This European Standard specifies the sampling of PCDDs/PCDFs. It is an integral part of the complete measurement procedure. The use of the other two parts prEN 1948-2:2005 and prEN 1948-3:2005 describing extraction and clean-up and identification and quantification, respectively, is necessary for the determination of the PCDDs/PCDFs.This European Standard has been developed to measure PCDD/PCDF concentrations at about 0,1 ng I TEQ/m3 in stationary source emissions.This European Standard specifies both method validation and a framework of quality control requirements which shall be fulfilled by any PCDD/PCDF sampling.The user has the possibility to choose between three different methods:-"filter/condenser method"-"dilution method"-"cooled probe method"Each sampling method is illustrated by some sampling systems described in detail in Annex B as examples of proven procedures.During comparison measurements of the three sampling methods on municipal waste incinerators at the level of about 0,1 ng I-TEQ/m3 these methods have been deemed comparable within the expected range of uncertainty. Validation trials were performed on the flue gas of municipal waste incinerators at the level of about 0,1 ng I-TEQ/m3 and a dust loading of from 1 mg/m3 to 15 mg/m3. Although this European Standard is primarily developed and validated for gaseous streams emitted by waste incinerators, the practical experience shows that it can be applied for wide concentration ranges and various emission sources.The procedure described in the three parts of prEN 1948:2005 specifies requirements which shall be met in order to measure the 17 congeners necessary to calculate the total I-TEQ (see Table A.1).Besides the determination of PCDDs/PCDFs the described measurement methods are suitable for determination of other low-volatile substances, e.g. of dioxin-like PCBs (details for sampling and analyses see CEN/TS 1948-4), although no validated performance characteristics are avail