2. Radon Measurement Techniques

The specific activities of ²²²Rn in environmental samples (atmospheric and soil air, surface and groundwater, etc) can vary over 5 orders of magnitude and hence the methods and instruments to measure radon activities vary widely. The measurement techniques are classified based three characteristics—i) whether measurement involves ²²²Rn or its progeny; ii) time resolution; and iii) detection of the type of emission, whether alpha or beta particle or gamma radiation resulting from radioactive decay. The three broad classes of time resolution, based on sampling and analysis, include i) grab-sample technique; ii) continuous technique and iii) integrating technique. The preferred technique is based on the purpose of the study and the research question addressed. Precise determination of radon activity in surface waters of the ocean and lakes for tracer studies requires careful sampling. A review of most commonly-used techniques for measuring radon in air and water samples along with quality control, precision and accuracy in radon measurements are presented in this chapter.