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  • Radon Laws and Regulations in Pennsylvania: Complete Guide

    The Distillery — Brew № 1 · Radon Mitigation

    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

  • Radon Laws and Regulations in Iowa: Complete Guide

    The Distillery — Brew № 1 · Radon Mitigation

    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

  • Radon in New Construction: Building Codes and RRNC Requirements

    The Distillery — Brew № 1 · Radon Mitigation

    The most cost-effective moment to address radon is during new home construction — before the slab is poured, before walls are framed, before any remediation is necessary. Building codes are the mechanism through which governments mandate this timing advantage, requiring builders to incorporate radon-resistant features into new residential construction. But because the U.S. building code system is decentralized, RRNC requirements vary dramatically by state and locality.

    The International Residential Code and Radon

    The International Residential Code (IRC) is a model building code developed by the International Code Council (ICC) and adopted — in some form — by most U.S. states. The IRC includes an appendix (Appendix F: Radon Control Methods) that specifies RRNC requirements for new residential construction. Key IRC Appendix F requirements align with EPA guidance and AARST-ANSI RRNC-2022:

    • 4-inch thick gas-permeable layer (3/4″ gravel or equivalent) under the slab
    • Polyethylene vapor barrier (minimum 6-mil) between the gas-permeable layer and the slab
    • 3-inch or 4-inch PVC vent pipe routed from the sub-slab to above the roofline
    • Electrical junction box or outlet in the attic at the anticipated fan location
    • Sealing of all major slab penetrations and joints

    The critical limitation: IRC appendices are optional. Jurisdictions that adopt the IRC base code are not automatically required to adopt Appendix F. A state can adopt the full IRC with Appendix F (making RRNC mandatory), adopt the IRC without Appendix F (making RRNC voluntary), or adopt a modified version with different RRNC requirements.

    Where RRNC Is Mandatory

    As of 2026, the following categories of jurisdictions require RRNC:

    States with Statewide RRNC Mandates

    Several high-radon-risk states have enacted statewide RRNC requirements for new residential construction in Zone 1 (or sometimes all) counties. States with statewide or zone-specific RRNC mandates include portions of Colorado, Iowa, Maryland, Minnesota, Montana, North Dakota, South Dakota, and others. Requirements vary in scope — some mandate full RRNC for all new single-family construction, others require it only in Zone 1 counties or for structures with ground-contact foundations.

    Municipalities with Local RRNC Requirements

    In states without statewide RRNC mandates, individual counties and municipalities may have adopted RRNC requirements locally. This is common in Zone 1 counties where local officials have responded to elevated community radon levels even in the absence of state mandate. Local adoption varies and is not comprehensively tracked — contact your local building department to confirm requirements for a specific project location.

    HUD-Assisted New Construction

    Federally assisted new construction projects in EPA Zone 1 counties are subject to HUD radon requirements, which include RRNC features for multifamily projects. This is a federal requirement that operates independently of state or local building codes.

    Where RRNC Is Strongly Recommended but Not Required

    In the majority of U.S. jurisdictions, RRNC is EPA-recommended but not legally required. Builders in these areas can include RRNC features voluntarily. EPA recommends RRNC for all new construction in Zone 1 counties regardless of local mandate, and recommends it for Zone 2 and Zone 3 as well given the low incremental cost during construction.

    Buyers of new construction in non-mandating jurisdictions should ask their builder directly:

    • “Does this home include RRNC features per IRC Appendix F or AARST-ANSI RRNC-2022?”
    • “Is a passive radon vent pipe included in the construction plans?”
    • “Is there a dedicated electrical outlet in the attic for a future radon fan?”

    If the builder does not include RRNC, request it as a contract upgrade. The incremental cost is typically $350–$700 — a fraction of post-construction mitigation ($800–$2,500+) and a fraction of the home’s overall purchase price.

    The AARST-ANSI RRNC-2022 Standard

    Where IRC Appendix F provides the building code mechanism, AARST-ANSI RRNC-2022 provides the comprehensive technical specification. RRNC-2022 is more detailed than the IRC appendix on several points:

    • Specifications for alternative gas-permeable materials where gravel is impractical
    • Detailed sealing requirements for vapor barrier seams, penetrations, and wall interfaces
    • Crawl space-specific RRNC provisions (vented vs. encapsulated designs)
    • Quality verification requirements during construction
    • Labeling requirements for passive RRNC installations
    • Provisions for manufactured home foundations

    Projects referencing AARST-ANSI RRNC-2022 in their specifications are held to a higher technical standard than IRC Appendix F alone. Some state radon programs have updated their RRNC requirements to reference RRNC-2022 rather than older EPA guidance documents.

    Frequently Asked Questions

    Is my new home required to have radon-resistant features?

    It depends entirely on your state and local jurisdiction. In states with statewide RRNC mandates, yes — new construction must include IRC Appendix F or AARST-ANSI RRNC features. In most U.S. jurisdictions, RRNC is EPA-recommended but not legally required. Ask your builder directly whether RRNC is included, and request it if it is not — the upgrade cost during construction is minimal.

    What is the difference between IRC Appendix F and AARST-ANSI RRNC-2022?

    IRC Appendix F is the building code mechanism — the legal framework through which jurisdictions mandate RRNC in new construction. AARST-ANSI RRNC-2022 is the technical standard — the detailed specification for how RRNC components should be installed. Both address the same system components (gas-permeable layer, vapor barrier, vent pipe, electrical outlet), but RRNC-2022 is more comprehensive and is the current authoritative technical reference.

    My new home has a passive radon pipe — do I need to do anything?

    Test for radon after at least 60 days of occupancy. If results are at or above 4.0 pCi/L, activate the system by adding a fan to the existing pipe — a 1–2 hour installation costing $200–$500. If results are below 4.0 pCi/L, retest every 2 years. The passive pipe is infrastructure for future activation; it does not guarantee low radon levels without a fan.

  • Radon Disclosure Laws: What Sellers Are Required to Tell Buyers

    The Distillery — Brew № 1 · Radon Mitigation

    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.

  • Radon Contractor Licensing Requirements by State: What You Need to Know

    The Distillery — Brew № 1 · Radon Mitigation

    Not all radon contractors are equally regulated. In some states, performing radon mitigation or measurement requires a state license — examination, insurance, continuing education, and annual renewal. In others, there is no requirement at all: anyone can install a radon system or conduct a radon test legally, regardless of training or competence. Knowing which type of state you live in is the first step toward protecting yourself when hiring.

    The Spectrum of State Radon Contractor Regulation

    State radon contractor requirements fall into several categories:

    States with Comprehensive State Licensing Programs

    These states have enacted radon-specific licensing statutes requiring contractors to obtain a state license to legally perform radon work. Licensing typically requires:

    • Passing a state examination or completing state-approved training
    • Demonstrating NRPP or NRSB national certification (some states accept national certification in lieu of a separate state exam)
    • Carrying general liability insurance and in some states E&O (errors and omissions) insurance
    • Paying a licensing fee and renewing annually or biennially
    • Completing continuing education during each license period

    States with comprehensive licensing programs (as of 2026) include: Florida, Illinois, Iowa, Kansas, Maine, Maryland, Minnesota, Montana, New Jersey, New York, Ohio, Pennsylvania, Tennessee, and others. Requirements change — verify current status with your state radon program.

    States That Accept National Certification as Licensing

    Some states do not have separate state licensing requirements but have enacted laws or regulations that require contractors to hold current NRPP or NRSB certification to perform radon work legally. The practical effect is similar to licensing — the national certification serves as the state qualification. States in this category include several that require certification for at least some types of radon work (real estate measurement, school testing, or mitigation work with homeowner contracts).

    States with No Radon Contractor Regulation

    Roughly half of U.S. states have no radon-specific contractor licensing or certification requirements. In these states, there is no legal barrier to anyone performing radon work — from installation of mitigation systems to conducting real estate radon tests — regardless of training or competence. This does not mean good contractors do not exist in these states; many voluntarily maintain NRPP or NRSB certification. But it means you cannot rely on legal licensing as a screening tool — you must verify credentials directly.

    Measurement vs. Mitigation Licensing: Different Requirements

    Many states regulate measurement and mitigation separately. A contractor may be licensed for one but not the other:

    • Measurement-only licensing: Required for conducting certified radon tests (particularly for real estate), even in states where mitigation has no licensing requirement
    • Mitigation-only licensing: Required for installing systems; the contractor may not be authorized to conduct certified post-mitigation measurements
    • Dual certification/licensing: Some professionals hold both; many do not — confirm which credential a professional holds before engaging them for a specific service

    How to Verify a Contractor’s State License

    • Your state health department radon program: The most authoritative source. State radon programs maintain lists of currently licensed contractors and often have an online lookup tool. Search for “[your state] radon program” or “[your state] radon contractor license”.
    • NRPP directory: nrpp.info — searchable by name, zip code, or certification number. Shows current certification status and discipline (measurement, mitigation, or both).
    • NRSB directory: nrsb.org — same search capability for NRSB-certified professionals.
    • Ask directly: Request the contractor’s state license number and national certification number. Ask which certification they hold (measurement, mitigation, or both). A legitimate professional provides this immediately.

    What “No State Licensing Requirement” Means in Practice

    In states without radon contractor regulation, your protection comes from:

    • Voluntarily certified contractors: NRPP and NRSB directories include contractors in unregulated states who have chosen to obtain and maintain national certification. Prioritize these contractors.
    • Contract terms: A written contract specifying that installation will follow AARST-ANSI SGM-SF requirements creates an enforceable standard even where licensing does not.
    • Workmanship warranty: Reputable contractors in unregulated states typically offer warranties equivalent to those required in licensed states. Get the warranty in writing before work begins.
    • Post-mitigation independent testing: Regardless of contractor certification status, placing your own post-mitigation test device independently confirms whether the system is achieving its purpose.

    Frequently Asked Questions

    Does my state require a licensed radon contractor?

    Approximately half of U.S. states require some form of radon contractor licensing or certification. The fastest way to find your state’s specific requirements is to search “[your state] radon program” through your state health or environment department website. Many state radon programs maintain a list of licensed contractors and post current requirements online. Requirements change — information that is two or more years old may be outdated.

    Can an unlicensed contractor install a radon system?

    In states without radon contractor licensing requirements, yes — legally. In states with licensing requirements, performing radon mitigation without a license is illegal and may void warranty coverage, create liability for the homeowner (if work requires a building permit), and result in a system that does not meet AARST-ANSI standards. Always verify your state’s requirements and the contractor’s credentials before engaging anyone for radon work.

    Does a radon contractor need to be licensed to test and mitigate?

    Often yes for both activities — but through separate credentials. In most states with licensing, measurement (testing) and mitigation (system installation) are separately licensed or certified. A contractor licensed only for mitigation may not be authorized to conduct the certified post-mitigation measurement. Verify both credentials when a single contractor proposes to both install and certify the post-installation result.

  • AARST-ANSI Radon Standards: What They Are and Why They Matter

    The Distillery — Brew № 1 · Radon Mitigation

    When a radon professional says they follow “AARST standards,” they are referring to a specific set of American National Standards developed by the American Association of Radon Scientists and Technologists (AARST) and approved by the American National Standards Institute (ANSI). These standards are the technical backbone of professional radon practice in the United States — governing how systems are installed, how measurements are conducted, and what constitutes acceptable post-mitigation performance. Understanding what these standards require helps you evaluate whether a contractor is following best practice or cutting corners.

    What Is AARST?

    The American Association of Radon Scientists and Technologists (AARST) is the primary professional organization for radon professionals in the United States. Founded in 1988 — the same year as the Indoor Radon Abatement Act — AARST administers the National Radon Proficiency Program (NRPP), develops technical standards through a consensus process, and advocates for radon-related policy. AARST’s standards are developed collaboratively by measurement professionals, mitigators, researchers, regulators, and public health specialists.

    What Is ANSI Approval?

    The American National Standards Institute (ANSI) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, and systems in the United States. ANSI accreditation ensures that standards are developed through a documented, consensus-based process with balanced stakeholder representation and opportunities for public comment. AARST’s key radon standards are ANSI-approved, meaning they carry the authority of the U.S. voluntary consensus standards system — the same system that produces ASTM, ASHRAE, and ASME standards used throughout U.S. construction and engineering.

    The Core AARST-ANSI Radon Standards

    ANSI/AARST SGM-SF: Mitigation Standard for Single-Family Homes

    Standard of Practice for Mitigation of Radon in Schools and Large Buildings — Single-Family (SGM-SF) is the governing standard for radon mitigation system design and installation in single-family residential buildings. This is the standard that determines:

    • Required pre-installation diagnostic testing procedures
    • Fan placement requirements (unconditioned space only)
    • Pipe sizing, routing, and joint cementing requirements
    • Slab sealing requirements
    • System performance indicator (manometer) requirements
    • Required labeling on installed systems
    • Post-installation testing timing and protocol
    • Documentation requirements for installed systems

    SGM-SF is referenced in NRPP certification requirements and is the standard against which certified Radon Mitigation Specialists are tested. Many state radon programs and contractor licensing requirements specifically cite SGM-SF compliance as a requirement for licensed work.

    ANSI/AARST RMS-LB: Mitigation Standard for Large Buildings

    The Radon Mitigation Standard for Large Buildings (RMS-LB) covers radon mitigation in schools, commercial buildings, multifamily housing, and other large structures. It addresses the additional complexity of large-building mitigation: multiple foundation zones, complex HVAC integration, sub-membrane depressurization for large crawl spaces, and the heightened documentation and verification requirements appropriate for public-use buildings.

    ANSI/AARST MAMF: Measurement Standard for Multi-Family and Large Buildings

    The Measurement and Mitigation Protocol for Large Buildings (MAMF) governs radon measurement in commercial and multifamily residential settings. For real estate professionals, the most relevant application is its guidance on certified measurement for real estate transactions — particularly in multifamily and commercial properties where residential measurement standards (which address single-family protocol) may not directly apply.

    ANSI/AARST RRNC-2022: Radon-Resistant New Construction Standard

    The Radon-Resistant New Construction standard (RRNC-2022) defines the technical requirements for incorporating radon-resistant features into new residential construction. It is the most current and comprehensive technical document governing RRNC — superseding earlier EPA guidance documents on the topic. Key content includes:

    • Gas-permeable layer specifications (aggregate type, depth, coverage)
    • Vapor barrier specifications (minimum thickness, seam overlap, sealing requirements)
    • Vent pipe specifications (diameter, schedule, routing, termination)
    • Electrical outlet requirements for future fan activation
    • Crawl space-specific RRNC provisions
    • Quality verification requirements

    ANSI/AARST Series SSDS: Soil Suction Depressurization Standards

    The SSDS series covers specific mitigation methods including sub-slab depressurization, sub-membrane depressurization, drain-tile depressurization, and block-wall depressurization — providing technical specifications for each method type that exceed the general requirements in SGM-SF.

    How Standards Are Used in Practice

    AARST-ANSI standards function as the technical reference layer for radon professional practice in several ways:

    • Certification examinations: NRPP and NRSB certification exams test knowledge of AARST-ANSI standards — a certified professional is expected to know and follow these requirements
    • State licensing requirements: States with radon contractor licensing often cite AARST-ANSI standards as the technical basis for licensed work — contractors must demonstrate compliance
    • Workmanship warranty basis: When a mitigator’s workmanship warranty specifies what they will and will not do on a callback, the underlying technical obligation is typically SGM-SF compliance
    • Litigation reference: In disputes about radon mitigation quality or post-mitigation testing results, AARST-ANSI standards provide the objective technical benchmark against which contractor work is evaluated
    • Real estate due diligence: Buyers and home inspectors can reference AARST-ANSI standards to evaluate whether an existing mitigation system was installed to professional standards

    Frequently Asked Questions

    Are AARST-ANSI radon standards legally binding?

    AARST-ANSI standards are voluntary consensus standards — they are not automatically law. However, they become legally operative when incorporated by reference into state licensing requirements, building codes, or contract specifications. When a state radon licensing law requires compliance with SGM-SF, that standard becomes legally binding in that state. When a contractor’s contract specifies AARST-ANSI standard compliance, violation becomes a breach of contract. Courts also routinely treat industry consensus standards as evidence of the duty of care applicable to professionals in negligence cases.

    How do I know if my mitigation contractor followed AARST standards?

    Key SGM-SF compliance indicators to check: fan is in unconditioned space (attic, exterior, or garage — not a finished basement or utility room); all PVC joints are cemented (not dry-fitted); a U-tube manometer is installed and visible; required warning label is on the pipe; slab core hole is sealed with hydraulic cement (not just foam); and the contractor provided written documentation of pre-mitigation radon level, system specifications, and post-mitigation test results. A system missing any of these elements is likely not fully SGM-SF compliant.

    Where can I get copies of AARST-ANSI radon standards?

    AARST-ANSI standards are available for purchase through the AARST website (aarst.org) and through the ANSI standards store (ansi.org). Some standards are available for free download from AARST as part of their public education mission. State radon programs sometimes make the most relevant standard (typically SGM-SF) available as a reference document.

  • EPA Radon Zone Map: What Zone 1, 2, and 3 Mean for Your Home

    The Distillery — Brew № 1 · Radon Mitigation

    EPA’s Map of Radon Zones divides every U.S. county into one of three zones based on predicted average indoor radon levels. The map is widely cited in radon regulations, building codes, and HUD requirements — but it is frequently misunderstood. Zone designation does not tell you your home’s radon level. It tells you the predicted average for your county, which may have little bearing on the specific geology beneath your foundation.

    The Three Radon Zones

    Zone 1: Highest Potential (Predicted Average Above 4.0 pCi/L)

    Zone 1 counties have the highest predicted indoor radon potential. EPA’s methodology predicts that the average indoor radon level in Zone 1 counties exceeds the EPA action level of 4.0 pCi/L. Zone 1 counties are concentrated in the Northern Plains, Rocky Mountain states, Pennsylvania, Ohio, Iowa, and parts of the mid-Atlantic — regions with uranium-rich geology including granite formations, black shale, and glacial deposits.

    Zone 1 status triggers several regulatory consequences:

    • HUD requires radon testing for federally assisted multifamily housing in Zone 1 counties
    • Some states mandate RRNC (Radon-Resistant New Construction) for residential construction in Zone 1 counties
    • EPA recommends RRNC for all new construction in Zone 1 regardless of state requirements
    • Some states with school radon testing mandates prioritize Zone 1 districts

    Zone 2: Moderate Potential (Predicted Average 2.0–4.0 pCi/L)

    Zone 2 counties have predicted average indoor radon levels between the EPA “consider mitigating” level (2.0 pCi/L) and the action level (4.0 pCi/L). Zone 2 represents a substantial portion of U.S. counties. EPA still recommends testing in Zone 2 and recommends RRNC for new construction — the lower priority relative to Zone 1 reflects statistical averages, not safety.

    Zone 3: Lowest Potential (Predicted Average Below 2.0 pCi/L)

    Zone 3 counties have the lowest predicted radon potential. The average predicted indoor level is below 2.0 pCi/L. EPA still recommends testing in Zone 3 — individual homes in Zone 3 counties can and do have elevated radon due to local geology, soil conditions, and construction variations. “Low-radon zone” does not mean “radon-free zone.”

    How the Zone Map Was Developed

    EPA published the original Radon Zone Map in 1993 based on data from three sources:

    • Indoor radon surveys: State radon measurement data from the EPA/State Residential Radon Survey conducted in the late 1980s, providing actual indoor radon measurements from thousands of homes across the country
    • Aerial radiometric surveys: U.S. Geological Survey (USGS) airborne gamma-ray data measuring surface uranium, thorium, and potassium concentrations — proxies for radon-producing geology
    • Geology: USGS geologic map data identifying rock and soil types with known radon-producing potential

    These three data layers were combined at the county level to produce the zone assignments. The map has not been substantially revised since 1993, despite significant improvements in radon testing data availability. Some researchers have noted that the 1993 map may underpredict Zone 1 designation in certain geologic regions based on more recent measurement data.

    Critical Limitation: County Averages vs. Individual Homes

    The most important thing to understand about the radon zone map is what it cannot tell you: your home’s actual radon level. The map assigns zones based on county-level averages. Within any county — including Zone 3 counties — individual homes can vary from 0.2 pCi/L to 50+ pCi/L depending on:

    • Local soil type and permeability (sandy soils allow faster radon movement than clay)
    • Local bedrock uranium content (a single granitic intrusion can elevate radon in a small cluster of homes surrounded by low-radon geology)
    • Foundation type and construction quality (slab vs. basement vs. crawl space; sealed vs. cracked)
    • Building pressure dynamics (stack effect, HVAC, ventilation rate)
    • Proximity to the water table and seasonal moisture levels

    EPA’s own guidance explicitly states: “Any home can have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements.” Zone designation is a statistical predictor of regional risk, not a predictor of individual home risk.

    How to Find Your County’s Radon Zone

    EPA’s radon zone map is available at epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information. The map is searchable by state, and each state’s zone assignments are listed by county. The EPA also links to state-specific radon contact information, which often includes more detailed local radon data than the federal county-level map.

    Many state radon programs publish sub-county radon data — zip code level or census tract level — that provides more precise local risk information than the EPA’s county-level map. For the most accurate local picture, consult your state radon program’s data in addition to the EPA map.

    Frequently Asked Questions

    Does living in a Zone 3 county mean I don’t need to test for radon?

    No. Zone 3 means your county has the lowest predicted average radon potential nationally — it does not mean individual homes in your county are free of radon risk. EPA recommends testing in all zones. Significant local radon elevations occur in Zone 3 counties due to localized geology, soil conditions, and construction factors that the county-level map cannot capture.

    Is the EPA radon zone map accurate?

    The map is accurate as a statistical predictor of county-level averages based on 1993 data — which was the best available methodology at the time. It is not accurate as a predictor of individual home radon levels. The map’s limitations are well-documented in the literature: some counties are misclassified relative to more recent measurement data, and county-level averaging obscures significant within-county variation. Use it as context, not as a substitute for testing.

    What does Zone 1 mean for new construction?

    EPA recommends RRNC (Radon-Resistant New Construction) for all new homes in Zone 1 counties. Some states mandate RRNC for Zone 1 construction regardless of whether the specific site has been tested. HUD requires radon testing and mitigation for federally assisted multifamily projects in Zone 1. Even where not mandated, RRNC is strongly advisable in Zone 1 — the cost during construction ($350–$700) is a fraction of post-construction remediation ($800–$2,500).

  • Radon Regulations in the United States: Federal, State, and Local Overview

    The Distillery — Brew № 1 · Radon Mitigation

    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.

  • Radon Units Explained: pCi/L vs. Bq/m³ vs. WL

    The Distillery — Brew № 1 · Radon Mitigation

    If you have ever researched radon internationally, you may have encountered test results or guidelines expressed in units that look unfamiliar — Bq/m³ from European sources, WL from occupational health documents, or pCi/L from U.S. EPA guidance. All three measure the same phenomenon (radon radioactivity in air) but express it differently. Understanding the conversions and the context in which each unit is used lets you compare international research, interpret older documents, and understand why your neighbor’s European renovation report quotes a different number than your EPA-sourced action level.

    picocuries per liter (pCi/L) — The U.S. Standard

    The picocurie per liter is the standard unit for radon concentration in air used by the U.S. EPA, U.S. state radon programs, and most North American regulatory frameworks.

    What It Measures

    A curie (Ci) is a unit of radioactivity equal to 37 billion disintegrations per second — defined as the activity of one gram of radium-226. A picocurie (pCi) is one trillionth of a curie, or 0.037 disintegrations per second. Picocuries per liter expresses how many radon disintegrations per second are occurring in one liter of air.

    At EPA’s action level of 4.0 pCi/L, approximately 0.148 radon disintegrations occur per second per liter of air in your home — or about 9 per minute per liter.

    Key Reference Values in pCi/L

    • Outdoor average (U.S.): ~0.4 pCi/L
    • Indoor average (U.S.): ~1.3 pCi/L
    • EPA “consider mitigating” level: 2.0 pCi/L
    • EPA action level: 4.0 pCi/L
    • EPA “fix immediately” level: 8.0 pCi/L (or higher — no waiting for confirmatory test)

    becquerels per cubic meter (Bq/m³) — The International Standard

    The becquerel per cubic meter is the SI (International System of Units) standard for radon concentration. It is used by the World Health Organization, European Union radon regulations, and most countries outside North America.

    What It Measures

    A becquerel (Bq) is one radioactive disintegration per second. Becquerels per cubic meter (Bq/m³) expresses how many radon disintegrations per second occur in one cubic meter of air. Because 1 cubic meter = 1,000 liters, the conversion between Bq/m³ and pCi/L involves both the volume conversion and the unit conversion.

    Conversion Formula

    1 pCi/L = 37 Bq/m³ (exact conversion)
    1 Bq/m³ = 0.027 pCi/L

    Practical conversions:

    • EPA action level (4.0 pCi/L) = 148 Bq/m³
    • WHO reference level (100 Bq/m³) = 2.7 pCi/L
    • EU reference level (300 Bq/m³ for existing buildings) = 8.1 pCi/L
    • EU reference level (200 Bq/m³ for new construction) = 5.4 pCi/L

    Key Reference Values in Bq/m³

    • Outdoor average: ~15 Bq/m³
    • Indoor average (U.S.): ~48 Bq/m³
    • WHO reference level: 100 Bq/m³ (2.7 pCi/L)
    • EU reference level (existing buildings): 300 Bq/m³ (8.1 pCi/L)

    Working Levels (WL) — The Occupational Standard

    The working level (WL) is an older unit developed for measuring radon exposure in uranium mines and other occupational settings. It measures the combined energy of all short-lived radon decay products (progeny) in one liter of air — not radon itself. It remains in use in some occupational health, regulatory, and older literature contexts, but is rarely used in modern residential radon programs.

    What It Measures

    One working level (1 WL) is defined as any combination of short-lived radon progeny in one liter of air that will result in the emission of 1.3 × 10⁵ MeV of alpha energy upon complete decay. At equilibrium between radon and its progeny, 1 WL corresponds to approximately 200 pCi/L of radon.

    Conversion Formula

    At typical indoor equilibrium ratios (approximately 0.4 equilibrium factor):
    1 WL ≈ 200 pCi/L of radon (at complete equilibrium)
    EPA’s 4.0 pCi/L action level ≈ 0.02 WL

    Working level months (WLM) is the cumulative exposure metric — one WLM equals exposure to 1 WL for one working month (170 hours). Occupational exposure limits and mining health regulations are often expressed in WLM per year.

    Quick Conversion Reference

    pCi/LBq/m³WL (approx.)Context
    0.4150.002Outdoor average
    1.3480.007U.S. indoor average
    2.71000.014WHO reference level
    4.01480.02EPA action level
    8.02960.04EPA immediate action
    8.13000.04EU reference level (existing buildings)
    20.07400.1High-risk residential

    Frequently Asked Questions

    Why does the WHO action level seem lower than EPA’s?

    The WHO reference level of 100 Bq/m³ (2.7 pCi/L) is lower than EPA’s 4.0 pCi/L (148 Bq/m³) because the WHO chose to set a more conservative reference level reflecting updated health evidence. EPA’s 4.0 pCi/L level was set in the 1980s and has not been formally revised, though EPA acknowledges that radon between 2.0 and 4.0 pCi/L still poses meaningful risk and recommends considering mitigation in that range.

    If my test result is in Bq/m³, how do I know if I should mitigate?

    Divide your Bq/m³ result by 37 to get the pCi/L equivalent. If the result is 148 Bq/m³ or higher (4.0 pCi/L), EPA recommends mitigation. If you are following WHO guidance, the reference level is 100 Bq/m³ (2.7 pCi/L). If following EU guidance for existing buildings, the reference level is 300 Bq/m³ (8.1 pCi/L).

    My old test report shows results in WL — how do I convert to pCi/L?

    Multiply the WL value by 200 to get the approximate equivalent pCi/L at complete equilibrium. For example, 0.02 WL × 200 = 4.0 pCi/L. Because actual indoor equilibrium factors vary (typically 0.3–0.5, not 1.0), WL-to-pCi/L conversions have some inherent uncertainty. For modern residential decisions, use pCi/L or Bq/m³ from a current lab test.

  • Radon Testing for Schools and Daycares: EPA Guidelines and AARST Standards

    The Distillery — Brew № 1 · Radon Mitigation

    Children spend 6–8 hours per day in schools and daycares — second only to their homes in daily occupancy time. Because radon exposure risk is cumulative and children’s developing lungs may be more sensitive to radiation, radon in school buildings is a significant public health concern. EPA has published specific guidelines for school radon testing, and AARST-ANSI has developed standards (SGM-SF) that govern professional testing in educational and large commercial buildings.

    Why Schools Are a Priority

    School buildings face the same radon entry pathways as residences — soil gas entering through foundation cracks, floor penetrations, slab joints, and block wall cavities. Several factors make schools a particular concern:

    • Long daily occupancy by vulnerable populations: Children spend 1,000+ hours per year in school buildings. Cumulative radon exposure during childhood contributes to lifetime lung cancer risk.
    • Ground-floor and below-grade classrooms: Many schools have ground-floor or basement classrooms — the highest-radon zones in any building.
    • Large building volumes: Large buildings dilute radon more than small residences, but individual classrooms in poorly ventilated areas can accumulate significant concentrations.
    • Variable ventilation: Older school buildings frequently have inadequate or inconsistent mechanical ventilation, allowing radon to accumulate during the school day.

    EPA’s School Radon Testing Program

    EPA does not federally mandate radon testing in schools — there is no federal law requiring schools to test. However, EPA has published detailed guidance through its “Radon in Schools” program, recommending testing of all ground-level and below-grade spaces in school buildings. EPA provides free technical assistance to states and school districts through this program.

    EPA’s recommended action level for schools is the same as for residences: 4.0 pCi/L. EPA recommends that schools test every 5 years and after any major renovation that affects the foundation, HVAC, or building envelope.

    State Requirements for School Radon Testing

    Several states have enacted mandatory radon testing requirements for schools:

    • Illinois: Requires radon testing in all public schools; has established a state school radon testing program
    • New Jersey: Requires periodic radon testing in public schools
    • Pennsylvania: Has enacted school radon testing requirements
    • Iowa: State radon program provides resources for school testing; requirements have evolved
    • Other states: Requirements vary and change — check your state’s radon program or department of education for current mandates

    In states without mandatory testing, individual school districts may have adopted their own radon testing policies. Many districts in high-radon zones (EPA Zone 1) test voluntarily regardless of state mandate.

    AARST-ANSI SGM-SF Standard for Schools

    AARST-ANSI SGM-SF (Standard for Radon Mitigation in Schools, Large Buildings, and Multifamily Structures) governs both testing and mitigation in school buildings. Key differences from residential standards:

    • School buildings must be tested by a certified measurement professional (not DIY testing)
    • Short-term tests (48–96 hours) must be conducted during school occupancy and under normal HVAC operating conditions — not during summer break or weekends when HVAC schedules may differ
    • Testing must cover each “test area” (room or zone with a separate HVAC zone or floor level)
    • Results above 4.0 pCi/L trigger mitigation planning requirements
    • Post-mitigation testing must be conducted by an independent certified professional, not the installing contractor

    What Parents Can Do

    • Ask whether your school has been tested: Request the most recent radon test results from the school principal or district facilities manager. In states with public disclosure requirements, results may be available through the state radon program or department of education.
    • Ask when the school was last tested: EPA recommends testing every 5 years. If your school has not tested within that window, request that testing be scheduled.
    • Advocate for testing through the school board: If the district has not tested and is not responsive to individual requests, bringing the matter to the school board is the next step. Present EPA’s school radon guidance documents as the basis for the request.
    • Contact your state radon program: State programs often provide testing resources, technical assistance, or can apply pressure on districts that are not complying with state requirements.

    Radon in Daycares and Childcare Facilities

    Daycares and childcare facilities face the same radon risks as schools, with an additional concern: infants and toddlers spend much of their day on the floor — closer to radon entry surfaces — and breathe at higher respiratory rates than adults, increasing intake of radon decay products per unit of time.

    State licensing requirements for childcare facilities may include radon testing as a condition of operation in high-radon states. Even where not required, reputable childcare facilities in radon-prone areas should test and disclose results to parents.

    Frequently Asked Questions

    Are schools required to test for radon?

    There is no federal mandate for radon testing in schools. Several states (including Illinois, New Jersey, and Pennsylvania) have enacted mandatory school testing requirements. In other states, testing is voluntary — though EPA strongly recommends it for all ground-level and below-grade school spaces. Check your state’s radon program or department of education for current requirements.

    Can parents request radon test results from their child’s school?

    Yes. In most states, school radon test results are public records and must be disclosed upon request. Start by requesting results from the school principal or district facilities manager. If results are unavailable or the school has not tested, escalate to the school board and contact your state radon program for assistance.

    What happens if a classroom tests above 4.0 pCi/L?

    Under EPA guidance and AARST SGM-SF, a result above 4.0 pCi/L in a school space requires mitigation planning and action. The affected space should not be used for extended occupancy until mitigation is complete and post-mitigation testing confirms levels below 4.0 pCi/L. Schools may close affected classrooms, relocate occupants to above-grade spaces, or implement interim ventilation measures while permanent mitigation is installed.