with high radon prevalence have enacted landlord disclosure or testing requirements for rental properties. These are typically narrower in scope than homeowner requirements and vary substantially between states.
Building Codes: The RRNC Adoption Map
Radon-Resistant New Construction (RRNC) is addressed in the International Residential Code (IRC), which most U.S. jurisdictions have adopted in some form. The IRC includes an appendix (Appendix F) with RRNC requirements — but appendices are optional, and adoption varies by state and locality:
- Some states mandate IRC Appendix F adoption statewide for high-radon counties
- Some counties and municipalities in non-mandating states have adopted RRNC locally
- Many jurisdictions have adopted the IRC base code but not the RRNC appendix — RRNC is not required even though a general building code exists
States with statewide RRNC mandates or strong local adoption include portions of Colorado, Iowa, Maryland, Minnesota, Montana, North Dakota, and South Dakota — all Zone 1 states. Even in these states, enforcement varies by jurisdiction.
HUD and Federally Assisted Housing
The U.S. Department of Housing and Urban Development (HUD) has established radon requirements for multifamily housing projects receiving federal assistance. HUD’s Office of Lead Hazard Control and Healthy Homes (OLHCHH) administers radon policy for HUD-assisted properties:
- Properties in EPA Zone 1 counties receiving certain HUD assistance must test for radon
- Properties exceeding 4.0 pCi/L must mitigate before or shortly after occupancy
- New HUD-assisted multifamily construction in Zone 1 must incorporate RRNC features
Frequently Asked Questions
Is there a federal law requiring radon testing in homes?
No. The Indoor Radon Abatement Act of 1988 established federal radon policy and directed EPA to develop guidance and voluntary programs, but it does not mandate testing in private residences. Radon testing requirements for homeowners, if any, come from state law — and most states do not mandate testing in owner-occupied residences.
Which level of government regulates radon contractors?
States regulate radon contractors. There is no federal radon contractor licensing requirement. Approximately 20+ states require state licensing or accept national certification (NRPP or NRSB) for radon measurement and/or mitigation work. In states without contractor regulation, anyone can legally perform radon work regardless of training.
Does EPA set legally binding radon limits?
No. EPA’s 4.0 pCi/L action level is a guidance recommendation, not a legally binding regulatory standard. There is no federal penalty for radon levels above 4.0 pCi/L in a private residence, no federal requirement to remediate, and no federal enforcement mechanism for residential radon. The action level guides voluntary decisions and state programs, but it is not a regulatory threshold with legal consequences in the same way that OSHA exposure limits or EPA ambient air standards are.
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