SIST ISO 13164-3:2013 defines a standardized emanometry test method for determining radon-222 activity concentration in water. The method transfers radon from the aqueous phase to the air phase by degassing, then detects radon in the gas phase. It is designed for rapid measurements (under 1 hour) and is applicable both in the laboratory and on field sites. Typical measurable activity concentrations for a 100 ml test sample range from 0.1 Bq·L⁻¹ to several hundred thousand Bq·L⁻¹. The standard is intended primarily for drinking-water monitoring but requires laboratories to verify applicability to untested water matrices.
Key technical topics and requirements
- Principle: Degassing of water to transfer radon-222 to an air volume followed by gas-phase detection (emanometry).
- Detection options: Silver-activated zinc sulfide (ZnS(Ag)) scintillation cells, air ionization chambers, and semiconductor alpha detectors are described as viable detection technologies.
- Sample considerations: Guidance on sampling, sample volume (examples use 100 ml), container characteristics, transport and storage to preserve radon content.
- Performance range and sensitivity: Measurement capability from low levels (0.1 Bq·L⁻¹) up to very high activity concentrations for standard sample sizes; annexes provide counting-condition examples to meet drinking-water sensitivity needs.
- Quality management: Requirements and recommendations for QA/QC programs, instrument verification, method verification, analyst capability demonstration, calibration, and uncertainty evaluation.
- Result reporting: Procedures for expressing activity concentration, calculating standard uncertainty, and determining decision thresholds/detection limits and confidence limits.
- Safety and competence: Emphasizes laboratory competence, safety practices, and compliance with relevant regulatory and accreditation requirements (e.g., ISO/IEC 17025).
Practical applications
- Drinking-water monitoring: Rapid screening and confirmation of radon-222 in public and private water supplies to inform treatment and public-health actions.
- Field surveys and well testing: On-site emanometry for groundwater wells, springs and boreholes where radon levels may be elevated.
- Environmental and hydrogeological studies: Assessing radon as a tracer for groundwater flow, rock-water interactions, and seasonal variations.
- Regulatory compliance and risk assessment: Supports laboratories and authorities in meeting guideline levels (e.g., WHO guidance) and in deciding mitigation actions for sources exceeding recommended radon concentrations.
Who should use this standard
- Water and environmental testing laboratories
- Public health agencies and regulatory bodies
- Field technicians performing groundwater and well surveys
- Drinking-water suppliers and water resource managers
- Accreditation bodies evaluating radon measurement competence
Related standards and references
Keywords: ISO 13164-3, radon-222, emanometry, water quality, radon test method, degassing, drinking water monitoring, radon measurement, activity concentration.