ISO 11665-1:2019

Overview

ISO 11665-1:2019 - Measurement of radioactivity in the environment - Air: radon-222 - Part 1 describes the origins of radon and its short-lived decay products and gives guidance on commonly used measurement methods. The standard focuses on measuring radon-222 activity concentration and the potential alpha energy concentration of its short-lived decay products in air, and on determining the inherent uncertainty associated with these methods.

Key points:

• Defines measurement categories: spot, continuous, and integrated methods
• Describes sampling, detection, calibration and quality-control considerations
• Includes informative annexes on radon origins, example measurement results and example test reports

Key technical topics and requirements

• Measurement categories: guidance on choosing between spot measurements (instantaneous), continuous monitoring (time-resolved) and integrated sampling (time-averaged).
• Sampling considerations: objectives, sampling duration, sampled air volume, installation and operational conditions affecting representativeness.
• Detection techniques: common detectors and methods referenced include ZnS(Ag) scintillation, gamma-ray spectrometry, liquid scintillation, air ionization, semiconductor alpha detectors, solid-state nuclear track detectors (SSNTD) and other ionization/discharge-based methods.
• Measurement process: treatment of influence quantities, calibration procedures, and quality control to ensure traceability (references ISO/IEC 17025 and IEC 61577 series).
• Results and reporting: expression of activity concentrations, potential alpha energy concentrations, uncertainty estimation, and contents of a compliant test report (examples in Annex C).
• Health context: emphasizes that radon decay products drive radiological risk and cites WHO guidance for indoor radon reference levels (recommended 100 Bq·m⁻³, not to exceed 300 Bq·m⁻³ where 100 is not practical).

Practical applications and users

ISO 11665-1:2019 is intended for:

• Environmental and radiological testing laboratories
• Public health authorities and regulators setting reference levels and inspection programs
• Building surveyors, architects and radon mitigation specialists performing indoor exposure assessments
• Environmental consultants and researchers conducting radon mapping, epidemiological studies, or soil/structure exhalation assessments

Typical uses:

• Designing radon measurement campaigns (indoor and ambient air)
• Selecting appropriate detectors and sampling strategies
• Ensuring calibration, quality assurance and uncertainty estimation for regulatory or research reporting
• Informing building codes and remediation strategies

Related standards and references

• ISO/IEC 17025 - laboratory competence
• IEC 61577-1/2/3 - radon and radon decay product instrumentation
• Other parts of ISO 11665 series (e.g., Parts 2–9, 11) cover specific methods, exhalation rates, soil measurements and building methodologies.