This part of IEC 61577 provides basic data and technical information in order to support the design of instruments and their practical application for the measurement. The document covers 222Rn as well as 220Rn and the short-lived decay products of both. It is an accompanying document for the application of the technical standards series IEC 61577, and provides physical and technical fundamentals of the measurements methods. For more information, reference is made to the Bibliography. Cross References:IEC 61577-1IEC 61577-3IEC 61577-2IEC 61577-4IEC TR 62461:2015ISO 11665-6ISO 11665-5ISO 11665-2ISO 13164-1 ISO/IEC Guide 98-3ISO 13164-4ISO/IEC 17025ISO 16641ISO 13164-3ISO 11665-4ISO 11665-3ISO 13164-2ISO 11929:2010All current amendments available at time of purchase are included with the purchase of this document.