Radon Measurements in Multifamily Buildings

A multifamily building with verdant greenery assured to safety with ANSI/AARST MAMF-2017 radon measurements.

ANSI/AARST MAMF-2017 – Protocol for Conducting Measurements of Radon and Radon Decay Products in Multifamily Buildings offers guidance for conducting measurements to identify locations that have elevated radon concentrations.

Radon Gas Hazards

Radon is a chemically-unreactive inert gas, but it is also highly radioactive. Two radon isotopes, Rn-222 and Rn-220, are found in significant concentrations in the human environment, forming in the decay chain of other radioactive elements. The alarming truth, when it comes to radon, is that the radioactive gas derives simply from soil gas, following the breakdown of uranium in the soil. This means that many people maintain airborne contact with the carcinogenic element.

In fact, radon causes 21,000 lung cancer deaths in the United States every year, being second only to smoking as the main cause of the terminal illness. Continuous exposure at a level high enough to contribute to these fatalities occurs after radon and its decay products remain inside a building, in which it enters through cracks in the slabs and walls, the expansion joints between floor and walls, porous concrete block walls, open sump pits, crawlspaces, and openings around utility penetrations.

According to the EPA, the concentration of radon in the air within a building should be reduced below 4 pCi/L (picocuries per liter), an amount that nearly 1 out of every 15 homes in the United States are estimated to exceed. Since radon is colorless, odorless, and tasteless, the only way to detect the incredibly-harmful radioactive chemical is through testing.

Radon testing varies based on the specific type of residence in which individuals live, and the appropriate testing procedures should be pursued for single dwellings, multi-use dwellings, and multifamily buildings, as the homes bear differences in structure and purpose. For multifamily buildings, ANSI/AARST MAMF-2017 offers radon measurement guidance.


The ANSI/AARST MAMF-2017 standard can be used to determine, through repeatable and reliable tests, if mitigation is necessary in order to protect current or future occupants. It addresses the following radon measurements:

“in buildings having more than one attached dwelling or other occupied unit under the same ownership or designated maintenance or management authority”

“in buildings or structures, or a portion thereof that are used, for example, as apartment houses, dormitories, military congregate residences, fraternities and sororities, nontransient boarding houses, hotels, convents, monasteries, motels, and live/work units”

“in multifamily structures that can include those with shared ownership or maintenance such as co-op units, townhouses, condominiums or vacation timeshare properties”

“in multifamily structures, whether conducted for nonreal estate purposes or when associated with a real estate transaction”

ANSI/AARST MAMF-2017 covers preparations for the measurements, requirements for protocol, quality control, and the testing procedures themselves for assessing radon concentrations.

It is also important to note that, while the EPA’s radon action level is 4 pCi/L, any exposure to the element creates some danger. Some buildings containing radon concentrations under this value may even benefit by having those concentrations lowered through mitigation.

2021 Update to ANSI/AARST MAMF-2017

While the latest edition of this standard was released in 2017, some revisions made in 2021 are reflected in the current edition of the document, ANSI/AARST MAMF-2017 rev.1-21.

Specifically, the new publication improves and harmonizes provisions with ANSI/AARST MALB. It features an attached Companion Guidance document, which can be found at the end of ANSI/AARST MAMF-2017 rev.1-21.

The Companion Guidance features five informative sections:

  1. Introduction to Radon
  2. Guidance for Building Managers
  3. Descriptions of Test Devices
  4. Chain of Custody
  5. Calculating Average Building Operating Conditions

ANSI/AARST MAMF-2017 rev.1-21 – Protocol for Conducting Measurements of Radon and Radon Decay Products in Multifamily Buildings is available on the ANSI Webstore.


ANSI/AARST MAMF-2017 was written and published by the American Association of Radon Scientists and Technologists (AARST), an ANSI-accredited standards-developing organization. This non-profit, member-based organization is, as stated in AARST’s mission:

“dedicated to the highest standard of excellence and ethical performance of radon measurement, radon mitigation and transfer of radon information for the benefit of members, consumers and the public at large.”

Other AARST standards for radon consideration in building design are focused on testing for radon in single family dwellings, schools, and large buildings, as well as mitigating the presence of radon in new buildings and reducing radon activity in existing structures.

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One thought on “Radon Measurements in Multifamily Buildings
  1. The blog is well-written and serves as a useful resource for anyone interested in understanding radon measurements in multifamily buildings. The importance of using certified professionals to conduct radon measurements and provides valuable resources for finding certified professionals in the field.

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