ISO 20044:2022

Overview

ISO 20044:2022 - Measurement of radioactivity in the environment: Air - aerosol particles - Test method using sampling by filter media provides standardized guidance for sampling aerosol-bound radionuclides from ambient air using filter media. The standard defines procedures for both deferred (filter-based) measurements and real-time monitoring with continuous air monitors (CAM). Results are reported as activity concentration (Bq·m‑3) and the document is intended for use within accredited laboratory quality systems (e.g., ISO/IEC 17025).

Key technical topics and requirements

• Sampling principles: Guidance on representative site selection, documentation of site characteristics (coordinates, vegetation, obstacles) and adherence to meteorological criteria (referencing WMO recommendations).
• Sampling equipment and filters: Criteria for choice, characterization and handling of filter media designed to trap aerosol particles; examples and filter characteristics included in informative annexes.
• Air volume and flow-rate: Requirements for accurate measurement of sampled air volume and flow-rate to enable correct conversion of deposited activity to activity concentration.
• Measurement workflow: Procedures from filter collection to reporting of deferred measurement results; includes models for evaluation, expression of activity, and calculation examples.
• Uncertainty and detection: Treatment of relative standard uncertainty, decision thresholds, and detection limits for quantitative reporting.
• Real-time monitoring (CAM): Description, operating use and empirical minimum detectable activity concentration concepts for continuous air monitors.
• Quality assurance / quality control: Sample identification, handling, storage, equipment maintenance, documentation and record-keeping to support traceability and accreditation.
• Informative annexes: Radionuclide examples, aerosol behaviour (Annex B), sampling head examples, calculation worksheets and CAM illustrations.

Note: ISO 20044:2022 does not specify laboratory measurement techniques (gamma spectroscopy, alpha/beta counting, liquid scintillation, alpha spectrometry) nor address sampling from nuclear facility effluent air (see ISO 2889:2021) or variability due to aerosol size distributions.

Practical applications and users

ISO 20044:2022 is applicable to:

• Environmental and radiological monitoring laboratories
• Nuclear site operators and regulatory authorities
• Emergency preparedness and response teams
• Research institutions conducting atmospheric radioactivity studies
• Accreditation bodies and laboratories implementing ISO/IEC 17025 quality systems

Typical uses:

• Routine environmental air monitoring and baseline surveys
• Trend detection and dose-assessment after releases
• Support for emergency decision-making with CAM data
• Interlaboratory comparisons and proficiency testing

Related standards and guidance

• ISO/IEC 17025 (laboratory competence and QA)
• ISO 2889:2021 (sampling of effluent air from nuclear facilities)
• IAEA safety standards and WMO guidelines for meteorological site characterization

Keywords: ISO 20044:2022, aerosol sampling, filter media, activity concentration, Bq m-3, continuous air monitor, environmental radioactivity measurement, ISO/IEC 17025, CAM.