Maryland Radon Laws

    Understanding radon testing requirements in Montgomery County, Gaithersburg, and Rockville

    Comprehensive Guide to Local Radon Laws

    Montgomery County leads the nation in radon safety legislation, with additional requirements in Gaithersburg and Rockville. Our team stays current with all local regulations to ensure your compliance.

    Law Comparison Table
    Key similarities and differences between Montgomery County, Gaithersburg, and Rockville radon laws
    RequirementMontgomery CountyGaithersburgRockville
    Effective Date
    October 1, 2016 (Resale)

    July 1, 2023 (Rental)
    January 1, 2025
    January 1, 2023 (Sales)

    September 27, 2023 (Rental)
    Property Type Coverage
    ✅ Single-family homes (resale)
    ✅ Single-family & ground-contact units (rental)
    ❌ Single-family homes
    ✅ Rental units (4+ units only)
    ✅ Single-family homes
    ✅ Ground-contact units
    Test Validity Period
    1 year (resale)
    3 years (rental)
    		2 years2 years
    Required for New Leases
    Required for Lease Renewals
    Mitigation Required
    (Resale)
    (Rental ≥4.0 pCi/L)
    ≥4.0 pCi/L
    ≥4.0 pCi/L
    Tenant Rights
    ✅ Disclosure within 14 days
    ✅ Lease termination rights
    ✅ Disclosure within 14 days
    ✅ Lease termination rights
    ✅ Disclosure within 14 days
    ✅ Lease termination rights
    Montgomery County Resale Law
    Bill 31-15
    October 1, 2016
    First in the nation requiring radon testing for all real estate transactions

    Unique: Only county in the US requiring radon testing before settlement

    • All single-family home sales
    • Test valid for 1 year
    • Mitigation not mandatory
    Learn More
    Montgomery County Rental Law
    Bill 26-22
    July 1, 2023
    Comprehensive rental property radon testing and mitigation requirements

    Tenant Protection: Right to lease termination if mitigation not completed within 90 days

    • Test valid for 3 years
    • Mandatory mitigation ≥4.0 pCi/L
    • Disclosure to all tenants required
    Learn More
    Gaithersburg Radon Law
    November 4, 2024
    January 1, 2025
    Rental property requirements for properties with 4 or more units only

    Limited Scope: Only applies to rental properties with 4+ units, not single-family homes

    • Single-family homes (not covered)
    • Rental properties with 4+ units only
    • Mandatory mitigation ≥4.0 pCi/L
    • 2-year testing requirement
    • Same tenant rights as county
    Learn More
    Rockville Radon Laws
    Ordinance 12-22 & 06-23
    Two Ordinances
    Separate ordinances for home sales and rental properties

    Stricter: 2-year test validity for rentals (vs. county's 3-year)

    • Sales: Jan 1, 2023 effective
    • Rentals: Sep 27, 2023 effective
    • More frequent testing required
    Learn More
    Smart Home Radon: Your Compliance Partner
    NRPP certified professionals ensuring full legal compliance

    Our Expertise

    • NRPP certified professionals
    • EPA approved ANSI-AARST standards compliance
    • GCAAR members with SentriLock access
    • Same-day laboratory analysis

    Testing Only Policy

    We provide testing services only. By not offering mitigation services, we maintain complete objectivity and ensure unbiased results. This ethical approach protects both property owners and tenants from conflicts of interest.

    Need help understanding which law applies to your property or transaction?