ISO 11665 Measurement of Ambient Radioactivity - Air: Radon-222

The “ISO 11665 Measurement of ambient radioactivity - Air: Radon-222” standard, developed by the International Organization for Standardization (ISO), consists of the following sub-sections published under the same title:

• The standard “ISO 11665-1 Part 1: Origins of radon and its short-lived decay products and related measurement methods” provides guidance on measuring the radon-222 activity concentration in the air and the potential alpha-energy concentration of its short-lived decay products.

Measurement methods are divided into three categories:

• Point measurement methods
• Continuous measurement methods
• Integrated measurement methods.

This standard includes various commonly used methods for measuring radon-222 and its short-lived decay products in the air. It also provides guidance on determining the inherent uncertainty associated with the measurement methods described in its various sections.

• The standard “ISO 11665-2 Part 2: Integrated measurement method for determining the average potential alpha energy concentration of short-lived decay products” describes integrated measurement methods for short-lived radon-222 decay products. This standard provides indicators and operating conditions for measuring instruments related to the measurement of the average potential alpha energy concentration of short-lived radon-222 decay products in the air.

This standard covers samples taken over periods ranging from several weeks to one year. This standard does not apply to systems with a maximum sampling period of less than one week.

The described measurement method is applicable to air samples with potential alpha energy concentrations of short-lived radon-222 decay products greater than 10 nJ/m3 and less than 1000 nJ/m3.

For informational purposes only, this standard also addresses the case of radon-220 decay products, given the similarity in the behavior of radon isotopes 222 and 220.

In principle, the integrated measurement of the potential alpha energy concentration of short-lived radon decay products is based on the following elements:

• Continuous sampling of short-lived radon decay products in an air volume representing the atmosphere under study, using a high-efficiency filtration membrane.
• Counting and distinguishing alpha particles emitted by the collected short-lived radon-222 decay products in four energy ranges using a solid-state nuclear track detector.
• Calculation of the potential alpha energy concentration of short-lived radon-222 decay products.
• The standard “ISO 11665-3 Part 3: Point measurement method for potential alpha energy concentration of short-lived decay products” describes point measurement methods for determining the activity concentration of short-lived radon-222 decay products in the air and calculating their potential alpha energy concentration.

This standard contains information on how to perform point measurements of potential alpha energy concentration after sampling for a few minutes at a specific location, and the operating conditions of the measuring instruments.

The described measurement method is applicable for the rapid assessment of potential alpha energy concentration. However, the results obtained cannot be generalized to the estimated annual potential alpha energy concentration of short-lived radon-222 decay products. Therefore, this type of measurement is not applicable for assessing annual exposure or determining whether citizens' exposure to radon or radon decay products should be reduced.

This measurement method is applicable to air samples with a potential alpha energy concentration greater than 5 nJ/m3. This standard does not address the potential contribution of radon-220 decay products.

• The standard “ISO 11665-4 Part 4: Integrated measurement method for determining mean activity concentration using passive sampling and delayed analysis” describes integrated radon-222 measurement techniques using passive sampling. This standard includes indicators and sensor usage conditions for determining the mean activity concentration of airborne radon-222 from measurements based on passive sampling, which is easy to use and low-cost.

This standard covers samples taken continuously over periods ranging from a few days to one year. This measurement method is applicable to air samples with radon activity concentrations higher than 5 Bq/m3.

• The standard “ISO 11665-5 Part 5: Continuous measurement methods of activity concentration” describes continuous measurement methods for radon-222. It provides indicators for the continuous measurement of temporal variations in radon activity concentration in open or closed environments.

This standard is designed to assess temporal variations in radon activity concentration in the environment, public buildings, homes, and workplaces, depending on influencing factors such as ventilation or meteorological conditions. The described measurement method is applicable to air samples with radon activity concentrations higher than 5 Bq/m³.

• The standard “ISO 11665-6 Part 6: In-situ measurement methods for activity concentration” describes point measurement methods for radon-222. This standard provides guidelines on how to perform point measurements of radon activity concentration in indoor and outdoor environments at a specific location over a few minutes.

This measurement method is designed for the rapid assessment of radon activity concentration in the air. The result cannot be converted into an annual estimate of radon activity concentration. Therefore, this type of measurement is not suitable for assessing annual exposure or determining whether citizens' exposure to radon or radon decay products should be reduced.

The described measurement method is applicable to air samples with radon activity concentrations greater than 50 Bq·m3. For example, using a suitable device, radon activity concentration can be measured as a point in soil and at the interface of a material with the atmosphere.

• The standard “ISO 11665-7 Part 7: Deposition method for estimating surface exhalation rate” describes guidelines for estimating the surface emission rate of radon-222 over a short period (several hours) at the interface between the medium (soil, rock, building materials, walls, etc.) and the atmosphere at a given location. This estimation is based on measuring the radon activity concentration emitted from the surface under study and deposited in a container of a known volume over a known period of time.

This method is purely estimatory, as quantifying the effect of many parameters in environmental conditions is difficult. However, this standard is applicable, especially in the case of research, resource exploration, or a comparative study of emission rates in the same location. This standard does not cover calibration requirements for velocity estimation devices.

• The standard “ISO 11665-8 Part 8: Methods for initial and additional inspections in buildings” describes the requirements for determining radon activity concentration in all types of buildings. Buildings can include detached houses, public buildings, industrial buildings, underground buildings, and the like.

This standard includes measurement methods used to assess the average annual radon activity concentration in buildings during the initial inspection phase. It also addresses the necessary investigations (additional investigations) to identify the source, entry routes, and transfer routes of radon in the building.

Finally, this standard includes applicable conditions for testing immediately following the implementation of mitigation techniques, monitoring their effectiveness, and testing the sustainability of the building's behavior in the face of radon.

This standard does not address technical building diagnostics or the prescription of mitigation works.

• The standard “ISO 11665-9 Part 9: Test methods for the release rate of building materials” describes a method for determining the free radon release rate of a batch of mineral-based building materials. This standard refers to the determination of 222Rn release using only two test methods: liquid scintillation counting and gamma ray spectrometry (Annex A and Annex B). When the determination methods described in this standard are applied, the release of thoron (220Rn) does not affect the test result.
• The standard “ISO 11665-10 Part 10: Determination of diffusion coefficient in waterproof materials using activity concentration measurement” describes the assumptions and boundary conditions that methods used to determine the radon diffusion coefficient in waterproofing materials such as bitumen or polymeric membranes, coatings, or paints must meet. This standard does not apply to porous materials where radon diffusion depends on porosity and moisture content.
• The standard “ISO 11665-11 Part 11: Testing method for soil gas by depth sampling” describes methods for testing radon-222 in soil gas using passive and active in-situ sampling methods at depths between the surface and 2 m. This standard provides general requirements for passive or active, and instantaneous or continuous sampling techniques for in-situ measurement of radon-222 activity concentrations in soil gas.

Radon-222 activity concentration in soil can be measured using point or continuous measurement methods. In point measurement methods (ISO 11665-6), soil gas sampling is only active. Continuous methods (ISO 11665-5), on the other hand, are typically associated with passive soil gas sampling.

The measurement methods are applicable to all soil types and are determined according to the ultimate use of the measurement results (such as phenomenological observation, identification or verification of mitigation techniques) taking into account the expected level of radon-222 activity concentration. These measurement methods are applicable to soil gas samples with radon activity concentrations higher than 100 Bq/m3. This standard is complementary to the ISO 11665-7 standard for the characterization of radon soil potential.

• The standard “ISO 11665-12 Part 12: Determination of diffusion coefficient in waterproof materials: method for measuring membrane unilateral activity concentration” describes the method designed for evaluating the radon diffusion coefficient in waterproofing materials such as bitumen or polymeric membranes, coatings, or paints, as well as the assumptions and boundary conditions to be met during the test.

The test method described in this standard allows for the estimation of the radon diffusion coefficient in the range of 10⁻⁵ m²/s to 10⁻¹² m²/s with an uncertainty of between 10% and 40%.

• The standard “ISO 11665-13 Part 13: Determination of the diffusion coefficient in waterproofing materials: membrane double-sided activity concentration test method” describes different methods designed for evaluating the radon diffusion coefficient in waterproofing materials such as bitumen or polymeric membranes, coatings, or paints, as well as the assumptions and boundary conditions that must be met during testing. This standard does not apply to porous materials where radon diffusion depends on porosity and moisture content. However, this standard was later withdrawn.
• The standard “ISO 11665-14 Part 14: Quality assurance / quality control for calibration facilities” is still under development.
• The standard “ISO 11665-15 Part 15: Quality assurance/quality control for measurement instrument analysis providers” is still under development.
• The standard “ISO 11665-16 Part 16: Quality assurance / quality control for radon measuring device manufacturers” is still under development.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "ISO 11665 Measurement of ambient radioactivity - Air: Radon-222" standard.