Overview
EN ISO 16641:2016 (ISO 16641:2014) - Measurement of radioactivity in the environment - Air - Radon‑220 - specifies integrated measurement methods using passive solid‑state nuclear track detectors (SSNTDs) to determine the average activity concentration of radon‑220 (thoron) in air. Published by CEN as the European adoption of ISO 16641:2014, the standard focuses on easy‑to‑use, low‑cost passive sampling methods and the operational conditions for such devices. Sampling periods covered range from a few months up to one year. The method is also applicable for radon‑222 measurements when required.
Key Topics
- Measurement principle: Integrated passive sampling with SSNTDs to record nuclear tracks produced by decay products of radon‑220.
- Equipment: Requirements and characteristics of passive detectors and sampling housings suited for thoron’s short half‑life and spatial gradients.
- Sampling strategy: Guidance on sampling objectives, locations and uninterrupted sampling durations (months to a year) to obtain representative average activity concentrations.
- Detection and readout: Procedures for detector etching, track counting and interpretation specific to SSNTDs for radon‑220.
- Calibration and influencing variables: Calibration approaches, environmental factors that affect results (e.g., proximity to walls, ventilation) and how to control or account for them.
- Quality metrics: Expression of results, standard uncertainty, decision threshold, detection limit and confidence limits to support reliable reporting.
- Documentation: Required contents of the test report and informative material on radon‑220 decay products and behavior in air.
Applications and Practical Value
- Environmental and indoor air monitoring for thoron (radon‑220) to support accurate assessment of natural radiation exposure.
- Building material and construction characterization where thoron gradients from walls or floors are relevant.
- Supporting epidemiological studies and radon mapping by distinguishing radon‑220 contribution from radon‑222 in passive detector readings.
- Cost‑effective large‑scale surveys using low‑cost passive detectors over extended periods.
- Useful for regulatory compliance, public‑health agencies, environmental consultants, and research institutions needing standardized, reproducible thoron measurements.
Who Should Use It
- National and accredited testing laboratories (ISO/IEC 17025 context)
- Environmental protection agencies and public‑health organizations
- Radon measurement service providers and building inspectors
- Academics and researchers studying indoor air quality and natural radiation exposure
Related Standards
Keywords: EN ISO 16641:2016, ISO 16641:2014, radon‑220, thoron, passive solid‑state nuclear track detectors, SSNTD, integrated measurement, passive sampling, average activity concentration, environmental radioactivity measurement.