This European Standard specifies a semi-continuous measurement method for the determination of the concentration of benzene present in ambient air based on automated sampling and analysis by gas chromatography. This European Standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate automated gas chromatograph (GC) by means of type approval tests. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site so as to meet the data quality requirements as specified in Annex I of Directive 2008/50/EC and requirements during sampling, calibration and quality assurance for use. The method is applicable to the determination of the mass concentration of benzene present in ambient air in the range up to 50 µg/m3 benzene. This concentration range represents the certification range for the type approval test. Other ranges may be used depending on the levels present in ambient air. NOTE 1 When the standard is used for other purposes than for measurements required by Directive 2008/50/EC, the ranges and uncertainty requirements may not apply. The method covers the determination of ambient air concentrations of benzene in zones classified as rural areas, urban-background areas and traffic-orientated locations and locations influenced by industrial sources. The results are expressed in µg/m3 (at 20 °C and 101,3 kPa). NOTE 250 µg/m3 of benzene corresponds to 15,4 nmol/mol of benzene. This European Standard contains information for different groups of users. Clauses 5 to 7 and Annexes C and D contain general information about the principles of benzene measurement by automated gas chromatography and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of benzene analysers. These sections contain information about:- type-approval test conditions, test procedures and test requirements; - analyser performance requirements; - evaluation of the type-approval test results; - evaluation of the uncertainty of the measurement results of the benzene analyser based on the type-approval test results. Clauses 9 to 11 and Annex F are directed towards monitoring networks performing the practical measurements of benzene in ambient air. These sections contain information about; - initial installation of the analyser in the monitoring network and acceptance testing; - ongoing quality assurance/quality control; - calculation and reporting of measurement results; - evaluation of the uncertainty of measurement results under practical monitoring conditions.