ANSI/AARST MS-PC-2022: Radon Gas In Air

Two construction workers are making a hole in the basement floor to install a radon mitigation system adhering to ANSI/AARST MS-PC-2022.

Radon—an odorless and invisible radioactive gas naturally released from rocks, soil, and water—is a part of your life regardless of where you live. It can get trapped inside homes and buildings, and the gas may build up in the air. Over time, inhaling high levels of radon can cause lung cancer, so measuring radon levels in indoor environments is critical for ensuing public safety. ANSI/AARST MS-PC-2022: Performance Specifications For Instrumentation Systems Designed To Measure Radon Gas In Air identifies minimum performance criteria for devices or systems used for measurements of radon in indoor environments for the purpose of determining whether or not the home or building should be mitigated to reduce the radon concentration below an applicable guideline concentration.

Radon in Homes and Buildings

Every building contains radon but the levels are usually low. The question arises: how does radon enter an indoor environment? The answer is radon comes from the natural decay of uranium and radium found in nearly all rocks and soils. It moves up from the ground and into buildings through the openings that exist in floors or walls. Where groundwater is the primary source for drinking water, radon can enter with the home’s water. Since radon comes from rocks and soils, it usually collects in rooms that are in contact with the ground, like basements. Hence, radon levels are often highest in the lowest part of a home or building, so testing in the basement or first floor is a useful place to start.


ANSI/AARST MS-PC-2022 specifies minimum performance requirements for radon measuring devices, as well as testing criteria for demonstrating and documenting compliance. Further, it details minimum performance criteria and testing procedures for instruments and/or systems designed to quantify the concentration of 222Rn gas in air. These are consistent but general performance criteria applicable to the wide variety of radon measurement devices used for indoor measurements, primarily in residential environments or buildings not associated with the possession or handling of radioactive materials. The standard addresses performance criteria for radiological and environmental parameters.

ANSI/AARST MS-PC-2022 does not address the calibration or other quality assurance requirements for the use of the instruments and/or systems, or the measurement of other isotopes of radon such as 220Rn and 219Rn or progeny of any radon isotope. This standard does not address interference from isotopes of radon other than 222Rn, grab sampling methods, mechanical and electrical issues related to the devices, or performance criteria for laboratory equipment that might be used to analyze devices, such as a gamma-ray spectroscopy system for analyzing a charcoal canister. Sampling periods of less than 1 hour in duration are explicitly excluded from consideration in this standard. Although the performance criteria could be adopted for use in a certification program, such a program is beyond the scope of this standard.

Ways to Reduce Radon

Aiming for the lowest radon level you in an indoor environment will reduce the risk of harmful health effects, including lung cancer. Here are some radon reduction solutions:

  • Replacing or adding ventilation bricks in outside walls
  • Installing a small pump in the loft that gently blows in air
  • Increasing air flow in the house by opening windows and using fans and vents to circulate air (natural ventilation in any type of house should not be considered radon mitigation since it is only a temporary strategy to reduce radon)
  • Seal cracks in floors and walls with plaster, caulk, or other mate­rials designed for this purpose.

Most remedies work for years and only need an occasional check; although, you should always test radon levels again after you have implemented any of these changes. Further, it is important to contact a qualified professional to install a radon reduction (i.e., radon mitigation) system if your home radon level is at or above 4 pCi/L of air. It is also recommended by the EPA to take action to reduce radon if your home radon level is from 2 pCi/L through 4 pCi/L.


ANSI/AARST MS-PC-2022 provides guidance to manufacturersand/or laboratories regarding minimum performance criteria for their instruments or measurement systems with the associated tests that they should perform, or have performed by a third party, to demonstrate compliance with the standard. Such tests are conducted in a Standard Test Atmosphere for Radon (STAR):a standard test atmosphere for radon (often called a “radon chamber”), sufficient in size and configuration, radon concentration range, and radon concentration control. ANSI/AARST MS-PC-2022 maintains that tests conducted under conditions other than the controlled conditions of a STAR are insufficient to determine whether the requirements of this standard have been met.

ANSI/AARST MS-PC-2022: Performance Specifications For Instrumentation Systems Designed To Measure Radon Gas In Air is available on the ANSI Webstore.

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