ISO 11665-11:2016

Overview

ISO 11665-11:2016 - Measurement of radioactivity in the environment - Air: radon-222 - Part 11 specifies in‑situ test methods for measuring radon-222 in soil gas with sampling at depths between the surface and 2 m. It defines general requirements for active and passive sampling, grab (spot) and continuous sampling approaches, and how results should be detected, calibrated and reported. The standard applies to soil gas samples with radon activity concentrations greater than 100 Bq/m3 and is complementary to ISO 11665‑7 for radon soil‑potential characterization.

Key topics and requirements

• Sampling depth and volume: Methods cover in‑situ soil gas sampling at depths up to 2 m and provide guidance on minimal depths to avoid atmospheric dilution (see Annex A for soil‑gas volume considerations).
• Sampling techniques: Distinguishes active sampling (forced extraction, typically used for spot/ grab methods) from passive sampling (diffusive/continuous collection, commonly used with continuous measurement systems).
• Measurement modes:
  • Spot (grab) measurements - aligned with ISO 11665‑6; sampling is active.
  • Continuous measurements - aligned with ISO 11665‑5; typically use passive sampling.
• Equipment and probes: Sets out equipment requirements and gives examples of soil‑gas sampling probes (Annex D).
• Detection, calibration and uncertainty: Addresses detection methods, calibration procedures, influence quantities, and how to express radon activity concentration, standard uncertainty, decision thresholds and detection limits (reference to ISO 11929).
• Reporting: Specifies the content of a test report to ensure comparability in time and space (sampling conditions, depths, methods, calibration, results and uncertainties).

Applications and users

ISO 11665-11 is designed for professionals engaged in radon risk management and environmental radiation monitoring, including:

• Radiological protection specialists and environmental scientists
• Building surveyors and construction planners (characterizing building sites)
• Geologists and hydrogeologists (studying radon transport mechanisms)
• Public health authorities and regulators (defining radon‑prone areas, mitigation verification)
• Contractors performing radon mitigation and verification
• Researchers mapping radon potential and performing phenomenological observations

Practical applications include radon potential mapping, characterizing soil for mitigation design, verifying mitigation effectiveness, and surveying soils contaminated with radium‑226.

Related standards

• ISO 11665‑1 (general methods and origins of radon)
• ISO 11665‑5 (continuous measurement)
• ISO 11665‑6 (spot measurement)
• ISO 11665‑7 (radon soil potential)
• ISO 10381‑7 (soil gas sampling guidance)
• ISO 11929 (detection and decision limit calculations)

Keywords: ISO 11665-11, radon-222, soil gas sampling, passive sampling, active sampling, in-situ measurement, radon activity concentration, radon potential, radon mitigation.