• 07/31/2023 1:47 PM | Lorin Stieff (Administrator)

    Understanding Montgomery County Bill 26-22

    Bill 26-22 became effective on July 1, 2023. This Bill mandates radon testing (and mitigation, if necessary) in single- and multi-family rental dwellings. Montgomery County is no stranger to radon legislation, and previously enacted Bill 31-15 several years ago, which requires radon testing for single-family home sales.

    Bill 26-22 (July 2023)

    • Requires landlords (of both single- and multi-family dwellings) to conduct radon testing in all ground-contact units before lease.
    • Requires landlord to disclose test results to tenants.
    • Requires landlord to mitigate the dwelling if the radon concentration meets or exceeds the EPA action level (4.0 pCi/L).
    • Allows tenant to terminate a lease agreement if the landlord does not adhere to mitigation requirements.

    Bill 31-15 (October 2016)

    • Requires radon testing for single-family home sales.
    • Test must have been conducted within a year of the home’s sale.
    • Test results must be provided to both the seller and the buyer.
    When did Bill 26-22 become effective?

    After a six-month extension, Bill 26-22 became effective on July 1, 2023. The Montgomery Housing Partnership, GCAAR (Greater Capital Area Association of REALTORS®), and AOBA (Apartment & Office Building Association) had originally requested additional delays, but the Montgomery County Council decided that July 1 would provide sufficient time to prepare.

    Who will be affected by these changes?

    Those most impacted by Bill 26-22 are landlords in Montgomery County, and tenants who are living in properties with elevated radon concentrations. Bill 26-22 provides protection to the public by requiring landlords to mitigate properties with radon levels at or above 4.0 pCi/L.

    What are the rules on retesting?

    Test results must be within three years before the date of the lease (this is reduced to two years in Rockville, by Ordinance 06-23). As the majority of leases are shorter than three years, this ensures periodic retesting.

    What is the jurisdiction of this legislation?

    In principle, Bill 26-22 is effective throughout all of Montgomery County. However, each incorporated municipality in the county must “opt-in” to Chapter 29 (Landlord-Tenant Relations) of the Montgomery County Code or pass an Ordinance adopting it, in order to be affected by this regulation. To the best of our knowledge, landlords in the incorporated municipalities of Friendship Heights, Garrett Park, Kensington, Poolesville, and Rockville fall under the jurisdiction of this regulation.

    How does Montgomery County Code interact with ordinances passed by incorporated municipalities?

    This is a neat question that deserves a bit of a preface. In the United States, federal law (including the U.S. Constitution, federal statutes, and regulations) generally supersedes state law – it is “the supreme law of the land.” And state law (including state constitutions, state statutes, etc.) supersedes county law. It’s therefore interesting to note, per Section 1-203 of the Montgomery County Code, county law does not automatically supersede municipality law. Incorporated municipalities are exempt from county legislation unless they choose to accept it. The intent of this is to foster the practice of “municipal home rule.”

    TL;DR Unless they opt-in, incorporated municipalities (such as Rockville, Gaithersburg, etc.) are exempt from Montgomery County legislation.

    Do the radon tests need to be conducted by a certified professional?

    With the sole exception of post-mitigation radon testing, it does not appear that Bill 26-22 specifically requires that testing or mitigation be conducted by certified professionals.

    Does the landlord need to disclose results?

    Yep! If results meet or exceed the action level, the landlord must disclose results to each tenant in the dwelling.

  • 01/14/2023 5:31 PM | Anonymous

    National Radon Awareness Month is an important annual campaign that aims to raise awareness about the dangers of radon and the importance of testing for it in homes and buildings. By taking action to test for radon and reduce levels of the gas, we can help protect ourselves and our loved ones from the dangers of radon exposure.


    ***Go to our member page to find certified professionals to help you with your radon needs.***

  • 12/01/2022 8:31 PM | Anonymous

    Early History of Radiology (and Radon)   

    As the 19th century drew to a close, the world ushered in a golden age of innovation that would introduce us to stainless steel, diesel engines, and plastic. It was during this era that the emerging field of radiology was born. Wilhelm Röntgen discovered X-rays in 1895, Henri Becquerel observed uranium emitting its own “rays” in 1896, and Marie Curie coined the term “radiation” shortly thereafter in 1898. This new concept of radiation would both challenge and advance our understanding of physics, the repercussions of which would not be fully realized until nearly fifty years later.

    Radon was discovered in 1899 at McGill University in Canada, with the official credit usually going to Ernest Rutherford, Robert Owens, and Harriet Brooks. Rutherford and his team were actually studying the thorium decay chain, and therefore had discovered an isotope of radon that would eventually become known as thoron (220Rn). Other radiological pioneers around the world, such as Marie Curie and Friedrich Dorn, were also conducting their own experiments with uranium and radium.

    Back in the 1920s, Many Radium Water Producers Advocated Drinking Radium Water as a Necessity of Healthy Living ~ Vintage Everyday
    At first, these scientists focused on the physical properties of radioactive elements. They calculated masses, densities, and melting points with surprising accuracy, especially given their limited instrumentation. They identified new isotopes, argued over names, and began conceiving practical – and profitable – applications. They tended to be reckless and gleeful with their discoveries in these early days, and it didn’t take long to commercialize the burgeoning field of radiology.

    Toothpaste, cosmetics, drinking water, and even chocolate soon had “radium-infused” versions available to buy. Medical patients were exposed to ionizing radiation for hours at a time, and even shoe stores would offer customers complimentary X-ray scans to match the bones in their feet with “just the right footwear.”

    Fact Friday: Radium Schokolade – The British Candy Connoisseur

      (Yep, that's German for “Radium Chocolate.” It was manufactured between 1931 and 1936, and would later be lovingly referred to as “suicide chocolate” by British chemists.)


    In retrospect, it’s easy to condemn our foolhardiness with these novel radioactive elements. But as the world had never before witnessed such rapid transformation, this daredevil enthusiasm can perhaps be understood – and forgiven – in the broader context of the times. Electricity, automobiles, and telephones had sparked a revolution in lifestyles and landscapes; fluorescent lights illuminated cities, hydrogen airships lumbered through the skies, and glow-in-the-dark clocks were nestled next to beds. The Modern Age had arrived, and humankind was intoxicated by its glitter and glamour.

    The warning signs of exposure to ionizing radiation were often observed, but it proved difficult to pinpoint the cause. The initial “dose” didn’t seem to cause any harm, and the mechanisms of cellular damage from radiation were still unknown. Many scientists and inventors – including Nikola Tesla and Thomas Edison – experienced eye irritation and burns from their experiments, but such symptoms would often take weeks to manifest. And although Marie Curie urged caution when handling radioactive materials, many scientists claimed there were no ill effects at all. As a result, many of these radiological pioneers, including Marie Curie, would die from causes later attributed to long-term radiation exposure.

    AD: UNDARK, 1921. American advertisement for Undark Radium (Photos Framed,...) #12223944

    Radium Undark.svg

    Although anecdotal evidence mounted over the years (such as the deaths of the Radium Girls in the 1920s), it would not be until 1945 when the world fully awakened to the cataclysmic and destructive capabilities of ionizing radiation.


    Approximately five years later, in 1950, radon’s presence in indoor air was first documented. Although studies were conducted over the next few decades, very little was accomplished in regards to public awareness or exposure prevention. However, this would change after a fateful event in 1984 brought recognition to the potential dangers of indoor radon concentrations. While working at a newly built nuclear power plant in Pennsylvania, a construction engineer triggered radiation warning alarms. Interestingly enough, these alarms occurred when the engineer was arriving at work – and before there was any radioactive material at the power plant.

    The resulting investigation would reveal the engineer’s house contained indoor concentrations above 2500 picocuries per liter (pCi/L), which catapulted radon to national awareness. Two years after this incident, the Environmental Protection Agency prescribed the recommended “action limit” at 4 pCi/L. This would mark the beginning of the radon testing and mitigation industry in the United States.

    Author Biography:
    Lorin Stieff is the Vice President of Rad Elec, where he assists with software development and technical support. Before writing this blog post, he had no idea that radium chocolate actually existed.





The Maryland Chapter's parent organization, Indoor Environments Association, formerly the American Association of Radon Scientists and Technologists is a 501(c) (6) non-profit organization.

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